Effects of an 8-week aerobic exercise training on saliva steroid hormones, physical capacity, and quality of life in diabetic obese men

The purpose of the study was to assess the effects of aerobic exercise training on saliva steroid hormones [i.?e., cortisol, dehydroepiandrosterone (DHEA), and testosterone], physical capacity, and quality of life in obese diabetic men. 8 abdominally obese type 2 diabetic men (59.5±1.7 years old, BMI=35.5±1.6?kg/m(2), waist circumference=119.4±3.3?cm) and 9 healthy men (57.4±1.5 years old, BMI=24.5±0.8?kg/m(2), waist circumference=92.3±1.9?cm) participated in the study. The obese diabetic men underwent 8 weeks of aerobic exercise training: twice a week 45?min sessions at 75% of peak heart rate and once a week 45?min session of intermittent exercise. Before and after training, steroid hormone concentrations were analyzed from saliva samples, physical capacity was assessed by the 6-minute walking test, and quality of life was estimated by a specific questionnaire for obese subjects. These data were compared with the data from the healthy untrained men. The basal saliva DHEA and testosterone concentrations, physical capacity, and quality of life scores of the obese diabetic men were significantly lower than those of the healthy men. Aerobic training induces a significant increase in the 6-min walking distance and improve the psychosocial impact dimension of quality of life, without modifying significantly any other parameter investigated. These data suggest that an 8-week aerobic exercise program improves physical capacity and quality of life in obese diabetic men, but was insufficient to correct the anthropometric and hormonal alterations observed in this population.     

Effect of exercise training at different intensities on fat metabolism of obese men.

The present study investigated the effect of exercise training at different intensities on fat oxidation in obese men. Twenty-four healthy male obese subjects were randomly divided in either a low- [40% maximal oxygen consumption (VO(2 max))] or high-intensity exercise training program (70% VO(2 max)) for 12 wk, or a non-exercising control group. Before and after the intervention, measurements of fat metabolism at rest and during exercise were performed by using indirect calorimetry, [U-(13)C]palmitate, and [1,2-(13)C]acetate. Furthermore, body composition and maximal aerobic capacity were measured. Total fat oxidation did not change at rest in any group. During exercise, after low-intensity exercise training, fat oxidation was increased by 40% (P < 0.05) because of an increased non-plasma fatty acid oxidation (P < 0.05). High-intensity exercise training did not affect total fat oxidation during exercise. Changes in fat oxidation were not significantly different among groups. It was concluded that low-intensity exercise training in obese subjects seemed to increase fat oxidation during exercise but not at rest. No effect of high-intensity exercise training on fat oxidation could be shown.     

Effect of resistance exercise on muscle steroid receptor protein content in strength-trained men and women

The purpose of this study was to examine the acute effect of resistance exercise (RE) on muscle androgen receptor (AR) and glucocorticoid receptor (GR) protein content. Fifteen resistance-trained men (n = 8; 21 ± 1 years, 175.3 ± 6.7 cm, 90.8 ± 11.6 kg) and women (n = 7; 24 ± 5 years, 164.6 ± 6.7 cm, 76.4 ± 15.6 kg) completed 6 sets of 10 repetitions of heavy squats. Blood samples were obtained before RE, after 3 and 6 sets of squats, and 5, 15, 30 and 70 min after RE. Muscle biopsies from the vastus lateralis were obtained before RE, and 10 min and 70 min after RE. Blood samples were analyzed for total and free testosterone concentrations and muscle samples were analyzed for AR and GR protein content. Circulating total testosterone increased significantly (p ≤ 0.05) in men and free testosterone increased in men and women with exercise. AR was significantly reduced at 70 min post-exercise in men and at 10 min post-exercise in women compared to pre-exercise. There were no changes in GR following RE, but GR was significantly higher in women compared to men. These findings support a current paradigm for stabilization followed by a reduction and then a rebound in the acute AR response to RE but demonstrate that gender differences exist in the timeline of the AR response.     

Effect of training status on fuel selection during submaximal exercise with glucose ingestion.

