The Role of Dehydroepiandrosterone Levels on Physiologic Acclimatization to Chronic Mountaineering Activity

Does ovulation affect performance in tennis players?

Background

Scientific data on the performance of collegiate female tennis players during the menstrual phases are scarce.

Trial design

Double-blind, counter-balanced, crossover trials were conducted to examine whether tennis performance was affected during menstruation, with and without dehydroepiandrosterone sulfate (DHEA-S) supplementation.

Methods

Ten Division 1 collegiate tennis players (aged 18-22 years) were evenly assigned into placebo-supplemented and DHEA-supplemented (25 mg/day) trials. Treatments were exchanged among the participants after a 28-day washout. Tennis serve performance was assessed on the first day of menstrual bleeding (day 0/28) and on days 7, 14 and 21.

Results

Mood state was unaltered during the menstrual cycles in both trials. The lowest tennis serve performance score (speed times accuracy) occurred on day 14 (P=0.06 vs day 0; P=0.01 vs day 21) in both placebo and DHEA trials. Decreased performance on day 14 was explained by decreased accuracy (P=0.03 vs day 0/28; P=0.01 vs day 21), but not velocity itself. Isometric hip strength, but not quadriceps strength, was moderately lower on day 14 (P=0.08). Increasing plasma DHEA-S (by ~65%) during the DHEA-supplemented trial had no effects on mood state, sleep quality or tennis serve performance.

Conclusion

We have shown that menses does not affect serve performance of collegiate tennis players. However, the observed decrement in the accuracy of serve speed near ovulation warrants further investigation.

THE ACUTE EFFECT OF ERYTHROPOIETIN ON GLUCOSE LEVELS DURING ISCHEMIA REPERFUSION INJURY IN RATS

The aim of this experimental study was to examine the effect of erythropoietin on rat model and particularly in an ischemia reperfusion (HR) protocol. The effect of that molecule was studied biochemically using blood mean glucose (Gl) levels. Materials and methods: 40 rats of mean weight 247.7 g were used in the study. Gl levels were measured at 60 min (groups A and C) and at 120 min (groups B and D) of reperfusion. Erythropoietin was administered only in groups C and D. Results were that Epo administration non-significantly increased the gl levels by 5.59% +6.46% (p=0.3208). Reperfusion time non-significantly increased the gl levels by 5.63%+6.45% (p=0.4098). However, erythropoietin administration and reperfusion time together produced a non significant combined effect in increasing the gl levels by 4.94%+3.81% (p= 0.1892). Conclusions: Results of this study indicate that erythropoietin administration, reperfusion time, or their interaction non-significantly increase the blood glucose levels in short-term. Opposite bibliographic data are considered more reliable, until a greater sample provide clearer results.

Decrease of DHEA-S concentration succeeding a micro-dose thumb exertion: mood-state determinants reflect stress-biomarker responses

Background

The present study examined the effect of a micro-dose of resistance-exercise on serum DHEA-S, IL-6 and mood-state determinants. Potential relationships between mood and the biomarkers were also studied with the aim of directing research on non-invasive exercise-monitoring methods.

Methods

30 male participants (20 weightlifting-trained; 10 untrained) were separated into 3 groups of 10: weightlifting experimental (WL_EXP); untrained experimental (UT_EXP); weightlifting placebo (WL_PLA). WL_EXP and UT_EXP performed four 60-s isometric thumb exertions separated by 60-s rest intervals in a single-blinded placebo-controlled study. Participants were assessed over a 60-min post-intervention recovery period for changes in serum DHEA-S and IL-6, and mood-state determinants (vigour, tension, fatigue).

Results

DHEA-S changed in UT_EXP only; a decrease from 20- to 60-min post-exercise (Δ36.9 %, p < 0.01). DHEA-S remained below baseline at the final time-point (Δ35.3 %, p = 0.012). Tension decreased immediately post-exercise in WL_EXP (Δ86.7 %, p = 0.022), whereas UT_EXP showed a delayed decrease which continued up to 60-min post-intervention (Δ100 %, p < 0.01). Relative to fatigue scores recorded immediately post-exercise, WL_EXP decreased within the first 10-min post-intervention (Δ22.2 %, p < 0.01) whereas UT_EXP showed a delayed decrease evident at 20-min post-intervention (Δ25 %, p < 0.01). Serum IL-6 and vigour scores remained unchanged across groups (p > 0.05) and WL_PLA did not change for any measured variable (p > 0.05).

Conclusions

The authors conclude that a micro-dose of resistance-exercise can reduce serological DHEA-S concentration within 60-min of exercise cessation. Additionally, mood-state assessment in untrained individuals can be considered for non-invasively indicating exercise-induced concentration changes in the stress biomarker, DHEA-S, providing prospects for the development of safer, more sophisticated exercise-monitoring practice.

