document_title: Labor unions in the United States

question_text: who was an important figure in developing the strength of labor unions in the united states

question_tokens: who was an important figure in developing the strength of labor unions in the united states

text: Labor unions in the United States

text: History[edit]

text: Unions began forming in the mid-19th century in response to the social and economic impact of the industrial revolution. National labor unions began to form in the post-Civil War Era. The Knights of Labor emerged as a major force in the late 1880s, but it collapsed because of poor organization, lack of effective leadership, disagreement over goals, and strong opposition from employers and government forces.

text: The American Federation of Labor, founded in 1886 and led by Samuel Gompers until his death in 1924, proved much more durable. It arose as a loose coalition of various local unions. It helped coordinate and support strikes and eventually became a major player in national politics, usually on the side of the Democrats.

text: American labor unions benefited greatly from the New Deal policies of Franklin Delano Roosevelt in the 1930s. The Wagner Act, in particular, legally protected the right of unions to organize. Unions from this point developed increasingly closer ties to the Democratic Party, and are considered a backbone element of the New Deal Coalition.

text: Post-World War II[edit]

text: Pro-business conservatives gained control of Congress in 1946, and in 1947 passed the Taft-Hartley Act, drafted by Senator Robert A. Taft. President Truman vetoed it but the Conservative coalition overrode the veto. The veto override had considerable Democratic support, including 106 out of 177 Democrats in the House, and 20 out of 42 Democrats in the Senate.[14] The law, which is still in effect, banned union contributions to political candidates, restricted the power of unions to call strikes that "threatened national security," and forced the expulsion of Communist union leaders (the Supreme Court found the anticommunist provision to be unconstitutional, and it is no longer in force). The unions campaigned vigorously for years to repeal the law but failed. During the late 1950s, the Landrum Griffin Act of 1959 passed in the wake of Congressional investigations of corruption and undemocratic internal politics in the Teamsters and other unions.[15][16]

text: The percentage of workers belonging to a union (or "density") in the United States peaked in 1954 at almost 35% and the total number of union members peaked in 1979 at an estimated 21.0 million. Membership has declined since, with private sector union membership beginning a steady decline that continues into the 2010s, but the membership of public sector unions grew steadily.

text: After 1960 public sector unions grew rapidly and secured good wages and high pensions for their members. While manufacturing and farming steadily declined, state- and local-government employment quadrupled from 4 million workers in 1950 to 12 million in 1976 and 16.6 million in 2009.[17] Adding in the 3.7 million federal civilian employees, in 2010 8.4 million government workers were represented by unions,[18] including 31% of federal workers, 35% of state workers and 46% of local workers.[19] As Daniel Disalvo notes, "In today's public sector, good pay, generous benefits, and job security make possible a stable middle-class existence for nearly everyone from janitors to jailors."[20]

text: By the 1970s, a rapidly increasing flow of imports (such as automobiles, steel and electronics from Germany and Japan, and clothing and shoes from Asia) undercut American producers.[21] By the 1980s there was a large-scale shift in employment with fewer workers in high-wage sectors and more in the low-wage sectors.[22] Many companies closed or moved factories to Southern states (where unions were weak),[23] countered the threat of a strike by threatening to close or move a plant,[24] or moved their factories offshore to low-wage countries.[25] The number of major strikes and lockouts fell by 97% from 381 in 1970 to 187 in 1980 to only 11 in 2010.[24][26] On the political front, the shrinking unions lost influence in the Democratic Party, and pro-Union liberal Republicans faded away.[27] Union membership among workers in private industry shrank dramatically, though after 1970 there was growth in employees unions of federal, state and local governments.[28][29] The intellectual mood in the 1970s and 1980s favored deregulation and free competition.[30] Numerous industries were deregulated, including airlines, trucking, railroads and telephones, over the objections of the unions involved.[31] The climax came when President Ronald Reagan—a former union president—broke the Professional Air Traffic Controllers Organization (PATCO) strike in 1981, dealing a major blow to unions.[26][32]

text: Republicans, using conservative think tanks as idea farms, began to push through legislative blueprints to curb the power of public employee unions as well as eliminate business regulations.[25][33][34]

text: Labor unions today[edit]

text:
Labor unions in the United States

National trade union organization(s)
AFL-CIO, CtW, IWW

National government agency(ies)
United States Department of Labor
National Labor Relations Board

Primary trade union legislation
National Labor Relations Act
Taft-Hartley Act

Trade union membership
16.2 million[35]

Percentage of workforce;

  ▪ Total: 11.1%
  ▪ Public sector: 35.7%
  ▪ Private sector: 6.6%
Demographics
  ▪ Age 16–24: 5.1%
  ▪ 25–34: 10.0%
  ▪ 35–44: 13.0%
  ▪ 45–54: 14.4%
  ▪ 55–64: 14.9%
  ▪ 65 and over: 10.4%
  ▪ Women: 10.5%
  ▪ Men:
11.7%

Standard Occupational Classification

  ▪ Management, professional: 11.9%
  ▪ Service: 9.2%
  ▪ Sales and office: 6.5%
  ▪ Natural resources, construction, and
  maintenance: 15.3%
  ▪ Production, transportation, and
  material moving:
14.8%

International Labour Organization

United States is a member of the ILO

Convention ratification

Freedom of Association
Not ratified

Right to Organise
Not ratified

text: Today most labor unions in the United States are members of one of two larger umbrella organizations: the American Federation of Labor–Congress of Industrial Organizations (AFL-CIO) or the Change to Win Federation, which split from the AFL-CIO in 2005-2006. Both organizations advocate policies and legislation favorable to workers in the United States and Canada, and take an active role in politics favoring the Democratic party but not exclusively so. The AFL-CIO is especially concerned with global trade and economic issues.

text: Private sector unions are regulated by the National Labor Relations Act (NLRA), passed in 1935 and amended since then. The law is overseen by the National Labor Relations Board (NLRB), an independent federal agency. Public sector unions are regulated partly by federal and partly by state laws. In general they have shown robust growth rates, because wages and working conditions are set through negotiations with elected local and state officials. The unions' political power thus comes into play, and of course the local government cannot threaten to move elsewhere, nor is there any threat from foreign competition.

text: To join a traditional labor union, workers must either be given voluntary recognition from their employer or have a majority of workers in a bargaining unit vote for union representation.[citation needed] In either case, the government must then certify the newly formed union.[citation needed] Other forms of unionism include minority unionism, solidarity unionism, and the practices of organizations such as the Industrial Workers of the World, which do not always follow traditional organizational models.

text: Public sector worker unions are governed by labor laws and labor boards in each of the 50 states. Northern states typically model their laws and boards after the NLRA and the NLRB. In other states, public workers have no right to establish a union as a legal entity. (About 40% of public employees in the USA do not have the right to organize a legally established union.)[36][37]

text: A review conducted by the federal government on pay scale shows that employees in a labor union earn up to 33% more income than their nonunion counterparts, as well as having more job security, and safer and higher-quality work conditions.[38] The median weekly income for union workers was $973 in 2014, compared with $763 for nonunion workers.[35]

text: Labor negotiations[edit]

text: This section's factual accuracy is disputed. Relevant discussion may be found on Talk:Labor unions in the United States. Please help to ensure that disputed statements are reliably sourced. (August 2016) (Learn how and when to remove this template message)

text: Once the union has won the support of a majority of the bargaining unit and is certified in a workplace, it has the sole authority to negotiate the conditions of employment. However, under the NLRA, if a minority of employees voted for a union, those employees can then form a union which represents the rights of only those members who voted for the union.[citation needed] This minority model was once widely used, but was discarded when unions began to consistently win majority support. Unions are beginning to revisit the "members only" model of unionism because of new changes to labor law which unions view as curbing workers' ability to organize.

text: The employer and the union write the terms and conditions of employment in a legally binding contract. When disputes arise over the contract, most contracts call for the parties to resolve their differences through a grievance process to see if the dispute can be mutually resolved. If the union and the employer still cannot settle the matter, either party can choose to send the dispute to arbitration, where the case is argued before a neutral third party.