In this study, an oral glucose load was enriched with a [U-(13)C]glucose tracer to determine differences in substrate utilization between endurance-trained (T) and untrained (UT) subjects during submaximal exercise at the same relative and absolute workload when glucose is ingested. Six highly trained cyclists/triathletes [maximal workload (Wmax), 400 +/- 9 W] and seven UT subjects (Wmax, 296 +/- 8 W) were studied during 120 min of cycling exercise at 50% Wmax ( approximately 55% maximal O(2) consumption). The T subjects performed a second trial at the mean workload of the UT group (148 +/- 4 W). Before exercise, 8.0 ml/kg of a (13)C-enriched glucose solution (80 g/l) was ingested. During exercise, boluses of 2.0 ml/kg of the same solution were administered every 15 min. Measurements were made in the 90- to 120-min period when a steady state was present in breath (13)CO(2) and plasma glucose (13)C enrichment. Energy expenditure was higher in T than in UT subjects (58 vs. 47 kJ/min, respectively; P < 0.001) at the same relative intensity. This was completely accounted for by an increased fat oxidation (0.57 vs. 0.40 g/min; P < 0.01). At the same absolute intensity, fat oxidation contributed more to energy expenditure in the T compared with the UT group (44 vs. 33%, respectively; P < 0.01). The reduction in carbohydrate oxidation in the T group was explained by a diminished oxidation rate of muscle glycogen (indirectly assessed by using tracer methodology at 0.72 +/- 0.1 and 1.03 +/- 0.1 g/min, respectively; P < 0.01) and liver-derived glucose (0.15 +/- 0.03 and 0.22 +/- 0.02 g/min, respectively; P < 0.05). Exogenous glucose oxidation rates were similar during all trials (+/-0.70 g/min).     

Sex steroid hormones and cognitive functioning in healthy, older men

The precise impact of age-related changes in hormone levels on cognition in men is still unclear due to differing study designs and contradictory findings. This study was undertaken to examine the relationship between endogenous sex hormone levels and cognitive functioning in healthy older men using a comprehensive battery of neuropsychological tests and measurement of serum sex hormone levels. Verbal learning and memory, visual-motor processing, spatial abilities, working memory and attention, and levels of testosterone and estradiol were evaluated in 54 healthy older men. Regression analyses revealed significant curvilinear associations between working memory function and both free and bioavailable testosterone levels, suggesting that an optimal hormone level may exist for maximal performance on tasks of executive/frontal lobe functioning. However, no other relationships were evident between either estradiol or testosterone levels and any of the other cognitive functions evaluated. Hormone assays performed at the end of the study revealed that a considerable portion of the healthy elderly men in our sample met criteria for hypogonadism and suggests that their low hormone levels may have mitigated against discovering other significant hormone-cognition relationships.     

Sex steroid hormones, sex hormone-binding globulin, and obesity in men and women.

Sex steroid hormones in both males and females have been closely related to the regulation of adiposity, either through direct or indirect physiological mechanisms. Evidence also suggests a direct relationship between sex hormones and risk factors for cardiovascular disease. In the present review article, we will discuss recent studies that have examined the complex interrelationships between sex hormones, SHBG, obesity and risk factors for cardiovascular disease. Male obesity and excess abdominal adipose tissue accumulation is associated with reductions in gonadal androgen and low adrenal C19 steroid concentrations. Reduced C19 steroids are also related to an altered metabolic risk factor profile including glucose intolerance and an atherogenic dyslipidemic state. However, the concomitant visceral obese state appears as a major correlate in these associations. In women, menopause-induced estrogen deficiency and increased androgenicity are associated with increased abdominal obesity and with the concomitant alterations in the metabolic risk profile. The accelerated accretion of adipose tissue in the intra-abdominal region coincident with the onset of menopause may explain part of the increased risk of cardiovascular disease in postmenopausal women. In both men and women, plasma levels of sex hormone-binding globulin are strong correlates of obesity and risk factors for cardiovascular disease, and more importantly, the relationships between low SHBG and altered plasma lipid levels appear to be independent from the concomitant increased levels of visceral adipose tissue. SHBG concentration may, therefore, represent the most important and reliable marker of the sex hormone profile in the examination of the complex interrelation of sex steroid hormones, obesity, and cardiovascular disease risk.     

