Exercise ending 30 min pre-dive has no effect on bubble formation in the rat
Berge, V.J.; Jørgensen, A.; Løset, A.; Wisløff, U.; Brubakk, A.O.
Aviation Space and Environmental Medicine 76(4): 326-328
2005
ISSN/ISBN: 0095-6562 PMID: 15828630 Document Number: 594202
Introduction: We have previously shown that exercise performed 20 h before a dive significantly reduces bubble formation in both rats and humans. Furthermore, exercise performed closer to the dive did not prevent bubble formation. Hypothesis: The present study was designed to determine whether exercise 30 min prior to a dive promotes bubble formation. The occurrence of many bubbles is linked to a higher risk of developing decompression sickness. Methods: A total of 58 Sprague-Dawley rats were randomly divided into a sedentary control group (n = 29) and an exercise group (n = 29). Rats in the exercise group ran on a treadmill for a total of 90 min at variable intensity up to 85-90% of (V) over dot O(2)max. Then, 30 min after exercise, one rat from each group rested in a pressure chamber at 700 kPa (7 atm) breathing air, performing a simulated dive. Bottom time was 45 min; decompression rate was 50 kPa center dot min(-1) (0.5 atm center dot min(-1)). Immediately after surfacing (100 kPa, 1 atm), the rats were anesthetized and bubbles were measured discontinuously for the next 60 min. Results: There were no significant differences in survival (p = 0.55), median bubble grade (p = 0.67), survival time (p = 0.53), or the number of rats getting a bubble score >= 2 (p = 0.79) between the groups. Conclusion: The same type and intensity of exercise that reduces bubble formation when performed 20 h prior to a dive neither promotes nor reduces bubble formation if performed 30 min before a dive. The present data indicate that exercise completed 30 min before a dive does not increase the risk of developing decompression sickness in the rat.