text: Right-to-work statutes forbid unions from negotiating union shops and agency shops. Thus, while unions do exist in "right-to-work" states, they are typically weaker.

text: Members of labor unions enjoy "Weingarten Rights." If management questions the union member on a matter that may lead to discipline or other changes in working conditions, union members can request representation by a union representative. Weingarten Rights are named for the first Supreme Court decision to recognize those rights.[39]

text: The NLRA goes farther in protecting the right of workers to organize unions. It protects the right of workers to engage in any "concerted activity" for mutual aid or protection. Thus, no union connection is needed. Concerted activity "in its inception involves only a speaker and a listener, for such activity is an indispensable preliminary step to employee self-organization."[40]

text: Unions are currently advocating new federal legislation, the Employee Free Choice Act (EFCA), that would allow workers to elect union representation by simply signing a support card (card check). The current process established by federal law requires at least 30% of employees to sign cards for the union, then wait 45 to 90 days for a federal official to conduct a secret ballot election in which a simple majority of the employees must vote for the union in order to obligate the employer to bargain.

text: Unions report that, under the present system, many employers use the 45- to 90-day period to conduct anti-union campaigns. Some opponents of this legislation fear that removing secret balloting from the process will lead to the intimidation and coercion of workers on behalf of the unions. During the 2008 elections, the Employee Free Choice Act had widespread support of many legislators in the House and Senate, and of the President. Since then, support for the "card check" provisions of the EFCA subsided substantially.

text: Membership[edit]

text: Union membership had been declining in the US since 1954, and since 1967, as union membership rates decreased, middle class incomes shrank correspondingly.[41] In 2007, the labor department reported the first increase in union memberships in 25 years and the largest increase since 1979. Most of the recent gains in union membership have been in the service sector while the number of unionized employees in the manufacturing sector has declined. Most of the gains in the service sector have come in West Coast states like California where union membership is now at 16.7% compared with a national average of about 12.1%.[42] Historically, the rapid growth of public employee unions since the 1960s has served to mask an even more dramatic decline in private-sector union membership.

text: At the apex of union density in the 1940s, only about 9.8% of public employees were represented by unions, while 33.9% of private, non-agricultural workers had such representation. In this decade, those proportions have essentially reversed, with 36% of public workers being represented by unions while private sector union density had plummeted to around 7%. The US Bureau of Labor Statistics most recent survey indicates that union membership in the US has risen to 12.4% of all workers, from 12.1% in 2007. For a short period, private sector union membership rebounded, increasing from 7.5% in 2007 to 7.6% in 2008.[35] However, that trend has since reversed. In 2013 there were 14.5 million members in the U.S., compared with 17.7 million in 1983. In 2013, the percentage of workers belonging to a union was 11.3%, compared to 20.1% in 1983. The rate for the private sector was 6.7%, and for the public sector 35.3%.[1]

text: In the ten years 2005 through 2014, the National Labor Relations Board recorded 18,577 labor union representation elections; in 11,086 of these elections (60 percent), the majority of workers voted for union representation. Most of the elections (15,517) were triggered by employee petitions for representation, of which unions won 9,933. Less common were elections caused by employee petitions for decertification (2792, of which unions won 1070), and employer-filed petitions for either representation or decertification (268, of which unions won 85).[43][44]

text: Labor education programs[edit]

text: In the US, labor education programs such as the Harvard Trade Union Program [45] created in 1942 by Harvard University professor John Thomas Dunlop sought to educate union members to deal with important contemporary workplace and labor law issues of the day. The Harvard Trade Union Program is currently part of a broader initiative at Harvard Law School called the Labor and Worklife Program[46] that deals with a wide variety of labor and employment issues from union pension investment funds to the effects of nanotechnology on labor markets and the workplace.

text: Cornell University is known to be one of the leading centers for labor education in the world, establishing the Cornell University School of Industrial and Labor Relations in 1945. The school's mission is to prepare leaders, inform national and international employment and labor policy, and improve working lives through undergraduate and graduate education. The school publishes the Industrial and Labor Relations Review and had Frances Perkins on its faculty. The school has six academic departments: Economics, Human Resource Management, International and Comparative Labor, Labor Relations, Organizational Behavior, and Social Statistics. Classes include "Politics of the Global North" and "Economic Analysis of the University." [47][48]

text: Jurisdiction[edit]

text: Labor unions use the term jurisdiction to refer to their claims to represent workers who perform a certain type of work and the right of their members to perform such work. For example, the work of unloading containerized cargo at United States ports, which the International Longshoremen's Association, the International Longshore and Warehouse Union and the International Brotherhood of Teamsters have claimed rightfully should be assigned to workers they represent. A jurisdictional strike is a concerted refusal to work undertaken by a union to assert its members' right to such job assignments and to protest the assignment of disputed work to members of another union or to unorganized workers. Jurisdictional strikes occur most frequently in the United States in the construction industry.[49]

text: Unions also use jurisdiction to refer to the geographical boundaries of their operations, as in those cases in which a national or international union allocates the right to represent workers among different local unions based on the place of those workers' employment, either along geographical lines or by adopting the boundaries between political jurisdictions.[49]

text: Public opinion[edit]

text: Although not as overwhelmingly supportive as it was from the 1930s through the early 1960s, a clear majority of the American public approves of labor unions. The Gallup organization has tracked public opinion of unions since 1936, when it found that 72 percent approved of unions. The overwhelming approval declined in the late 1960s, but - except for one poll in 2009 in which the unions received a favorable rating by only 48 percent of those interviewed, majorities have always supported labor unions. The latest poll in August 2016 gave labor unions a 56 percent approval rating, versus 36 percent who disapproved of unions.

text: On the question of whether or not unions should have more influence or less influence, Gallup has found the public consistently split since Gallup first posed the question in 2000, with no majority favoring either more influence or less influence. In August 2016, 36 percent wanted unions to have more influence, 34 percent less influence, with 26 percent wanting the influence of labor unions to remain about the same.[50]

text: Possible causes of drop in membership[edit]

text: Although most industrialized countries have seen a drop in unionization rates, the drop in union density (the unionized proportion of the working population) has been more significant in the United States than elsewhere.[11]

text: Global trends[edit]

text: The US Bureau of Labor Statistics surveyed the histories of union membership rates in industrialized countries from 1970 to 2003, and found that of 20 advanced economies which had union density statistics going back to 1970, 16 of them had experienced drops in union density from 1970 to 2003. Over the same period during which union density in the US declined from 23.5 percent to 12.4 percent, some counties saw even steeper drops. Australian unionization fell from 50.2 percent in 1970 to 22.9 percent in 2003, in New Zealand it dropped from 55.2 percent to 22.1 percent, and in Austria union participation fell from 62.8 percent down to 35.4 percent. All the English-speaking countries studied saw union membership decline to some degree. In the United Kingdom, union participation fell from 44.8 percent in 1970 to 29.3 percent in 2003. In Ireland the decline was from 53.7 percent down to 35.3 percent. Canada had one of the smallest declines over the period, going from 31.6 percent in 1970 to 28.4 percent in 2003. Most of the countries studied started in 1970 with higher participation rates than the US, but France, which in 1970 had a union participation rate of 21.7 percent, by 2003 had fallen to 8.3 percent. The remaining four countries which had gained in union density were Finland, Sweden, Denmark, and Belgium.[53]

text: Popularity[edit]

text: Public approval of unions climbed during the 1980s much as it did in other industrialized nations,[54] but declined to below 50% for the first time in 2009 during the Great Recession. It is not clear if this is a long term trend or a function of a high unemployment rate which historically correlates with lower public approval of labor unions.[55]

text: One explanation for loss of public support is simply the lack of union power or critical mass. No longer do a sizable percentage of American workers belong to unions, or have family members who do. Unions no longer carry the "threat effect": the power of unions to raise wages of non-union shops by virtue of the threat of unions to organize those shops.[55]

