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  • Journal
    Summary: Emerging public health information suggests that to reach the U.S. Centers for Disease Control and Prevention's goal to improve health and fitness, prevent disease and disability, and enhance quality of life for all Americans through physical activity, we must create a culture that integrates physical activity into our daily lives. The ACSM American Fitness Index[tm] (AFI) program developed a valid and reliable measure of health and community fitness at a metropolitan level to: Provide community leaders with information to understand the personal, community, societal and environmental influences on physical activity and healthy eating; Develop strategies to promote physical activity at multiple levels of influence; and Take action through local community mobilization with the AFI Community Action Guide, health promotion partners and other best practices.
    Digital Access 2008-
  • Article
    Homsher E, Kean CJ, Wallner A, Garibian-Sarian V.
    J Gen Physiol. 1979 May;73(5):553-67.
    Unpoisoned sartorius muscles of Rana temporaria were stimulated tetanically in isometric contractions lasting up to 20 s at 0 degrees C. The observed enthalpy (heat + work) production and the chemical changes in these contractions were measured, and a comparison was made between the observed enthalpy and the enthalpy that could be explained by the chemical changes. Like earlier workers, we found that the only net known reaction of energetic significance that occurred was dephosphorylation of n-phosphoryl creatine (PC), and we found a significant evolution of unexplained enthalpy (UE), a portion of the observed enthalpy which could not be explained by the extent of PC dephosphorylation. We measured the total quantity and the rate of production of the UE, and we found that its rate of evolution, which was most rapid during the first 750 ms of contraction, fell progressively to zero by the 8th s of contraction: i.e., after 8 s of contraction, all the observed enthalpy is adequately explained by PC dephosphorylation. The time-course of evolution of the UE was slower than that of the labile enthalpy (a component of the enthalpy evolved in isometric contraction whose rate of production declines exponentially at approximately 1 s-1). We conclude that, although the magnitudes of these enthalpy quantities may be similar, they are not derived from the same chemical reaction in muscle.
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