Muscle Activity During Gait

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Top Contributors - Wanda van Niekerk, Jess Bell and Lucinda hampton  

Breakdown of Gait Cycle Sub-Phases

Initial Contact (or Heel Strike)

The moment the foot touches the ground and begins the first phase of double support. Its function is to establish contact with the ground surface and initiate weight acceptance.

	Kinematics/Joint Motion	Kinetics
		External forces	Internal Forces
Ankle	Neutral, 0°	Ground reaction force posterior to ankle joint Plantarflexion moment created	Dorsiflexors activated: Tibialis anterior Extensor digitorum longus Extensor hallucis longus Eccentric contraction of ankle dorsiflexors to slow plantar flexion during the range of motion change from initial contact to foot flat
Knee	Extension before initial contact, moving into 15° of flexion (initial contact to foot flat)	Ground reaction force anterior to knee joint Extensor moment created Ground reaction force shifts posterior Flexion moment created	Concentric contraction of knee flexors (hamstrings) Eccentric contraction of knee extensors (quadriceps femoris) to control knee flexion
Hip

	Kinematics/Joint Motion	Muscle Action
Ankle	Neutral, 0°	Eccentric contraction of dorsiflexors ( tibialis anterior, extensor digitorum longus, extensor hallucis longus)
Knee	5° flexion	Eccentric extensors
Hip	30° flexion	Concentric extensors and eccentric flexors

Loading Response (or Foot Flat) - 0-10%

Begins with initial contact and continues until the contralateral foot leaves the ground. The foot continues to accept weight and absorb shock by rolling into pronation.

	Kinematics/Joint Motion	Muscle Action
Ankle	Rapid plantarflexion to 10°	Eccentric dorsiflexors
Knee	Flexes to 10-15°	Eccentric extensors and concentric flexors
Hip	Gradual extension	Concentric extensors

Midstance - 10-30%

Begins when the contralateral foot leaves the ground and continues until ipsilateral heel lifts off the ground. The body is supported by a single leg and begins to move from force absorption at impact to force propulsion forward.

	Kinematics/Joint Motion	Muscle Action
Ankle	Gradual dorsiflexion	Eccentric plantarflexors and concentric dorsiflexors
Knee	Begins to extend	Concentric extensors
Hip	Gradual extension	Concentric extensors

Terminal Stance (or Heel Off) - 30-50%

Begins when the heel leaves the floor and continues until the contralateral foot contacts the ground. In addition to single limb support and stability, this event serves to propel the body forward. Bodyweight is divided over the metatarsal heads.

	Kinematics/Joint Motion	Muscle Action
Ankle	Gradual dorsiflexion until a maximum of 10° before beginning to plantarflex	Eccentric plantarflexors, then concentric plantarflexors
Knee	Continues extending until a maximum of 5° of flexion before beginning to flex	Concentric extensors, then eccentric extensors and concentric flexors
Hip	Extends until a maximum of 10° extension	Eccentric flexors

Pre-Swing (or Toe Off) - 50-60%

Begins when the contralateral foot contacts the ground and continues until the ipsilateral foot leaves the ground. Provides the final burst of propulsion as the toes leave the ground.

	Kinematics/Joint Motion	Muscle Action
Ankle	Begins to plantarflex rapidly before foot leaves the ground	Concentric plantarflexors
Knee	Begins to flex rapidly	Eccentric extensors
Hip	Begins to flex before foot leaves the ground	Concentric flexors

Early Swing - 60-75%

Begins when the foot leaves the ground until it is aligned with the contralateral ankle. This event functions to advance the limb and shorten the limb for foot clearance.

	Kinematics/Joint Motion	Muscle Action
Ankle	Continues to plantarflex until a maximum of 20° before moving back towards a neutral position	Eccentric dorsiflexors, then concentric dorsiflexors and eccentric plantarflexors
Knee	Rapid knee flexion until a maximum of about 60°	Eccentric extensors and concentric flexors
Hip	Gradually flexes	Concentric flexors

Mid-Swing - 75-85%

Begins from the ankle and foot alignment and continues until the swing leg tibia is vertical. As in early swing, it functions to advance the limb and shorten the limb for foot clearance.

	Kinematics/Joint Motion	Muscle Action
Ankle	Maintains a neutral position	Concentric dorsiflexors
Knee	Begins to extend	Eccentric flexors
Hip	Continues to flex until a maximum of just over 30°	Concentric flexors

Late Swing/Deceleration - 85-100%

Begins when the swing leg tibia is vertical and ends with initial contact. Limb advancement slows in preparation.

	Kinematics/Joint Motion	Muscle Action
Ankle	Maintains a neutral position	Concentric dorsiflexors
Knee	Extends until full extension, and flexes just slightly before initial contact	Eccentric flexors, then concentric flexors
Hip	Hip remains flexed to around 30 °	Concentric flexors and eccentric extensors, then concentric extensors

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