Exercise during a 3-min decompression stop reduces postdive venous gas bubbles.
OBJECTIVE
Decompression sickness is initiated by the formation of gas bubbles in tissue and blood if the divers return to surface pressure too fast. The effect of exercise before, during, and after dive on bubble formation is still controversial. We have reported recently that strenuous aerobic exercise 24 h before simulated dive ameliorates venous bubble formation. The objective of this field study was to evaluate whether mild, continuous exercise during decompression has a similar impact.


METHODS
Ten healthy, military male divers performed an open-sea field dive to 30 m of sea water breathing air, remaining at pressure for 30 min. During the bottom and decompression the subjects performed fin underwater swimming at about 30% of maximal oxygen uptake. Each diver underwent two randomly assigned dives, one with and one without exercise during the 3-min decompression period. Monitoring of venous gas emboli was performed in the right heart with ultrasonic scanner every 20 min for 60 min after reaching surface pressure in supine rest and during forced two-cough procedure.


RESULTS
The study demonstrates that a mild, continuous exercise during decompression significantly reduced the average number of bubbles in the pulmonary artery from 0.9 +/- 0.8 to 0.3 +/- 0.5 bubbles per square centimeter in supine rest, as well as during two-cough procedure, which decreased from 4.6 +/- 4.5 to 0.9 +/- 0.9 bubbles per square centimeter. No symptoms of decompression sickness were observed in any subject.


CONCLUSIONS
These results, obtained in the field conditions, indicate that a mild, underwater swimming during a 3-min decompression period reduces postdive gas bubbles formation.
Dujić
Zeljko
Z
Department of Physiology and Biophysics, University of Split School of Medicine, Split, Croatia. zdujic@bsb.mefst.hr
Palada
Ivan
I
Obad
Ante
A
Duplancić
Darko
D
Baković
Darija
D
Valic
Zoran
Z
D017523:Croatia; D003665:Decompression Sickness / Q000517:prevention & control*; D004242:Diving; D015444:Exercise; D005740:Gases / Q000097:blood*; D006801:Humans; D014680:Veins
D005740:Gases