Learning precision ball throwing was mostly studied to explore the early rapid improvement of accuracy, with poor attention on possible adaptive processes occurring later when the rate of improvement is reduced. Here, we tried to demonstrate that the strategy to select angle, speed and height at ball release can be managed during the learning periods following the performance stabilization. To this aim, we used a multivariate linear model with angle, speed and height as predictors of changes in accuracy. Participants performed underarm throws of a tennis ball to hit a target on the floor, 3.42 m away. Two training sessions (S1, S2) and one retention test were executed. Performance accuracy increased over the S1 and stabilized during the S2, with a rate of changes along the throwing axis slower than along the orthogonal axis. However, both the axes contributed to the performance changes over the learning and consolidation time. A stable relationship between the accuracy and the release parameters was observed only during S2, with a good fraction of the performance variance explained by the combination of speed and height. All the variations were maintained during the retention test. Overall, accuracy improvements and reduction in throwing complexity at the ball release followed separate timing over the course of learning and consolidation.

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 between-session 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.