text: Polls of public opinion and labor unions[edit]

text: A New York Times/CBS Poll found that 60% of Americans opposed restricting collective bargaining while 33% were for it. The poll also found that 56% of Americans opposed reducing pay of public employees compared to the 37% who approved. The details of the poll also stated that 26% of those surveyed, thought pay and benefits for public employees were too high, 25% thought too low, and 36% thought about right. Mark Tapscott of the Washington Examiner criticized the poll, accusing it of over-sampling union and public employee households.[56]

text: A Gallup poll released on March 9, 2011, showed that Americans were more likely to support limiting the collective bargaining powers of state employee unions to balance a state's budget (49%) than disapprove of such a measure (45%), while 6% had no opinion. 66% of Republicans approved of such a measure as did 51% of independents. Only 31% of Democrats approved.[57]

text: A Gallup poll released on March 11, 2011, showed that nationwide, Americans were more likely to give unions a negative word or phrase when describing them (38%) than a positive word or phrase (34%). 17% were neutral and 12% didn't know. Republicans were much more likely to say a negative term (58%) than Democrats (19%). Democrats were much more likely to say a positive term (49%) than Republicans (18%).[58]

text: A nationwide Gallup poll (margin of error ±4%) released on April 1, 2011,[59] showed the following;

text:
When asked if they supported the labor unions or the governors in state disputes; 48% said they supported the unions, 39% said the governors, 4% said neither, and 9% had no opinion.
Women supported the governors much less than men. 45% of men said they supported the governors, while 46% said they supported the unions. This compares to only 33% of women who said they supported the governors and 50% who said they supported the unions.
All areas of the US (East, Midwest, South, West) were more likely to support unions than the governors. The largest gap being in the East with 35% supporting the governors and 52% supporting the unions, and the smallest gap being in the West with 41% supporting the governors and 44% the unions.
18- to 34-year-olds were much more likely to support unions than those over 34 years of age. Only 27% of 18- to 34-year-olds supported the governors, while 61% supported the unions. Americans ages 35 to 54 slightly supported the unions more than governors, with 40% supporting the governors and 43% the unions. Americans 55 and older were tied when asked, with 45% supporting the governors and 45% the unions.
Republicans were much more likely to support the governors when asked with 65% supporting the governors and 25% the unions. Independents slightly supported unions more, with 40% supporting the governors and 45% the unions. Democrats were overwhelmingly in support of the unions. 70% of Democrats supported the unions, while only 19% supported the governors.
Those who said they were following the situation not too closely or not at all supported the unions over governors, with a 14–point (45% to 31%) margin. Those who said they were following the situation somewhat closely supported the unions over governors by a 52–41 margin. Those who said that they were following the situation very closely were only slightly more likely to support the unions over the governors, with a 49-48 margin.

text: A nationwide Gallup poll released on August 31, 2011, revealed the following:[60]

text:
52% of Americans approved of labor unions, unchanged from 2010.
78% of Democrats approved of labor unions, up from 71% in 2010.
52% of Independents approved of labor unions, up from 49% in 2010.
26% of Republicans approved of labor unions, down from 34% in 2010.

text: A nationwide Gallup poll released on September 1, 2011, revealed the following:[61]

text:
55% of Americans believed that labor unions will become weaker in the United States as time goes by, an all-time high. This compared to 22% who said their power would stay the same, and 20% who said they would get stronger.
The majority of Republicans and Independents believed labor unions would further weaken by a 58% and 57% percentage margin respectively. A plurality of Democrats believed the same, at 46%.
42% of Americans want labor unions to have less influence, tied for the all-time high set in 2009. 30% wanted more influence and 25% wanted the same amount of influence.
The majority of Republicans wanted labor unions to have less influence, at 69%.
A plurality of Independents wanted labor unions to have less influence, at 40%.
A plurality of Democrats wanted labor unions to have more influence, at 45%.
The majority of Americans believed labor unions mostly helped members of unions by a 68 to 28 margin.
A plurality of Americans believed labor unions mostly helped the companies where workers are unionized by a 48-44 margin.
A plurality of Americans believed labor unions mostly helped state and local governments by a 47-45 margin.
A plurality of Americans believed labor unions mostly hurt the US economy in general by a 49-45 margin.
The majority of Americans believed labor unions mostly hurt workers who are not members of unions by a 56-34 margin.

text: Institutional environments[edit]

text: A broad range of forces have been identified as potential contributors to the drop in union density across countries. Sano and Williamson outline quantitative studies that assess the relevance of these factors across countries.[62] The first relevant set of factors relate to the receptiveness of unions' institutional environments. For example, the presence of a Ghent system (where unions are responsible for the distribution of unemployment insurance) and of centralized collective bargaining (organized at a national or industry level as opposed to local or firm level) have both been shown to give unions more bargaining power and to correlate positively to higher rates of union density.[62]

text: Unions have enjoyed higher rates of success in locations where they have greater access to the workplace as an organizing space (as determined both by law and by employer acceptance), and where they benefit from a corporatist relationship to the state and are thus allowed to participate more directly in the official governance structure. Moreover, the fluctuations of business cycles, particularly the rise and fall of unemployment rates and inflation, are also closely linked to changes in union density.[62]

text: Labor legislation[edit]

text: Labor lawyer Thomas Geoghegan attributes the drop to the long-term effects of the 1947 Taft-Hartley Act, which slowed and then halted labor's growth and then, over many decades, enabled management to roll back labor's previous gains.[63]

text: First, it ended organizing on the grand, 1930s scale. It outlawed mass picketing, secondary strikes of neutral employers, sit downs: in short, everything [Congress of Industrial Organizations founder John L.] Lewis did in the 1930s.

text:
The second effect of Taft-Hartley was subtler and slower-working. It was to hold up any new organizing at all, even on a quiet, low-key scale. For example, Taft-Hartley ended "card checks." … Taft-Hartley required hearings, campaign periods, secret-ballot elections, and sometimes more hearings, before a union could be officially recognized.

It also allowed and even encouraged employers to threaten workers who want to organize. Employers could hold "captive meetings," bring workers into the office and chew them out for thinking about the Union.

And Taft-Hartley led to the "union-busting" that started in the late 1960s and continues today. It started when a new "profession" of labor consultants began to convince employers that they could violate the [pro-labor 1935] Wagner Act, fire workers at will, fire them deliberately for exercising their legal rights, and nothing would happen. The Wagner Act had never had any real sanctions.
[…]

text: In general, scholars debate the influence of politics in determining union strength in the US and other countries. One argument is that political parties play an expected role in determining union strength, with left-wing governments generally promoting greater union density, while others contest this finding by pointing out important counterexamples and explaining the reverse causality inherent in this relationship.[64]

text: Economic globalization[edit]

text: More recently, as unions have become increasingly concerned with the impacts of market integration on their well-being, scholars have begun to assess whether popular concerns about a global "race to the bottom" are reflected in cross-country comparisons of union strength. These scholars use foreign direct investment (FDI) and the size of a country's international trade as a percentage of its GDP to assess a country's relative degree of market integration. These researchers typically find that globalization does affect union density, but is dependent on other factors, such as unions' access to the workplace and the centralization of bargaining.[65]

text: Sano and Williamson argue that globalization's impact is conditional upon a country's labor history.[66] In the United States in particular, which has traditionally had relatively low levels of union density, globalization did not appear to significantly affect union density.

text: Employer strategies[edit]

text: Studies focusing more narrowly on the U.S. labor movement corroborate the comparative findings about the importance of structural factors, but tend to emphasize the effects of changing labor markets due to globalization to a greater extent. Bronfenbrenner notes that changes in the economy, such as increased global competition, capital flight, and the transitions from a manufacturing to a service economy and to a greater reliance on transitory and contingent workers, accounts for only a third of the decline in union density.[68]

text: Bronfenbrenner claims that the federal government in the 1980s was largely responsible for giving employers the perception that they could engage in aggressive strategies to repress the formation of unions. Richard Freeman also points to the role of repressive employer strategies in reducing unionization, and highlights the way in which a state ideology of anti-unionism tacitly accepted these strategies [54]

text: Goldfield writes that the overall effects of globalization on unionization in the particular case of the United States may be understated in econometric studies on the subject.[69] He writes that the threat of production shifts reduces unions' bargaining power even if it does not eliminate them, and also claims that most of the effects of globalization on labor's strength are indirect. They are most present in change towards a neoliberal political context that has promoted the deregulation and privatization of some industries and accepted increased employer flexibility in labor markets.

