The stance phase is the period during the gait cycle when the foot is in contact with the ground, bearing the body's weight and providing propulsion for forward movement. Understanding stance phase mechanics is critical for analyzing gait efficiency, identifying injury risk factors, and optimizing performance.
Duration and Characteristics
- During walking: Approximately 60% of the gait cycle
- During running: Approximately 40% of the gait cycle (shorter due to increased speed)
- During sprinting: Can be as low as 20-25% of the cycle
Sub-Phases of Stance
1. Initial Contact (Heel Strike)
- The moment the foot first touches the ground - Typically occurs with the heel in normal walking - Marks the beginning of stance and the start of a new gait cycle
2. Loading Response (Weight Acceptance)
- Immediately follows initial contact - Body weight is rapidly transferred onto the stance limb - The knee flexes slightly to absorb impact - Ankle plantarflexes as foot makes full contact with ground
3. Mid-Stance (Single Support)
- Body weight passes directly over the stance foot - The opposite limb is in swing phase - Requires balance and stability on one leg - Hip, knee, and ankle work to maintain upright posture
4. Terminal Stance (Heel-Off)
- Heel begins to lift from the ground - Body weight moves toward the forefoot - Opposite limb prepares to make contact - Ankle begins plantarflexion for push-off
5. Pre-Swing (Toe-Off)
- Final push-off before foot leaves the ground - Rapid ankle plantarflexion provides propulsive force - Marks the end of stance phase - Brief period of double support during walking
Ground Reaction Forces
During stance phase:
- Vertical ground reaction forces typically peak at 1.2x body weight during walking
- Running generates forces of 2-3x body weight
- Forces are absorbed and transmitted through the foot, ankle, knee, and hip
- Proper mechanics distribute forces efficiently, reducing injury risk
Clinical Significance
Stance phase analysis reveals:
- Asymmetries between limbs that may indicate injury or weakness
- Excessive impact forces suggesting over-striding or poor shock absorption
- Insufficient push-off indicating weakness in calf muscles or ankle mobility issues
- Compensatory patterns from pain or limited range of motion
Video Analysis Considerations
Analyzing stance phase requires:
- Side view for optimal observation of foot contact and weight transfer
- High enough frame rate to capture rapid movements (minimum 60 fps, preferably 120-240 fps for running)
- Clear markers or visibility of foot position throughout contact
- Calibration for measuring time durations and ground reaction patterns
The relative duration and characteristics of stance phase change with speed, fatigue, injury, and training. Regular assessment helps track progress, identify problems early, and optimize movement efficiency.