S: ADAMS, M. L., N. W. EASTMAN, R. P. TOBIN, D. L. MORRIS, and W. L. DEWEY. Increased plasma [beta]-endorphin immunoreactivity in scuba divers after submersion. Med. Sci. Sports Exerc, Vol. 19, No. 2, pp. 87-90, 1987. After submersion under water in a motionless state of neutral buoyancy, scuba divers frequently report feelings of well-being or euphoria similar to those reported after strenuous exercise. Since strenuous exercise is associated with a stress-related increase in plasma [beta]-endorphin immunoreactivity ([beta]-EIR), this study was undertaken to measure plasma [beta]-EIR after submersion in a state of neutral buoyancy under conditions that do not involve strenuous exercise or other extreme stresses. Plasma [beta]-EIR was measured by radioimmunoassay in male scuba divers before and immediately after remaining motionless 10 ft under water in a state of neutral buoyancy. A significant (P < 0.01) increase in plasma [beta]-EIR was found under these conditions. Venipuncture and scuba breathing out of the water did not alter [beta]-EIR levels. These results indicate that the milder stress associated with submersion in a state of neutral buoyancy involves an increase in plasma [beta]-EIR similar to that caused by severe stress.
(C)1987The American College of Sports Medicine