INTRODUCTION: Freedivers possess several special physiological features and have been reported to have stronger diving response and larger vital capacity (VC) than non-divers. Several populations in South-East Asia live as marine hunter-gatherers dependent upon daily freediving with little equipment. One group is the Sama-Bajau in Indonesia, Philippines and Malaysia. Our aim was to investigate the diving response and lung physiology of the Sama-Bajau breath-hold diving population in the Phillipines, which has not previously been studied.
MATERIALS AND METHODS: Nine male professional breath-hold divers were recruited from a Sama-Bajau diving community near Davao in the Philippines. Their mean(SD) age was 27(3)years, height 166(2)cm, and weight 58(2)kg. Divers made simulated dives by maximal apneas with face immersion in cool water, while heart-rate (HR) was recorded to determine the diving response by the HR reduction. Lung variables were measured using a portable spirometer, and diving time and depth of working dives in the sea were logged.
RESULTS: Mean(SE) HR-reduction was 39(3)%, at a maximal voluntary apnea of 67(7)s duration. VC was 3.9(0.6)L (96% of predicted for a Malaysian population, NS) and forced expiratory volume in the 1st second/forced VC was 89.6(3.4)% (105% of predicted, P<0.05). Maximal diving depth was 15 m, and mean depth 5(2) m. Diving shifts lasted 2-3h, with approximately 50% of the time spent underwater.
CONCLUSION: The diving response was more pronounced than in non divers but in the range typical for breath-hold divers. VC was similar to predicted for non-divers but smaller than in e.g. competition divers. FEV1/FVC was slightly higher than in the normal population. We concluded that long term daily "natural" diving to 5-15m does not increase lung volume, but may have some effects on lung function.
2017. Vol. 219, no S710, P-66
Scandinavian Physiological Society Meeting in Oslo, Norway, 26-28 August 2016