Altered joint kinematics and increased electromyographic muscle activity during walking in patients with intermittent claudication
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Background: Patients with intermittent claudication (IC) tend to walk at a slower pace, have less lower leg muscle strength, and consume approximately 40% more oxygen during walking compared with healthy individuals. An unfavorable locomotion pattern has been suggested to explain this metabolic inefficiency. However, knowledge on gait patterns in IC is limited. Muscle activity patterns during walking measured using surface electromyography (EMG) have not been investigated in this patient population. Methods: In this cross-sectional study, gait pattern of patients newly diagnosed with IC and age-matched controls were evaluated using kinematic parameters and medial gastrocnemius (MG) and tibialis anterior (TA) muscles activity patterns. The protocol included pain-free and painful (only IC patients) treadmill walking sessions. Results: A total of 22 IC patients and 22 healthy control subjects were included. Patients walked 1.4 km/h slower (3.2 km/h vs 4.6 km/h; P <.001) than control subjects, coinciding with a 10% slower cadence (110 steps/min vs 122 steps/min; P <.001). The kinematic analysis resulted in a patient's ankle plantar flexion reduction of 45% during the propulsion phase, and ankle dorsal flexion reduction of 41% at initial contact. No additional kinematic changes were observed when claudication pain presented. Interestingly, kinematic differences did not influence the muscle activity duration during walking, because equal duration of muscle activity was found in IC patients and healthy controls. However, the amount of muscle activity in microvolts did significantly increase in IC patients when claudication pain presented (TA: Delta 23%; P <.001; MG: Delta 54%; P = .007). Conclusions: Patients with IC show significant kinematic changes during walking. These alterations did not affect EMG activity duration of MG and TA muscles. However, EMG amplitude of both muscles did significantly increase during painful walking in IC patients.