Acute metabolic, hormonal, and psychological responses to strength training with superimposed EMS at the beginning and the end of a 6 week training period.

OBJECTIVES: The aim was to determine metabolic and hormonal responses to strength training with or without superimposed electromyostimulation (EMS) at the beginning and the end of a 6 week training period. METHODS: 20 strength trained subjects were randomly assigned to two groups. The first group (S) performed 4 sets of back squats with a constantly adjusted additional load of their individual 10 repetition maximum (10 RM) twice a week over 6 weeks. The second group (S+E) did the same training program with superimposed EMS on leg and trunk muscles. Physiological responses were determined before and after the first (TS 1) and the last training session (TS 12). RESULTS: No significant differences of hormonal responses could be observed between groups and TSs. However, small to large effects on metabolism occurred between groups and TSs. Delayed onset muscle soreness (DOMS) was significantly higher 48h after TS 1 for S+E. CONCLUSIONS: Despite a higher DOMS after S+E, there is no acute effect of superimposed EMS on hormonal response to exhaustive resistance exercise. We suggest that, because of the high resistance during 10 RM bouts, most of the muscle fibers are already activated and superimposed EMS only activates few additional muscle fibers.

Acute effects of superimposed electromyostimulation during cycling on myokines and markers of muscle damage.

OBJECTIVES: The purpose of the present study was to evaluate the effects of superimposed electromyostimulation (E) during cycling on myokines and markers of muscle damage, as E might be a useful tool to induce a high local stimulus to skeletal muscle during endurance training without performing high external workloads. METHODS: 13 subjects participated in three experimental trials each lasting 60 min in a randomized order. 1) Cycling (C), 2) Cycling with superimposed E (C+E) and 3) E. Interleukin-6 (IL-6), brain-derived neurotrophic factor (BDNF), creatine kinase (CK) and myoglobin were determined before (pre) and 0', 30', 60', 240' and 24h after each intervention. RESULTS: Only C+E caused significant increases in levels of CK and myoglobin. BDNF and IL-6 significantly increased after C and C+E, however increases for IL-6 were significantly higher after C+E compared to C. CONCLUSION: The present study showed that superimposed E during cycling might be a useful tool to induce a high local stimulus to skeletal muscle even when performing low to moderate external workloads. This effect might be due the activation of additional muscle fibers and mild eccentric work due to the concomitant activation of agonist and antagonist. However the higher load to skeletal muscle has to be taken into account.

Active vs. passive recovery during high-intensity training influences hormonal response.

The aim of the present study was to compare the effects of active (A) vs. passive (P) recovery during high-intensity interval training on the acute hormonal and metabolic response. Twelve triathletes/cyclists performed four 4 min intervals on a cycle ergometer, either with A- or P-recovery between each bout. Testosterone, hGH, cortisol, VEGF, HGF and MIF were determined pre, 0', 30', 60' and 180' after both interventions. Metabolic perturbations were characterized by lactate, blood gas and spirometric analysis. A-recovery caused significant increases in circulating levels of cortisol, testosterone, T/C ratio, hGH, VEGF and HGF. Transient higher levels were found for cortisol, testosterone, hGH, VEGF, HGF and MIF after A-recovery compared to P-recovery, despite no differences in metabolic perturbations. A-recovery was more demanding from an athlete's point of view. Based on the data of testosterone, hGH and the T/C-ratio, as well as on the data of VEGF and HGF it appears that this kind of exercise protocol with A-recovery phases between the intervals may promote anabolic processes and may lead to pro-angiogenic conditions more than with P-recovery. These data support the findings that also the long term effects of both recovery modes seem to differ, and that both can induce specific adaptations.

Acute hormonal responses before and after 2 weeks of HIT in well trained junior triathletes.

The aim was to compare the acute hormonal response to a single HIT session at the beginning and end of a HIT shock microcycle. 13 male junior triathletes (15.8±1.8 yrs.) performed 16 HIT sessions within a 2 week period. Venous blood samples were collected before and after the first and last HIT session. Significant increases in cortisol (first session +89.7%; last session +70.3%) and hGH (first session +435.1%; last session +314.6%) concentrations were observed after both training sessions (P<0.05). The acute responses of cortisol, hGH, T3, and fT3 were not different between the first and last HIT sessions (P=1.00). Although no acute changes in testosterone were detected after the training sessions, testosterone concentrations were significantly higher at all time points (62.6-80.1%) during the last compared to first training session (P≤0.001). Findings from the present study reveal that 16 sessions of HIT led to significant increases in baseline concentrations of serum testosterone. This might indicate a heightened anabolic state even in junior triathletes. Based on the hormonal data, we conclude that at the end of this 2 week microcycle no familiarization effect was evident and that the training stimulus produced by HIT was still great enough to "stress" the athletes and induce positive training adaptations.