Effect of acute DHEA administration on free testosterone in middle-aged and young men following high-intensity interval training

With advancing age, plasma testosterone levels decline, with free testosterone levels declining more significantly than total testosterone. This fall is thought to underlie the development of physical and mental weakness that occurs with advancing age. In addition, vigorous exercise can also lower total and free testosterone levels with the decline greatest in physically untrained men. The purpose of the study was to evaluate the effect of oral DHEA supplementation, a testosterone precursor, on free testosterone in sedentary middle-aged men during recovery from a high-intensity interval training (HIIT) bout of exercise. A randomized, double-blind, placebo-controlled crossover study was conducted for 8 middle-aged participants (aged 49.3 ± 2.4 years) and an additional 8 young control participants (aged 21.4 ± 0.3 years). Each participant received DHEA (50 mg) and placebo on separate occasions one night (12 h) before a 5-session, 2-min cycling exercise (100% VO₂max). While no significant age difference in total testosterone was found, middle-aged participants exhibited significantly lower free testosterone and greater luteinizing hormone (LH) levels than the young control group. Oral DHEA supplementation increased circulating DHEA-S and free testosterone levels well above baseline in the middle-aged group, with no significant effect on total testosterone levels. Total testosterone and DHEA-S dropped significantly until 24 h after HIIT for both age groups, while free testosterone of DHEA-supplemented middle-aged men remained unaffected. These results demonstrate acute oral DHEA supplementation can elevate free testosterone levels in middle-aged men and prevent it from declining during HIIT. Therefore, DHEA supplementation may have significant benefits related to HIIT adaptation.

Self-rated mental stress and exercise training response in healthy subjects

Purpose: Individual responses to aerobic training vary from almost none to a 40% increase in aerobic fitness in healthy subjects. We hypothesized that the baseline self-rated mental stress may influence to the training response. Methods: The study population included 44 healthy sedentary subjects (22 women) and 14 controls. The laboratory controlled training period was 2 weeks, including five sessions a week at an intensity of 75% of the maximum heart rate for 40 min/session. Self-rated mental stress was assessed by inquiry prior to the training period from 1 (low psychological resources and a lot of stressors in my life) to 10 (high psychological resources and no stressors in my life), respectively. Results: Mean peak oxygen uptake (VO2peak) increased from 34 ± 7 to 37 ± 7 ml kg⁻¹ min⁻¹ in training group (p < 0.001) and did not change in control group (from 34 ± 7 to 34 ± 7 ml kg⁻¹ min⁻¹). Among the training group, the self-rated stress at the baseline condition correlated with the change in fitness after training intervention, e.g., with the change in maximal power (r = 0.45, p = 0.002, W/kg) and with the change in VO2peak (r = 0.32, p = 0.039, ml kg⁻¹ min⁻¹). The self-rated stress at the baseline correlated with the change in fitness in both female and male, e.g., r = 0.44, p = 0.039 and r = 0.43, p = 0.045 for ΔW/kg in female and male, respectively. Conclusion: As a novel finding the baseline self-rated mental stress is associated with the individual training response among healthy females and males after highly controlled aerobic training intervention. The changes in fitness were very low or absent in the subjects who experience their psychological resources low and a lot of stressors in their life at the beginning of aerobic training intervention.

Parasympathetic nervous activity mirrors recovery status in weightlifting performance after training

Heart rate variability (HRV) and parasympathetic power are closely related to the well-being and health status in humans. The main goal of the study was to determine whether these measures can reflect recovery status after weight training. After a 10-day detraining period, 7 weightlifters were challenged with a 2-hour weight training which elicited approximately fourfold increases in circulating muscle creatine kinase level and protracted pain feeling (p < 0.05). Weightlifting performance was then evaluated 3, 24, 48, and 72 hours after training to determine the degree of recovery from fatigue. Heart rate variability, circulating dehydroepiandrostendione sulfate (DHEA-S), and muscle damage markers were measured before each performance test. An electrocardiogram was recorded for 5 minutes continuously at rest in seated positions. After training, weightlifting performance of the subjects decreased below baseline in paralleled with suppressed parasympathetic power (high-frequency [HF] HRV), whereas sympathetic power (normalized low-frequency HRV) was slightly elevated at 3 hours of recovery (p < 0.05). Both weightlifting performances and parasympathetic power returned to baseline values in 24 hours and further increased above baseline during 48-72 hours of recovery in a similar fashion (p < 0.05). Circulating DHEA-S level dropped at 24 hours (p < 0.05) and returned to normal values by 48 hours. Muscle pain increased at 3 hours after training and remained higher than baseline values for the 72-hour recovery period (p < 0.05). Our data suggest that parasympathetic power, indicated by HF HRV, is able to reflect the recovery status of weightlifters after training.

