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.     

The effect of aerobic exercise on the expression of genes in skeletal muscles of trained and untrained men

It is well recognized that PGC-1α protein is a key regulator of mitochondrial biogenesis. Mechanical and metabolic perturbations in a skeletal muscle during and after aerobic exercise lead to an increased expression of PGC-1α gene. This increased expression of PGC-1α gene after exercise depends on the relative workload intensity and does not depend on the fitness level. The goal of this study was to compare mRNA expression of PGC-1α, TFAM, and TFB2M regulators of mitochondrial biogenesis and FOXO1 and Atrogin-1 proteolysis-related genes in a skeletal muscle of untrained and trained men after aerobic exercise with the same relative workload. This study showed that PGC-1α gene expression after exercise was the same in the two groups, but the expression of TFAM and TFB2M genes was higher in untrained muscles than in trained ones. In contrast, the expression of FOXO1 and Atrogin-1 genes increased only in the muscles of trained men.     

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.     

Effect of prior exercise on glucose metabolism in trained men

Several studies have demonstrated that oral glucose tolerance is impaired in the immediate postexercise period. A double-tracer technique was used to examine glucose kinetics during a 2-h oral glucose (75 g) tolerance test (OGTT) 30 min after exercise (Ex, 55 min at 71 +/- 2% of peak O(2) uptake) and 24 h after exercise (Rest) in endurance-trained men. The area under the plasma glucose curve was 71% greater in Ex than in Rest (P = 0.01). The higher glucose response occurred even though whole body rate of glucose disappearance was 24% higher after exercise (P = 0.04, main effect). Whole body rate of glucose appearance was 25% higher after exercise (P = 0.03, main effect). There were no differences in total (2 h) endogenous glucose appearance (R(a)E) or the magnitude of suppression of R(a)E, although R(a)E was higher from 15 to 30 min during the OGTT in Ex. However, the cumulative appearance of oral glucose was 30% higher in Ex (P = 0.03, main effect). There were no differences in glucose clearance rate or plasma insulin responses between the two conditions. These results suggest that adaptations in splanchnic tissues by prior exercise facilitate greater glucose output from the splanchnic region after glucose ingestion, resulting in a greater glycemic response and, consequently, a greater rate of whole body glucose uptake.     

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.     

Effects of acute exercise and detraining on insulin action in trained men

Seven endurance-trained subjects [maximal O2 consumption (VO2max) 64 +/- 1 (SE) ml.min-1.kg-1] underwent sequential hyperinsulinemic euglycemic clamps on three occasions: 1) in the "habitual state" 15 h after the last training bout (C), 2) after 60 min of bicycle exercise at 72 +/- 3% of VO2max performed in the habitual state (E), and 3) 5 days after the last ordinary training session (detrained, DT). Sensitivity for insulin-mediated whole-body glucose uptake was not affected by acute exercise [insulin concentrations eliciting 50% of maximal insulin-mediated glucose uptake being 44 +/- 2 (C) vs. 46 +/- 3 (E) microU/ml] but was decreased after detraining (54 +/- 2 microU/ml, P less than 0.05) to levels comparable to those found in untrained subjects [Am. J. Physiol. 254 (Endocrinol. Metab. 17): E248-E259, 1988]. Near-maximal insulin-mediated glucose uptake (responsiveness) was higher than in untrained subjects and not influenced by acute exercise or detraining [13.4 +/- 1.2 (C), 12.2 +/- 0.9 (E), and 12.2 +/- 0.3 (DT) mg.min-1.kg-1]. Calculated by indirect calorimetry, the glucose-to-glycogen conversion was not influenced by E but was reduced during detraining (P less than 0.05) yet remained higher than previously found in untrained subjects (P less than 0.05). However, only on E days did muscle glycogen increase during insulin infusion. Glycogen synthase activity was increased on E and decreased on DT compared with C days.(ABSTRACT TRUNCATED AT 250 WORDS)     

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 epinephrine on muscle glycogenolysis during exercise in trained men

