Athletes complete large volumes of intensive physical training to improve performance. Excessive physical training, incomplete recovery and high general stress can induce overreaching – a term used to describe over-training in the short-term. Overreaching is often deliberately induced in competitive athletes before a scheduled period of recovery to induce a “peak” or performance super-compensation. This has been labeled functional overreaching as it will enhance performance.
The problem is that there is a fine line between overreaching and chronic over-training. Most athletes and coaches don’t know where that line is. For these reasons, scientists for years have been looking for “markers” that can identify over-training.
The aim of this study was to identify indicators of overtraining in team sports athletes undertaking intensive training loads. Eighteen semi-professional rugby league players were randomly assigned to two pairs, matched groups. One group completed 6 weeks of normal training while the other group was deliberately overreached through intensified training. Both groups then completed the same 7-day stepwise training load reduction taper and performed a battery of physical tests.
Results showed that the only biochemical measure that was significantly different between the two groups was blood glutamine to glutamate ratios. Changes in the testosterone to cortisol ratio, plasma creatine kinase activity was also observed. This suggests that blood glutamine to glutamate and a lesser extent, testosterone to cortisol ratios and plasma creatine kinase may provide useful markers of overtraining in athletes. We’ll keep an eye on the research to see if more studies confirm these results.
Source: European Journal of Applied Physiology 99:313–324
