Lecture Notes: The Gait Cycle

Introduction

• Focus on normal gait cycle.
• Abnormal gait patterns to be discussed in future videos.
• Definition of one gait cycle: initial contact to initial contact on the same leg.
• Three functional tasks in gait:
  • Weight acceptance
  • Single limb support
  • Limb advancement

Terminology

• Two sets of terminology:
  • Rancho Los Amigos
  • Traditional terminology (in parentheses)
• Importance of knowing both sets for exams like NPTE.

Gait Cycle Phases Without Muscle Activity

1. Initial Contact (Heel Strike):

   • Initial contact with the ground, usually with the heel.
   • Initiates the heel rocker.

2. Loading Response:

   • Foot goes flat, weight acceptance begins.
   • Needs stability and shock absorption.
   • Transition from heel rocker to foot flat.

3. Mid Stance:

   • Single limb supports the entire body weight.

4. Terminal Stance:

   • Transition from heel rocker to forefoot rocker.

5. Pre-Swing:

   • Transition to limb advancement.

6. Initial Swing:

   • Foot is picked up, swing phase begins.

7. Mid Swing:

   • Limb advances forward.

8. Terminal Swing:

   • Slowing down the leg and preparing for next gait cycle.

Gait Cycle Phases With Muscle Activity

General Principles

• Muscles either generate energy (concentric) or control energy (eccentric).
• Organized by phases and joint (hip, knee, ankle).

Phases with Muscle Focus

Initial Contact to Loading Response

• Hip: Concentric hip extensors to move from flexion to extension.
• Knee: Eccentric knee extensors for shock absorption.
• Ankle: Eccentric dorsiflexors to control plantar flexion.

Loading Response to Mid Stance

• Hip: Concentric hip extensors continue to work.
• Knee: Transition from eccentric to brief concentric knee extensors for support.
• Ankle: Eccentric plantar flexors control tibial advancement.

Mid Stance to Terminal Stance

• Hip: Concentric hip extensors.
• Knee: Transition from concentric extensors to flexors.
• Ankle: Concentric plantar flexors for push-off.

Terminal Stance to Pre-Swing

• Hip: Concentric hip flexors for limb advancement.
• Knee: Concentric knee flexors for increased flexion.
• Ankle: Concentric plantar flexors continue.

Pre-Swing to Initial Swing

• Hip: Continued hip flexion.
• Knee: Continued knee flexion.
• Ankle: End of plantar flexion, moving towards dorsiflexion.

Initial Swing to Mid Swing

• Hip: Concentric hip flexors.
• Knee: Concentric knee flexors.
• Ankle: Begin dorsiflexion to clear the ground.

Mid Swing to Terminal Swing

• Hip: Continuous hip flexion.
• Knee: Knee extensors begin to turn off.
• Ankle: Continued dorsiflexion.

Terminal Swing to Initial Contact

• Hip: Eccentric hip extensors to control flexion.
• Knee: Concentric knee extensors with eccentric control.
• Ankle: Concentric dorsiflexors for ground clearance.

Key Concepts

• Muscles conserve energy by turning off when not needed.
• Muscles create forward progression and stabilize the body.
• Relation to ground reaction forces:
  • Eccentric contractions control movements in the same direction as ground forces.
  • Concentric contractions overcome ground forces in the opposite direction.

Final Tips

• Review specific muscles involved (e.g., glutes, quads) beyond general categories.
• Engage with provided quizzes and review materials for better understanding.