Associations between job strain and the cortisol/DHEA-S ratio among management and nonmanagement personnel

OBJECTIVE

To assess associations between the main, nonlinear, and interactive effects of the demand-control-support (DCS) model and the cortisol/dehydroepiandrosterone sulfate (DHEA-S) ratio, a biomarker of psychophysical well-being.

METHODS

Subjects were 596 employees from all occupational levels of a German airplane manufacturing plant. Multiple regression models controlling for age and gender were computed separately for employees with (n = 103) and without (n = 493) management responsibilities.

RESULTS

Among employees without management responsibilities, the dimensions of the DCS model did not predict the cortisol/DHEA-S ratio. In contrast, among employees with management responsibilities, both linear and nonlinear job demand effects explained a substantial fraction of the cortisol/DHEA-S variance. Increasing levels of job demands were associated with decreasing cortisol/DHEA-S ratios (linear effect) with the quartile of moderately high levels of job demands representing an optimal level. Furthermore, we observed a significant nonlinear effect with job control and a significant interaction between job demands and job control among employees with management responsibilities. These results suggest a beneficial effect associated with moderate levels of job control. This may be due to a buffering effect against adverse levels of job demands (interactive effect) and the independent association with decreased cortisol/DHEA-S ratios (nonlinear effect).

CONCLUSION

This is the first study that provides evidence that the DCS model is associated with the cortisol/DHEA-S ratio. Among employees with management responsibilities, moderate levels of job control may help managers to cope effectively with job demands and may induce a favorable cortisol/DHEA-S ratio.

Effect of a prolonged altitude expedition on glucose tolerance and abdominal fatness

In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO2) was substantially reduced during hiking. Glucose tolerance and insulin responses were measured prior to and twice during the expedition period. Maximal oxygen consumption increased from 43.0 +/- 2.7 to 49.1 +/- 2.2 mL/kg/min. Percentage of body fat decreased from 19.4 +/- 6.8% to 16.9 +/- 5.9%. The area under the curves for insulin and glucose during the oral glucose tolerance test were also reduced in Days 3 and 25. The present study demonstrated that altitude hiking activity is an effective lifestyle intervention to improve insulin action.

Dehydroepiandrosterone sulfate linked to physiologic response against hot spring immersion

The steroid dehydroepiandrosterone sulfate (DHEA-S) is associated with longevity and adaptation against external stress in humans. The aim of the study was to investigate the acute effect of a 30-min hot spring immersion at 41 degrees C on insulin resistance measures of 16 male subjects, in relation to DHEA-S level. To elucidate the role of DHEA-S in the coping against the heat stress, all subjects were evenly divided into lower and upper halves according to their baseline DHEA-S concentrations. The levels of glucose, insulin, blood pressure, and stress hormones (growth hormone, testosterone, and cortisol) in both groups were compared before and after hot spring immersion. The result shows that hot spring immersion significantly increased heart rate and reduced diastolic blood pressure, both of which were paralleled with a drop of DHEA-S concentration. Homeostasis model assessment for insulin resistance (HOMA-IR) and area under curve of glucose (GAUC) of oral glucose tolerance test were significantly increased by the hot spring immersion only in the Low DHEA-S group. Likewise, hot spring immersion caused an opposing effect on cortisol changes for the Low and High DHEA-S groups (+95% vs. -33%, p<0.05), respectively. In conclusion, hot spring bathing induced insulin resistance confined only to those Low DHEA-S individuals. This response may be associated with a stress response such as increased cortisol levels.

A possible link between exercise-training adaptation and dehydroepiandrosterone sulfate- an oldest-old female study

The purpose of this study was to determine the association between the level of salivary dehydroepiandrosterone sulfate (DHEA-S) and the magnitude of adaptation to exercise training in insulin sensitivity for aged females. A group of 16 females, aged 80-93 years old, was divided into 2 groups according to their baseline DHEA-S levels: Lower Halves (N = 8) and Upper Halves (N = 8), and participated in a 4-month exercise intervention trial. Insulin response with an oral glucose tolerance test (OGTT), cholesterol, blood pressure (BP), motor performance, and DHEA-S were determined at baseline and 4 months after the training program. Glucose tolerance and body mass index (BMI) remained unchanged with training for both groups. Insulin, fasted cholesterol, diastolic blood pressure, reaction time, and locomotive function were significantly lowered by training only in the Upper Halves group. Changes in the area under curve of insulin (IAUC) were negatively correlated with the baseline DHEA-S level (R= - 0.60, P < 0.05). The current study provides the first evidence that oldest-old subjects with low DHEA-S level appear to be poor responders to exercise-training adaptations.