School of Health and Human Performance, Dublin City University, Dublin, Ireland.
Med Sci Sports Exerc. 2012 Apr;44(4):754-60. doi: 10.1249/MSS.0b013e3182376a13.
Accurate knowledge of results (KR), in the form of service speed, is important in learning to serve faster. The aim was to determine whether players could accurately judge if their serve was faster or slower than their preceding serve (experiment 1) and if providing them with accurate augmented KR feedback on service speed using a speed gun could enhance learning after training (experiment 2).
In experiment 1, 11 high-level national junior players served 10 serves to a target area and were asked to judge whether the serve was faster/slower that the preceding serve. In experiment 2, 12 high-level national junior players, divided into two groups, trained to improve their service speed for 12 wk (three sessions per week). During the first 6 wk (90 maximum-effort serves/session), they received either augmented (group 1) or no augmented (group 2) KR feedback. During the following 6 wk, participants did not complete the 90 serves per session and received no augmented KR feedback (retention test).
In experiment 1, players could not correctly determine whether serves were faster/slower than the preceding serve. In experiment 2, both groups significantly enhanced their service speed after the initial 6 wk of service training, but the enhancement was significantly greater (P = 0.01) in the augmented versus no augmented KR feedback group (0.84 ± 0.38 vs 0.22 ± 0.04 m·s⁻¹ ). These enhancements were still evident during the retention test (P = 0.01).
Players cannot accurately judge service speed, and by providing this information in the form of augmented feedback, a player can enhance the process of learning to serve faster with training. Players should therefore use augmented feedback on service speed when training to serve faster.
准确的成绩反馈（KR），以服务速度的形式，在学习更快发球中很重要。目的是确定运动员是否能准确判断他们的发球是否比前一个发球更快或更慢（实验 1），以及在训练后使用测速枪提供准确的增强型 KR 反馈是否能提高发球速度的学习效果（实验 2）。
在实验 1 中，11 名高水平的国家青年球员向目标区域发球 10 次，并被要求判断发球是否比前一个发球更快/更慢。在实验 2 中，12 名高水平的国家青年球员分为两组，接受为期 12 周的发球速度训练（每周三次训练）。在前 6 周（每次 90 次最大努力发球）中，他们接受了增强型（第 1 组）或非增强型（第 2 组）KR 反馈。在接下来的 6 周内，参与者没有完成每次 90 次的发球，也没有接受增强型 KR 反馈（保留测试）。
在实验 1 中，运动员无法正确判断发球是否比前一个发球更快/更慢。在实验 2 中，两组在最初的 6 周发球训练后都显著提高了发球速度，但在增强型 KR 反馈组中，提高的幅度明显更大（P = 0.01）（0.84 ± 0.38 比 0.22 ± 0.04 m·s⁻¹）。在保留测试中，这些提高仍然很明显（P = 0.01）。
运动员无法准确判断发球速度，通过提供增强型反馈形式的信息，运动员可以在训练中增强学习更快发球的过程。因此，运动员在训练发球速度时应使用增强型 KR 反馈。
