Social support reduces perceptions of fatigue while increasing energy expenditure and outputs during physical activity

Social cues affect psychological and physiological processes governing energy allocation across domains, but their effects on energy expenditure during physical activity remain unclear. We conducted two within-subjects field experiments with competitive rowers in the UK to test whether social support cues affect perceptions of effort and fatigue, energy expenditure, and physical outputs. In Study 1, 26 adolescents completed time-to-task- failure rowing trials while viewing photos of a supportive person or a stranger. In Study 2, 25 adults completed 20-minute fixed-pace trials followed by 2km time trials under three conditions: stranger photo, supportive person photo, or supportive person photo plus companion present. Social support conditions led to longer rowing times (Study 1), faster 2km times (Study 2), and less perceived fatigue during fixed-pace trials. Energy expenditure increased with longer exercise times, while energetic efficiency remained constant across conditions. Findings suggest social support can increase energy expenditure during physical activity via reducing fatigue.