Delayed benefits from spaced training when learning a precision throwing task

Spaced training produces gains in performance associated with memory consolidation, which develops between sessions (offline gain). Learning motor skills that require many repetitions may generate a delay in memory formation and in offline gain. We tested the presence of this delay by studying a precision throwing task. Sixteen participants performed 1020 underarm precision throws distributed over four sessions. Eight participants spaced the training by 40-min betweensession intervals, while the remaining subjects distributed the practice with 1-day intervals. Memory retention was tested 15 days after training. Differences in accuracy over groups, sessions, directions of throwing movements and blocks of throws were evaluated by analysis of variance. The 40-min group had better performance than the 1-day group after the first two sessions. As the level of skill stabilized, the 1-day group exhibited offline gains, with significant performance improvements during the fourth and retention session. Both medial-lateral and antero-posterior movement directions of throwing contributed to the performance. Initial decrements in performance appeared within sessions for both groups. Overall, when learning a precision throwing task, benefits from spaced training is delayed and occurs as the skill stabilizes. These findings may help to optimize training distribution schedules, particularly for precision motor skills requiring extensive practice.