Effect of physical exercise before diving on decompression bubbles

Despite the fact that it has previously been thought that physical exercise before diving predispose for bubble formation and decompression sickness (Vann & Thalmann 1993), some recent studies have shown that physical exercise 24 or 2 hours before diving reduces the presence of bubbles post decompression (Dujic et al 2004, Blatteau et al 2007). To investigate at which time before the dive physical exercise shall be carried out to provide the best protection against decompression bubbles experiments were carried out on ten healthy subjects. The subjects carried out three chamber dives to 280 kPa (18 msw) each. The first pressure exposure was not preceded by any physical exercise, whereas the other two dives were carried out in a randomised order, with a 40 min exercise bout on ergometer bicycle 2 hours or 24 hours before the dives. After decompresion bubbles were detected using precordial ultrasound Doppler. There were no difference in maximum bubble scores between the dives. Bubbles remained longer in the circulation after dives preceded by exercise. These results do not confirm the recent reports that exercise befor diving protects against bubble formation.