Comparison of changes in testosterone concentrations after strength and endurance exercise in well trained men

Changes in the testosterone concentrations after single sessions of endurance and strength training were measured in seven well trained men, experienced in both forms of training. Both training sessions were rated as hard to very hard on the Borg scale. Blood samples for testosterone measurements were taken before, immediately after, and 2, 4 and 6 h after the training sessions as well as the next morning. The mean testosterone concentration increased 27% (P less than 0.02) and 37% (P less than 0.02) during the strength and endurance training session, respectively. Two hours after the training sessions the mean testosterone concentration had returned to the pre-training level and remained at that level for the length of the observation period. There were no significant differences in the changes in testosterone concentration after strength and endurance training but there were large differences in the testosterone response at the level of the individual. A high correlation (r = 0.98; P less than 0.001) for individuals was found between increases in testosterone concentration after strength and after endurance training. It was concluded that the changes in mean testosterone values followed the same timecourse after single sessions of strength and endurance training of the same duration and perceived exertion. The interindividual differences in testosterone response may be of importance for individual adaptation to training.     

No effect of short-term testosterone manipulation on exercise substrate metabolism in men.

Compared with women, men use proportionately more carbohydrate and less fat during exercise at the same relative intensity. Estrogen and progesterone have potent effects on substrate use during exercise in women, but the role of testosterone (T) in mediating substrate use is unknown. The purpose of this investigation was to assess how large variations in the concentration of blood T would impact substrate use during exercise in men. Nine healthy, active men were studied in three distinct hormonal conditions: physiological T (no intervention), low T (pharmacological suppression of endogenous T with a gonadotrophin-releasing hormone antagonist), and high T (supplementation with transdermal T). Total carbohydrate oxidation, blood glucose rate of disappearance, and estimated muscle glycogen use were assessed by using stable isotope dilution and indirect calorimetry at rest and while bicycling at approximately 60% of peak O2 consumption for 90 min. Relative to the physiological condition (T = 5.5 +/- 0.5 ng/ml), total plasma T was considerably suppressed in low T (0.8 +/- 0.1) and elevated in high T (10.9 +/- 1.1). Despite the large changes in plasma T, carbohydrate oxidation, glucose rate of disappearance, and estimated muscle glycogen use were very similar across the three conditions. There were also no differences in plasma concentrations of glucose, insulin, lactate, or free fatty acids. Plasma estradiol (E) concentrations were elevated in high T, but correlations between substrate use and plasma concentrations of T, E, or the T-to-E ratio were very weak (r2 < 0.20). In conclusion, unlike the effect of acute elevation in E to constrain carbohydrate use in women, acute changes in circulating T concentrations do not appear to alter substrate use during exercise in men.     

The effect of short-term use of testosterone enanthate on muscular strength and power in healthy young men

Use of testosterone enanthate has been shown to significantly increase strength within 6-12 weeks of administration (2, 9), however, it is unclear if the ergogenic benefits are evident in less than 6 weeks. Testosterone enanthate is classified as a prohibited substance by the World Anti-Doping Agency (WADA) and its use may be detected by way of the urinary testosterone/epitestosterone (T/E) ratio (16). The two objectives of this study were to establish (a) if injection of 3.5 mg.kg(-1) testosterone enanthate once per week could increase muscular strength and cycle sprint performance in 3-6 weeks; and (b) if the WADA-imposed urinary T/E ratio of 4:1 could identify all subjects being administered 3.5 mg.kg(-1) testosterone enanthate. Sixteen healthy young men were match-paired and were assigned randomly in a double-blind manner to either a testosterone enanthate or a placebo group. All subjects performed a structured heavy resistance training program while receiving either testosterone enanthate (3.5 mg.kg(-1)) or saline injections once weekly for 6 weeks. One repetition maximum (1RM) strength measures and 10-second cycle sprint performance were monitored at the pre (week 0), mid (week 3), and post (week 6) time points. Body mass and the urinary T/E ratio were measured at the pre (week 0) and post (week 6) time points. When compared with baseline (pre), 1RM bench press strength and total work during the cycle sprint increased significantly at week 3 (p < 0.01) and week 6 (p < 0.01) in the testosterone enanthate group, but not in the placebo group. Body mass at week 6 was significantly greater than at baseline in the testosterone enanthate group (p < 0.01), but not in the placebo group. Despite the clear ergogenic effects of testosterone enanthate in as little as 3 weeks, 4 of the 9 subjects in the testosterone enanthate group ( approximately 44%) did not test positive to testosterone under current WADA urinary T/E ratio criteria.     

