EMG, muscle fibre and force production characteristics during a 1 year training period in elite weight-lifters

The effects of a 1 year training period on 13 elite weight-lifters were investigated by periodical tests of electromyographic, muscle fibre and force production characteristics. A statistically non-significant increase of 3.5% in maximal isometric strength of the leg extensors, from 4841 +/- 1104 to 5010 +/- 1012 N, occurred over the year. Individual changes in the high force portions of the force-velocity curve correlated (p less than 0.05-0.01) with changes in weight-lifting performance. Training months 5-8 were characterized by the lowest average training intensity (77.1 +/- 2.0%), and this resulted in a significant (p less than 0.05) decrease in maximal neural activation (IEMG) of the muscles, while the last four month period, with only a slightly higher average training intensity (79.1 +/- 3.0%), led to a significant (p less than 0.01) increase in maximum IEMG. Individual increases in training intensity between these two training periods correlated with individual increases both in muscular strength (p less than 0.05) and in the weight lifted in the clean & jerk (p less than 0.05). A non-significant increase of 3.9% in total mean muscle fibre area occurred over the year. The present findings demonstrate the limited potential for strength development in elite strength athletes, and suggest that the magnitudes and time courses of neural and hypertrophic adaptations in the neuromuscular system during their training may differ from those reported for previously untrained subjects. The findings additionally indicate the importance of training intensity for modifying training responses in elite strength athletes.     

Aldosterone and prolactin response to exercise in the heat in circumpubertal boys.

Thermoregulatory responses to exercise in the heat, especially sweating pattern, differ between children and adults. To determine whether such differences may be related to hormonal responses and to assess the possible association between this response and physical maturation, three groups of circumpubertal boys cycled at 50% of maximal O2 uptake (three 20-min bouts with 10 min of rest between bouts) in 42 degrees C at 20% relative humidity. On the basis of Tanner staging, 11 were prepubertal (PP), 12 midpubertal (MP), and 7 late pubertal (LP). Water ingestion was encouraged to minimize dehydration. Venous blood was sampled before and immediately after the session. Changes in heart rate, rectal temperature, and percent decrease in plasma volume did not differ among groups. There was no change in plasma osmolality in any of the groups. Resting testosterone concentrations were higher with increased level of physical maturity (PP = 0.4 +/- 0.1, MP = 8.2 +/- 1.9, LP = 13.8 +/- 1.2 nmol/l; P less than 0.05). In all groups, both aldosterone (ALD) and prolactin (PRL) markedly increased after exercise in the heat (ALD: PP = 161 +/- 40 vs. 1,289 +/- 263, MP = 173 +/- 47 vs. 1,245 +/- 153, LP = 250 +/- 76 vs. 1,681 +/- 400 pmol/l; PRL: PP = 8.1 +/- 1.2 vs. 24.9 +/- 4.2, MP = 8.8 +/- 1.0 vs. 22.0 +/- 8.9, LP = 8.4 +/- 0.8 vs. 39.0 +/- 3.6 micrograms/l; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Normal inhibition by somatostatin of glucose-stimulated B cell secretion in the obese subjects

