A treadmill-mounted force platform.
Muscle, bone, and tendon forces; the movement of the center of mass, and the spring properties of the body during terrestrial locomotion can be measured using ground-mounted force platforms. These measurements have been extremely time consuming because of the difficulty in obtaining repeatable constant speed trials (particularly with animals). We have overcome this difficulty by mounting a force platform directly under the belt of a motorized treadmill. With this arrangement, vertical force can be recorded from an unlimited number of successive ground contacts in a much shorter time. With this treadmill-mounted force platform it is possible to accurately make the following measurements over the full range of steady speeds and under various perturbations of normal gait: 1) vertical ground reaction force over the course of the contact phase; 2) peak forces in bone, muscle, and tendon; 3) the vertical displacement of the center of mass; and 4) contact time for the limbs. In our treadmill-force platform design, belt forces and frictional forces cause no measurable cross-talk problem. Natural frequency (160 Hz), nonlinearity (less than 5%), and position independence (less than 2%) are all quite acceptable. Motor-caused vibrations are greater than 150 Hz and thus can be easily filtered.
Kram
R
R
Museum of Comparative Zoology, Harvard University, Bedford, Massachusetts 01730.
Powell
A J
AJ
D001696:Biomechanical Phenomena; D001842:Bone and Bones / Q000502:physiology; D004864:Equipment and Supplies; D005069:Evaluation Studies as Topic; D008124:Locomotion / Q000502:physiology*; D009132:Muscles / Q000502:physiology; D013710:Tendons / Q000502:physiology