Introduction: The effect of pre-dive exercise on post-decompression venous gas emboli (VGE) remains contentious. The aim of our study was to investigate the effect of timing, intensity and mode of exercise before diving on post-decompression VGE production.
Methods: Fifteen male volunteers performed three identical 100 min chamber dives to 18 metres' sea water. Two of the three dives were conducted with prior exercise at 24 or 2 h; a dive without prior exercise formed the control. Moderate-intensity impact exercise consisted of jogging on the spot for one minute followed by ten star jumps, repeated for a total of 40 min at 70% of maximum heart rate. Post-dive Doppler monitoring began within 2 min of surfacing and was carried out for at least 180 min. VGE were assessed using the Kisman-Masurel (KM) code and the Kisman Integrated Severity Score (KISS).
Results: The median peak KM grade for each condition following the dives was not significantly different. Pre-dive exercise at 2 h resulted in a significant reduction in the mean KISS compared to the control (11.3 versus 17.2, P < 0.04, Wilcoxon sign-ranked test). Moderate-intensity jogging/star jump exercise used in this series of dives resulted in significantly lower mean KISS (11.3 versus 21.8, P < 0.04) and median KM grade over 180 min (P < 0.006, Mann Whitney U test) compared to high intensity cycling exercise used previously.
Conclusions: This study suggests that moderate-intensity impact exercise reduces VGE production when conducted 2 h prior to diving.