Sarcopenia is an age related decrease in the cross-sectional area of skeletal muscle fibers that consequently leads to a decline in physical function, gait speed, balance, coordination, decreased bone density, and quality of life.22 JQ1 Additionally, due to lower levels of vigorous activity, aging populations experience notably higher losses

in type II fibers than type I fibers,23 which can reduce strength, speed, power, and overall PA. Subsequently, maintenance of muscle mass and strength is imperative to maintain a high quality level of physical functioning, and attenuate measures of frailty. Muscular adaptations to exercise (increase in muscle size, cross-sectional area, and consequent strength) may counteract muscle loss and physical decline associated with sarcopenia. Thus it appears that PA plays a pivotal role in the attenuation of physical decline and can potentially improve physical functioning and quality of life with age.24 and 25 Furthermore, maintenance of adequate levels of PA can result in increased longevity, and a reduced 3-MA ic50 risk for metabolic disease along with other chronic diseases. A list of physiological changes associate with different modes of activity and their potential health outcome are listed

in Table 1.26, 27 and 28 CV disease is the major cause of death in older women.29, 30 and 31 It therefore becomes of utmost importance to decrease the risk for CV disease. Cross-sectional and intervention studies have repeatedly shown that endurance training can improve insulin sensitivity,32 and 33 lower Cell press blood pressure,34 improve lipid profiles,35, 36 and 37 and decrease body fat,36, 37 and 38 all factors related to CV disease. Furthermore, aerobic exercise has been shown to increase VO2max, an index of cardiorespiratory fitness that on average decreases 5%–15% per decade after the age of 25.39 These physiological

responses to aerobic exercise results in an increased efficiency of the system during exercise (increased stroke volume, capillary, and mitochondrial density; lower heart rate and blood pressure) and ability to better deliver oxygen and glucose to working muscles.40 In an investigation into the level of activity that may protect against CV disease mortality, Hamer and Stamatakis41 recruited 23,747 men and women without a known history of CV disease at baseline. The researchers tracked PA levels and causes of death over a period of 7.0 ± 3.0 years. By calculating a hazard ratio (HR), the authors found that a minimum of two sessions of moderate to vigorous PA per week was associated with a reduced risk of CV disease and all-cause mortality. Compared to active adults, those individuals who were inactive were at elevated risk of CV disease (HR of 1.41 vs. active: HR of 0.82) and all-cause mortality (HR of 1.50 vs. active: HR of 1.11).