Sex-specific effects of muscle fatigue on upper body kinematics and discomfort during a repetitive point task performed on a sit-stand stool

When performing repetitive work-like tasks while standing, people may develop leg discomfort and adapt their whole-body motion to arm fatigue. How these responses are affected when working while sitting on a sit-stand stool is unknown. Asymptomatic young adults (N = 29, 15 females) performed a repetitive pointing task sitting on a sit-stand stool, while whole-body kinematics was recorded. Results showed no leg discomfort increase with fatigue. The upper body leaned more backwards and towards the non-reaching side. Variability increased at the seat (p = 0.002), shoulder (p = 0.001) and elbow (p = 0.005) but was preserved at wrist (p = 0.058) and endpoint (p = 0.088). Participants who were more fatigable increased seat variability (males, p = 0.01) or seat range of motion (females, p = 0.022) after fatigue. The sit-stand stool contributed to the response to arm fatigue, although females and males developed different strategies. The maintained endpoint variability and leg discomfort suggest that the sit-stand stool could be recommended as an alternate workstation with minimal disruption to work performance or worker discomfort.