Effects of body mass and sex on kinematics and kinetics of the lower extremity during stair ascent and descent in older adults

The effects of body mass and sex on lower limb biomechanics during ascent and descent were examined in participants aged 50 to 75 with normal weight (n ​= ​19), overweight (n ​= ​18), and obese (n ​= ​8). Peak joint angles and joint moment of the lower limb were analyzed with the VICON motion analysis system. Results from multivariate analysis of variance showed that during descent, the overweight participants had significantly higher knee extensor moment (0.98 ​± ​0.30 ​N∙m/kg(-1)) than the normal-weight participants (0.70 ​± ​0.29 ​N∙m/kg(-1)). The obese group had significantly higher ankle abductor moment (0.21 ​± ​0.11 ​N∙m/kg(-1)) than the normal weight (0.12 ​± ​0.08 ​N∙m/kg(-1)) and overweight groups (0.09 ​± ​0.06 ​N∙m/kg(-1)). During ascent, the obese participants had significant higher hip flexor moment (0.42 ​± ​0.20 ​N∙m/kg(-1)) than overweight participants (0.22 ​± ​0.17 ​N∙m/kg(-1)). Significant sex differences were found in knee extension angles (4.2 ​± ​3.4° vs 7.0 ​± ​3.3°) during descent, plantar flexion angles during ascent (23.7 ​± ​5.3° vs 15.6 ​± ​3.7°) and descent (29.9 ​± ​5.0° vs 22.1 ​± ​7.9°), and ankle adduction angles (6.8 ​± ​4.8° vs 2.5 ​± ​2.5°) during ascent. It is concluded that body mass has significant impact on joint loading of lower limbs during stair walking. Being overweight and obese increased hip joint loading during ascent, and knee and ankle joint loading during descent in older adults. Sex difference in joint kinematics was presented during stair walking regardless of the body mass.