HORMONAL RESPONSES ARE INFLUENCED BY TIME-OF-DAY AND EXERCISE
Graham, K., Bourke, D, Buddee, A., Townsend, N., & Rehrer, N. (2008). Hormonal responses to a period of training and recovery in trained male rowers. ACSM 55th Annual Meeting Indianapolis, Presentation Number 798.
This study observed changes in hormonal responses to a sub-maximal exercise challenge across three days of intense training followed by three days of recovery in male trained rowers (N = 8). A 2,000m rowing ergometer test before and after the 3-day training period and the morning after the 3-day recovery was preformed. A 6-minute sub-maximal exercise challenge with blood samples taken before, immediately after exercise, and 10 minutes after exercise was undertaken on the morning before, and on the afternoon of each of the three training days. The exercise challenge was also undertaken on the morning and afternoon of each of the recovery days.
Mean power in the performance tests declined across the training period. Across the three days of recovery the exercise mean power increased. Mean power was not different between pre-training and post-recovery performance tests. Testosterone concentration increased across the sub-maximal exercise challenge and declined to below pre-exercise values at 10 minutes post-exercise. Testosterone showed a time-of-day effect for the recovery phase of the study with higher values in the morning. Relative to other sessions, cortisol was elevated in blood samples collected before the performance tests. Testosterone-cortisol ratio was lower in the morning than the afternoon during the recovery period.
Implication. Hormonal responses to a period of intense training and recovery are marked. Hormone concentrations can be influenced by time-of-day and subsequent exercise. Caution should be heeded when interpreting hormonal data as a means of monitoring the training and recovery response.
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