Objectives. To examine the effects of reward structures on the performance of a motor task. We evaluated the effects of reward interdependence on performance, cohesion, emotion, and effort during intergroup (team) competition. Design. An experimental design was used to compare the effects of reward interdependence (no, low, high) on performance of a strength and endurance task. Method. Participants (N = 111) performed a 3-min handgrip task as a member of a team of four under three reward interdependence conditions (no; low, with an even split of prize money; high, with an uneven split of prize money) in head-to-head competitions against another team. Task performance was assessed using the cumulative force production total. Task-related cohesion, enjoyment, anxiety and effort were measured using self-report scales. Results. Performance was better with rewards than no reward, and better with high than low reward interdependence. Team cohesion was highest with low reward interdependence. Effort was greater with rewards than no reward. Anxiety and enjoyment did not vary among the reward conditions. Mediation analyses indicated that increased cohesion mediated improvements in performance from no reward to low reward interdependence conditions, and increased effort mediated improvements in performance from no reward to both low and high reward interdependence conditions. Conclusion. Performance of a simple physical task in team competition was facilitated by rewards, with optimal performance associated with unequal rewards (i.e., performance-related pay). The benefits of performing with rewards compared to no rewards were explained by increased cohesion and effort. Social interdependence theory can help explain performance of simple motor tasks during team-based competitions. The findings have implications for the pay structures adopted by sports teams.