Autonomic-nervous-system activity during the preparation phase for the snatch in Olympic weight lifting.

Purpose: To examine the preparation phase for the snatch lift in Olympic weight lifting. Two behavioral periods were studied, each corresponding to specific mental processes: a stance in front of the bar and placement of hands on the bar. Each period was hypothesized to elicit different responses of autonomic-nervous-system activity.

Methods: Twelve elite male subjects completed 12 lifts at 90% to 95% of their best grade after warm-up (80% of their best grade). Because peripheral autonomic-nervous-system activity is related to arousal and activation variation, 6 variables were continuously recorded: electrodermal (skin resistance and potential), thermovascular (skin temperature and skin blood flow), and cardiorespiratory (heart rate and respiratory frequency).

Results: Responses (ie, phasic activities) were evident during the first behavioral period. Decrease in heart rate (mean = 19 beats/min) or in respiratory frequency (mean = 8.6 beats/min) was related to attention processes. These responses were weaker (-0.16 degrees C vs -0.25 degrees C in skin temperature) and shorter (2.7 seconds vs 4.3 seconds in skin resistance) than those recorded during execution. The second phase showed variations in basal levels (mean increase in heart rate of 25%), related to increase in activation, thus attesting the muscle system's process of preparation for effort.

Conclusion: Weight lifters separated the preparation phase into 2 stages that were closely matched by different physiological activities. Weight lifting requires participants to share their mental resources among the 2 demanding concentration phases by first focusing their attention on the execution and then mobilizing energizing resources.