Motivational self-talk improves time-trial swimming endurance performance in amateur triathletes

The aim of this study was to compare the effects of an instructional and a motivational self-talk intervention on swimming endurance performance in amateur triathletes. To this purpose, we designed a parallel two groups, randomised, longitudinal (pre- and post-test) study. During 12 days in all exercise-training sessions, the motivational self-talk (M-ST) group (n = 10) was asked to rehearse motivational sentences driving to improve effort to finish the swimming test (750 m) as fast as they could. The instructional self-talk (I-ST) group (n = 11) was asked to rehearse sentences driven to keep pace and movement fluency. The performance in the swimming test increased significantly only in the M-ST group from pre- to post-intervention (2.8%, ηp2=.55). In addition, only the M-ST group increased significantly the swimming pace (ηp2=.52), which was measured every 150 m, and maintained the same perception of effort level when comparing pre- and post-intervention. The M-ST group also increased significantly their outcome expectancy (6%, ηp2= .34) from pre- to post-intervention, in which the variance of swimming performance was approximately 60% explained by the outcome expectancy (B = .656, SE = .086, p < .001, 95% CI [.482, .830]). Findings suggest that M-ST enhanced outcome expectancy, helping triathletes to improve endurance performance probably due to the higher level of potential motivation which mobilised more effort. Therefore, M-ST intervention has been probably effective to improve swimming endurance performance in amateur triathletes, whereas I-ST has maintained it.