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Biomedical subjects

J L Hagy

Publications and source records attributed to J L Hagy.

5 recordsLinked to original sources
PubMed1979

The initiation of gait.

The initiation of gait was studied utilizing electromyography, force-plate data, measurements of walking velocities, and ranges of motion of joints, all of which demonstrated that gait is initiated by the body becoming unbalanced in such a way as to permit a subject to pick one foot the ground in order to take the first step. The subsequent transition of the body to the steady gait pattern occurs rapidly over a period of appproximately three steps. This transition involves rapid changes in the measured forces and activities of the muscles of the lower extremity and the motion of the joints reflects these changes.

Adult↗
PubMed1978

Role of the posterior calf muscles in normal gait.

The role of the calf muscles during the single-limb stance phase of gait was assessed in fifteen normal subjects and in seven with either an amputation or a neuromuscular deficit. Normal activity of the muscles, paralysis by nerve blocks, and stability versus instability of the ankle were studied. Pelvic displacement and velocity, step length, and step time were evaluated for each limb during the gait cycle, and the contribution of activity of calf muscles to each was determined. Limb-segment position, lower-limb joint angles, over-all cadence, velocity, and stride length were measured to reveal compensatory mechanisms in the absence of muscle strength in the calf. The results indicate that the force produced by activity of calf muscles is used to restrain the body's own forward momentum and not used to propel it further. Absence of the calf muscle causes an immediate compensatory reaction directed toward maintaining over-all stability rather than speed.

Adolescent↗
PubMed1977

The popliteus muscle.

The popliteus muscle was studied during both normal gait and a series of planned exercises. Its activity during the walking cycle was shown to begin shortly before heel-strike and to continue throughout three-quarters of the stance phase. During the exercises the muscle was active during internal rotation of the tibia on the femur, and during normal gait the phasic activity of the popliteus coincided with internal rotation of the tibia on the femur. It was concluded that the basic function of the popliteus is to help to bring about and maintain internal rotation of the tibia on the femur.

Adult↗
PubMedDate not supplied

The function of the toes in walking, jogging and running.

The foot has been studied in walking, running and jogging using high speed cinema photography in the laboratory for gait analysis in the Shriner's Hospital for Crippled Children, San Francisco. During running, as well as in walking, the extrinsic toe flexors restrain progression of the tibia. The extrinsic extensors accelerate the tibia over the fixed foot. The intrinsic toe muscles function from mid-stance to lift-off when the subject runs on his toes. In sprinting, the intrinsics are active throughout the weight-bearing phase.

Gait↗