Febbraio, M. A., D. L. Lambert, R. L. Starkie, J. Proietto,and M. Hargreaves. Effect of epinephrine on muscle glycogenolysis during exercise in trained men. J. Appl.Physiol. 84(2): 465-470, 1998.To test thehypothesis that an elevation in circulating epinephrine increasesintramuscular glycogen utilization, six endurance-trained men performedtwo 40-min cycling trials at 71 ± 2% of peak oxygen uptake in20-22°C conditions. On the first occasion, subjects wereinfused with saline throughout exercise (Con). One week later, afterdetermination of plasma epinephrine levels in Con, subjects performedthe second trial (Epi) with an epinephrine infusion, which resulted ina twofold higher (P < 0.01) plasmaepinephrine concentration in Epi compared with Con. Although oxygenuptake was not different when the two trials were compared, respiratoryexchange ratio was higher throughout exercise in Epi compared with Con(0.93 ± 0.01 vs. 0.89 ± 0.01; P < 0.05). Muscle glycogenconcentration was not different when the trials were comparedpreexercise, but the postexercise value was lower(P < 0.01) in Epi compared with Con.Thus net muscle glycogen utilization was greater during exercise withepinephrine infusion (224 ± 37 vs. 303 ± 30 mmol/kg for Con andEpi, respectively; P < 0.01). Inaddition, both muscle and plasma lactate and plasma glucoseconcentrations were higher (P < 0.05) in Epi compared with Con. These data indicate that intramuscularglycogen utilization, glycolysis, and carbohydrate oxidation areaugmented by elevated epinephrine during submaximal exercise in trainedmen.

     

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.     

Metabolic changes following eccentric exercise in trained and untrained men

The effects of one 45-min bout of high-intensity eccentric exercise (250 W) were studied in four male runners and five untrained men. Plasma creatine kinase (CK) activity in these runners was higher (P less than 0.001) than in the untrained men before exercise and peaked at 207 IU/ml 1 day after exercise, whereas in untrained men the maximum was 2,143 IU/ml 5 days after exercise. Plasma interleukin-1 (IL-1) in the trained men was also higher (P less than 0.001) than in the untrained men before exercise but did not significantly increase after exercise. In the untrained men, IL-1 was significantly elevated 3 h after exercise (P less than 0.001). In the untrained group only, 24-h urines were collected before and after exercise while the men consumed a meat-free diet. Urinary 3-methylhistidine/creatinine in the untrained group rose significantly from 127 mumol/g before exercise to 180 mumol/g 10 days after exercise. The results suggest that in untrained men eccentric exercise leads to a metabolic response indicative of delayed muscle damage. Regularly performed long distance running was associated with chronically elevated plasma IL-1 levels and serum CK activities without acute increases after an eccentric exercise bout.     

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.     

Effects of prolonged exercise in highly trained traumatic paraplegic men

This study investigated the cardiovascular and metabolic responses to prolonged wheelchair exercise in a group of highly trained, traumatic paraplegic men. Six endurance-trained subjects with spinal cord lesions from T10 to T12/L3 underwent a maximal incremental exercise test in which they propelled their own track wheelchairs on a motor-driven treadmill to exhaustion to determine maximal O2 uptake (VO2max) and related variables. One week later each subject exercised in the same wheelchair on a motorized treadmill at 60-65% of VO2max for 80 min in a thermoneutral environment (dry bulb 22 degrees C, wet bulb 17 degrees C). Approximately 10 ml of venous blood were withdrawn both 20 min and immediately before exercise (0 min), after 40 and 80 min of exercise, and 20 min postexercise. Venous blood was analyzed for hematocrit (Hct), hemoglobin (Hb), and lactate, and the separated plasma was analyzed for glucose, K+, Na+, Cl-, free fatty acid (FFA), and osmolality. VO2, CO2 production (VCO2), minute ventilation (VE), respiratory exchange ratio (R), net efficiency, and wheelchair strike rate were determined at four intervals throughout the exercise period. Data were analyzed with an analysis of variance repeated-measures design and a Scheffé post hoc test. VO2max was 47.5 +/- 1.8 (SE) ml.min-1.kg-1 with maximal VE BTPS and maximal heart rate (HR) being 100.1 +/- 3.8 l/min and 190 +/- 1 beats/min, respectively. During prolonged exercise there were no significant changes in VO2, VCO2, VE, R, net efficiency, wheelchair strike rate, and lactate, glucose, and Na+ concentrations. Significant increases occurred in HR, FFA, K+, Cl-, osmolality, Hb, and Hct throughout exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potassium and ventilation during incremental exercise in trained and untrained men.