The effect of resistance exercise on p53, caspase-9, and caspase-3 in trained and untrained men

Apoptosis is a programmed cell death that has been demonstrated in human and animal studies and plays an essential role to remove injured cells after acute strenuous exercise. Protein p53 plays important roles in regulating apoptosis via mitochondrial pathway. Therefore, the aims of this study were to determine the effects of acute resistance exercise (RE) on serum p53, caspase-9, and caspase-3, markers of apoptosis, and whether resistance training status influences the magnitude of the RE-induced apoptosis. Nine resistance-trained (RT) (age, 22.37 ± 1.99 years; height, 174 ± 5.04 cm; body weight, 71.32 ± 5.57 kg; and body mass index [BMI] 23.58 ± 2.05 kg·m(-2)) and 9 untrained (UT) college-age men (age, 22.25 ± 2.13 years; height, 171 ± 3.4 cm; body weight, 68.45 ± 3.23 kg; and BMI, 23.41 ± 1.08 kg·m(-2)) volunteered to participate in this study. Resistance-trained and UT men completed an RE bout consisting of 4 sets of 6 exercise at 80% of 1 repetition maximum until failure. Serum levels of p53, caspase-9, and caspase-3 were examined at preexercise (pre), immediately post (IP), 3 hours post (3 hours post), and 24 hours post RE (24 hours post). In UT, serum levels of p53, caspase-9, and caspase-3 were significantly increased at IP compared with RT. However, plasma insulin-like growth factor 1 level was higher for RT compared with UT at IP. Collectively, our data suggest the role of p53 in regulating apoptosis through mitochondrial pathway as measured by caspase-9 and caspase-3 after acute RE in UT. Our results also revealed that regular RT alters apoptosis biomarkers, especially the intrinsic pathway of apoptosis.     

Effect of timing of protein and carbohydrate intake after resistance exercise on nitrogen balance in trained and untrained young men

Background

Resistance exercise alters the post-exercise response of anabolic and catabolic hormones. A previous study indicated that the turnover of muscle protein in trained individuals is reduced due to alterations in endocrine factors caused by resistance training, and that muscle protein accumulation varies between trained and untrained individuals due to differences in the timing of protein and carbohydrate intake. We investigated the effect of the timing of protein and carbohydrate intake after resistance exercise on nitrogen balance in trained and untrained young men.

Methods

Subjects were 10 trained healthy men (mean age, 23 ± 4 years; height, 173.8 ± 3.1 cm; weight, 72.3 ± 4.3 kg) and 10 untrained healthy men (mean age, 23 ± 1 years; height, 171.8 ± 5.0 cm; weight, 64.5 ± 5.0 kg). All subjects performed four sets of 8 to 10 repetitions of a resistance exercise (comprising bench press, shoulder press, triceps pushdown, leg extension, leg press, leg curl, lat pulldown, rowing, and biceps curl) at 80% one-repetition maximum. After each resistance exercise session, subjects were randomly divided into two groups with respect to intake of protein (0.3 g/kg body weight) and carbohydrate (0.8 g/kg body weight) immediately after (P0) or 6 h (P6) after the session. All subjects were on an experimental diet that met their individual total energy requirement. We assessed whole-body protein metabolism by measuring nitrogen balance at P0 and P6 on the last 3 days of exercise training.

Results

The nitrogen balance was significantly lower in the trained men than in the untrained men at both P0 (P <0.05) and P6 (P <0.01). The nitrogen balance in trained men was significantly higher at P0 than at P6 (P <0.01), whereas that in the untrained men was not significantly different between the two periods.

