Exercise before scuba diving ameliorates decompression-induced neutrophil activation

The goals of this study were to investigate the difference in responses between a scuba dive preceded by aerobic exercise (EX) and a nonexercise control dive (CON) and to further evaluate the potential relation between venous gas emboli (VGE) and microparticles (MP). We hypothesized that exercise would alter the quantity and subtype of annexin V-positive MP and VGE.

Nineteen divers performed two dives to 18 m seawater for 41 min separated by at least 3 d, one of which was preceded by 60 min of treadmill interval exercise. Blood was obtained before exercise, before diving, and 15 min, 2 h, 4 h, and 24 h after surfacing. Intravascular bubbles were quantified by transthoracic echocardiography at 15, 40, 80, and 120 min.

The median VGE remained unchanged between the two dives; however, there was a significant increase in VGE in the exercise dive at 40 and 80 min at rest. MP were significantly elevated by approximately 2 times at all time points after CON compared with those after EX. Markers of neutrophil and platelet activation were elevated by both dives, and these elevations were attenuated in the EX dive.

We conclude that some of the differences observed between the EX and CON related to MP and platelet and neutrophil activation provide additional insight into the potential protective benefits of exercise; however, further study is needed to understand the mechanism and true potential of these benefits.