Biomechanics of Gait Cycle Notes

Biomechanics of the Gait Cycle

Phases of Gait

• Stance Phase:
  • Consists of 60% of the gait cycle.
• Swing Phase:
  • Consists of 40% of the gait cycle.

Additional Definitions:

• Stride Length
• Step Length

Gait Cycle Phases and Events

The gait cycle is divided into two main phases: Stance and Swing, each further subdivided.

• Stance Phase:
  • Double Support I
  • Single Support
  • Double Support II
  • Initial Contact (Heel Strike)
  • Loading Response (Foot Flat)
  • Mid Stance
  • Terminal Stance (Heel Off)
  • Pre-Swing (Toe Off)
• Swing Phase:
  • Initial Swing
  • Mid Swing
  • Terminal Swing

Timeline of Events in the Gait Cycle

The gait cycle can be broken down into percentages, with specific events occurring at each point:

• 0%: Initial Contact
• 10%: Opposite Toe Off
• 30%: Heel Rise
• 50%: Opposite Tibia Vertical
• 60%: Heel Contact (Adjacent)
• 73%: Toe Off
• 87%: Feet Adjacent
• 100%: Next Initial Contact

Tasks & Periods Within Gait Cycle:

• Weight Acceptance (Loading Response)
• Single-Limb Support (Mid Stance, Terminal Stance)
• Limb Advancement (Swing Phase)

Detailed Breakdown of Phases

• Initial Contact (Heel Strike):
  • The moment the foot initially makes contact with the ground.
• Foot Flat:
  • The point when the entire foot is in contact with the ground.
• Mid-Stance:
  • Occurs when the body weight is aligned directly over the supporting limb.
• Heel Off:
  • Describes the point when the heel lifts off the ground.
• Toe Off:
  • The point when only the toes remain on the ground before the foot leaves the ground entirely.
• Swing Phase:
  • The period when the foot is off the ground, advancing forward.

Range of Motion (ROM) in the Gait Cycle

The hip, knee, and ankle exhibit different ranges of motion throughout the gait cycle. Measurements provided in degrees.

• Hip:
  • Heel Contact: 20 degrees
  • Foot Flat: 20-25 degrees
  • Mid Stance: 10 degrees
  • Heel Off: 0-16 degrees
  • Toe Off: 15-20 degrees
  • Mid Swing: 30 degrees
  • Heel Contact: 20 degrees
• Knee:
  • Heel Contact: 0 degrees
  • Foot Flat: 5-10 degrees
  • Mid Stance: -10 degrees
  • Heel Off: 10-15 degrees
  • Toe Off: 0 degrees
  • Mid Swing: 60 degrees
  • Heel Contact: 0 degrees
• Ankle:
  • Heel Contact: 0 degrees
  • Foot Flat: 0 degrees
  • Mid Stance: 0 degrees
  • Heel Off: 10 degrees
  • Toe Off: 20 degrees
  • Mid Swing: 10 degrees
  • Heel Contact: 0 degrees
• Movement from DF (Dorsiflexion) to PF (Plantarflexion), which may be in a range of 20-35 degrees.

Muscle Activation During Gait

Key muscles activate during stance and swing phases:

• Stance Phase:
  • Gluteus Maximus
  • Hamstrings
  • Quadriceps
  • Triceps Surae
  • Tibialis Anterior
• Swing Phase:
  • Iliopsoas

Ground Reaction Forces

• Vertical ground reaction force plotted against time, showing a heel-strike transient.
• BW = body weight.