Conclusion

The timing of protein and carbohydrate intake after resistance exercise influences nitrogen balance differently in trained and untrained young men.     

Fat metabolism and acute resistance exercise in trained men.

The purpose of this study was to investigate the effect of acute resistance exercise (RE) on lipolysis within adipose tissue and subsequent substrate oxidation to better understand how RE may contribute to improvements in body composition. Lipolysis and blood flow were measured in abdominal subcutaneous adipose tissue via microdialysis before, during, and for 5 h following whole body RE as well as on a nonexercise control day (C) in eight young (24 +/- 0.7 yr), active (>3 RE session/wk for at least 2 yr) male participants. Fat oxidation was measured immediately before and after RE via indirect calorimetry for 45 min. Dialysate glycerol concentration (an index of lipolysis) was higher during (RE: 200.4 +/- 38.6 vs. C: 112.4 +/- 13.1 micromol/l, 78% difference; P = 0.02) and immediately following RE (RE: 184 +/- 41 vs. C: 105 + 14.6 micromol/l, 75% difference; P = 0.03) compared with the same time period on the C day. Energy expenditure was elevated in the 45 min after RE compared with the same time period on the C day (RE: 104.4 +/- 6.0 vs. C: 94.5 +/- 4.0 kcal/h, 10.5% difference; P = 0.03). Respiratory exchange ratio was lower (RE: 0.71 +/- 0.004 vs. C: 0.85 +/- .03, 16.5% difference; P = 0.004) and fat oxidation was higher (RE: 10.2 +/- 0.8 vs. C: 5.0 +/- 1.0 g/h, 105% difference; P = 0.004) following RE compared with the same time period on the C day. Therefore, the mechanism behind RE contributing to improved body composition is in part due to enhanced abdominal subcutaneous adipose tissue lipolysis and improved whole body fat oxidation and energy expenditure in response to RE.     

The effect of exercise on circulating immunoreactive calcitonin in men

Moderate-duration exercise increases serum catecholamine and serum calcium levels and might as a result be also expected to increase the levels of circulating serum immunoreactive human calcitonin (HCT). To explore this possibility, HCT was studied during and after moderate duration symptom-limited dynamic exercise in 13 healthy males, mean age 28 +/- 6.9 (SD) years. The mean duration of exercise using the Bruce treadmill protocol was 14.1 +/- 2.2 (SD) minutes. The mean heart rate (HR) peaked at 185 +/- 6 (SD) bpm which was 96.1% of the predicted maximal HR for age. Values for HCT, uncorrected for changes in plasma volume, showed a minimal decrease in the recovery phase, whilst HCT corrected for changes in plasma volume did not alter during exercise or recovery. The serum parathyroid hormone (PTH) also did not change. At peak exercise, uncorrected but not corrected values for plasma noradrenaline, adrenaline and dopamine had increased significantly. Corrected plasma total calcium increased during recovery. In summary, dynamic weight-bearing moderate-duration exercise did not elevate HCT in healthy males.     

Hormonal responses to resistance exercise in long-term trained and untrained middle-aged men

This cross-sectional study compared hormonal responses to resistance exercise between trained and untrained men to investigate the adaptations of the endocrine system to long-term strength training in middle-aged men. Twenty-one middle-aged men were recruited for this study and matched into a strength-trained group (SG) (n = 10) and an untrained group (UG) (n = 11). In the SG, the individuals had practiced strength training for hypertrophy for at least 3 years. Upper- and lower-body muscle strength was measured with a 1 repetition maximum (1RM) test. Blood samples were collected at rest and after multiple sets of a superset strength training protocol (SSTP), with an intensity of 75% of 1RM values. With these blood samples, the levels of total testosterone (TT), free testosterone (FT), dehydroepiandrosterone (DHEA), cortisol, and sex hormone-binding globulin (SHBG) were determined. In addition, the TT-to-cortisol ratio and TT-to-SHBG ratio were calculated. There was no difference at rest between groups in hormonal values for TT, FT, DHEA, cortisol, the TT-to-SHBG ratio, and the TT-to-cortisol ratio. There were increases after SSTP in the levels of TT, FT, DHEA, and cortisol and the TT-to-SHBG ratio in the UG, but only FT increased in the SG. The SG demonstrated lower values in the TT-to-SHBG ratio after the training session. These results suggest the presence of alterations in anabolic and catabolic hormonal responses to resistance exercise in long-term trained middle-aged men, with the trained subjects demonstrating lower responsiveness in the hormone values. Long-term trained men seem to require a higher volume of training, at least similar to their daily workout, to stimulate greater hormone responses.     