Aim of the present study was to evaluate whether the inhibitory effect of somatostatin on pancreatic B-cell secretion is normal in nondiabetic obese subjects. For this purpose plasma C-peptide concentrations were measured in 10 nondiabetic obese subjects and 10 nonobese healthy controls during a 4-h hyperglycemic (11 mmol/l) glucose clamp. Somatostatin was infused (2.5 nmol/min) during the third hour of the study period in order to inhibit glucose-stimulated B-cell secretion. Fasting C-peptide averaged 0.46 +/- 0.04 nmol/l (mean +/- SEM) in nonobese subjects, and 0.85 +/- 0.08 nmol/l in obese patients (P less than 0.001). In the period 0-120 min the area under the plasma C-peptide curve was significantly higher in obese than in nonobese subjects (292 +/- 23 vs. 230 +/- 17 nmol/l x 120 min, P less than 0.05), however, in the last 20 min of the glucose infusion period without somatostatin (100-120 min) plasma C-peptide was not significantly different in the two groups (2.94 +/- 0.32 nmol/l in nonobese subjects and 3.21 +/- 0.19 nmol/l in obese patients, p = NS). During somatostatin infusion while maintaining hyperglycemia, plasma C-peptide decreased in both groups, and in the period 160-180 min it averaged 0.89 +/- 0.12 nmol/l in control subjects and 0.93 +/- 0.08 nmol/l in obese patients (P = NS), with a percent reduction similar in the two groups (70 +/- 2% in controls and 71 +/- 2% in obese patients). After discontinuing somatostatin infusion, plasma C-peptide increased to concentrations which were higher in obese than in nonobese subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of training on muscle metabolism during treadmill sprinting

Sixteen subjects volunteered for the study and were divided into a control (4 males and 4 females) and experimental group (4 males and 4 females, who undertook 8 wk of sprint training). All subjects completed a maximal 30-s sprint on a nonmotorized treadmill and a 2-min run on a motorized treadmill at a speed designed to elicit 110% of maximum oxygen uptake (110% run) before and after the period of training. Muscle biopsies were taken from vastus lateralis at rest and immediately after exercise. The metabolic responses to the 110% run were unchanged over the 8-wk period. However, sprint training resulted in a 12% (P less than 0.05) and 6% (NS) improvement in peak and mean power output, respectively, during the 30-s sprint test. This improvement in sprint performance was accompanied by an increase in the postexercise muscle lactate (86.0 +/- 26.4 vs. 103.6 +/- 24.6 mmol/kg dry wt, P less than 0.05) and plasma norepinephrine concentrations (10.4 +/- 5.4 vs. 12.1 +/- 5.3 nmol/l, P less than 0.05) and by a decrease in the postexercise blood pH (7.17 +/- 0.11 vs. 7.09 +/- 0.11, P less than 0.05). There was, however, no change in skeletal muscle buffering capacity as measured by the homogenate technique (67.6 +/- 6.5 vs. 71.2 +/- 4.5 Slykes, NS).     

Training-specific changes in cardiac structure and function: a prospective and longitudinal assessment of competitive athletes.

This prospective, longitudinal study examined the effects of participation in team-based exercise training on cardiac structure and function. Competitive endurance athletes (EA, n = 40) and strength athletes (SA, n = 24) were studied with echocardiography at baseline and after 90 days of team training. Left ventricular (LV) mass increased by 11% in EA (116 +/- 18 vs. 130 +/- 19 g/m(2); P < 0.001) and by 12% in SA (115 +/- 14 vs. 132 +/- 11 g/m(2); P < 0.001; P value for the compared Delta = NS). EA experienced LV dilation (end-diastolic volume: 66.6 +/- 10.0 vs. 74.7 +/- 9.8 ml/m(2), Delta = 8.0 +/- 4.2 ml/m(2); P < 0.001), enhanced diastolic function (lateral E': 10.9 +/- 0.8 vs. 12.4 +/- 0.9 cm/s, P < 0.001), and biatrial enlargement, while SA experience LV hypertrophy (posterior wall: 4.5 +/- 0.5 vs. 5.2 +/- 0.5 mm/m(2), P < 0.001) and diminished diastolic function (E' basal lateral LV: 11.6 +/- 1.3 vs. 10.2 +/- 1.4 cm/s, P < 0.001). Further, EA experienced right ventricular (RV) dilation (end-diastolic area: 1,460 +/- 220 vs. 1,650 +/- 200 mm/m(2), P < 0.001) coupled with enhanced systolic and diastolic function (E' basal RV: 10.3 +/- 1.5 vs. 11.4 +/- 1.7 cm/s, P < 0.001), while SA had no change in RV parameters. We conclude that participation in 90 days of competitive athletics produces significant training-specific changes in cardiac structure and function. EA develop biventricular dilation with enhanced diastolic function, while SA develop isolated, concentric left ventricular hypertrophy with diminished diastolic relaxation.     

