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 4x4 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) 4x4 min at 95% PPO; 3) 4x30 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 (-), pO(2), PCO2), and spirometric analysis. Furthermore, changes of the person's perceived physical state were determined. The 4x30 s training caused the highest increases in cortisol and hGH, followed by 4 x 4 min and HVT. Testosterone levels were significantly increased by all 3 exercise protocols. Metabolic stress was highest during and after 4x30 s, followed by 4x4 min and HVT. The 4x30 s training was also the most demanding intervention from an athlete's point of view. In conclusion, the results suggest that 4x30 s and 4x4 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.