The Effect of Group Size and Synchrony on Pain Threshold Changes

Synchronization of behavior has repeatedly been shown to increase pain threshold, which is understood to be an indicator of endorphin activity. Although Weinstein et al. found that large and small groups showed the same effect, to date no study has manipulated group size to determine if it has an effect on change in pain threshold. Thirty-three participants rowed two 20-min time trials under two counterbalanced conditions—paired and large group. Pain threshold was assessed before, immediately post, 5-min post, and 10-min post each session. A repeated-measures (3 × 2) factorial ANOVA revealed a significant interaction between condition and time. Specifically, there was a significantly higher pain threshold in the large group than in the paired condition after 10 min of exercise