What Researchers Did
Researchers tested whether a bout of exercise done 2 hours before a simulated dive changed blood circulation and bubble formation in trained divers.
What They Found
This was a crossover study of 16 trained divers who each completed two simulated dives in a hyperbaric chamber (compressed to 400 kPa for 30 minutes, following the French Navy MN90 decompression procedure), one preceded by 40 minutes of submaximal exercise and one without exercise, and doppler monitoring after surfacing showed significantly fewer circulating bubbles following the exercise dive. After exercise, divers showed post-exercise hypotension, with reduced diastolic and mean blood pressure and reduced stroke volume, while total peripheral resistance was unchanged. Cardiac output dropped by a similar amount after diving regardless of whether exercise was performed beforehand, and the researchers linked the blood pressure changes to the reduced stroke volume rather than to peripheral resistance.
Canadian Relevance
No direct Canadian connection identified.
Study Limitations
The study involved only 16 trained divers in a single simulated chamber dive protocol, so the findings may not generalize to other diver populations, dive profiles, or real open-water conditions.