Bubble formation in animals. IV. The relative importance of carbon dioxide concentration and mechanical tension during muscle contraction

Aerobic exercise before diving reduces venous gas bubble formation in humans

“…The number of these nucleation sites may be influenced by exercise and it has been shown in cats that bubble formation can be affected by both exercise and trauma to large muscle groups (Harvey et al 1944). Muscle contraction and tissue movement associated with exercise may activate additional micronuclei by reducing absolute tissue pressure (McElroy et al 1944). Although these studies exploited electrically stimulated muscle contractions in anaesthetized animals, exercise has been generally considered an additional risk factor for DCS and divers and aviators were advised not to engage in unnecessary physical activity.…”

“…Although these studies exploited electrically stimulated muscle contractions in anaesthetized animals, exercise has been generally considered an additional risk factor for DCS and divers and aviators were advised not to engage in unnecessary physical activity. Exercise following diving or shortly before or after decompression to altitude can promote bubble formation (McElroy et al 1944; Dervay et al 2002). The uptake and elimination of gas is dependent on the blood flow.…”

Dysbarism

“…In man, exercise at altitude greatly increases the incidence of bends and chokes. In animals, it has been shown that exercise at altitude may greatly stimulate the formation of bubbles (177,254,255).…”

Exercise fizzy‐ology

“…During diving, gas must be breathed at ambient pressure and tissues equilibrate with the elevated inspired inert gas partial pressure forming a reservoir for bubble growth; with exercise, tissues that receive increased blood flow equilibrate more rapidly. By a separate mechanism, exercise following diving or shortly before or after decompression to altitude can promote bubble formation (for references see McElroy et al 1944; Jankowski et al 1997; Dervay et al 2001).…”

“…Bubbles form during decompression where dissolved gas pressure exceeds the absolute pressure in the tissues (supersaturation) plus the pressure required to maintain the bubble surface against surface tension. This tensile strength of a pure liquid is orders of magnitude higher than the supersaturation pressures that produce bubbles, which are therefore believed to grow from theoretical pre‐existing gas micronuclei temporarily stabilised by adhesion to a surface (McElroy et al 1944; Liebermann, 1957) or by a coating of surface‐active molecules (Yount, 1982). A particular degree of decompression activates only those micronuclei above a corresponding critical size and the resulting micro‐bubbles are unstable, growing or shrinking via diffusion of gas under the influences of dissolved gas pressure and surface tension.…”