Influence of exercise on body sway in the standing rifle shooting position.

Standing stability was measured in 16 male subjects during standing at rest, and aiming an air rifle at both rest and after an exercise bout simulating cross-country ski racing. Subjects consisted of a control group with no previous shooting experience, groups of rookie and established biathletes, and experienced position rifle shooters. Anteriposterior and lateral positions of the subject's centre of pressure were determined by a force platform, sampled at 30 Hz over a 60 second period. Horizontal movement was calculated digitally from the anteriposterior and lateral position data. Body sway was greater (p less than 0.05) during aiming at rest than while standing at rest, and also greater during aiming after exercise than at rest. Body sway was significantly smaller (p less than 0.05) in the position shooters compared to subjects with 4 months or less of shooting training. The contribution of anteriposterior movement to body sway while standing at rest was approximately twice that of lateral movement. Greater increases in lateral movement with aiming and after exercise lead to similar contributions by both components of body sway.