text: Union responses to globalization[edit]

text: Regardless of the actual impact of market integration on union density or on workers themselves, organized labor has been engaged in a variety of strategies to limit the agenda of globalization and to promote labor regulations in an international context. The most prominent example of this has been the opposition of labor groups to free trade initiatives such as the North American Free Trade Agreement (NAFTA) and the Dominican Republic-Central American Free Trade Agreement (DR-CAFTA). In both cases, unions expressed strong opposition to the agreements, but to some extent pushed for the incorporation of basic labor standards in the agreement if one were to pass.[71]

text: However, Mayer has written that it was precisely unions' opposition to NAFTA overall that jeopardized organized labor's ability to influence the debate on labor standards in a significant way.[72] During Clinton's presidential campaign, labor unions wanted NAFTA to include a side deal to provide for a kind of international social charter, a set of standards that would be enforceable both in domestic courts and through international institutions. Mickey Kantor, then U.S. trade representative, had strong ties to organized labor and believed that he could get unions to come along with the agreement, particularly if they were given a strong voice in the negotiation process.[72]

text: When it became clear that Mexico would not stand for this kind of an agreement, some critics from the labor movement would not settle for any viable alternatives. In response, part of the labor movement wanted to declare their open opposition to the agreement, and to push for NAFTA's rejection in Congress.[72] Ultimately, the ambivalence of labor groups led those within the Administration who supported NAFTA to believe that strengthening NAFTA's labor side agreement too much would cost more votes among Republicans than it would garner among Democrats, and would make it harder for the United States to elicit support from Mexico.[73]

text: Graubart writes that, despite unions' open disappointment with the outcome of this labor-side negotiation, labor activists, including the AFL-CIO have used the side agreement's citizen petition process to highlight ongoing political campaigns and struggles in their home countries.[74] He claims that despite the relative weakness of the legal provisions themselves, the side-agreement has served a legitimizing functioning, giving certain social struggles a new kind of standing.

text: Transnational labor regulation[edit]

text: Unions have recently been engaged in a developing field of transnational labor regulation embodied in corporate codes of conduct. However, O'Brien cautions that unions have been only peripherally involved in this process, and remain ambivalent about its potential effects.[75] They worry that these codes could have legitimizing effects on companies that do not actually live up to good practices, and that companies could use codes to excuse or distract attention from the repression of unions.

text: Braun and Gearhart note that although unions do participate in the structure of a number of these agreements, their original interest in codes of conduct differed from the interests of human rights and other non-governmental activists. Unions believed that codes of conduct would be important first steps in creating written principles that a company would be compelled to comply with in later organizing contracts, but did not foresee the establishment of monitoring systems such as the Fair Labor Association. These authors point out that are motivated by power, want to gain insider status politically and are accountable to a constituency that requires them to provide them with direct benefits.[76]

text: In contrast, activists from the non-governmental sector are motivated by ideals, are free of accountability and gain legitimacy from being political outsiders. Therefore, the interests of unions are not likely to align well with the interests of those who draft and monitor corporate codes of conduct.

text: Arguing against the idea that high union wages necessarily make manufacturing uncompetitive in a globalized economy is labor lawyer Thomas Geoghegan. Busting

text: unions, in the U.S. manner, as the prime way of competing with China and other countries [does not work]. It's no accident that the social democracies, Sweden, France, and Germany, which kept on paying high wages, now have more industry than the U.S. or the UK. … [T]hat's what the U.S. and the UK did: they smashed the unions, in the belief that they had to compete on cost. The result? They quickly ended up wrecking their industrial base.[77]

text: Unions have made some attempts to organize across borders. Eder observes that transnational organizing is not a new phenomenon but has been facilitated by technological change.[78] Nevertheless, he claims that while unions pay lip service to global solidarity, they still act largely in their national self-interest. He argues that unions in the global North are becoming increasingly depoliticized while those in the South grow politically, and that global differentiation of production processes leads to divergent strategies and interests in different regions of the world. These structural differences tend to hinder effective global solidarity. However, in light of the weakness of international labor, Herod writes that globalization of production need not be met by a globalization of union strategies in order to be contained. Herod also points out that local strategies, such as the United Auto Workers' strike against General Motors in 1998, can sometimes effectively interrupt global production processes in ways that they could not before the advent of widespread market integration. Thus, workers need not be connected organizationally to others around the world to effectively influence the behavior of a transnational corporation.[79]


document_title: Scottish Reformation Parliament

question_text: when did scotland abolish the authority of the pope

root

text: Scottish Reformation Parliament

text: Background[edit]

text: In 1559, John Knox returned to Scotland, marking a new effort in his battle to reform the nation. Scottish Protestants in the 1520s and 1530s were Lutherans such as Patrick Hamilton, George Wishart, who translated the First Helvetic Confession written by Heinrich Bullinger, marking the impact of the Swiss Reformation. With the return of Knox from Geneva Scottish Protestants rallied around him and the Scottish Reformation continued to be characterised by the example of John Calvin in Geneva

tag: p

text: Queen dowager Mary of Guise, acting as regent for her daughter Mary, Queen of Scots, wanted to crush the Protestants and felt the use of force would be necessary. Civil war appeared imminent, but each side shrank from the first step. Knox at once became the clerical leader of the reformers. He preached against "idolatry" with the greatest boldness, with the result that what he later called the "rascal multitude" began the "purging" of churches and the destruction of monasteries. Mary of Guise died on 11 June 1560, at which point the youthful Mary Queen of Scots, then resident in France, gave permission, through her husband, Francis II, for Parliament to meet in her absence, but religious questions were specifically to be submitted to the 'intention and pleasure' of the king and queen.

text: Course[edit]

text: Still, in August 1560 the 'Reformation Parliament' abolished the jurisdiction of the Roman Catholic Church in Scotland with the Papal Jurisdiction Act.

text: A Reformed confession of faith was drafted by six ministers: John Winram, John Spottiswoode, John Willock, John Douglas, John Row and John Knox. On 17 August 1560, the document was read twice, article by article, before the Parliament, and the Protestant ministers stood ready to defend "the cause of truth" if any article of belief was assailed.

text: When the vote was taken, the Confession was ratified and adopted. An assembly of several ministers and laymen, subsequently known as the first General Assembly of the Church of Scotland met in Edinburgh, and the First Book of Discipline (1560) was drawn up. The Second Book of Discipline (1581) was ratified much later by Parliament in 1592 (see General Assembly Act 1592[3]). This definitely settled the Presbyterian form of polity and the Calvinistic doctrine as the recognised Protestant establishment in the country.

text: The Confession of Faith was established by parliament on 17 August.[4] The Parliament also agreed on 16 August to pursue the marriage of Elizabeth I of England to James Hamilton, 3rd Earl of Arran. Randolph "never saw so important matters sooner dispatched". When the first session of the Parliament was concluded, the Duke of Châtellherault gave the Clerk Register a silver coin to have the proceedings recorded.[5]

text: On 26 August the Parliament approved the Treaty of Berwick (1560), and James Stewart, Earl of Moray requested and received special confirmation that the acts of the Lords of the Congregation were lawful. The authority of the Pope in Scotland was abrogated without contradiction.[6]

text: The work of the 'Reformation Parliament' was popularly acclaimed but not formally ratified until seven years later by James VI. Mary never ratified it.

