Measurement of heart rate variability and salivary cortisol levels in beginner scuba divers

Abstract

Scuba diving, an expensive form of extreme sport, remains popular despite the world wide economic recess. Part of its popularity is ascribed to the fact that it allows for sensation seekers to experience novel experiences. Research has indicated that novel experiences induce stress responses in human beings. Amongst scuba divers, this stress response was often measured with psychometric instruments after dives had occurred. The problem, however, is that to understand the stress response one must not only study the psychological dimension, but also needs to investigate its physiological impact on the body. In the scuba diving environment though, it not preferable to measure it after a scuba dive had occurred. Researchers have discovered that anticipating being confronted with a novel experience could elicit a physiological stress response. Because of this, it is theorized that scuba divers would experience a stress response by merely anticipating being underwater. The aim of the present study was to determine if a physiological stress response occurred in a group of beginner divers. Since these divers are also confronted with a series of novel experiences during their training, another aim of the study was to investigate how the stress response manifested physiologically as the course progressed. Sixty divers participated in the study. Heart rate measurements and salivary specimen were taken on three occasions: at rest (baseline), before entering the pool to practice scuba skills and before participating in the first open water dive. Cortisol was extracted from the salivary specimen. The results indicated that significant differences occurred in cortisol levels between the baseline and before entering the pool measurements. Significant differences were also observed between the baseline and before the open water dive measurements. Heart rate yielded significant differences between the baseline and before the pool measurements, as well as between the pool and before the open water dive measures. The findings indicated that beginner divers experienced a physiological stress response as a result of anticipating taking part in a novel experience. It further suggested that, as their training progressed, the stress response did not disappear but was controlled or inhibited after the first encounter with the underwater environment. The reason for this is that different systems in the sympathetic nervous system are responsible for the activation of cortisol and heart rate.