Correlations between serum hormones, strength and endurance in healthy elderly South-American men.

AIM: Declines in muscular strength resulting from reduced serum anabolic hormones and neural activity may influence the reduction in aerobic capacity in older men. However, there has been little investigation into the relationship between steroid hormones and muscular strength, as well as endurance capacity in elderly subjects. The purpose of this study was to investigate the possible relationship between serum steroid hormones, strength and aerobic performance in older men. METHODS: Twenty-eight aged men (65±4 years) were evaluated in dynamic strength (one repetition maximum test), isometric strength (maximal voluntary contraction) and rate of force development. Peak oxygen uptake and maximal workload were determined during a ramp protocol on a cycle ergometer. In addition, blood samples were taken to determine basal cortisol, total and free testosterone. RESULTS: No correlations were found between steroid hormonal concentrations and the performance parameters investigated. CONCLUSION: Our results suggest that single measurements of steroids hormones concentrations are not related to the strength and endurance capacity of healthy South-American elderly men.

Physiological effects of concurrent training in elderly men.

The aim of the present study was to investigate the effects of concurrent strength and endurance training on neuromuscular and hormonal parameters in elderly men. 23 healthy men (65±4 years) were randomly assigned to 1 of 3 groups: concurrent (CG, n=8), strength (SG, n=8) or endurance group (EG, n=7). The programs consisted, of strength training, endurance training on a cycle ergometer or a combination of both in the same session 3 times per week over a duration of 12 weeks. Subjects were evaluated on parameters related to muscle strength, muscle activation and serum hormones. There were significant increases in lower-body strength in all groups (P<0.05), with higher increases in SG (67%) than CG (41%) and both were higher than EG (25%) (p<0.01). Only SG and CG increased upper-body strength (p<0.01), with no significant difference between the 2 groups. Furthermore, there were significant decreases in free testosterone in EG after training. Significant increases in isometric strength and maximal muscle activation (p<0.05) as well as decreases in the submaximal muscle activation to the same load, were only seen in SG (p<0.05). The present results suggest that the interference effect observed due to concurrent strength and endurance training could be related to impairment of neural adaptations.

Salivary hormonal responses to resistance exercise in trained and untrained middle-aged men.

AIM: The aim of the present study was to investigate if there are differences in salivary hormonal responses to resistance exercise between long-term strength-trained and untrained men. METHODS: Twenty-eight subjects were recruited to this study, matched into a strength-trained group (SG, N=13) and an untrained group (UG, N=15). Upper and lower body absolute muscle strength was measured through the one-repetition maximum (1-RM) test. Saliva samples were collected at rest and after a resistance exercise protocol (REP) with intensity relative to 1-RM values. With these samples, testosterone (TES), dehydroepiandrosterone (DHEA) and cortisol (COR) were determined. RESULTS: SG subjects demonstrated significantly higher values in all muscle strength variables. While a significant increase in TES after REP was found in the SG (0.114 + or - 0.1 vs. 0.15 + or - 0.09 pg/mL, P<0.05), no differences were observed in the UG (0.144 + or - 0.1 vs. 0.17 + or - 0.1 pg/mL). In both groups, there were increases in salivary COR (SG: 1.4 + or - 0.6 vs. 2.06 + or - 1; UG: 1.5 + or - 0.8 vs. 2.3 + or - 1.2 ug/dL, P<0.05) and DHEA (SG: 0.6 + or - 0.3 vs. 0.9 + or - 0.6; UG: 0.65 + or - 0.3 vs. 0.97 + or - 0.7 ng/dL, P<0.05). CONCLUSIONS: These results suggest the possible presence of adaptation of TES responses to resistance exercise in long-term strength-trained men, with these subjects presenting higher responses to the same stimulus, compared with untrained subjects, while no such adaptation was seen at the adrenocortical level in these subjects as the responses observed were similar in both groups.

Dehydroepiandrosterone increases synaptosomal glutamate release and improves the performance in inhibitory avoidance task.

Dehydroepiandrosterone (DHEA) exerts multiple effects in the rodent central nervous system (CNS), mediated through its nongenomic actions on several neurotransmitter systems, increasing neuronal excitability, modulating neuronal plasticity and presenting neuroprotective properties. It has been demonstrated that DHEA is a potent modulator of GABA(A), NMDA and Sigma receptors. In the present study, we investigated the effect of DHEA on (i) basal- and K(+)-stimulated l-[(3)H]glutamate release from synaptosomes (both in vitro and ex vivo), (ii) synaptosomal l-[(3)H]glutamate uptake (in vitro), and (iii) an inhibitory avoidance task (in vivo). The results indicated that DHEA in vitro increased glutamate release by 57%, and its intracerebroventricular infusion increased the basal-[(3)H]glutamate release by 15%. After 30 min of intraperitoneal administration, DHEA levels in the serum or CSF increased 33 and 21 times, respectively. Additionally, DHEA, intraperitoneally administrated 30 min before training, improved memory for inhibitory avoidance task. Concluding, DHEA could improve memory on an inhibitory avoidance task, perhaps due to its ability to physiologically strength the glutamatergic tonus by increasing glutamate release.

Molecular aspects involved in swimming exercise training reducing anhedonia in a rat model of depression.

Patients suffering from depression frequently display hyperactivity of the hypothalamic-pituitary-adrenal axis (HPA) resulting in elevated cortisol levels. One main symptom of this condition is anhedonia. There is evidence that exercise training can be used as a rehabilitative intervention in the treatment of depressive disorders. In this scenario, the aim of the present study was to assess the effect of an aerobic exercise training protocol on the depressive-like behavior, anhedonia, induced by repeated dexamethasone administration. The study was carried out on adult male Wistar rats randomly divided into four groups: the "control group" (C), "exercise group" (E), "dexamethasone group" (D) and the "dexamethasone plus exercise group" (DE). The exercise training consisted of swimming (1 h/d, 5 d/wk) for 3 weeks, with an overload of 5% of the rat body weight. Every day rats were injected with either dexamethasone (D/DE) or saline solution (C/E). Proper positive controls, using fluoxetine, were run in parallel. Decreased blood corticosterone levels, reduced adrenal cholesterol synthesis and adrenal weight (HPA disruption), reduced preference for sucrose consumption and increased immobility time (depressive-like behavior), marked hippocampal DNA oxidation, increased IL-10 and total brain-derived neurotrophic factor (BDNF; pro-plus mature-forms) and a severe loss of body mass characterized the dexamethasone-treated animals. Besides increasing testosterone blood concentrations, the swim training protected depressive rats from the anhedonic state, following the same profile as fluoxetine, and also from the dexamethasone-induced impaired neurochemistry. The data indicate that physical exercise could be a useful tool in preventing and treating depressive disorders.