Effect of steroid hormones on Bufo arenarum oviduct. Ultrastructural study

The endocrine regulation of the mucosa of the oviductal pars convoluta was analyzed by ultrastructural studies demonstrating that ovariectomy, together with a decrease in ovarian steroids circulating levels, caused a marked regression in this portion of Bufo arenarum oviduct. Twenty-five days after ovariectomy, a decrease in the depth of the epithelial and glandular layers was observed due to the notable loss of secretory cells, whose number was clearly smaller than in nonovariectomized females. The remaining secretory cells showed involution signs, with few secretory granules in their cytoplasm, little endoplasmic reticulum near poorly developed Golgi complexes and a large amount of lipid droplets. Cells in an advanced autolysis state were found in the lumen. These characteristics evidence a nonfunctional state of the pars convoluta. Treatment with 5alpha-dihydrotestosterone (DHT) completely reversed the ovariectomy effect, inducing pars convoluta growths and restoring the characteristics of epithelial and glandular secretory cells in the whole pars convoluta, with micrographs similar to the control. These same effects were observed after treatment with estradiol-17beta (E2), progesterone (P) o E(2)+P in the glandular layer of the whole pars convoluta, but only in the epithelial layer of the most anterior region of this duct. In the secretory cells of other segments these treatments induced the formation of granules of high electron density and homogeneous aspect. Each steroid had a particular effect on the pars convoluta. Although E2 and DHT induced the development of the organoids involved in the proteins biosynthesis, P and DHT acted as secretagogues.     

Effect of exercise training on insulin sensitivity and glucose metabolism in lean, obese, and diabetic men.

To clarify the impact of vigorous physical training on in vivo insulin action and glucose metabolism independent of the intervening effects of concomitant changes in body weight and composition and residual effects of an acute exercise session, 10 lean, 10 obese, and 6 diet-controlled type II diabetic men trained for 12 wk on a cycle ergometer 4 h/wk at approximately 70% of maximal O2 uptake (VO2max) while body composition and weight were maintained by refeeding the energy expended in each training session. Before and 4-5 days after the last training session, euglycemic hyperinsulinemic (40 mU.m2.min-1) clamps were performed at a plasma glucose of 90 mg/dl, combined with indirect calorimetry. Total insulin-stimulated glucose disposal (M) was corrected for residual hepatic glucose output. Body weight, fat, and fat-free mass (FFM) did not change with training, but cardiorespiratory fitness increased by 27% in all groups. Before and after training, M was lower for the obese (5.33 +/- 0.39 mg.kg FFM-1.min-1 pretraining; 5.33 +/- 0.46 posttraining) than for the lean men (9.07 +/- 0.49 and 8.91 +/- 0.60 mg.kg FFM-1.min-1 for pretraining and posttraining, respectively) and lower for the diabetic (3.86 +/- 0.44 and 3.49 +/- 0.21) than for the obese men (P less than 0.001). Insulin sensitivity was not significantly altered by training in any group, but basal hepatic glucose production was reduced by 22% in the diabetic men. Thus, when intervening effects of the last exercise bout or body composition changes were controlled, exercise training per se leading to increased cardiorespiratory fitness had no independent impact on insulin action and did not improve the insulin resistance in obese or diabetic men.     

Effects of exercise training on thermoregulatory responses and blood volume in older men.

We assessed the effects of aerobic and/or resistance training on thermoregulatory responses in older men and analyzed the results in relation to the changes in peak oxygen consumption rate (VO(2 peak)) and blood volume (BV). Twenty-three older men [age, 64 +/- 1 (SE) yr; VO(2 peak), 32.7 +/- 1.1 ml. kg(-1). min(-1)] were divided into three training regimens for 18 wk: control (C; n = 7), aerobic training (AT; n = 8), and resistance training (RT; n = 8). Subjects in C were allowed to perform walking of ~10,000 steps/day, 6-7 days/wk. Subjects in AT exercised on a cycle ergometer at 50-80% VO(2 peak) for 60 min/day, 3 days/wk, in addition to the walking. Subjects in RT performed a resistance exercise, including knee extension and flexion at 60-80% of one repetition maximum, two to three sets of eight repetitions per day, 3 days/wk, in addition to the walking. After 18 wk of training, VO(2 peak) increased by 5.2 +/- 3.4% in C (P > 0.07), 20.0 +/- 2.5% in AT (P < 0.0001), and 9.7 +/- 5.1% in RT (P < 0.003), but BV remained unchanged in all trials. In addition, the esophageal temperature (T(es)) thresholds for forearm skin vasodilation and sweating, determined during 30-min exercise of 60% VO(2 peak) at 30 degrees C, decreased in AT (P < 0.02) and RT (P < 0.02) but not in C (P > 0.2). In contrast, the slopes of forearm skin vascular conductance/T(es) and sweat rate/T(es) remained unchanged in all trials, but both increased in subjects with increased BV irrespective of trials with significant correlations between the changes in the slopes and BV (P < 0.005 and P < 0.0005, respectively). Thus aerobic and/or resistance training in older men increased VO(2 peak) and lowered T(es) thresholds for forearm skin vasodilation and sweating but did not increase BV. Furthermore, the sensitivity of the increase in skin vasodilation and sweating at a given increase in T(es) was more associated with BV than with VO(2 peak).     