Suppression of endogenous testosterone production attenuates the response to strength training: a randomized, placebo-controlled, and blinded intervention study

We hypothesized that suppression of endogenous testosterone would inhibit the adaptations to strength training in otherwise healthy men. Twenty-two young men with minor experience with strength training participated in this randomized, placebo-controlled, double-blinded intervention study. The subjects were randomized to treatment with the GnRH analog goserelin (3.6 mg) or placebo (saline) subcutaneously every 4 wk for 12 wk. The strength training period of 8 wk, starting at week 4, included exercises for all major muscles [3-4 sets per exercise x 6-10 repetitions with corresponding 6- to 10-repetition maximum (RM) loads, 3/wk]. A strength test, blood sampling, and whole body DEXA scan were performed at weeks 4 and 12. Endogenous testosterone decreased significantly (P < 0.01) in the goserelin group from 22.6 +/- 5.5 (mean +/- SD) nmol/l to 2.0 +/- 0.5 (week 4) and 1.1 +/- 0.6 nmol/l (week 12), whereas it remained constant in the placebo group. The goserelin group showed no changes in isometric knee extension strength after training, whereas the placebo group increased from 240.2 +/- 41.3 to 264.1 +/- 35.3 Nm (P < 0.05 within and P = 0.05 between groups). Lean mass of the legs increased 0.37 +/- 0.13 and 0.57 +/- 0.30 kg in the goserelin and placebo groups, respectively (P < 0.05 within and P = 0.05 between groups). Body fat mass increased 1.4 +/- 1.0 kg and decreased 0.6 +/- 1.2 kg in the goserelin and placebo groups, respectively (P < 0.05 within and between groups). We conclude that endogenous testosterone is of paramount importance to the adaptation to strength training.     

Subnormal serum testosterone levels in male internal medicine residents.

The consequences of sleep deprivation and stress in residency training have not been quantified. In the course of assembling a control group for other studies, we unexpectedly observed a significant (P less than 0.005) and marked depression of serum testosterone levels in healthy male internal medicine residents (means = 11.8 +/- 1.1 nmol/L, n = 7) compared with other hospital personnel (means = 20.6 +/- 5.3 nmol/L, n = 18). Testosterone concentrations in the two groups were entirely nonoverlapping, while luteinizing hormone levels were not significantly different. We conclude that the stress of residency training leads to a quantifiable depression of gonadal function, and that gonadal steroid concentrations may be useful in evaluating measures intended to reduce that stress.     

Development of muscle strength in relation to training level and testosterone in young male soccer players.

Isometric and functional strength of ninety-eight 11-yr-old male soccer players at an elite (E) and nonelite (NE) level were determined (3-4 times) through a 2-yr period, and the changes were related to growth and maturation. The initial isometric strength for extension with dominant leg [1,502 +/- 35 (E) vs. 1,309 +/- 39 (NE) N], extension with nondominant leg (1,438 +/- 37 vs. 1,267 +/- 45 N), extension with both legs (2,113 +/- 76 vs. 1,915 +/- 72 N), back muscles (487 +/- 11 vs. 414 +/- 10 N), abdominal muscles (320 +/- 9 vs. 294 +/- 8 N), and handgrip (304 +/- 10 vs. 259 +/- 8 N) increased by 15-40% during the period. Broad jump increased (P < 0. 05) by 15 (E) and 10% (NE). The E players had higher (P < 0.05) initial isometric strength and broad jump performance compared with NE players, and differences were maintained throughout the period (multiple ANOVA for repeated measures) also when adjustment was made for age, dimensions, testosterone, and insulin-like growth factor I (generalized estimating equations analyses). The development of strength for both E and NE players together was significantly (P < 0. 001) related to changes in serum testosterone concentrations. The present data indicate that testosterone is important for development of strength in young boys and that, independent of serum testosterone concentration, E players have developed greater muscle strength compared with NE players.     