text: Process and Ceremony[edit]

text: The English correspondent Thomas Randolph described the ceremony surrounding the selection of the Lords of the Articles on 9 August 1560. The lords convened at Holyroodhouse then rode to the Tollbooth near St Giles. Mary, Queen of Scots was represented by the crown, mace and sword. After a speech by William Maitland, the articles of the peace with France were read and confirmed. The Lords of the Articles were chosen - these decided the agenda for the full parliament session. Then all the lords processed with the Duke to the Netherbow, and back to the Palace. The whole town wore armour, with trumpets sounding, and all other kinds of music. Randolph was confident the Lords of the Articles would commune on the "dysannullinge" of Papal authority.[7]


document_title: Muscle

question_text: what type of muscle is the digestive system

text: Muscle

text: Structure

text: The anatomy of muscles includes gross anatomy, which comprises all the muscles of an organism, and microanatomy, which comprises the structures of a single muscle.

text: Types

text: Muscle tissue is a soft tissue, and is one of the four fundamental types of tissue present in animals. There are three types of muscle tissue recognized in vertebrates:

text:
Skeletal muscle or "voluntary muscle" is anchored by tendons (or by aponeuroses at a few places) to bone and is used to effect skeletal movement such as locomotion and in maintaining posture. Though this postural control is generally maintained as an unconscious reflex, the muscles responsible react to conscious control like non-postural muscles. An average adult male is made up of 42% of skeletal muscle and an average adult female is made up of 36% (as a percentage of body mass).[5]
Smooth muscle or "involuntary muscle" is found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, uterus, urethra, bladder, blood vessels, and the arrector pili in the skin (in which it controls erection of body hair). Unlike skeletal muscle, smooth muscle is not under conscious control.
Cardiac muscle (myocardium), is also an "involuntary muscle" but is more akin in structure to skeletal muscle, and is found only in the heart.

tag: ul

text: Cardiac and skeletal muscles are "striated" in that they contain sarcomeres that are packed into highly regular arrangements of bundles; the myofibrils of smooth muscle cells are not arranged in sarcomeres and so are not striated. While the sarcomeres in skeletal muscles are arranged in regular, parallel bundles, cardiac muscle sarcomeres connect at branching, irregular angles (called intercalated discs). Striated muscle contracts and relaxes in short, intense bursts, whereas smooth muscle sustains longer or even near-permanent contractions.

text: Skeletal (voluntary) muscle is further divided into two broad types: slow twitch and fast twitch:

text:
Type I, slow twitch, or "red" muscle, is dense with capillaries and is rich in mitochondria and myoglobin, giving the muscle tissue its characteristic red color. It can carry more oxygen and sustain aerobic activity using fats or carbohydrates as fuel.[6] Slow twitch fibers contract for long periods of time but with little force.
Type II, fast twitch muscle, has three major subtypes (IIa, IIx, and IIb) that vary in both contractile speed[7] and force generated.[6] Fast twitch fibers contract quickly and powerfully but fatigue very rapidly, sustaining only short, anaerobic bursts of activity before muscle contraction becomes painful. They contribute most to muscle strength and have greater potential for increase in mass. Type IIb is anaerobic, glycolytic, "white" muscle that is least dense in mitochondria and myoglobin. In small animals (e.g., rodents) this is the major fast muscle type, explaining the pale color of their flesh.

text: The density of mammalian skeletal muscle tissue is about 1.06 kg/liter.[8] This can be contrasted with the density of adipose tissue (fat), which is 0.9196 kg/liter.[9] This makes muscle tissue approximately 15% denser than fat tissue.

text: Microanatomy

text: Skeletal muscles are sheathed by a tough layer of connective tissue called the epimysium. The epimysium anchors muscle tissue to tendons at each end, where the epimysium becomes thicker and collagenous. It also protects muscles from friction against other muscles and bones. Within the epimysium are multiple bundles called fascicles, each of which contains 10 to 100 or more muscle fibers collectively sheathed by a perimysium. Besides surrounding each fascicle, the perimysium is a pathway for nerves and the flow of blood within the muscle. The threadlike muscle fibers are the individual muscle cells (myocytes), and each cell is encased within its own endomysium of collagen fibers. Thus, the overall muscle consists of fibers (cells) that are bundled into fascicles, which are themselves grouped together to form muscles. At each level of bundling, a collagenous membrane surrounds the bundle, and these membranes support muscle function both by resisting passive stretching of the tissue and by distributing forces applied to the muscle.[10] Scattered throughout the muscles are muscle spindles that provide sensory feedback information to the central nervous system. (This grouping structure is analogous to the organization of nerves which uses epineurium, perineurium, and endoneurium).

text: This same bundles-within-bundles structure is replicated within the muscle cells. Within the cells of the muscle are myofibrils, which themselves are bundles of protein filaments. The term "myofibril" should not be confused with "myofiber", which is a simply another name for a muscle cell. Myofibrils are complex strands of several kinds of protein filaments organized together into repeating units called sarcomeres. The striated appearance of both skeletal and cardiac muscle results from the regular pattern of sarcomeres within their cells. Although both of these types of muscle contain sarcomeres, the fibers in cardiac muscle are typically branched to form a network. Cardiac muscle fibers are interconnected by intercalated discs,[11] giving that tissue the appearance of a syncytium.

text: The filaments in a sarcomere are composed of actin and myosin.

text: Gross anatomy

text: The gross anatomy of a muscle is the most important indicator of its role in the body. There is an important distinction seen between pennate muscles and other muscles. In most muscles, all the fibers are oriented in the same direction, running in a line from the origin to the insertion. However, In pennate muscles, the individual fibers are oriented at an angle relative to the line of action, attaching to the origin and insertion tendons at each end. Because the contracting fibers are pulling at an angle to the overall action of the muscle, the change in length is smaller, but this same orientation allows for more fibers (thus more force) in a muscle of a given size. Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris.

text: Skeletal muscle is arranged in discrete muscles, an example of which is the biceps brachii (biceps). The tough, fibrous epimysium of skeletal muscle is both connected to and continuous with the tendons. In turn, the tendons connect to the periosteum layer surrounding the bones, permitting the transfer of force from the muscles to the skeleton. Together, these fibrous layers, along with tendons and ligaments, constitute the deep fascia of the body.

text: Muscular system

text: The muscular system consists of all the muscles present in a single body. There are approximately 650 skeletal muscles in the human body,[12] but an exact number is difficult to define. The difficulty lies partly in the fact that different sources group the muscles differently and partly in that some muscles, such as palmaris longus, are not always present.

text: A muscular slip is a narrow length of muscle that acts to augment a larger muscle or muscles.

text: The muscular system is one component of the musculoskeletal system, which includes not only the muscles but also the bones, joints, tendons, and other structures that permit movement.

text: Development

text: All muscles are derived from paraxial mesoderm. The paraxial mesoderm is divided along the embryo's length into somites, corresponding to the segmentation of the body (most obviously seen in the vertebral column.[13] Each somite has 3 divisions, sclerotome (which forms vertebrae), dermatome (which forms skin), and myotome (which forms muscle). The myotome is divided into two sections, the epimere and hypomere, which form epaxial and hypaxial muscles, respectively. The only epaxial muscles in humans are the erector spinae and small intervertebral muscles, and are innervated by the dorsal rami of the spinal nerves. All other muscles, including those of the limbs are hypaxial, and inervated by the ventral rami of the spinal nerves.[13]

text: During development, myoblasts (muscle progenitor cells) either remain in the somite to form muscles associated with the vertebral column or migrate out into the body to form all other muscles. Myoblast migration is preceded by the formation of connective tissue frameworks, usually formed from the somatic lateral plate mesoderm. Myoblasts follow chemical signals to the appropriate locations, where they fuse into elongate skeletal muscle cells.[13]

text: Physiology

text: Contraction

text: The three types of muscle (skeletal, cardiac and smooth) have significant differences. However, all three use the movement of actin against myosin to create contraction. In skeletal muscle, contraction is stimulated by electrical impulses transmitted by the nerves, the motoneurons (motor nerves) in particular. Cardiac and smooth muscle contractions are stimulated by internal pacemaker cells which regularly contract, and propagate contractions to other muscle cells they are in contact with. All skeletal muscle and many smooth muscle contractions are facilitated by the neurotransmitter acetylcholine.