The present investigation was undertaken to examine the relationship between plasma potassium (K+) and ventilation (VE) during incremental exercise. Blood lactate (La-) was also measured, and its relationship with VE was similarly examined. Eight endurance-trained triathletes (ET) and eight active but untrained men (UT) performed an incremental cycling test to volitional fatigue. Maximal oxygen uptake (VO2max) and oxygen uptake (VO2) at lactate threshold (LT) were higher (P < 0.05) in ET (VO2max 4.60 +/- 0.10 l/min, LT 2.77 +/- 0.85 l/min) than in UT (VO2max 3.79 +/- 0.11 l/min, LT 1.94 +/- 0.60 l/min). There were significant (P < 0.05) correlations between VE and K+ (UT 0.87, ET 0.77) and between VE and La- (UT 0.88, ET 0.85). In ET compared with UT, VE was lower (P < 0.05) at 330 W, K+ was lower at 300 and 330 W, and La- was lower at all work loads > 90 W. These results suggest that K+ may make an important contribution to the regulation of ventilation during incremental exercise and that endurance training attenuates the K+ response to that exercise.     

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.     

Beta-blockade reduces tidal volume during heavy exercise in trained and untrained men

The effects of beta-blockade on tidal volume (VT), breath cycle timing, and respiratory drive were evaluated in 14 endurance-trained [maximum O2 uptake (VO2max) approximately 65 ml X kg-1 X min-1] and 14 untrained (VO2max approximately 50 ml X kg-1 X min-1) male subjects at 45, 60, and 75% of unblocked VO2max and at VO2max. Propranolol (PROP, 80 mg twice daily), atenolol (ATEN, 100 mg once a day) and placebo (PLAC) were administered in a randomized double-blind design. In both subject groups both drugs attenuated the increases in VT associated with increasing work rate. CO2 production (VCO2) was not changed by either drug during submaximal exercise but was reduced in both subject groups by both drugs during maximal exercise. The relationship between minute ventilation (VE) and VCO2 was unaltered by either drug in both subject groups due to increases in breathing frequency. In trained subjects VT was reduced during maximal exercise from 2.58 l/breath on PLAC to 2.21 l/breath on PROP and to 2.44 l/breath on ATEN. In untrained subjects VT at maximal exercise was reduced from 2.30 l/breath on PLAC to 1.99 on PROP and 2.12 on ATEN. These observations indicate that 1) since VE vs. VCO2 was not altered by beta-adrenergic blockade, the changes in VT and f did not result from a general blunting of the ventilatory response to exercise during beta-adrenergic blockade; and 2) blockade of beta 1- and beta 2-receptors with PROP caused larger reductions in VT compared with blockade of beta 1-receptors only (ATEN), suggesting that beta 2-mediated bronchodilation plays a role in the VT response to heavy exercise.     

Effect of ultra-endurance exercise on left ventricular performance and plasma cytokines in healthy trained men

The purpose of this study was to investigate the effect of ultra-endurance exercise on left ventricular (LV) performance and plasma concentration of interleukin (IL)-6, IL-10, IL-18 and tumour necrosis factor alpha (TNF-α) as well as to examine the relationships between exercise-induced changes in plasma cytokines and those in echocardiographic indices of LV function in ultra-marathon runners. Nine healthy trained men (mean age 30±1.0 years) participated in a 100-km ultra-marathon. Heart rate, blood pressure, ejection fraction (EF), fractional shortening (FS), ratio of early (E) to late (A) mitral inflow peak velocities (E/A), ratio of early (E’) to late (A’) diastolic mitral annulus peak velocities (E’/A’) and E-wave deceleration time (DT) were obtained by echocardiography before, immediately after and in the 90th minute of the recovery period. Blood samples were taken before each echocardiographic evaluation. The ultra-endurance exercise caused significant increases in plasma IL-6, IL-10, IL-18 and TNF-α. Echocardiography revealed significant decreases in both E and the E/A ratio immediately after exercise, without any significant changes in EF, FS, DT or the E/E’ ratio. At the 90th minute of the recovery period, plasma TNF-α and the E/A ratio did not differ significantly from the pre-exercise values, whereas FS was significantly lower than before and immediately after exercise. The increases in plasma TNF-α correlated with changes in FS (r=0.73) and DT (r=-0.73). It is concluded that ultra-endurance exercise causes alterations in LV diastolic function. The present data suggest that TNF-α might be involved in this effect.