Variable practice versus constant practice in the acquisition of wheelchair propulsive speeds

Previous studies have demonstrated that varied practice (involving several versions of a skill) has advantage over constant practice (involving only one version of a skill) in learning a motor skill. However, the support for variable practice mainly came from studies using discrete motor skills. Therefore, the purpose of the study was to assess if variable practice was more effective than constant practice for the purpose of learning a continuous and real-life motor skill: wheelchair propulsion. A total of 36 able-bodied undergraduate students participated in this study. There were two constant-practice groups. One group practiced wheelchair propulsion on a roller system with a single speed, 30% of the maximum speed (30%-only group), and one group practiced using 55% of the maximum speed (55%-only group). One variable-practice group (variable group) practiced the propulsion with two different speeds, 30 and 55% of the maximum speed. In addition to retention tests, two transfer tests (i.e., tests on 40 and 70% of the maximum speeds) were performed by the three groups after the 10 weeks of training. The results were mixed. The variable-practice group produced significantly fewer absolute errors on both transfer tests than the 30%-only group. However, when compared to the 55%-only group, the variable-practice group only produced significantly fewer absolute errors on the transfer test at 70% speed, but not at 40% speed.