text: The action a muscle generates is determined by the origin and insertion locations. The cross-sectional area of a muscle (rather than volume or length) determines the amount of force it can generate by defining the number of "sarcomeres" which can operate in parallel. Each skeletal muscle contains long units called myofibrils, and each myofibril is a chain of sarcomeres. Since contraction occurs at the same time for all connected sarcomeres in a muscles cell, these chains of sarcomeres shorten together, thus shortening the muscle fiber, resulting in overall length change.[14] The amount of force applied to the external environment is determined by lever mechanics, specifically the ratio of in-lever to out-lever. For example, moving the insertion point of the biceps more distally on the radius (farther from the joint of rotation) would increase the force generated during flexion (and, as a result, the maximum weight lifted in this movement), but decrease the maximum speed of flexion. Moving the insertion point proximally (closer to the joint of rotation) would result in decreased force but increased velocity. This can be most easily seen by comparing the limb of a mole to a horse - in the former, the insertion point is positioned to maximize force (for digging), while in the latter, the insertion point is positioned to maximize speed (for running).

text: Nervous control

text: Muscle movement

text: The efferent leg of the peripheral nervous system is responsible for conveying commands to the muscles and glands, and is ultimately responsible for voluntary movement. Nerves move muscles in response to voluntary and autonomic (involuntary) signals from the brain. Deep muscles, superficial muscles, muscles of the face and internal muscles all correspond with dedicated regions in the primary motor cortex of the brain, directly anterior to the central sulcus that divides the frontal and parietal lobes.

text: In addition, muscles react to reflexive nerve stimuli that do not always send signals all the way to the brain. In this case, the signal from the afferent fiber does not reach the brain, but produces the reflexive movement by direct connections with the efferent nerves in the spine. However, the majority of muscle activity is volitional, and the result of complex interactions between various areas of the brain.

text: Nerves that control skeletal muscles in mammals correspond with neuron groups along the primary motor cortex of the brain's cerebral cortex. Commands are routed though the basal ganglia and are modified by input from the cerebellum before being relayed through the pyramidal tract to the spinal cord and from there to the motor end plate at the muscles. Along the way, feedback, such as that of the extrapyramidal system contribute signals to influence muscle tone and response.

text: Deeper muscles such as those involved in posture often are controlled from nuclei in the brain stem and basal ganglia.

text: Proprioception

text: In skeletal muscles, muscle spindles convey information about the degree of muscle length and stretch to the central nervous system to assist in maintaining posture and joint position. The sense of where our bodies are in space is called proprioception, the perception of body awareness, the "unconscious" awareness of where the various regions of the body are located at any one time. Several areas in the brain coordinate movement and position with the feedback information gained from proprioception. The cerebellum and red nucleus in particular continuously sample position against movement and make minor corrections to assure smooth motion.[citation needed]

text: Energy consumption

text: Muscular activity accounts for much of the body's energy consumption. All muscle cells produce adenosine triphosphate (ATP) molecules which are used to power the movement of the myosin heads. Muscles have a short-term store of energy in the form of creatine phosphate which is generated from ATP and can regenerate ATP when needed with creatine kinase. Muscles also keep a storage form of glucose in the form of glycogen. Glycogen can be rapidly converted to glucose when energy is required for sustained, powerful contractions. Within the voluntary skeletal muscles, the glucose molecule can be metabolized anaerobically in a process called glycolysis which produces two ATP and two lactic acid molecules in the process (note that in aerobic conditions, lactate is not formed; instead pyruvate is formed and transmitted through the citric acid cycle). Muscle cells also contain globules of fat, which are used for energy during aerobic exercise. The aerobic energy systems take longer to produce the ATP and reach peak efficiency, and requires many more biochemical steps, but produces significantly more ATP than anaerobic glycolysis. Cardiac muscle on the other hand, can readily consume any of the three macronutrients (protein, glucose and fat) aerobically without a 'warm up' period and always extracts the maximum ATP yield from any molecule involved. The heart, liver and red blood cells will also consume lactic acid produced and excreted by skeletal muscles during exercise.

text: At rest, skeletal muscle consumes 54.4 kJ/kg (13.0 kcal/kg) per day. This is larger than adipose tissue (fat) at 18.8 kJ/kg (4.5 kcal/kg), and bone at 9.6 kJ/kg (2.3 kcal/kg).[15]

text: Efficiency

text: The efficiency of human muscle has been measured (in the context of rowing and cycling) at 18% to 26%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost, as can be calculated from oxygen consumption. This low efficiency is the result of about 40% efficiency of generating ATP from food energy, losses in converting energy from ATP into mechanical work inside the muscle, and mechanical losses inside the body. The latter two losses are dependent on the type of exercise and the type of muscle fibers being used (fast-twitch or slow-twitch). For an overall efficiency of 20 percent, one watt of mechanical power is equivalent to 4.3 kcal per hour. For example, one manufacturer of rowing equipment calibrates its rowing ergometer to count burned calories as equal to four times the actual mechanical work, plus 300 kcal per hour,[16] this amounts to about 20 percent efficiency at 250 watts of mechanical output. The mechanical energy output of a cyclic contraction can depend upon many factors, including activation timing, muscle strain trajectory, and rates of force rise & decay. These can be synthesized experimentally using work loop analysis.

text: Strength

text: Muscle is a result of three factors that overlap: physiological strength (muscle size, cross sectional area, available crossbridging, responses to training), neurological strength (how strong or weak is the signal that tells the muscle to contract), and mechanical strength (muscle's force angle on the lever, moment arm length, joint capabilities).[citation needed]

text: Physiological strength

text:
Grading of muscle strength

Grade 0
No contraction

Grade 1
Trace of contraction, but no movement at the joint

Grade 2
Movement at the joint with gravity eliminated

Grade 3
Movement against gravity, but not against added resistance

Grade 4
Movement against external resistance, but less than normal

Grade 5
Normal strength

tag: table

text: Vertebrate muscle typically produces approximately 25–33 N (5.6–7.4 lbf) of force per square centimeter of muscle cross-sectional area when isometric and at optimal length.[17] Some invertebrate muscles, such as in crab claws, have much longer sarcomeres than vertebrates, resulting in many more sites for actin and myosin to bind and thus much greater force per square centimeter at the cost of much slower speed. The force generated by a contraction can be measured non-invasively using either mechanomyography or phonomyography, be measured in vivo using tendon strain (if a prominent tendon is present), or be measured directly using more invasive methods.

text: The strength of any given muscle, in terms of force exerted on the skeleton, depends upon length, shortening speed, cross sectional area, pennation, sarcomere length, myosin isoforms, and neural activation of motor units. Significant reductions in muscle strength can indicate underlying pathology, with the chart at right used as a guide.

text: The "strongest" human muscle

text: This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (March 2016) (Learn how and when to remove this template message)

text: Since three factors affect muscular strength simultaneously and muscles never work individually, it is misleading to compare strength in individual muscles, and state that one is the "strongest". But below are several muscles whose strength is noteworthy for different reasons.

