The effect of air scuba dives up to a depth of 30 metres on serum cortisol in male divers.

INTRODUCTION

Environmental pressure changes with depth may lead to changes in various hormone levels in the body. Of interest are the so-called stress hormones, such as cortisol. Other factors altering cortisol levels are anxiety, exercise and cold. We investigated serum cortisol changes after air scuba dives in 24-27⁰C open water up to a depth of 30 metres.

METHOD

Ten, experienced, male divers participated in the study. Four dives, to depths of 1, 10, 20 and 30 metres' sea water (msw) for 20 minutes bottom time, at rest, were conducted at about 1000 h on four consecutive days in the Persian Gulf. Before diving and soon after surfacing, approximately 5 ml blood was drawn from a right antecubital vein for serum cortisol assay, using a radioactive immunoassay technique. Repeated measures was used to analyse cortisol changes with depth.

RESULTS

There were significant differences in the pre-dive cortisol levels (df = 1, F = 5.978 , P < 0.037) and post-dive levels (df = 1, F = 34.567, P < 0.001). Cortisol levels increased with immersion irrespective of depth compared to pre-dive levels, whilst they were further significantly raised after dives to 10 m (mean 312.6 nmol·L⁻¹), 20 m (mean 299.1 nmol·L⁻¹) and 30 m (mean 406.7 nmol·L⁻¹) depth compared to levels after the 1 m dive (mean 189 nmol·L⁻¹).

CONCLUSION

The observed changes in serum cortisol were considered to be the result of the physiological effects of immersion combined with increased environmental pressure, rather than resulting from anxiety, heavy exercise or cold stress.