Effects of age on testosterone responses to resistance exercise and musculoskeletal variables in men

This study compared serum total testosterone (TT) and free testosterone (FT) responses of young (20-26 years, n = 8), middle-aged (38-53 years, n = 7), and older (59-72 years, n = 9) men to resistance exercise. We also examined the relationships between testosterone (T) levels and strength, bone mineral density (BMD), and body composition variables for each age group. Subjects were tested for isotonic muscular strength (1 repetition maximum [1RM]), BMD (dual-energy x-ray absorptiometry [DXA]) and body composition (DXA). Each group performed an acute exercise protocol (3 sets, 10 repetitions, 80% of 1RM, 6 exercises). Blood samples were obtained at baseline, immediately postexercise, and 15 minutes postexercise for the TT and FT assays. The older age group had significantly (p < 0.05) lower T levels than the young group, but each group exhibited an increase (p < 0.05) in TT and FT immediately postexercise. Total T and FT were significantly correlated (p < 0.05) with strength in middle-aged and older men and with bone-free lean tissue mass in older men. In conclusion, middle-aged and older men showed similar relative T responses to those of younger men to a single bout of high-intensity resistance exercise. However, T levels were related to strength and muscle mass only in middle-aged or older men. On a practical application level, older men can complete a high-intensity resistance exercise program resulting in spikes in T that may attenuate age-related muscle and BMD loss.     

Hyperprolactinaemia and testosterone production. Observations in 2 men on long-term dialysis

2 men had received maintenance dialysis for more than 5 years because of uraemia. Gradual impairment of libido had led to total impotence of more than 6 months duration. Concurrently hyperprolactinaemia occurred. Bromocriptine was given for 2 and 4 months, respectively. Potency was not restored, but in 1 patient the blood transfusion requirements were halved and general well-being and strength increased. In both men, the serum prolactin levels normalized. Inversely, the low plasma testosterone levels increased during the treatment period.     

The effects of intensity of exercise on excess postexercise oxygen consumption and energy expenditure in moderately trained men and women

This experiment investigated the effects of intensity of exercise on excess postexercise oxygen consumption (EPOC) in eight trained men and eight women. Three exercise intensities were employed 40%, 50%, and 70% of the predetermined maximal oxygen consumption (VO_2max). All ventilation measured was undertaken with a standard, calibrated, open circuit spirometry system. No differences in the 40%, 50% and 70% VO_2max trials were observed among resting levels of oxygen consumption (V0₂) for either the men or the women. The men had significantly higher resting VO₂ values being 0.31 (SEM 0.01) 1·min^–1 than did the women, 0.26 (SEM 0.01) 1·min^–1 (P < 0.05). The results indicated that there were highly significant EPOC for both the men and the women during the 3-h postexercise period when compared with resting levels and that these were dependent upon the exercise intensity employed. The duration of EPOC differed between the men and the women but increased with exercise intensity: for the men 40% – 31.2 min; 50% – 42.1 min; and 70% – 47.6 min and for the women, 40% – 26.9 min; 50% – 35.6 min; and 70% – 39.1 min. The highest EPOC, in terms of both time and energy utilised was at 70% VO_2max. The regression equation for the men, where y=O₂ in litres, and x=exercise intensity as a percentage of maximum was y=0.380x + 1.9 (r ²=0.968) and for the women is y=0.374x–0.857 (r ²=0.825). These findings would indicate that the men and the women had to exercise at the same percentage of their VO_2max to achieve the maximal benefits in terms of energy expenditure and hence body mass loss. However, it was shown that a significant EPOC can be achieved at moderate to low exercise intensities but without the same body mass loss and energy expenditure.     