Effects of exercise mode and intensity on postprandial thermogenesis in lean and obese men.

To characterize further the impact of exercise before a meal on thermogenesis, the effects of exercise intensity and mode and the duration of the effect of exercise on the thermic effect (TEF) of a 720-kcal mixed meal were compared in 10 lean and 10 obese men (16 +/- 1 vs. 34 +/- 2% fat). In study A, TEF (kcal/3 h) was significantly greater for the lean than the obese men during rest and immediately after 1 h of cycling at 50 and 100 W. TEF was significantly greater after both exercise intensities than during rest for the obese men, but exercise had no effect on TEF in the lean men. In study B, TEF was significantly greater for the lean than the obese men during rest and immediately after 1 h of leg cycling at an O2 consumption of 1.09 l/min but only marginally different after 1 h of arm exercise at the same O2 consumption (P = 0.15). For the obese men, TEF was greater after arm than leg cycling and greater after leg cycling than at rest (P less than 0.01), but TEF was not different among the three conditions for the lean men. In study C, TEF was compared at rest and immediately and 24 h after 1 h of cycling at 100 W. TEF was greater for the lean than the obese men under all conditions (P less than 0.05). For the obese but not the lean men, TEF was greater both immediately after and on the day after exercise than at rest (P less than 0.01). Thus, acute exercise improves but does not normalize the blunted TEF in obesity; a minimally intense bout of exercise is needed to improve TEF; exercise mode alters thermogenesis in the obese men, even at a fixed intensity; and TEF in the obese men is enhanced for as long as 24 h after exercise.     

Effect of steroid hormones on endotoxin-mediated cartilage degradation

Summary Cartilage degradation is a characteristic feature of various types of human arthritis, notably rheumatoid arthritis and osteoarthritis. The influence of glucocorticoid and other steroid hormones on cartilage proteoglycan breakdown was examined in a model system in which breakdown is readily quantified by the release of proteoglycan from cultured bovine nasal cartilage discs. Endotoxin (bacterial lipopolysaccharides) treatment enhanced the depletion of cartilage proteoglycan by 2–3 fold. This was inhibited in a concentration-dependent manner by hydrocortisone (10^–9 to 10^–5M) or other glucocorticoid hormones (dexamethasone, prednisolone, cortisone). Inhibition required the continued presence of the steroid. Removal of hydrocortisone (3 × 10^–7M) after 4 days from endotoxin-treated cultures resulted in the rapid restoration of an endotoxin response, so that proteoglycan release approached maximum levels during a second 4-day culture period. Other C-21 steroid hormones (progesterone, aldosterone) were also inhibitory at 10^–5M, but testosterone and -estradiol showed little influence on endotoxin action. Proteoglycan products of smaller average mol wt (Sepharose CL-2B chromatography), consistent with core protein cleavages, were released from endotoxin-treated cartilage. Cleavage was unaffected by -estradiol, partially blocked by aldosterone and largely prevented by hydrocortisone administration.     

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.     

Influence of endurance exercise training status and gender on postexercise hypotension.

In sedentary individuals, postexercise hypotension after a single bout of aerobic exercise is due to a peripheral vasodilation. Endurance exercise training has the potential to modify this response and perhaps reduce the degree of postexercise hypotension. We tested the hypothesis that endurance exercise-trained men and women would have blunted postexercise hypotension compared with sedentary subjects but that the mechanism of hypotension would be similar (i.e., vasodilation). We studied 16 endurance-trained and 16 sedentary men and women. Arterial pressure, cardiac output, and total peripheral resistance were determined before and after a single 60-min bout of exercise at 60% peak oxygen consumption. All groups exhibited a similar degree of postexercise hypotension (approximately 4-5 mmHg; P < 0.05 vs. preexercise). In sedentary men and women, hypotension was the result of vasodilation (Deltaresistance: -8.9 +/- 2.2%). In endurance-trained women, hypotension was also the result of vasodilation (-8.1 +/- 4.1%). However, in endurance-trained men, hypotension was the result of a reduced cardiac output (-5.2 +/- 2.4%; P < 0.05 vs. all others) and vasodilation was absent (-0.7 +/- 3.3%; P < 0.05 vs. all others). Thus we conclude the magnitude of postexercise hypotension is similar in sedentary and endurance-trained men and women but that endurance-trained men and women achieve this fall in pressure via different mechanisms.     

