The swing phase is the period during the gait cycle when the foot is off the ground and moving forward to prepare for the next stance phase. During this phase, the limb must advance far enough and with appropriate trajectory to achieve efficient forward progression while clearing the ground.
Duration and Characteristics
- During walking: Approximately 40% of the gait cycle
- During running: Approximately 60% of the gait cycle (longer due to increased speed)
- During sprinting: Can be as high as 75-80% of the cycle
Sub-Phases of Swing
1. Initial Swing (Acceleration Phase)
- Immediately follows toe-off from stance phase - Foot just leaves the ground and begins moving forward - Hip flexors actively accelerate the thigh forward - Knee flexion increases to help clear the foot from the ground - Ankle typically dorsiflexes to maintain toe clearance
2. Mid-Swing
- The swinging limb passes directly beneath the body - Maximum knee flexion typically occurs early in this sub-phase - Foot reaches its highest point above the ground - Momentum carries the limb forward with minimal active muscle force - Ankle continues in dorsiflexion for ground clearance
3. Terminal Swing (Deceleration Phase)
- The leg extends and decelerates as it prepares for contact - Knee extends toward full extension - Hamstrings activate eccentrically to control the forward swing - Foot is positioned for optimal contact angle - Leg reaches maximum forward position just before contact
Muscle Activity During Swing
Key muscles active during swing phase:
- Hip Flexors (iliopsoas, rectus femoris): Initiate and drive forward thigh movement
- Knee Flexors (hamstrings): Flex knee during early swing and decelerate leg during terminal swing
- Ankle Dorsiflexors (tibialis anterior): Lift toes to clear ground
- Hip Abductors: Stabilize pelvis while opposite leg is in stance
Ground Clearance
Adequate ground clearance during swing phase requires:
- Sufficient knee flexion (approximately 60° during normal walking)
- Adequate ankle dorsiflexion to lift toes
- Proper hip flexion to advance the thigh
- Coordination of all segments for efficient movement
Common Swing Phase Abnormalities
Issues that may occur during swing:
- Foot Drop: Insufficient ankle dorsiflexion causes toes to drag
- Hip Hiking: Excessive elevation of hip to compensate for inadequate knee or ankle flexion
- Circumduction: Swinging leg in an arc laterally to avoid toe drag
- Decreased Knee Flexion: Results in reduced ground clearance
- Asymmetry: Differences between left and right swing patterns
Clinical and Performance Implications
Swing phase analysis helps identify:
- Weakness in hip flexors, knee flexors, or ankle dorsiflexors
- Compensatory strategies for limited range of motion
- Neurological conditions affecting motor control
- Fatigue patterns (swing phase mechanics often deteriorate when tired)
- Training adaptations in athletes
Video Analysis Considerations
Optimal swing phase analysis requires:
- Clear side view showing full limb trajectory
- Sufficient frame rate to capture rapid movements (60-240 fps)
- Multiple gait cycles to assess consistency
- Comparison between limbs to identify asymmetries
- Slow motion playback to observe subtle movement details
During running, the swing phase takes on greater importance because its duration increases relative to stance. Efficient swing mechanics become critical for maintaining speed while minimizing energy expenditure. Elite runners typically demonstrate compact, efficient swing patterns with optimal coordination of hip, knee, and ankle movements.