Testosterone Physiology in Resistance Exercise and Training

Abstract

Testosterone is one of the most potent naturally secreted androgenic-anabolic hormones, and its biological effects include promotion of muscle growth. In muscle, testosterone stimulates protein synthesis (anabolic effect) and inhibits protein degradation (anti-catabolic effect); combined, these effects account for the promotion of muscle hypertrophy by testosterone. These physiological signals from testosterone are modulated through the interaction of testosterone with the intracellular androgen receptor (AR). Testosterone is important for the desired adaptations to resistance exercise and training; in fact, testosterone is considered the major promoter of muscle growth and subsequent increase in muscle strength in response to resistance training in men. The acute endocrine response to a bout of heavy resistance exercise generally includes increased secretion of various catabolic (breakdown-related) and anabolic (growth-related) hormones including testosterone. The response of testosterone and AR to resistance exercise is largely determined by upper regulatory elements including the acute exercise programme variable domains, sex and age. In general, testosterone concentration is elevated directly following heavy resistance exercise in men. Findings on the testosterone response in women are equivocal with both increases and no changes observed in response to a bout of heavy resistance exercise. Age also significantly affects circulating testosterone concentrations. Until puberty, children do not experience an acute increase in testosterone from a bout of resistance exercise; after puberty some acute increases in testosterone from resistance exercise can be found in boys but not in girls. Aging beyond 35-40 years is associated with a 1-3% decline per year in circulating testosterone concentration in men; this decline eventually results in the condition known as andropause. Similarly, aging results in a reduced acute testosterone response to resistance exercise in men. In women, circulating testosterone concentration also gradually declines until menopause, after which a drastic reduction is found. In summary, testosterone is an important modulator of muscle mass in both men and women and acute increases in testosterone can be induced by resistance exercise. In general, the variables within the acute programme variable domains must be selected such that the resistance exercise session contains high volume and metabolic demand in order to induce an acute testosterone response.

Physiological elevation of endogenous hormones results in superior strength training adaptation

“…Although the mechanisms behind this speculation are unclear, it seems logical that an additive training effect may be achieved when blood with elevated levels of testosterone and GH is directed to the working muscles during the heavy strength training. The current findings leads support to the notion that testosterone is one of the major promoters of gains in muscle mass and strength in response to strength training (Vingren et al 2010). …”

“…Therefore, exercise-induced stimulation of the endocrine system may be a trigger for additive adaptation processes in skeletal muscle cells, leading to increased content of contractile proteins. In fact, testosterone is considered the major promotor of muscle growth and subsequent increase in muscle strength and in response to strength training in men (Vingren et al 2010). …”

“…It has been suggested that the acute hormonal response induced by a single strength training session is an important contributor to muscle hypertrophy during long-term strength training (Kraemer et al 1990;Kraemer and Mazzetti 2003;Vingren et al 2010). However, there is no consensus regarding the longterm effects of the transient exercise induced increase in anabolic hormones on strength training adaptations.…”

Effect of Conjugated Linoleic Acid on Testosterone Levels In Vitro and In Vivo After an Acute Bout of Resistance Exercise

“…The testosterone and the cortisol results seem to suggest that the resistance exercise program was not markedly stressful for our subjects (i.e., young healthy physically active men). In fact, to induce an acute testosterone response, an acute resistance exercise program needs to contain higher volume and higher metabolic demand in relation of the sex and the age of the subjects tested (23). In humans, the blood level of total testosterone after CLA supplementation after the resistance exercise bouts did not increase significantly as in vitro, although the ES analysis showed a large increase in total testosterone level after CLA supplementation and a moderate increase after placebo supplementation.…”

Physical and physiological profile of Iranian world-class karate athletes

“…[20] but lower than those found in their Brazilian counterparts (28.0 ± 5.1 years) [36]. The aging of athletes has been shown to decrease strength, power, and reaction time, and consequently lead to inferior performance [41,30]. Accordingly, it appears that older athletes tend to win using decision and strategies, and they seek to avoid situations where they are at a disadvantage [35].…”