Assessment of endocrine stress status in athletes – new twists to the tale
CITATION: Smith, C. & Myburgh, K. H. 2005. Assessment of endocrine stress status in athletes – new twists to the tale. South African Journal of Sports Medicine, 17(3):19-29, doi:10.17159/5124.
The original publication is available at https://journals.assaf.org.za/sajsm
Objective. Cortisol concentration at rest seems to be an insensitive marker for endocrine stress status in athletes. Therefore, the aim of this review was to identify potentially more sensitive parameters which could be used to monitor endocrine stress status during chronic exercise training. In order to gain more insight from studies not directly related to exercise science, this review also includes findings from studies investigating responses to psychological stress in healthy individuals and in patients suffering from chronic disease. Data sources. Medline. Study selection and data extraction. Key words (e.g. exercise stress, psychological stress, overtraining, chronic fatigue, dehydroepiandrosterone (DHEA), chronic inflammation). Only studies published in peer-reviewed journals included in the International Science Index were used. Care was specifically taken not to over-represent any particular research group’s articles. Data synthesis. A qualitative synthesis was done, based on all papers included in the review. Conclusions. Four main conclusions were drawn: (i) instead of considering changes in mean cortisol concentration over time for a group of athletes, high- and low-responders should be identified at baseline and their responses considered separately; (ii) it may be more useful to express cortisol concentration as a ratio to either testosterone or DHEA-sulphate (DHEAs) concentration than assessing either the catabolic or anti-catabolic variable on its own; (iii) in response to stress, cortisol binding globulin (CBG) and sex hormone binding globulin (SHBG) do not seem to play major roles in the regulation of circulating concentrations of bioactive cortisol and testosterone respectively; and (iv) it is crucial to allow sufficient recovery from the most recent exercise session to ensure that proper resting blood samples are obtained for assessment of chronic effects of training on endocrine status.