Energy cost and muscular activity required for leg swing during walking

Abstract

To investigate the metabolic cost and muscular actions required for the initiation and propagation of leg swing, we applied a novel combination of external forces to subjects walking on a treadmill. We applied a forward pulling force at each foot to assist leg swing, a constant forward pulling force at the waist to provide center of mass propulsion, and a combination of these foot and waist forces to evaluate leg swing. When the metabolic cost and muscle actions were at a minimum, the condition was considered optimal. We reasoned that the difference in energy consumption between the optimal combined waist and foot force trial and the optimal waist force-only trial would reflect the metabolic cost of initiating and propagating leg swing during normal walking. We also reasoned that a lower muscle activity with these assisting forces would indicate which muscles are normally responsible for initiating and propagating leg swing. With a propulsive force at the waist of 10% body weight (BW), the net metabolic cost of walking decreased to 58% of normal walking. With the optimal combination, a propulsive force at the waist of 10% BW plus a pulling force at the feet of 3% BW the net metabolic cost of walking further decreased to 48% of normal walking. With the same combination, the muscle activity of the iliopsoas and rectus femoris muscles during the swing phase was 27 and 60% lower, respectively, but the activity of the medial gastrocnemius and soleus before swing did not change. Thus our data indicate that approximately 10% of the net metabolic cost of walking is required to initiate and propagate leg swing. Additionally, the hip flexor muscles contribute to the initiation and propagation leg swing.

Modulation of work and power by the human lower-limb joints with increasing steady-state locomotion speed

“…Second, the normalized net joint power data were integrated over the duration of the stride cycle to calculate the work done (J kg Previous studies have demonstrated that differences exist in the metabolic cost associated with stance versus swing phase muscle actions during human walking and running, with at least 70% of the total metabolic cost attributable to stance phase muscle actions (Gottschall and Kram, 2005;Modica and Kram, 2005;Umberger, 2010). We therefore calculated all parameters of interest for stance and swing separately.…”

“…They found the hip's contribution to significantly decrease (from 44% to 32%) and the ankle's contribution to significantly increase (from 39% to 47%). We have expanded upon these findings by reporting: (1) the relative contributions from each joint towards P þ tot (and W þ tot ) for stance and swing separately (given that previous studies have demonstrated that at least 70% of the total metabolic cost during locomotion is attributable to stance-phase muscle actions; Gottschall and Kram, 2005;Modica and Kram, 2005;Umberger, 2010); and (2) the relative contributions from each joint towards P À tot (and W À tot ). The relative contributions from each joint were influenced by a change in locomotion mode, especially for the hip (Fig.…”

Changing the demand on specific muscle groups affects the walk–run transition speed

“…We analyzed and compared EMG activity for subjects while walking at their PTS during each condition. For the impeding J. L. Bartlett and R. Kram (Gottschall and Kram, 2005). The system of rubber tubing and pulleys apply forces at either the feet or near the center of mass.…”

Minimally Actuated Walking: Identifying Core Challenges to Economical Legged Locomotion Reveals Novel Solutions

“…Although this is an important aspect of locomotion that ultimately cannot be ignored, we have chosen to focus on the underlying mechanisms that have a dominant influence on the energetics of whole-body trajectory management (Donelan et al, 2002a;Kuo et al, 2005). There is some evidence that swinging the leg consumes approximately 10-33% of metabolic expenditure during bipedal walking (Doke et al, 2005;Gottschall and Kram, 2005;Umberger, 2010), however the dynamics of a pendular leg (or more specifically, a double pendulum) can likely be facilitated with mostly passive dynamics.…”