Gonadal dysfunction in the spontaneously diabetic BB rat: alterations of testes morphology, serum testosterone and LH

Serum testosterone, luteinizing hormone (LH), testicular histology and ultrastructure were examined in 91 spontaneously diabetic BB, semi-starved, and control Wistar rats. Between 80-120 days of age serum testosterone was decreased (1.67 +/- .25 vs. 2.95 +/- .48 ng/ml; P less than .05) in the BB rats compared to controls but not different from semi-starved rats. LH values were similar in control and BB rats (49.4 +/- 10.9 vs. 46.8 +/- 6.2 ng/ml). Abnormal lipid droplets were noted within Leydig cells at this period. From 121-150 days of age serum testosterone was lower in BB (1.38 +/- .23 vs. 3.42 +/- .45 vs. 2.94 +/- .81 ng/ml; P less than .05) than controls or semi-starved rats. Serum LH was not significantly higher in controls than in BB rats (63.2 +/- 7.4 vs. 36.6 +/- 12 ng/ml; P = NS). Between 151-200 days of age, there was further lipid accumulation in Leydig cells in the BB rat and occasional epithelial disorganization. After 200 days, serum testosterone decreased (P less than .05) to similar levels in both control and BB rats (1.42 +/- .87 vs. 1.22 +/- .25; P = NS) and was similar in BB rats after 250 days (1.02 +/- .2 ng/ml). After 250 days of age Leydig cell morphology appeared relatively normal but marked alterations were apparent in Sertoli cells, germ cells and morphology of the tubule wall.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum hormones and physical performance capacity in young boy athletes during a 1-year training period

Serum hormones and physical performance capacity in boy athletes (AG; n = 19) were investigated during a 1-year training period (between the ages of 11.6 and 12.6 years). Six young untrained boys served as the control group (CG). The mean serum testosterone concentration increased significantly in AG (P less than 0.05) following the training period from 2.92 nmol.l-1, SD 1.04 to 5.81 nmol.l-1, SD 1.33. Significant differences were not observed in the cortisol, sex hormone binding globulin and growth hormone levels during the follow-up period. The AG clearly increased speed (P less than 0.001), speed-strength (P less than 0.01-P less than 0.001) and anaerobic capacity (P less than 0.001) whereas CG had only slight increases (NS) in physical performance capacity during a 1-year period. During the last 6-month training period significant positive correlations (r = 0.49-0.58; P less than 0.05-P less than 0.01) were observed in AG between the relative changes in testosterone, testosterone:cortisol ratio and growth hormone and the relative performance change in speed, maximal isometric force and endurance, respectively. At the end of the period significant positive correlations were observed in all subjects between the level of testosterone and speed-strength (r = 0.52-0.64; P less than 0.01-P less than 0.001) and anaerobic capacity (r = 0.49; P less than 0.05). It was concluded that an increase in anabolic activity with the synchronous training already has positive effects on trainability and physical performance capacity at an early stage in puberty.     

Effects of strength training on muscle power and serum hormones in middle-aged and older men.