Acute metabolic, hormonal, and psychological responses to different endurance training protocols.

In the last years, mainly 2 high-intensity-training (HIT) protocols became common: first, a Wingate-based "all-out" protocol and second, a 4×4 min protocol. However, no direct comparison between these protocols exists, and also a comparison with high-volume-training (HVT) is missing. Therefore, the aim of the present study was to compare these 3 endurance training protocols on metabolic, hormonal, and psychological responses. Twelve subjects performed: 1) HVT [130 min at 55% peak power output (PPO)]; 2) 4×4 min at 95% PPO; 3) 4×30 s all-out. Human growth hormone (hGH), testosterone, and cortisol were determined before (pre) and 0', 30', 60', 180' after each intervention. Metabolic stimuli and perturbations were characterized by lactate, blood gas (pH, BE, HCO3⁻, pO2, PCO2), and spirometric analysis. Furthermore, changes of the person's perceived physical state were determined. The 4×30 s training caused the highest increases in cortisol and hGH, followed by 4 × 4 min and HVT. Testosterone levels were significantly increased by all 3 exercise protocols. Metabolic stress was highest during and after 4×30 s, followed by 4×4 min and HVT. The 4×30 s training was also the most demanding intervention from an athlete's point of view. In conclusion, the results suggest that 4×30 s and 4×4 min promote anabolic processes more than HVT, due to higher increases of hGH, testosterone, and the T/C ratio. It can be speculated that the acute hormonal increase and the metabolic perturbations might play a positive role in optimizing training adaptation and in eliciting health benefits as it has been shown by previous long term training studies using similar exercise protocols.

Responses of angiogenic growth factors to exercise, to hypoxia and to exercise under hypoxic conditions.

The purpose of the present study was to compare the acute hormonal response of angiogenic regulators to a short-term hypoxic exposure at different altitudes with and without exercise. 7 subjects participated in 5 experimental trials. 2 times subjects stayed in a sedentary position for 90 min at 2000 m or 4000 m, respectively. The same was carried out again in combination with exercise at the same relative intensity (2 mmol∙L(-1) of lactate). The fifth trial consisted of 90 min exercise at sea level. Venous blood samples were taken under resting conditions, 0 and 180 min after each condition to determine VEGF, EPO, IL-6, IL-8 and IGF-1 serum concentrations. EPO, VEGF, and IL-8 showed increases only, when hypoxia was combined with exercise. IL-6 was increased after exercise, independent of altitude. IGF-1 showed no changes in any intervention. The present study suggests that short term hypoxic exposure combined with low intensity exercise is able to up-regulate angiogenic regulators, which might be beneficial to induce angiogenesis and to improve endurance performance. However, in some cases high altitudes are needed, or it can be speculated that exercise intensity needs to be increased.

Effects of high intensity exercise on isoelectric profiles and SDS-PAGE mobility of erythropoietin.

Exercise induced proteinuria is a common phenomenon in high performance sports. Based on the appearance of so called "effort urines" in routine doping analysis the purpose of this study was to investigate the influence of exercise induced proteinuria on IEF profiles and SDS-PAGE relative mobility values (rMVs) of endogenous human erythropoietin (EPO). Twenty healthy subjects performed cycle-ergometer exercise until exhaustion. VO (2)max, blood lactate, urinary proteins and urinary creatinine were analysed to evaluate the exercise performance and proteinuria. IEF and SDS-PAGE analyses were performed to test for differences in electrophoretic behaviour of the endogenous EPO before and after exercise. All subjects showed increased levels of protein/creatinine ratio after performance (8.8+/-5.2-26.1+/-14.4). IEF analysis demonstrated an elevation of the relative amount of basic band areas (13.9+/-11.3-36.4+/-12.6). Using SDS-PAGE analysis we observed a decrease in rMVs after exercise and no shift in direction of the recombinant human EPO (rhEPO) region (0.543+/-0.013-0.535+/-0.012). Following identification criteria of the World Anti Doping Agency (WADA) all samples were negative. The implementation of the SDS-PAGE method represents a good solution to distinguish between results influenced by so called effort urines and results of rhEPO abuse. Thus this method can be used to confirm adverse analytical findings.