Changing ecological constraints of practice alters coordination of dynamic interceptive actions

Abstract

Ecological constraints of practice significantly affect the acquisition of functional information-movement couplings and learners need to converge on information-specifying perceptual variables. Consequently, prolonged and widespread use of ball projection machines for practice of interceptive actions may lack theoretical foundation because they afford information-specifying variables which are not present in competitive performance. To examine this issue, timing and coordination of the forward defensive stroke in cricket batting were examined in experienced batters under two typical practice task constraints: batting against a representative 'real' bowler (B) and a representative bowling machine (BM) (mean delivery velocity 26.76 m s-1 under both conditions). Results showed significant adaptation of coordination and timing under the different practice task constraints. For example, initiation of the backswing was later against a bowler and downswing was faster with a different ratio of backswing–downswing when batting in the BM condition (47%: 53%) compared to B (54%: 46%). Peak bat height differed under the two constraints (BM: 1.56m, s=19.89 m and B: 1.72m, s=10.36 m). Mean length of front foot stride was shorter against the BM (0.55m, s=0.07 m) compared to B (0.59m, s=0.06 m). Correlation between initiation of backswing and front foot movement was much higher against B (r=0.88) than BM (r=0.65). Results suggested that coaches should ensure opportunities for regular practice against 'real' bowlers, so that batters become attuned to the information available for pick up in those specific practice constraints. Projectile machines may be best used under special conditions in which coaches randomise the bounce point and deliver balls at slower speeds to allow batters to sample early ball flight before selecting shot responses.