The existing literature often exhibits inconsistent findings regarding lower extremity kinetics during sloped running, likely due to high variability of typical individual joint moments between and within runners. A better understanding of the kinetic effects of sloped running may be achieved by comparing the support moment and joint contributions among level, upslope, and downslope running. Twenty recreational runners (10 females) ran on three different conditions (level, 6° upslope and 6° downslope). Total support moment and joint contributions of the hip, knee, and ankle joints were compared among the three slope conditions using a one-way ANOVA with repeated measures and post-hoc pairwise comparisons. Our results showed that peak total support moment was highest during upslope running and was lowest during downslope running. The joint contribution to total support moment was similar in upslope and level running where the ankle joint has highest contribution followed by the knee and hip joints. During downslope running, highest knee joint contribution but least ankle and hip joint contributions were found when compared to level and upslope running.

• Runners experience different task demands from biomechanical, physiological and neuromuscular aspects among upslope, downslope, and level running.

• Inconsistent findings comparing individual lower extremity joint moments among different sloped conditions were reported previously.

• Support moment provides a comprehensive insight into the kinetic synergy of the overall limb; however, the influences of upslope, level and downslope running on the support moment were not thoroughly examined.

• Our results demonstrated that upslope running increased the summed moment of the lower extremity joints, while the increased summed moment was evenly distributed among the three joints.

• We also found that running downslope decreased the summed moments of the lower extremity joints in total as well as the hip and ankle joint contributions. However, the knee joint contribution during downslope running increased compared to level and upslope running.