Testosterone in Aging Men

Australian researchers report that elderly men with low levels of testosterone or other sex hormones have twice the likelihood of having declining physical function over two years' time compared with their peers who have the highest hormone levels.  Benjumin Hsu, from the University of Sydney (Australia), and colleagues assessed data collected on 1,318 men ages 70 and older, enrolled in the Concord Health and Ageing Project (CHAMP), who had health assessments when they entered the study from 2005 to 2007, and again two years later. As a measure of their capacity to function independently, the men reported their ability to perform activities of daily living, such as walking, eating, getting dressed and personal hygiene. They also had blood tests that measured levels of important hormones, including their male hormones—testosterone and dihydrotestosterone—and two types of the female hormone estrogen (estradiol and estrone) that are present in men in lower amounts than in women. Also tested were measures of muscle strength: grip strength and the strength of their quadriceps muscles in the thigh. The researchers found that the lower the level of testosterone or either of the estrogens, the higher the chance that the men had worse functional abilities at the two-year follow-up evaluation.  The study authors observe that: “Low circulating [testosterone], [estradol], and [estrone] in older men were associated prospectively with functional decline over two years and this relationship is mediated by decreased muscle strength.”
In a separate study, Thomas W. Storer, from Harvard Medical School (Massachusetts, USA), and colleagues assessed the role of testosterone replacement therapy to improve measures of aerobic function ― the peak oxygen uptake and the gas exchange lactate threshold.  The researchers analyzed data from subjects in a larger randomized controlled study of men over age 65 who had low testosterone levels and difficulty performing the usual physical activities of daily living. For 6 months, 28 men in one group received 10 milligrams of testosterone gel and 36 men in a second group received a placebo gel. All subjects completed a cycle exercise test to measure their peak aerobic fitness before and after the 6 month study.  The men taking testosterone displayed a slight improvement in aerobic fitness while those taking placebo showed a slight decline. This small increase in aerobic capacity in the testosterone group eliminated the expected decrease that men generally experience with natural aging.  Among the men taking testosterone, the age-related decline in the peak oxygen uptake was 3.4 times less than expected, while the rate of decline among the men taking placebo accelerated to nearly twice the expected rate. The decrease in gas exchange lactate threshold was significantly smaller in the testosterone group than in the placebo group. The study authors conclude that: “Testosterone therapy in mobility-limited older men was associated with improved VO2peak and attenuated its age-related decline.”