Metabolic and biomechanical effects of velocity and weight support using a lower-body positive pressure device during walking.

OBJECTIVES: To determine how changes in velocity and weight support affect metabolic power and ground reaction forces (GRFs) during walking using a lower-body positive pressure (LBPP) device. To find specific velocity and weight combinations that require similar aerobic demands but different peak GRFs.

DESIGN: Repeated measures.

SETTING: University research laboratory.

PARTICIPANTS: Healthy volunteer subjects (N=10).

INTERVENTIONS: Subjects walked 1.00, 1.25, and 1.50 m/s on a force-measuring treadmill at normal weight (1.0 body weight [BW]) and at several fractions of BW (.25, .50, .75, .85 BW). The treadmill was enclosed within an LBPP apparatus that supported BW.

MAIN OUTCOME MEASURES: Metabolic power, GRFs, and stride kinematics.

RESULTS: At faster velocities, peak GRFs and metabolic demands were greater. In contrast, walking at lower fractions of BW attenuated peak GRFs and reduced metabolic demand compared with normal weight walking. Many combinations of velocity and BW resulted in similar aerobic demands, yet walking faster with weight support lowered peak GRFs compared with normal weight walking.

CONCLUSIONS: Manipulating velocity and weight using an LBPP device during treadmill walking can reduce force yet maintain cardiorespiratory demand. Thus, LBPP treadmill training devices could be highly effective for rehabilitation after orthopedic injury and/or orthopedic procedures.