Demonstrate significant improvements in physical function

Although testosterone replacement of androgen-deficient men increases fat-free mass and maximal voluntary strength, we do not know if testosterone improves physical function. Many previous studies of testosterone replacement in older men did not examine changes in physical function. The few studies that did examine this issue suffered from methodological problems in the measurements of physical function. We believe a major reason for the failure to demonstrate improvements in physical function is that the measures of physical function used in previous studies were relatively insensitive and "threshold-dependent". The widely used measures such as 0.625 m stair climb, standing up from a chair, and 20-meter walk are tasks that require only a small fraction of an individual's maximal voluntary strength. In most healthy, older men, the baseline maximal voluntary strength is far higher than the threshold below which these measures would detect impairment. Given the low intensity of the tasks used, these relatively healthy older individuals show neither impairment in these threshold-dependent measures of physical function at baseline, nor an improvement in performance on these tasks during testosterone administration. Because testosterone improves maximal voluntary leg strength, we posit that it would improve measures of physical function that are threshold-independent, and require near-maximal strength of critical muscle groups such as the quadriceps. Another confounder of the effects of anabolic interventions on muscle function is the learning effect. For instance, subjects who are unfamiliar with weight lifting exercises often demonstrate improvements in measures of muscle performance simply because of increased familiarity with the exercise equipment and technique. Therefore, in efficacy trials of anabolic interventions, it is important to incorporate strategies to minimize the confounding influence of the learning effect. Because of the considerable test-to-test variability in tests of physical function, it is possible that previous studies (Blackman et al. 2002; Ferrando et al. 1998; Kenny et al. 2001; 2002; Morley et al. 1993; Sih et al. 1997; Snyder et al. 1999a; 1999b; Steidle et al. 2003; Tenover 1992; 2000; Urban et al. 1995) did not have adequate power to detect meaningful differences in measures of physical function between the placebo and testosterone-treated groups.

Hair Loss Prevention

Hair Loss Prevention

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