EFFECT OF 14 DAYS AT 15 METRES DEPTH ON HORMONAL STRESS PARAMETERS. Abyss Project 2007 - The House on the sea bottom

INTRODUCTION : Recreational scuba divers are exposed to environmental stresses including increased environmental pressure, raising of oxygen partial pressure, increased resistance to movement, added weight of diving equipment and cold stress (1). During the scuba dive, increased ambient pressure generates an increase in and PO2. nitrogen partial pressure. A decrease in cardiac output (CO) related to the simultaneous decrease of the heart rate (HR) and the stroke volume (SV) is found at high PO2. The aim of this study was to measure hormonal stress parameters in six professional trainers scuba divers to test the hypotheses that hormones release may be influenced by prolonged water submersion. Six scuba divers, three males and three females, participated in the study while trying to achieve the Guinness 14 days scuba dive in september 2007. They spent 14 days at the depth of 15 metres in Ponza Island sea (Italy) to establish a new record. METHODS: Four different blood samples were collected to evaluate hormonal stress parameters (ACTH, cortisol, prolactin, quantified by routine clinical laboratory methods, Modular E, Roche, Basel, Switzerland). Serum was immediately separated by centrifugation at 1500xg for 15 min. and stored at -20°C until analysed. The first blood samples was collected in Rome 5 days before immersion and the next three collected every five days, during the immersion, in the underwater bell and carried out water in waterproof bag. Data have been compared by paired t test, differences were considered statistically significant at P<0.05.RESULTS: Our results show a significant decrease in plasma hormone levels in the three underwater drawing respect the basal. The results obtained during the staying to 15 metres depth show a significant raise in the second underwater drawing in cortisol and ACTH. The prolactin levels show the same variations of cortisol and ACTH, but less remarkable. All values of parameters measured fall in the normal range.CONCLUSION: According to our data, we may conclude that a prolonged water immersion does not seem to be a stressor condition. Indeed the plasma hormone concentrations significantly decrease after depth, remaining lower than basal. All the hormones tested show an increase after a week in the water immersion, these might suggest a state of elevated physical and mental activation and vigilance. It has even been reported that scuba diving decreases salivary cortisol levels in recreational scuba divers (2). During the diving period the subjects didn’t show anxiety and depression, or panic symptoms; on the contrary they seem be happy to live underwater. Depending on non existence of hormonal disorders we may hypothesized that long duration water submersion might has not influenced the hypothalamic-pituitary axis in our divers.