Sagittal plane joint kinetics during stair ascent in patients with peripheral arterial disease and intermittent claudication

Stair negotiation poses a substantial physical demand on the musculoskeletal system and this challenging task can place individuals at risk of falls. Peripheral arterial disease (PAD) can cause intermittent claudication (IC) pain in the calf and results in altered gait mechanics during level walking. However, whether those with PAD-IC adopt alternate strategies to climb stairs is unknown. Twelve participants with PAD-IC (six bilateral and six unilateral) and 10 healthy controls were recruited and instructed to ascend a five-step staircase whilst 3D kinematic data of the lower-limbs were recorded synchronously with kinetic data from force plates embedded into the staircase on steps two and three. Limbs from the unilateral group and both limbs from the bilateral claudicants were categorised as claudicating (N = 18), asymptomatic (N = 6) and control (N = 10). Claudicants walked more slowly than healthy controls (trend; P = < 0.066). Both claudicating- and asymptomatic-limb groups had reduced propulsive GRF (P = 0.025 and P = 0.002, respectively) and vertical GRF (P = 0.005 and P = 0.001, respectively) compared to controls. The claudicating-limb group had a reduced knee extensor moment during forward continuance (P = 0.060), ankle angular velocity at peak moment (P = 0.039) and ankle power generation (P = 0.055) compared to the controls. The slower gait speed, irrespective of laterality of symptoms, indicates functional capacity was determined by the limitations of the claudicating limb. Reduced ankle power generation and angular velocity (despite adequate plantarflexor moment) implies velocity-dependent limitations existed in the calf. The lack of notable compensatory strategies indicates reliance on an impaired muscle group to accomplish this potentially hazardous task, highlighting the importance of maintaining plantarflexor strength and power in those with PAD-IC.