Effects of adaptive error-threshold practice on soccer instep kick learning

This study examined the effects of contextual interference and algorithmic practice with 33% or 44% error thresholds on learning the soccer instep kick in novice participants. Seventy-one inexperienced students (18-25 years) were randomly assigned to Blocked, Random, algorithmic 33%, algorithmic 44%, or control groups. After pre-testing, practice involved 324 trials over two days from 5, 6, and 7 m distances. Algorithmic groups began with blocked practice and progressed to serial or random structures based on accuracy thresholds (≥ 67% for 33%; ≥ 56% for 44%). Blocked and random groups practiced according to classical random and blocked order. Retention and transfer tests occurred two days post-practice; psychological pressure was induced via financial incentives, audience, and social comparison. Acquisition results showed no group differences, but algorithmic 33% improved significantly from day 1 to 2. In retention, both algorithmic groups outperformed random and control groups. In the transfer test, algorithmic 44% surpassed all groups, including algorithmic 33%. Heart rate increased post-stress induction, confirming manipulation success, yet no group differences emerged under psychological pressure. The findings may be interpreted within the challenge point framework, although the underlying informational mechanisms were not directly assessed. As an initial application of algorithmic practice to a field-based motor skill, the present results suggest that error-threshold tuning may represent a promising avenue for future motor learning research.