text:
In ordinary parlance, muscular "strength" usually refers to the ability to exert a force on an external object—for example, lifting a weight. By this definition, the masseter or jaw muscle is the strongest. The 1992 Guinness Book of Records records the achievement of a bite strength of 4,337 N (975 lbf) for 2 seconds. What distinguishes the masseter is not anything special about the muscle itself, but its advantage in working against a much shorter lever arm than other muscles.
If "strength" refers to the force exerted by the muscle itself, e.g., on the place where it inserts into a bone, then the strongest muscles are those with the largest cross-sectional area. This is because the tension exerted by an individual skeletal muscle fiber does not vary much. Each fiber can exert a force on the order of 0.3 micronewton. By this definition, the strongest muscle of the body is usually said to be the quadriceps femoris or the gluteus maximus.
Because muscle strength is determined by cross-sectional area, a shorter muscle will be stronger "pound for pound" (i.e., by weight) than a longer muscle of the same cross-sectional area. The myometrial layer of the uterus may be the strongest muscle by weight in the female human body. At the time when an infant is delivered, the entire human uterus weighs about 1.1 kg (40 oz). During childbirth, the uterus exerts 100 to 400 N (25 to 100 lbf) of downward force with each contraction.
The external muscles of the eye are conspicuously large and strong in relation to the small size and weight of the eyeball. It is frequently said that they are "the strongest muscles for the job they have to do" and are sometimes claimed to be "100 times stronger than they need to be." However, eye movements (particularly saccades used on facial scanning and reading) do require high speed movements, and eye muscles are exercised nightly during rapid eye movement sleep.
The statement that "the tongue is the strongest muscle in the body" appears frequently in lists of surprising facts, but it is difficult to find any definition of "strength" that would make this statement true. Note that the tongue consists of eight muscles, not one.
The heart has a claim to being the muscle that performs the largest quantity of physical work in the course of a lifetime. Estimates of the power output of the human heart range from 1 to 5 watts. This is much less than the maximum power output of other muscles; for example, the quadriceps can produce over 100 watts, but only for a few minutes. The heart does its work continuously over an entire lifetime without pause, and thus does "outwork" other muscles. An output of one watt continuously for eighty years yields a total work output of two and a half gigajoules.[18]

text: Exercise

text: Exercise is often recommended as a means of improving motor skills, fitness, muscle and bone strength, and joint function. Exercise has several effects upon muscles, connective tissue, bone, and the nerves that stimulate the muscles. One such effect is muscle hypertrophy, an increase in size. This is used in bodybuilding.

text: Various exercises require a predominance of certain muscle fiber utilization over another. Aerobic exercise involves long, low levels of exertion in which the muscles are used at well below their maximal contraction strength for long periods of time (the most classic example being the marathon). Aerobic events, which rely primarily on the aerobic (with oxygen) system, use a higher percentage of Type I (or slow-twitch) muscle fibers, consume a mixture of fat, protein and carbohydrates for energy, consume large amounts of oxygen and produce little lactic acid. Anaerobic exercise involves short bursts of higher intensity contractions at a much greater percentage of their maximum contraction strength. Examples of anaerobic exercise include sprinting and weight lifting. The anaerobic energy delivery system uses predominantly Type II or fast-twitch muscle fibers, relies mainly on ATP or glucose for fuel, consumes relatively little oxygen, protein and fat, produces large amounts of lactic acid and can not be sustained for as long a period as aerobic exercise. Many exercises are partially aerobic and partially anaerobic; for example, soccer and rock climbing involve a combination of both.

text: The presence of lactic acid has an inhibitory effect on ATP generation within the muscle; though not producing fatigue, it can inhibit or even stop performance if the intracellular concentration becomes too high. However, long-term training causes neovascularization within the muscle, increasing the ability to move waste products out of the muscles and maintain contraction. Once moved out of muscles with high concentrations within the sarcomere, lactic acid can be used by other muscles or body tissues as a source of energy, or transported to the liver where it is converted back to pyruvate. In addition to increasing the level of lactic acid, strenuous exercise causes the loss of potassium ions in muscle and causing an increase in potassium ion concentrations close to the muscle fibres, in the interstitium. Acidification by lactic acid may allow recovery of force so that acidosis may protect against fatigue rather than being a cause of fatigue.[19]

text: Delayed onset muscle soreness is pain or discomfort that may be felt one to three days after exercising and generally subsides two to three days later. Once thought to be caused by lactic acid build-up, a more recent theory is that it is caused by tiny tears in the muscle fibers caused by eccentric contraction, or unaccustomed training levels. Since lactic acid disperses fairly rapidly, it could not explain pain experienced days after exercise.[20]

text: Health

text: Humans are genetically predisposed with a larger percentage of one type of muscle group over another. An individual born with a greater percentage of Type I muscle fibers would theoretically be more suited to endurance events, such as triathlons, distance running, and long cycling events, whereas a human born with a greater percentage of Type II muscle fibers would be more likely to excel at sprinting events such as 100 meter dash.[citation needed]

text: Clinical significance

text: Hypertrophy

text: Independent of strength and performance measures, muscles can be induced to grow larger by a number of factors, including hormone signaling, developmental factors, strength training, and disease. Contrary to popular belief, the number of muscle fibres cannot be increased through exercise. Instead, muscles grow larger through a combination of muscle cell growth as new protein filaments are added along with additional mass provided by undifferentiated satellite cells alongside the existing muscle cells.[12]

text: Biological factors such as age and hormone levels can affect muscle hypertrophy. During puberty in males, hypertrophy occurs at an accelerated rate as the levels of growth-stimulating hormones produced by the body increase. Natural hypertrophy normally stops at full growth in the late teens. As testosterone is one of the body's major growth hormones, on average, men find hypertrophy much easier to achieve than women. Taking additional testosterone or other anabolic steroids will increase muscular hypertrophy.

text: Muscular, spinal and neural factors all affect muscle building. Sometimes a person may notice an increase in strength in a given muscle even though only its opposite has been subject to exercise, such as when a bodybuilder finds her left biceps stronger after completing a regimen focusing only on the right biceps. This phenomenon is called cross education.[citation needed]

text: Atrophy

text: Inactivity and starvation in mammals lead to atrophy of skeletal muscle, a decrease in muscle mass that may be accompanied by a smaller number and size of the muscle cells as well as lower protein content.[21] Muscle atrophy may also result from the natural aging process or from disease.

text: In humans, prolonged periods of immobilization, as in the cases of bed rest or astronauts flying in space, are known to result in muscle weakening and atrophy. Atrophy is of particular interest to the manned spaceflight community, because the weightlessness experienced in spaceflight results is a loss of as much as 30% of mass in some muscles.[22][23] Such consequences are also noted in small hibernating mammals like the golden-mantled ground squirrels and brown bats.[24]

text: During aging, there is a gradual decrease in the ability to maintain skeletal muscle function and mass, known as sarcopenia. The exact cause of sarcopenia is unknown, but it may be due to a combination of the gradual failure in the "satellite cells" that help to regenerate skeletal muscle fibers, and a decrease in sensitivity to or the availability of critical secreted growth factors that are necessary to maintain muscle mass and satellite cell survival. Sarcopenia is a normal aspect of aging, and is not actually a disease state yet can be linked to many injuries in the elderly population as well as decreasing quality of life.[25]

text: There are also many diseases and conditions that cause muscle atrophy. Examples include cancer and AIDS, which induce a body wasting syndrome called cachexia. Other syndromes or conditions that can induce skeletal muscle atrophy are congestive heart disease and some diseases of the liver.

text: Disease

text: Neuromuscular diseases are those that affect the muscles and/or their nervous control. In general, problems with nervous control can cause spasticity or paralysis, depending on the location and nature of the problem. A large proportion of neurological disorders, ranging from cerebrovascular accident (stroke) and Parkinson's disease to Creutzfeldt–Jakob disease, can lead to problems with movement or motor coordination.

text: Symptoms of muscle diseases may include weakness, spasticity, myoclonus and myalgia. Diagnostic procedures that may reveal muscular disorders include testing creatine kinase levels in the blood and electromyography (measuring electrical activity in muscles). In some cases, muscle biopsy may be done to identify a myopathy, as well as genetic testing to identify DNA abnormalities associated with specific myopathies and dystrophies.

text: A non-invasive elastography technique that measures muscle noise is undergoing experimentation to provide a way of monitoring neuromuscular disease. The sound produced by a muscle comes from the shortening of actomyosin filaments along the axis of the muscle. During contraction, the muscle shortens along its longitudinal axis and expands across the transverse axis, producing vibrations at the surface.[26]

text: Evolution

text: The evolutionary origin of muscle cells in metazoans is a highly debated topic. In one line of thought scientists have believed that muscle cells evolved once and thus all animals with muscles cells have a single common ancestor. In the other line of thought, scientists believe muscles cells evolved more than once and any morphological or structural similarities are due to convergent evolution and genes that predate the evolution of muscle and even the mesoderm - the germ layer from which many scientists believe true muscle cells derive.