Short-term modulation of the exercise ventilatory response in young men.

Arterial isocapnia is a hallmark of moderate exercise in humans and is maintained even when resting arterial Pco(2) (Pa(CO(2))) is raised or lowered from its normal level, e.g., with chronic acid-base changes or acute increases in respiratory dead space. When resting ventilation and/or Pa(CO(2)) are altered, maintenance of isocapnia requires active adjustments of the exercise ventilatory response [slope of the ventilation (Ve)-CO(2) production (Vco(2)) relationship, DeltaVe/DeltaVco(2)]. On the basis of animal studies, it has been proposed that a central neural mechanism links the exercise ventilatory response to the resting ventilatory drive without need for changes in chemoreceptor feedback from rest to exercise, a mechanism referred to as short-term modulation (STM). We tested the hypothesis that STM is elicited by increased resting ventilatory drive associated with added external dead space (DS) in humans. Twelve young men were studied in control conditions and with added DS (200, 400, and 600 ml; randomized) at rest and during mild-to-moderate cycle exercise. DeltaVe/DeltaVco(2) increased progressively as DS volume increased (P < 0.0001). While resting end-tidal Pco(2) (Pet(CO(2))) increased with DS, the change in Pet(CO(2)) from rest to exercise was not increased, indicating that increased chemoreceptor feedback from rest to exercise cannot account for the greater exercise ventilatory response. We conclude that STM of the exercise ventilatory response is induced in young men when resting ventilatory drive is increased with external DS, confirming the existence of STM in humans.     

The effects of a customized over-the-counter mouth guard on neuromuscular force and power production in trained men and women

Although mouth guards were originally designed for injury prevention, even elite athletes are now using performance mouth guards to improve athletic success. Both expensive custom models and over-the-counter models are available, but the efficacy is not well known. Some athletes remain wary of the perceived potential for detriments using a mouth guard to their performance. Thus, the purpose of this study was to examine various physical performance tests when using a mouth guard including a customized over-the-counter mouth guard. Twenty-six trained men (25 ± 4 years; 1.78 ± 0.07 m; 83.3 ± 11.4 kg) and 24 trained women (23 ± 3 years; 1.65 ± 0.08 m; 62.6 ± 7.8 kg) volunteered for the investigation. The subjects completed a familiarization period and then balanced and randomized treatment conditions that included: (a) a customized Power Balance performance mouth guard (PB MG); (b) a regular over the counter boil-and-bite mouth guard (Reg MG); and (c) a no mouth guard (No MG) treatment condition. At each visit, the subjects completed a testing protocol that was sequenced in the following order: sit-and-reach flexibility, medial-lateral balance, visual reaction time, vertical jump, 10-m sprint, bench throw, and plyo press power quotient (3PQ). Heart rate and rating of perceived exertion (RPE) were recorded around the 3PQ. Significance was set at p ≤ 0.05. Expected significant sex differences existed for all power, strength, and speed variables. Bench throw power (watts) and force (newtons) were significantly higher under PB MG than either Reg MG or No MG or in both men and women. The 3PQ power and force production were higher than that for the other 2 treatments for the PB MG for men only. There were no significant differences for treatment conditions in the heart rate or RPE after the 3PQ test. Men were better able to maintain significantly higher 3PQ power production under PB MG treatment condition compared with the other 2 treatment conditions. Rate of power development was significantly higher in men for the vertical jump when using the PB MG compared with that for other treatment conditions in men only. No differences were observed in flexibility, balance, visual reaction time, or sprint time. The PB MG performance mouth guard improves performance of upper-body loaded power exercises in both men and women and lower body power exercise in men without compromising performance on any other performance parameters.     

