EXERCISE EFFECTS ON CENTRAL VENOUS NITROGEN TENSIONS AFTER SIMULATED NON-DECOMPRESSION DIVES

In five subjects we examined the effect of exercise on the pattern of central venous (right atrial) N-2 tensions (PVN2) after ascent from si mulated non-decompression dives. The dives consisted of exposure to ai r at 3 bar for 20 min with 10 min of exercise (workload 75 W) at depth to achieve near-complete N-2 saturation of the muscles. After the div e the subjects rested or, on another day, exercised for 30 min (worklo ad 100 W) starting 10 min after completing the ascent. Blood samples t aken every 10 min until the 60th min and 90 min after the dive were an alyzed for Pv(N2) using a manometric Van Slyke apparatus. The amount o f N-2 eliminated was estimated from the Pv(N2) by adapting the Fick pr inciple. Immediately after the ascent, PVN2 were 950 +/- 39 and 942 +/ - 27 mmHg, respectively, in the rest and experiment series. In the res t experiments Pv(N2) continuously decreased to 606 +/- 8 mmHg 90 min a fter the dive, remaining significantly higher (P < 0.05) than before t he dive. Exercise caused the Pv(N2) to increase beyond the correspondi ng levels of the rest experiments (P < 0.05 at 20 and 30 min exercise) . After the exercise Pv(N2) rapidly declined, reaching predive levels 60 min after the ascent. Exercise increased N-2 elimination to 970 +/- 143 ml, whereas it had been 311 +/- 61 ml (P < 0.05) in the correspon ding phase of the rest experiments. We conclude that if extensive supe rsaturation and bubble formation can be avoided, such as probably was the case in our shallow non-decompression dives, exercise after the as cent accelerates N-2 elimination.