Anticipated Task Difficulty Provokes Pace Conservation and Slower Running Performance

PURPOSE: Models of self-paced endurance performance suggest that accurate knowledge of the exercise end-point influences pace-related decision making. No studies have examined the effects of anticipated task difficulty during equidistant endurance activities. Accordingly, the purpose of this study was to investigate the effects of anticipated task difficulty on pacing, psychological, and physiological responses during running time trials. METHODS: Twenty-eight trained runners completed three self-paced 3000-m time trials. The first was a baseline time trial completed on a 0% treadmill gradient. Time trials 2 and 3 were counterbalanced. Before a known incline time trial, anticipated to be more difficult, subjects were accurately informed that the gradient would increase to 7% for the final 800 m. Before an equivalent, unknown incline (UI) time trial subjects were deceptively informed that the gradient would remain at 0% throughout. RESULTS: Expressed relative to baseline, running speed was 2.44% slower (d = -0.47) over the first 2200 m during known incline (KI) time trial than UI time trial. Effort perception, affective valence, heart rate, and blood lactate did not differ between time trials. Initial running speed during KI was related to pretrial motivation, pretrial vigor, perceived effort, and affective valence (all r ≥ 0.382). No such relationships existed during UI. More subjects also reported a conscious focus on pacing during KI. CONCLUSIONS: An anticipated increase in task difficulty provoked pace conservation during 3000 m running time trials. The reduced pace may have resulted from greater task uncertainty and consciously aware, effort- and affect-based decisions to conserve energy and maintain hedonic state during KI. The findings add to theoretical understandings of factors that influence pacing during endurance activity. Consequently, recommendations to minimize the potentially deleterious effects of anticipated increases in task difficulty are provided.