We're motivated to stay ahead more than to catch up? (Relates to fear of losing?)Peer effects in running are also heterogeneous across relationship types. For example, runners are more influenced by peers whose performance is slightly worse, but not far worse, than their own as well as by those who perform slightly better, but not far better, than they do (Fig. 2a). Moreover, less active runners influence more active runners more than more active runners influence less active runners (Fig. 2b). These results are corroborated by heterogeneity across consistent and inconsistent runners. Inconsistent runners influence consistent runners more than consistent runners influence inconsistent runners (Fig. 2c). Social comparisons may provide an explanation for these results. Festinger’s social comparison theory proposes that we self-evaluate by comparing ourselves to others27. But, in the context of exercise, a debate exists about whether we make upward comparisons to those performing better than ourselves28 or downward comparisons to those performing worse than ourselves29. Comparisons to those ahead of us may motivate our own self-improvement, while comparisons to those behind us may create ‘competitive behaviour to protect one’s superiority’ (27, p. 126). Our findings are consistent with both arguments, but the effects are much larger for downward comparisons than for upward comparisons.