Maintenance of vital capacity during repetitive breath-hold in a spearfishing competition

Background and objective: Cough and a reduction in vital capacity have recently been reported following breath-hold dives to depths of 25-75 m. We sought to investigate whether repetitive dives to depths of less than 30 m would elicit similar effects. Methods: Participants in a single-day spearfishing competition were recruited. Subjects performed spirometry before and after the 5-h event. Demographics, medical and diving history, respiratory symptoms and competition diving statistics were collected. Results: Twenty-five subjects (two females), age 33 years (11) (mean (SD)), were studied. During the competition each subject completed 76 (33) dives, to 10 (3) m depth, with each dive lasting 0.9 (0.3) min. Maximum depth was 17 (4) m. No respiratory symptoms were reported. There was no difference in spirometry before and after competition except for FEF _25-75%, which increased by 0.16(0.34) L (P < 0.05). Conclusions: Pulmonary oedema or lung injury is not common after repetitive breath-hold diving to depths to 25 m, or is too mild to be reflected in symptoms or spirometry. Based largely on case studies, concern has been raised that thoracic compression during breath-hold diving can cause lung injury. To explore this, we studied 25 divers and found no respiratory symptoms or spirometric changes after a mean of 79 dives of up to 25 m over a 5-h competition period.