Effects of 16-wk strength training on maximal strength and power performance of the arm and leg muscles and serum concentrations [testosterone (T), free testosterone (FT), and cortisol] were examined in 11 middle-aged (M46; 46 +/- 2 yr) and 11 older men (M64; 64 +/- 2 yr). During the 16-wk training, the relative increases in maximal strength and muscle power output of the arm and leg muscles were significant in both groups (P < 0.05-0.001), with no significant differences between the two groups. The absolute increases were higher (P < 0.01-0.05) in M46 than in M64 mainly during the last 8 wk of training. No significant changes were observed for serum T and FT concentrations. Analysis of covariance showed that, during the 16-wk training period, serum FT concentrations tended to decrease in M64 and increase in M46 (P < 0.05). However, significant correlations between the mean level of individual serum T and FT concentrations and the individual changes in maximal strength were observed in a combined group during the 16-wk training (r = 0.49 and 0.5, respectively; P < 0.05). These data indicate that a prolonged total strength-training program would lead to large gains in maximal strength and power load characteristics of the upper and lower extremity muscles, but the pattern of maximal and power development seemed to differ between the upper and lower extremities in both groups, possibly limited in magnitude because of neuromuscular and/or age-related endocrine impairments.     

Neuromuscular adaptations and serum hormones in women during short-term intensive strength training

The effects were investigated in ten women of intensive heavy resistance strength training lasting for 3 weeks on electromyographic (EMG) activity, muscle cross-sectional area (CSA) and voluntary force production characteristics of leg extensor muscles. Blood samples for the determinations of serum hormones were taken from five of the subjects. Significant increases occurred in the higher force portions of the isometric force-time curve with an increase of 9.7 (SD 8.4)% (P less than 0.01) in maximal peak force. An increase of 15.8 (SD 20.9)% (P less than 0.05) took place also in the maximal neural activation (integrated EMG) of the trained muscles, while an enlargement of 4.6 (SD 7.4)% (P less than 0.05) occurred in the CSA of the quadriceps femoris muscle. Maximal force per muscle CSA increased significantly (P less than 0.05). No statistically significant changes were observed during the training in the mean concentrations of serum testosterone, free testosterone, cortisol and sex hormone binding globulin (SHBG). The individual concentrations of serum testosterone:SHBG ratio correlated with the individual changes obtained during the training in the muscle CSA (r = 0.99; P less than 0.01). The present findings in women indicated that the increases in maximal strength during short-term but intensive strength training were primarily due to the increased voluntary activation of the trained muscles, while muscle hypertrophy remained limited in magnitude. Large interindividual differences in women in serum testosterone concentrations could indicate corresponding differences in muscle hypertrophy and strength development even during a short-term but intensive strength training period.     

Effect of oral DHEA on serum testosterone and adaptations to resistance training in young men.

This study examined the effects of acute dehydroepiandrosterone (DHEA) ingestion on serum steroid hormones and the effect of chronic DHEA intake on the adaptations to resistance training. In 10 young men (23 +/- 4 yr old), ingestion of 50 mg of DHEA increased serum androstenedione concentrations 150% within 60 min (P < 0.05) but did not affect serum testosterone and estrogen concentrations. An additional 19 men (23 +/- 1 yr old) participated in an 8-wk whole body resistance-training program and ingested DHEA (150 mg/day, n = 9) or placebo (n = 10) during weeks 1, 2, 4, 5, 7, and 8. Serum androstenedione concentrations were significantly (P < 0.05) increased in the DHEA-treated group after 2 and 5 wk. Serum concentrations of free and total testosterone, estrone, estradiol, estriol, lipids, and liver transaminases were unaffected by supplementation and training, while strength and lean body mass increased significantly and similarly (P < 0.05) in the men treated with placebo and DHEA. These results suggest that DHEA ingestion does not enhance serum testosterone concentrations or adaptations associated with resistance training in young men.     

Lipoproteins status in professional football players after period of vacation and one month after a new intensive training program

