influence of gait speeds on contact forces of lower limbs while walking with fast speed aims to promote health and fitness of individuals the potential risk on lower limb joint loading across walking speed is still unknown in order to determine the joint contact force loading associated with different walking speeds fifteen young male and fifteen female participants performed barefoot walking across different speeds regular11ms medium14ms and fast17ms the synchronized motion and ground reaction force grf data were captured by codamotion capture system and amti force platform all kinematics and grf information were input to the anybody musculoskeletal model to determine 3dimensional knee contact forces the results showed that increased walking speed was associated with a greater proximaldistal and anteriorposterior grf during early impact phase implying that the joint stability is more demanding at higher walking speed conditions p 005 in addition higher proximaldistal and anteriorposterior knee contact forces were found when participants were walking at higher speeds p 005 therefore the risk of knee cartilage and ligament damage associated with the increased knee contact forces should require further attention