text: Schmid and Seipel argue that the origin of muscle cells is a monophyletic trait that occurred concurrently with the development of the digestive and nervous systems of all animals and that this origin can be traced to a single metazoan ancestor in which muscle cells are present. They argue that molecular and morphological similarities between the muscles cells in cnidaria and ctenophora are similar enough to those of bilaterians that there would be one ancestor in metazoans from which muscle cells derive. In this case, Schmid and Seipel argue that the last common ancestor of bilateria, ctenophora, and cnidaria was a triploblast or an organism with three germ layers and that diploblasty, meaning an organism with two germ layers, evolved secondarily due to their observation of the lack of mesoderm or muscle found in most cnidarians and ctenophores. By comparing the morphology of cnidarians and ctenophores to bilaterians, Schmid and Seipel were able to conclude that there were myoblast-like structures in the tentacles and gut of some species of cnidarians and in the tentacles of ctenophores. Since this is a structure unique to muscle cells, these scientists determined based on the data collected by their peers that this is a marker for striated muscles similar to that observed in bilaterians. The authors also remark that the muscle cells found in cnidarians and ctenophores are often contests due to the origin of these muscle cells being the ectoderm rather than the mesoderm or mesendoderm. The origin of true muscles cells is argued by others to be the endoderm portion of the mesoderm and the endoderm. However, Schmid and Seipel counter this skepticism about whether or not the muscle cells found in ctenophores and cnidarians are true muscle cells by considering that cnidarians develop through a medusa stage and polyp stage. They observe that in the hydrozoan medusa stage there is a layer of cells that separate from the distal side of the ectoderm to form the striated muscle cells in a way that seems similar to that of the mesoderm and call this third separated layer of cells the ectocodon. They also argue that not all muscle cells are derived from the mesendoderm in bilaterians with key examples being that in both the eye muscles of vertebrates and the muscles of spiralians these cells derive from the ectodermal mesoderm rather than the endodermal mesoderm. Furthermore, Schmid and Seipel argue that since myogenesis does occur in cnidarians with the help of molecular regulatory elements found in the specification of muscles cells in bilaterians that there is evidence for a single origin for striated muscle.[27]

text: In contrast to this argument for a single origin of muscle cells, Steinmetz et al. argue that molecular markers such as the myosin II protein used to determine this single origin of striated muscle actually predate the formation of muscle cells. This author uses an example of the contractile elements present in the porifera or sponges that do truly lack this striated muscle containing this protein. Furthermore, Steinmetz et al. present evidence for a polyphyletic origin of striated muscle cell development through their analysis of morphological and molecular markers that are present in bilaterians and absent in cnidarians, ctenophores, and bilaterians. Steimetz et al. showed that the traditional morphological and regulatory markers such as actin, the ability to couple myosin side chains phosphorylation to higher concentrations of the positive concentrations of calcium, and other MyHC elements are present in all metazoans not just the organisms that have been shown to have muscle cells. Thus, the usage of any of these structural or regulatory elements in determining whether or not the muscle cells of the cnidarians and ctenophores are similar enough to the muscle cells of the bilaterians to confirm a single lineage is questionable according to Steinmetz et al. Furthermore, Steinmetz et al. explain that the orthologues of the MyHc genes that have been used to hypothesize the origin of striated muscle occurred through a gene duplication event that predates the first true muscle cells (meaning striated muscle), and they show that the MyHc genes are present in the sponges that have contractile elements but no true muscle cells. Furthermore, Steinmetz et all showed that the localization of this duplicated set of genes that serve both the function of facilitating the formation of striated muscle genes and cell regulation and movement genes were already separated into striated myhc and non-muscle myhc. This separation of the duplicated set of genes is shown through the localization of the striated myhc to the contractile vacuole in sponges while the non-muscle myhc was more diffusely expressed during developmental cell shape and change. Steinmetz et al. found a similar pattern of localization in cnidarians with except with the cnidarian N. vectensis having this striated muscle marker present in the smooth muscle of the digestive track. Thus, Steinmetz et al. argue that the pleisiomorphic trait of the separated orthologues of myhc cannot be used to determine the monophylogeny of muscle, and additionally argue that the presence of a striated muscle marker in the smooth muscle of this cnidarian shows a fundamentally different mechanism of muscle cell development and structure in cnidarians.[28]

text: Steinmetz et al. continue to argue for multiple origins of striated muscle in the metazoans by explaining that a key set of genes used to form the troponin complex for muscle regulation and formation in bilaterians is missing from the cnidarians and ctenophores, and of 47 structural and regulatory proteins observed, Steinmetz et al. were not able to find even on unique striated muscle cell protein that was expressed in both cnidarians and bilaterians. Furthermore, the Z-disc seemed to have evolved differently even within bilaterians and there is a great deal diversity of proteins developed even between this clade, showing a large degree of radiation for muscle cells. Through this divergence of the Z-disc, Steimetz et al. argue that there are only four common protein components that were present in all bilaterians muscle ancestors and that of these for necessary Z-disc components only an actin protein that they have already argued is an uninformative marker through its pleisiomorphic state is present in cnidarians. Through further molecular marker testing, Steinmetz et al. observe that non-bilaterians lack many regulatory and structural components necessary for bilaterians muscle formation and do not find any unique set of proteins to both bilaterians and cnidarians and ctenophores that are not present in earlier, more primitive animals such as the sponges and amoebozoans. Through this analysis the authors conclude that due to the lack of elements that bilaterians muscles are dependent on for structure and usage, nonbilaterian muscles must be of a different origin with a different set regulatory and structural proteins.[28]

text: In another take on the argument, Andrikou and Arnone use the newly available data on gene regulatory networks to look at how the hierarchy of genes and morphogens and other mechanism of tissue specification diverge and are similar among early deuterostomes and protostomes. By understanding not only what genes are present in all bilaterians but also the time and place of deployment of these genes, Andrikou and Arnone discuss a deeper understanding of the evolution of myogenesis.[29]

text: In their paper Andrikou and Arnone argue that to truly understand the evolution of muscle cells the function of transcriptional regulators must be understood in the context of other external and internal interactions. Through their analysis, Andrikou and Arnone found that there were conserved orthologues of the gene regulatory network in both invertebrate bilaterians and in cnidarians. They argue that having this common, general regulatory circuit allowed for a high degree of divergence from a single well functioning network. Andrikou and Arnone found that the orthologues of genes found in vertebrates had been changed through different types of structural mutations in the invertebrate deuterostomes and protostomes, and they argue that these structural changes in the genes allowed for a large divergence of muscle function and muscle formation in these species. Andrikou and Arnone were able to recognize not only any difference due to mutation in the genes found in vertebrates and invertebrates but also the integration of species specific genes that could also cause divergence from the original gene regulatory network function. Thus, although a common muscle patterning system has been determined, they argue that this could be due to a more ancestral gene regulatory network being coopted several times across lineages with additional genes and mutations causing very divergent development of muscles. Thus it seems that myogenic patterning framework may be an ancestral trait. However, Andrikou and Arnone explain that the basic muscle patterning structure must also be considered in combination with the cis regulatory elements present at different times during development. In contrast with the high level of gene family apparatuses structure, Andrikou and Arnone found that the cis regulatory elements were not well conserved both in time and place in the network which could show a large degree of divergence in the formation of muscle cells. Through this analysis, it seems that the myogenic GRN is an ancestral GRN with actual changes in myogenic function and structure possibly being linked to later coopts of genes at different times and places.[29]

text: Evolutionarily, specialized forms of skeletal and cardiac muscles predated the divergence of the vertebrate/arthropod evolutionary line.[30] This indicates that these types of muscle developed in a common ancestor sometime before 700 million years ago (mya). Vertebrate smooth muscle was found to have evolved independently from the skeletal and cardiac muscle types.