The effects of short-term resistance training on endocrine function in men and women

Abstract

This investigation examined hormonal adaptations to acute resistance exercise and determined whether training adaptations are observed within an 8-week period in untrained men and women. The protocol consisted of a 1-week pre-conditioning orientation phase followed by 8 weeks of heavy resistance training. Three lower-limb exercises for the quadriceps femoris muscle group (squat, leg press, knee extension) were performed twice a week (Monday and Friday) with every other Wednesday used for maximal dynamic 1 RM strength testing. Blood samples were obtained pre-exercise (Pre-Ex), immediately post-exercise (IP), and 5 min post-exercise (5-P) during the first week of training (T-1), after 6 weeks (T-2) and 8 weeks (T-3) of training to determine blood concentrations of whole-blood lactate (LAC), serum total testosterone (TT), sex-hormone binding globulin (SHBG), cortisol (CORT) and growth hormone (GH). Serum TT concentrations were significantly (P < or = 0.05) higher for men at all time points measured. Men did not demonstrate an increase due to exercise until T-2. An increase in pre-exercise concentrations of TT were observed both for men and women at T-2 and T-3. No differences were observed for CORT between men and women; increases in CORT above pre-exercise values were observed for men at all training phases and at T-2 and T-3 for women. A reduction in CORT concentrations at rest was observed both in men and women at T-3. Women demonstrated higher pre-exercise GH values than men at all training phases; no changes with training were observed for GH concentrations. Exercise-induced increases in GH above pre-exercise values were observed at all phases of training. Women demonstrated higher serum concentrations of SHBG at all time points. No exercise-induced increases were observed in men over the training period but women increased SHBG with exercise at T-3. SHBG concentrations in women were also significantly higher at T-2 and T-3 when compared to T-1 values. Increases in LAC concentrations due to exercise were observed both for men and women for all training phases but no significant differences were observed with training. These data illustrate that untrained individuals may exhibit early-phase endocrine adaptations during a resistance training program. These hormonal adaptations may influence and help to mediate other adaptations in the nervous system and muscle fibers, which have been shown to be very responsive in the early phase of strength adaptations with resistance training.

Aging, Physical Activity, and Hormones in Women—A Review

“…Chronic endurance exercise in young women tends to result in a decrease in the resting levels of testosterone, DHEA, and estrogen (Keizer, Kuipers, de Haan, Janssen, et al, 1987;Winters, Adams, Meredith, Loan, & Lasley, 1996) but an increase in growth hormone (Weltman et al, 1992). There is considerably less information available about the effects of chronic resistance training on circulating hormone levels in young women, and the results to date are equivocal (Kraemer, Staron, et al, 1998;Westerlind, Byrnes, Freedson, & Katch, 1987). These studies clearly demonstrate that physical stress can be a powerful stimulus of the endocrine system in women.…”

Acute and Chronic Testosterone Responses to Physical Exercise and Training

“…So far, available data indicate that only young individuals are capable of altering their resting hormone concentrations (Häkkinen et al, 1988;Staron et al, 1994;Tsolakis et al, 2004), whereas middle-aged and elderly individuals show no significant changes in such parameters (Häkkinen & Pakarinen, 1994;Häkkinen et al, 2000;2001a;Izquierdo et al, 2006;Ryan et al, 1994). Increases in resting levels of testosterone seem to occur during periods of highvolume (Kramer et al, 1995;Marx et al, 2001) and high-intensity training (Staron et al, 1994;Kraemer et al, 1998;Raastad et al, 2003). These changes may occur in men (Häkkinen et al, 1988) and women (Marx et al, 2001) in response to long (Häkkinen et al, 1988;Marx et al, 2001) or short training periods (Staron et al, 1994;Kraemer et al, 1998).…”

“…Increases in resting levels of testosterone seem to occur during periods of highvolume (Kramer et al, 1995;Marx et al, 2001) and high-intensity training (Staron et al, 1994;Kraemer et al, 1998;Raastad et al, 2003). These changes may occur in men (Häkkinen et al, 1988) and women (Marx et al, 2001) in response to long (Häkkinen et al, 1988;Marx et al, 2001) or short training periods (Staron et al, 1994;Kraemer et al, 1998). The influence of training volume on chronic adaptations of basal testosterone was described in a study by Marx et al (2001), which 34 women (22 ± 5 years) were evaluated before and after performing a 24-week ST protocol.…”

Kuvvet Antrenmanlarına Bağlı Akut Laktat Üretimi

“…Çelişkili sonuçlar da mevcuttur. Aynı kuvvet antrenman programının uygulanması sonucunda bayan ve erkeklerde benzer laktat yanıtlarının olduğu da rapor edilmiştir (25,26). …”