Postprandial lipemia in young men and women of contrasting training status.

This study compared the postprandial triacylglycerol (TAG) response to a high-fat meal in trained and untrained normolipidemic young adults after 2 days' abstinence from exercise. Fifty-three subjects (11 endurance-trained men, 9 endurance-trained women, 10 sprint/strength-trained men, 11 untrained men, 11 untrained women) consumed a meal (1.2 g fat, 1.1 g carbohydrate, 66 kJ per kg body mass) after a 12-h fast. Venous blood samples were obtained in the fasted state and at intervals until 6 h. Postprandial responses were the areas under the plasma or serum concentration-vs.-time curves. Neither fasting TAG concentrations nor the postprandial TAG response differed between trained and untrained subjects. The insulinemic response was 29% lower in endurance-trained men than in untrained men [mean difference -37.4 (95% confidence interval -62.9 to -22.9) microIU/ml x h, P = 0.01]. Responses of plasma glucose, serum insulin, and plasma nonesterified fatty acids were all lower for endurance-trained men than for untrained men. These findings suggest that, in young adults, no effect of training on postprandial lipemia can be detected after 60 h without exercise. The effect on postprandial insulinemia may persist for longer.     

Influence of endogenous opioids on the response of selected hormones to exercise in humans

To examine the influence of endogenous opioids on the hormonal response to isotonic exercise, eight males were studied 2 h after oral administration of placebo or 50 mg naltrexone, a long-lasting opioid antagonist. Venous blood samples were obtained before, during, and after 30 min of bicycle exercise at 70% VO2max. Naltrexone had no effect on resting cardiovascular, endocrine, or serum variables. During exercise epinephrine was higher [mean 433 +/- 100 (SE) pg/ml] at 30 min with naltrexone than during placebo (207 +/- 26 pg/ml, P less than 0.05). Plasma norepinephrine showed the same trend but the difference (2,012 +/- 340 pg/ml with naltrexone and 1,562 +/- 241 pg/ml with placebo) was not significant. Plasma glucose was higher at all times with naltrexone. However, the difference was significant only 10 min into recovery from exercise (104.7 +/- 4.7 vs. 94.5 +/- 2.8 mg/dl). Plasma growth hormone and cortisol increased during recovery and these elevations were significantly (P less than 0.05) augmented by naltrexone. Plasma vasopressin and prolactin increased with exercise as did heart rate, blood pressure, lactic acid, and several serum components; these increases were not affected by naltrexone. Psychological tension or anxiety was lower after exercise compared with before and this improved psychological state was not influenced by the naltrexone treatment. These data suggest that exercise-induced activation of the endogenous opioid system may serve to regulate the secretion of several important hormones (i.e., epinephrine) during and after exercise.     

Energy metabolism and regulatory hormones in women and men during endurance exercise

Gender differences in the changes substrates of carbohydrate and lipid metabolism as well as in adrenaline, noradrenaline, growth hormone, insulin and cortisol were investigated in 24 women and 24 men during exhaustive endurance exercise. Training history and current performance capacity were taken into consideration in the design of the study. Since previous papers present conflicting results the purpose of the present study was to obtain further information regarding possible gender differences in lipid metabolism and its regulation by hormones. Non-endurance-trained women and men each ran 10 km on a treadmill at an intensity of 75% of VO2max; endurance-trained women and men ran 14 and 17 km, respectively, at an intensity of 80% of VO2max. Blood glucose levels in non-endurance-trained women were higher when compared to non-endurance-trained men. This might be explained by increased mobilization of free fatty acids from intramuscular fat depots during energy production in non-specifically trained women. In contrast, no substantial gender differences in endurance-trained persons were seen in lipid metabolism. The changes in substrates of lipid metabolism confirm the higher lipolytic activity and greater utilization of free fatty acids in endurance-trained persons. During endurance exercise, changes in adrenaline, noradrenaline, growth hormone, insulin and cortisol were not substantially affected by the sex of the subjects. This study does not present any conclusive results that endurance-trained persons show gender differences in lipid metabolism and major regulatory hormones.