Blood lactate production and recovery from anaerobic exercise in trained and untrained boys

Blood lactate production and recovery from anaerobic exercise were investigated in 19 trained (AG) and 6 untrained (CG) prepubescent boys. The exercises comprised 3 maximal test performances; 2 bicycle ergometer tests of different durations (15 s and 60 s), and running on a treadmill for 23.20 +/- 2.61 min to measure maximal oxygen uptake. Blood samples were taken from the fingertip to determine lactate concentrations and from the antecubital vein to determine serum testosterone. Muscle biopsies were obtained from vastus lateralis. Recovery was passive (seated) following the 60 s test but that following the treadmill run was initially active (10 min), and then passive. Peak blood lactate was highest following the 60 s test (AG, 13.1 +/- 2.6 mmol.1-1 and CG, 12.8 +/- 2.3 mmol.1-1). Following the 15 s test and the treadmill run, peak lactate values were 68.7 and 60.6% of the 60 s value respectively. Blood lactate production was greater (p less than 0.001) during the 15 s test (0.470 +/- 0.128 mmol.1-1.s-1) than during the 60 s test (0.184 +/- 0.042 mmol.1-1.s-1). Although blood lactate production was only nonsignificantly greater in AG, the amount of anaerobic work in the short tests was markedly greater (p less than 0.05-0.01) in AG than CG. Muscle fibre area (type II%) and serum testosterone were positively correlated (p less than 0.05) with blood lactate production in both short tests. Blood lactate elimination was greater (p less than 0.001) at the end of the active recovery phase than in the next (passive) phase.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estradiol and testosterone metabolic clearance and production rates during puberal development in boars

Changes in metabolic clearance rate (MCR) and production rate (PR) of estradiol-17 beta (E2) and testosterone (T) were evaluated in crossbred boars averaging 35 +/- 1, 91 +/- 3, 118 +/- 4 and 177 +/- 6 kg at 80, 160, 260 and 560 days of age, respectively. A comparison of E2 and T MCR determined in blood or plasma was made in castrate and intact boars at 180 days of age. In the two experiments, estimates of MCR of E2 and T were consistently greater (22.0 and 23.8%) in blood than in plasma. These differences were not influenced by age of boar or castration. The MCR (l X day X kg BW) for E2 and T in plasma was greater (P less than 0.05) for 80-day-old prepuberal boars than the three groups of older boars. Production rates of E2 and T were lower in boars at 80 days of age than in older boars. Thus, a reduction in the MCR and an increase in PR of E2 and T in the boar are involved in the increased concentrations of circulating steroids associated with puberal development. Difference in MCR, determined in blood and plasma for both E2 and T, suggests that the contribution of the cellular component of blood to MCR studies in pigs should not be ignored.     

The Lichfield bone study: the skeletal response to exercise in healthy young men

The skeletal response to short-term exercise training remains poorly described. We thus studied the lower limb skeletal response of 723 Caucasian male army recruits to a 12-wk training regime. Femoral bone volume was assessed using magnetic resonance imaging, bone ultrastructure by quantitative ultrasound (QUS), and bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA) of the hip. Left hip BMD increased with training (mean ± SD: 0.85 ± 3.24, 2.93 ± 4.85, and 1.89 ± 2.85% for femoral neck, Ward's area, and total hip, respectively; all P < 0.001). Left calcaneal broadband ultrasound attenuation rose 3.57 ± 0.5% (P < 0.001), and left and right femoral cortical volume by 1.09 ± 4.05 and 0.71 ± 4.05%, respectively (P = 0.0001 and 0.003), largely through the rise in periosteal volume (0.78 ± 3.14 and 0.59 ± 2.58% for right and left, respectively, P < 0.001) with endosteal volumes unchanged. Before training, DXA and QUS measures were independent of limb dominance. However, the dominant femur had higher periosteal (25,991.49 vs. 2,5572 mm(3), P < 0.001), endosteal (6,063.33 vs. 5,983.12 mm(3), P = 0.001), and cortical volumes (19,928 vs. 19,589.56 mm(3), P = 0.001). Changes in DXA, QUS, and magnetic resonance imaging measures were independent of limb dominance. We show, for the first time, that short-term exercise training in young men is associated not only with a rise in human femoral BMD, but also in femoral bone volume, the latter largely through a periosteal response.