Plasmatic lipoproteins were evaluated in a group of 11 professional football-players after a 3-week rest, and one month later, after an intensive training (characterized by a succession of aerobic and anaerobic efforts), for engaging a new competition. At day 0, total cholesterol (TC = 4.4 +/- .04 mmol/l), triglycerides (TG = .6 +/- .04 mmol/l), and LDL-TC (2.54 +/- .18 mmol/l) were significantly decreased versus sex and age matched sedentary subjects (TC = 5.13 +/- .2 mmol/l, P less than .02; TG = .99 +/- . mmol/l, P less than .01; LDL-CT = 3.26 +/- .2 mmol/l, P less than .02). HDL-TC was increased (1.50 +/- .06 vs 1.30 +/- .05 mmol/l, P less than .05). The apoprotein A1 (apoA1) was higher in football-players (1.5 +/- .06 vs 1.16 g/l, P less than .001), while the apoprotein B (apoB) was lower (.6 +/- .03 vs .88 +/- .04 g/l, P less than .001). Even after 3 weeks of rest, the football-players lipoproteins were still identical to aerobic elite-athletes. At day +30, after a daily training involving 2 anaerobic sequences, the maximal aerobic capacity was increased by 21%, without any change in nutritional, plasmatic and hepatic status. Weight was diminished (-0.8 kg, P less than 0.05). TC (4.14 +/- .2 mmol/l), TG less than .64 +/- .08 mmol/l), LDL-TC (3.37 +/- .17 mmol/l), apo B (.64 +/- .05 g/l) were unchanged. HDL-CT fell to controls values while apoA1 increased (1.66 +/- .06 mmol/l, P less than .001). Thus, HDL-CT/apoA1 ratio (indicating the TC content of HDL) was decreased, whereas apoB/apoA1 ratio was unchanged. The decrease of TC content of HDL was not related to dietary change nor to weight decrease. As TG were stable, the lipoprotein lipase activity could not be modified.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum hormone concentrations during prolonged training in elite endurance-trained and strength-trained athletes

A study of 1 year was performed on nine elite endurance-trained athletes (swimmers) and on eight elite strength-trained athletes (weightlifters) in order to examine the effects of training on the endocrine responses and on physical performance capacity. The measurements for the determination of serum hormone concentrations were performed at about 4-month intervals during the course of the year. The primary findings demonstrated that during the first and most intensive training period of the year in preparing for the primary competitions similar but statistically insignificant changes were observed in the concentrations of serum testosterone, free testosterone and cortisol in both the endurance-trained and strength-trained groups. After that period the changes in hormonal response over the year were infrequent and minor. A significant (p less than 0.01) decrease occurred in the strength-trained group in serum-free testosterone during the second period, which was characterized by the highest overall amount of training. Over the entire year the concentrations of serum hormones remained statistically unaltered in both groups. Slight but statistically insignificant increases of 1.2% +/- 0.8% and 2.1% +/- 5.1% were observed in the competitive performances over the year in the endurance-trained and strength-trained groups, respectively. The present findings in the two groups of elite athletes, who differed greatly with regard to the type of physiological loading, demonstrated that the overall hormonal responses both during the most intensive and during prolonged training periods were rather similar and the infrequent small changes remained well within the normal physiological range.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early-phase neuroendocrine responses and strength adaptations following eccentric-enhanced resistance training

The purpose of this study was to evaluate the early-phase muscular performance adaptations to 5 weeks of traditional (TRAD) and eccentric-enhanced (ECC+) progressive resistance training and to compare the acute postexercise total testosterone (TT), bioavailable testosterone (BT), growth hormone (GH), and lactate responses in TRAD- and ECC+-trained individuals. Twenty-two previously untrained men (22.1 +/- 0.8 years) completed 1 familiarization and 2 baseline bouts, 15 exercise bouts (i.e., 3 times per week for 5 weeks), and 2 postintervention testing bouts. Anthropometric and 1 repetition maximum (1RM) measurements (i.e., bench press and squat) were assessed during both baseline and postintervention testing. Following baseline testing, participants were randomized into TRAD (4 sets of 6 repetitions at 52.5% 1RM) or ECC+ (3 sets of 6 repetitions at 40% 1RM concentric and 100% 1RM eccentric) groups and completed the 5-week progressive resistance training protocols. During the final exercise bout, blood samples acquired at rest and following exercise were assessed for serum TT, BT, GH, and blood lactate. Both groups experienced similar increases in bench press (approximately 10%) and squat (approximately 22%) strength during the exercise intervention. At the conclusion of training, postexercise TT and BT concentrations increased (approximately 13% and 21%, respectively, p < 0.05) and GH concentrations increased (approximately 750-1200%, p < 0.05) acutely following exercise in both protocols. Postexercise lactate accumulation was similar between the TRAD (5.4 +/- 0.4) and ECC+ (5.6 +/- 0.4) groups; however, the ECC+ group's lactate concentrations were significantly lower than those of the TRAD group 30 to 60 minutes into recovery. In conclusion, TRAD training and ECC+ training appear to result in similar muscular strength adaptations and neuroendocrine responses, while postexercise lactate clearance is enhanced following ECC+ training.     

