High intensity cycling before SCUBA diving reduces post-decompression microparticle production and neutrophil activation.

Abstract

Venous gas emboli (VGE) have traditionally served as a marker for decompression stress after SCUBA diving and a reduction in bubble loads is a target for precondition procedures. However, VGE can be observed in large quantities with no negative clinical consequences. The effect of exercise before diving on VGE has been evaluated with mixed results. Microparticle (MP) counts and sub-type expression serve as indicators of vascular inflammation and DCS in mice. The goal of the present study is to evaluate the effect of anaerobic cycling (AC) on VGE and MP following SCUBA diving. Ten male divers performed two dives to 18 m for 41 min, one dive (AC) was preceded by a repeated-Wingate cycling protocol; a control dive (CON) was completed without exercise. VGE were analyzed at 15, 40, 80, and 120 min post-diving. Blood for MP analysis was collected before exercise (AC only), before diving, 15 and 120 min after surfacing. VGE were significantly lower 15 min post-diving in the AC group, with no difference in the remaining measurements. MPs were elevated by exercise and diving, however, post-diving elevations were attenuated in the AC dive. Some markers of neutrophil elevation (CD18, CD41) were increased in the CON compared to the AC dive. The repeated-Wingate protocol resulted in an attenuation of MP counts and sub-types that have been related to vascular injury and DCS-like symptoms in mice. Further studies are needed to determine if MPs represent a risk factor or marker for DCS in humans.