The influence of muscles on knee flexion during the swing phase of gait

Stephen Jacob Piazza, Scott L. Delp

Research output: Contribution to journalArticle

214 Citations (Scopus)

Abstract

Although the movement of the leg during swing phase is often compared to the unforced motion of a compound pendulum, the muscles of the leg are active during swing and presumably influence its motion. To examine the roles of muscles in determining swing phase knee flexion, we developed a muscle-actuated forward-dynamic simulation of the swing phase of normal gait. Joint angles and angular velocities at toe-off were derived from experimental measurements, as were pelvis motions and muscle excitations. Joint angles and joint moments resulting from the simulation corresponded to experimental measurements made during normal gait. Muscular joint moments and initial joint angular velocities were altered to determine the effects of each upon peak knee flexion in swing phase. As expected, the simulation demonstrated that either increasing knee extension moment or decreasing toe-off knee flexion velocity decreased peak knee flexion. Decreasing hip flexion moment or increasing toe-off hip flexion velocity also caused substantial decreases in peak knee flexion. The rectus femoris muscle played an important role in regulating knee flexion; removal of the rectus femoris actuator from the model resulted in hyperflexion of the knee, whereas an increase in the excitation input to the rectus femoris actuator reduced knee flexion. These findings confirm that reduced knee flexion during the swing phase (stiff-knee gait) may be caused by overactivity of the rectus femoris. The simulations also suggest that weakened hip flexors and stance phase factors that determine the angular velocities of the knee and hip at toe-off may be responsible for decreased knee flexion during swing phase.

Original languageEnglish (US)
Pages (from-to)723-733
Number of pages11
JournalJournal of Biomechanics
Volume29
Issue number6
DOIs
StatePublished - Jan 1 1996

Fingerprint

Gait
Muscle
Knee
Angular velocity
Muscles
Quadriceps Muscle
Toes
Actuators
Joints
Hip
Pendulums
Leg
Computer simulation
Pelvis

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Orthopedics and Sports Medicine
  • Biomedical Engineering
  • Rehabilitation

Cite this

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abstract = "Although the movement of the leg during swing phase is often compared to the unforced motion of a compound pendulum, the muscles of the leg are active during swing and presumably influence its motion. To examine the roles of muscles in determining swing phase knee flexion, we developed a muscle-actuated forward-dynamic simulation of the swing phase of normal gait. Joint angles and angular velocities at toe-off were derived from experimental measurements, as were pelvis motions and muscle excitations. Joint angles and joint moments resulting from the simulation corresponded to experimental measurements made during normal gait. Muscular joint moments and initial joint angular velocities were altered to determine the effects of each upon peak knee flexion in swing phase. As expected, the simulation demonstrated that either increasing knee extension moment or decreasing toe-off knee flexion velocity decreased peak knee flexion. Decreasing hip flexion moment or increasing toe-off hip flexion velocity also caused substantial decreases in peak knee flexion. The rectus femoris muscle played an important role in regulating knee flexion; removal of the rectus femoris actuator from the model resulted in hyperflexion of the knee, whereas an increase in the excitation input to the rectus femoris actuator reduced knee flexion. These findings confirm that reduced knee flexion during the swing phase (stiff-knee gait) may be caused by overactivity of the rectus femoris. The simulations also suggest that weakened hip flexors and stance phase factors that determine the angular velocities of the knee and hip at toe-off may be responsible for decreased knee flexion during swing phase.",
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The influence of muscles on knee flexion during the swing phase of gait. / Piazza, Stephen Jacob; Delp, Scott L.

In: Journal of Biomechanics, Vol. 29, No. 6, 01.01.1996, p. 723-733.

Research output: Contribution to journalArticle

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