Exercise training prevents decline in stroke volume during exercise in young healthy subjects.

Stroke volume (SV) increases above the resting level during exercise and then declines at higher intensities of exercise in sedentary subjects. The purpose of this study was to determine whether an attenuation of the decline in SV at higher exercise intensities contributes to the increase in maximal cardiac output (Qmax) that occurs in response to endurance training. We studied six men and six women, 25 +/- 1 (SE) yr old, before and after 12 wk of endurance training (3 days/wk running for 40 min, 3 days/wk interval training). Cardiac output was measured at rest and during exercise at 50 and 100% of maximal O2 uptake (Vo2max) by the C2H2-rebreathing method. VO2max was increased by 19% (from 2.7 +/- 0.2 to 3.2 +/- 0.3 l/min, P less than 0.001) in response to the training program. Qmax was increased by 12% (from 18.1 +/- 1 to 20.2 +/- 1 l/min, P less than 0.01), SV at maximal exercise was increased by 16% (from 97 +/- 6 to 113 +/- 8 ml/beat, P less than 0.001) and maximal heart rate was decreased by 3% (from 185 +/- 2 to 180 +/- 2 beats/min, P less than 0.01) after training. The calculated arteriovenous O2 content difference at maximal exercise was increased by 7% (14.4 +/- 0.4 to 15.4 +/- 0.4 ml O2/100 ml blood) after training. Before training, SV at VO2max was 9% lower than during exercise at 50% VO2max (P less than 0.05). In contrast, after training, the decline in SV between 50 and 100% VO2max was only 2% (P = NS). Furthermore, SV was significantly higher (P less than 0.01) at 50% VO2max after training than it was before. Left ventricular hypertrophy was evident, as determined by two-dimensional echocardiography at the completion of training. The results indicate that in young healthy subjects the training-induced increase in Qmax is due in part to attenuation of the decrease in SV as exercise intensity is increased.     

Hormonal adaptations and modelled responses in elite weightlifters during 6 weeks of training

The concentrations of serum testosterone, sex-hormone-binding-globulin (SHBG) and luteinizing hormone (LH) were examined throughout 1-year of training in six elite weightlifters. A systems model, providing an estimation of fatigue and fitness, was applied to records of training volume and performance levels in clean and jerk. The analysis focused on a 6-week training period during which blood samples were taken at 2-week intervals. A 4-week period of intensive training (period I) could be distinguished from the following 2-week period of reduced training (period II). During period I, decreases in serum testosterone (P less than 0.05) and increases in serum LH concentrations (P less than 0.01) were observed; a significant correlation (r = 0.90, P less than 0.05) was also observed between the changes in serum LH concentration and in estimated fitness. The magnitude of LH response was not related to the change in serum androgens. On the other hand, the change in testosterone:SHBG ratio during period II was significantly correlated (r = 0.97, P less than 0.01) to the LH variations during period I. These finding suggested that the LH response indicated that the decrease in testosterone concentration was not primarily due to a dysfunction of the hypothalamic-pituitary system control, and that the fatigue/fitness status of an athlete could have influenced the LH response to the decreased testosterone concentration. The negative effect of training on hormonal balance could have been amplified by its influence on the hypothalamic-pituitary axis. A decrease in physiological stress would thus have been necessary for the completion of the effect of LH release on androgenic activity.     

