Influence of walking speed on lower limb muscle activity and energy consumption during treadmill walking of hemiparetic patients

Objective: To identify the relationship between treadmill speed and energy consumption and lower limb muscle activity in ambulatory hemiparetic patien ts. Design: Experimental cohort. Setting: Inpatient rehabilitation clinic. Participants: Twenty-four ambulatory hemiparetic subjects. Intervention: Subjects walked harness-secured on the treadmill with no body -weight support at self-reported (V SAS), slow (V SAS - 25%), and fast (V S AS + 25%) speed. Main Outcome Measures: Assessment of basic, limb-dependent cycle parameters , lower limb muscle activity, and energy consumption. Results: Cadence (r = .75), stride length (r = .78), relative double-suppor t duration (r = .31), mean muscle activity of the paretic tibialis anterior (r = .12), gastrocnemius (r = .37), vastus lateralis (r = .19), rectus fem oris (r = .31), and biceps femoris (r = .45) muscles, as well as heart rate (r = .54), correlated positively with treadmill speed. Mean maximum heart rate was 131 beats/min. Energy (r = -.67) and cardiac cost V = -.55) correl ated negatively with gait speed (ie, patients walked more efficiently at fa ster velocities). The qualitative muscle activation pattern analysis reveal ed earlier (more normal) onset of activation of gastrocnemius, vastus later alis, biceps femoris, and gluteus medius. Conclusions: Patients should try to walk fast on the treadmill, thereby fac ilitating relevant weight-bearing muscles and improving gait efficiency. (C ) 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.