title: Direction of foot force for pushes against a fixed pedal: role of effort level.
abstract: Control of the force exerted by the foot on the ground is critical to human locomotion. During running on a treadmill and pushing against a fixed pedal, humans increased foot force in a linear manner in sagittal plane force space. However, for pushes against a moving pedal, force output was linear for some participants but slightly curved for others. A primary difference between the static and dynamic pedaling studies was that the dynamic study required participants to push with varying peak effort levels, whereas a constant peak effort level was used for the fixed pedal pushes. The present study evaluated the possibility that force direction varied with level of effort. Seated humans pushed against a fixed pedal to a series of force magnitude targets. The force direction varied systematically with effort level consistent with the force path curvature observed for dynamic pedaling.
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706-1189, USA.
authors.forename: Kreg G
authors.initials: KG
authors.lastname: Gruben
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Rogers
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology; D005260:Female; D005528:Foot / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D011187:Posture / Q000502:physiology; D012016:Reference Values; D016474:Weight-Bearing / Q000502:physiology