Elevated oestrogen and reduced testosterone levels in the serum of male septic shock patients

The variations in oestrogen levels which occur in men with septic shock were determined and analysed in terms of the changes seen in the levels of other steroid hormones of testicular and adrenal origin. The concentrations of the hormones, oestrone (E1), oestradiol (E2), testosterone (T), delta 4-androstenedione (delta 4), cortisol (F) and progesterone (P4) were determined by radioimmunoassay. The serum levels of cholesterol, triglycerides, phospholipids and non-esterified fatty acids (NEFAs) were also determined. Two groups of male septic shock patients were studied within the first 24 h following the admission to the Intensive Care Unit. Group I (n = 24) patients died. Group II (n = 22) patients recovered. Both groups were compared to a control group (n = 44) of healthy men. In group I patients, serum E1 levels were 3900 +/- 900 pmol/l, 12-fold higher than controls (296 +/- 22 pmol/l) [P less than 0.001], serum E2 levels were 880 +/- 170 pmol/l, 6-fold above control levels (158 +/- 30 pmol/l) [P less than 0.001] and serum T levels were 1.7 +/- 0.3 nmol/l, 11-fold lower than in controls (18.7 +/- 1.9 nmol/l) [P less than 0.001]. Serum P4 and F levels were slightly increased (P less than 0.05) and delta 4 androstenedione levels were unchanged. Groups II serum estrogen levels (814 +/- 350 pmol/l) [P less than 0.01] were higher than controls and serum T levels were 2-3 times less than control levels (5.5 +/- 2 nmol/l) [P less than 0.01]. The group II serum P4, F and delta 4 androstenedione levels did not differ from control levels. The levels of cholesterol, triglycerides, phospholipids and NEFAs were all decreased to similar, significant, degrees in both groups of shock patients. The dramatic increase in E1 levels associated with the decrease in T suggests an adrenal-testicular relationship with possible potentiation of aromatization of adrenal or testicular androgens in men in septic shock. The determination of serum E1 and T during septic shock in men could form the basis for prognostic estimations of septic shock severity and for a new therapeutic approach to shock.     

Human muscle metabolism during sprint running

Biopsy samples were obtained from vastus lateralis of eight female subjects before and after a maximal 30-s sprint on a nonmotorized treadmill and were analyzed for glycogen, phosphagens, and glycolytic intermediates. Peak power output averaged 534.4 +/- 85.0 W and was decreased by 50 +/- 10% at the end of the sprint. Glycogen, phosphocreatine, and ATP were decreased by 25, 64, and 37%, respectively. The glycolytic intermediates above phosphofructokinase increased approximately 13-fold, whereas fructose 1,6-diphosphate and triose phosphates only increased 4- and 2-fold. Muscle pyruvate and lactate were increased 19 and 29 times. After 3 min recovery, blood pH was decreased by 0.24 units and plasma epinephrine and norepinephrine increased from 0.3 +/- 0.2 nmol/l and 2.7 +/- 0.8 nmol/l at rest to 1.3 +/- 0.8 nmol/l and 11.7 +/- 6.6 nmol/l. A significant correlation was found between the changes in plasma catecholamines and estimated ATP production from glycolysis (norepinephrine, glycolysis r = 0.78, P less than 0.05; epinephrine, glycolysis r = 0.75, P less than 0.05) and between postexercise capillary lactate and muscle lactate concentrations (r = 0.82, P less than 0.05). The study demonstrated that a significant reduction in ATP occurs during maximal dynamic exercise in humans. The marked metabolic changes caused by the treadmill sprint and its close simulation of free running makes it a valuable test for examining the factors that limit performance and the etiology of fatigue during brief maximal exercise.