Endurance exercise immediately before sea diving reduces bubble formation in scuba divers

Abstract

Previous studies have observed that a single bout of exercise can reduce the formation of circulating bubbles on decompression but, according to different authors, several hours delay were considered necessary between the end of exercise and the beginning of the dive. The objective of this study was to evaluate the effect of a single bout of exercise taken immediately before a dive on bubble formation. 24 trained divers performed open-sea dives to 30 msw depth for 30 min followed by a 3 min stop at 3 msw, under two conditions: (1) a control dive without exercise before (No-Ex), (2) an experimental condition in which subjects performed an exercise before diving (Ex). In the Ex condition, divers began running on a treadmill for 45 min at a speed corresponding to their own ventilatory threshold 1 h before immersion. Body weight, total body fluid volume, core temperature, and volume of consumed water were measured. Circulating bubbles were graded according to the Spencer scale using a precordial Doppler every 30 min for 90 min after surfacing. A single sub-maximal exercise performed immediately before immersion significantly reduces bubble grades (p < 0.001). This reduction was correlated not only to sweat dehydration, but also to the volume of water drunk at the end of the exercise. Moderate dehydration seems to be beneficial at the start of the dive whereas restoring the hydration balance should be given priority during decompression. This suggests a biphasic effect of the hydration status on bubble formation.

The impact of predive exercise on repetitive SCUBA diving

“…The statistically insignificant change in BG following the exercise dive compared to the control dive is in line with previous research using similar open sea diving protocols. The impact of exercise on VGE is positive in some studies, although none of these can be directly compared to this experiment as they utilized simulated diving (Gennser et al, 2012) or diving profiles that utilized decompressions stops (Castagna et al 2011). One study with rats utilized a relatively extreme downhill running protocol (100 min at À16°) to induce myofibrillar damage and found no difference in bubble amounts or survival rates following a simulated dive (Jorgenson et al, 2013).…”

“…Venous gas emboli are often used as a surrogate marker for decompression stress following exercise; however, the data on VGE and exercise are limited to a few conflicting field studies (Blatteau et al, 2005;Castagna et al, 2011;Madden et al, 2014) and simulated dives (Dujic et al, 2004;Gennser et al, 2012). MPs and endothelial function show promise as other markers to assess decompression stress and these may contribute to DCS or other forms of illness with mechanisms separate from circulating gas emboli.…”

Pre-dive Whole-Body Vibration Better Reduces Decompression-Induced Vascular Gas Emboli than Oxygenation or a Combination of Both

“…Indeed, since several years, field research focuses on “preconditioning” methods that might attenuate bubble formation post-dive. Several practical, simple and feasible pre-dive measures have been studied such as endurance exercise (Blatteau et al, 2005; Castagna et al, 2011), pre-dive exposition to a warm environment (Blatteau et al, 2008), oral hydration (Gempp et al, 2009) or ingestion of dark chocolate (Theunissen et al, 2015). Others have tested the benefit of pre-dive oxygenation (Castagna et al, 2009; Bosco et al, 2010), or whole-body vibration (Germonpré et al, 2009).…”

Diving physiopathology: the end of certainties? Food for thought

“…33 in human divers also, pre-dive exercise has been shown influential 34 and, depending on the timing and intensity, seems to reduce or augment Vge counts. [35][36][37] Interestingly, significant effects of exercise on post-dive Vge can be observed when work is conducted either two hours before or 24 hours before the dive. this two-peak phenomenon has been also proposed in ischemic preconditioning for altitude exposures, 38 where protection shortly olate, taken two hours before a dive, was measured.…”