Muscles of Gait Phases

Pre-Swing (Toe off): Knee

- Flexion caused passively by hip flexion and slight gastroc activation.

Mid Swing: Knee

- Again, momentum, along with gravity, flex the knee with some BF short head contraction.

Initial swing (early swing): Knee

- At this stage, the knee is mostly flexed due to the momentum from the activated hip flexors. Some biceps (short head) concentric contraction may contribute to knee flexion throughout swing. Rectus femoris and gastric may also provide some stabilization to control extent of flexion.

Terminal Swing (Late Swing): Ankle/Foot

- Dorsiflexors isometrically contract to hold ankle locked to ensure solid heel contact.

Midstance: Ankle/Foot

- Gastrocnemius and Soleus (PF's) eccentrically activate to slow dorsiflexion momentum which stabilizes the ankle. - Tibialis posterior slows foot pronation. - Intrinsic foot muscles stabilize the forefoot.

Terminal Swing (Late Swing): Hip

- Gluteus Maximus and Hamstrings (biceps femoris, semimembranosus, semitendinosus) act concentrically to slow the leg down from its forward momentum so the leg can accept the weight. - Gluteus medius, miniumus and tensor fascia latae stabilize the pelvis to prepare for heel contact.

Initial contact (heel-strike or heel contact/RLA): Hip

- Gluteus Maximus and Hamstrings (biceps femoris, semimembranosus, semitendinosus) act concentrically to slow the leg down. - Hip adductors assist this as they help with extension when hip is flexed. - CL Gluteus medius and minimus also help to lower the pelvis on the swing side. - Erector Spinae also contracts to control forward lean.

Loading response (foot flat): Hip

- Gluteus max and hamstrings control flexion torque through eccentric contraction, then begin to concentrically extend the hip. - Glut medius, minimus, TFL (stance side) eccentrically control pelvic drop on swing side. - Hip external rotators eccentrically control internal rotation of the lower limb in early stance.

Midstance: Hip

- Gluteus max. extends the hip until end of midstance (indirectly assists with knee extension). - Hip abductors stabilize femur. - Internal Rotators active throughout phase to swing pelvis. - External rotators eccentrically contract to stabilize hip throughout swing while limb is fixed on ground

Initial swing (early swing): Hip

- Hip flexors (rectus femoris and Sartorius) along with the hip adductors (while leg is in extension) concentrically contract to swing the leg forward. - Some stabilization from rectus abdominis and hip abductors.

Terminal Stance (heel-off or "push-off"): Hip

- Hip flexors control/counteract hip extension. - Hip abductors concentrically activate to pull limb into relative abduction. - L erector spinae turn on to control forward angular trunk momentum until L foot is flat...40-70% of gait cycle - Some rectus abdominus.

Pre-Swing (Toe-off): Hip

- Iliopsoas, rectus femoris, and minimal activation of sartorius decelerate hip extension just prior to toe-off, then start to bring hip into flexion.

Terminal Stance (heel-off or "push-off"): Ankle/Foot

- Large concentric contraction of PF's at "heel off". - Tibialis anterior and PF's supinate (invert) the foot, which is controlled by Fibularis longus and brevis. - Fibularis Longus also fixes the first metatarsal to the ground to serve a strong lever point - Intrinsic muscles stabilize foot and raise medial longitudinal arch. - PF's and Extensor Digitorum Longus and Hallicus coactivate to stabilize the foot.

Initial contact (heel-strike or heel contact/RLA): Ankle/Foot

- Motion of foot at this phase is the result of momentum. The dorsiflexors merely eccentrically contract to allow for controlled plantar flexion as the heel hits and the forefoot lowers to the ground.

Mid Swing: Hip

- Motion/flexion is created by momentum that was initiated in the initial swing phase.

Terminal Stance (heel-off or "push-off"): Knee

- No muscle activation, PF's stabilize knee.

Pre-Swing (Toe-off): Ankle/Foot

- Plantar flexion occurs until "toe off". - Intrinsics and EDL/EDH continue to play same role as in terminal stance. - Intirinsics also eccentrically activate toe extension. - Tibialis Posterior supinates foot.

Terminal Swing (Late Swing): Knee

- Quadriceps (Rectus Femoris, Vastus Lateralis/ Intermedius/Medialis) concentrically contract to fully extend knee while hamstrings eccentrically contract to control knee extension and prepare to bear weight.

Midstance: Knee

- Quads concentrically activate to extend knee to support the body weight.

Loading response (foot flat): Knee

- Quads eccentrically control knee flexion in first 10% of gait cycle. They eccentrically contract to prevent excessive flexion, aid in shock absorption, and prepare the leg for loading.

Mid Swing: Ankle/Foot

- TA, EDL, EHL concentrically contract to dorsiflex the ankle and extend the toes to clear the toes above the floor. (1.3 cm)

Initial swing (early swing): Ankle/Foot

- Tibialis Anterior and Extensor digitorum longus and hallicus longus (TA, EDL, EHL) concentrically contract to dorsiflex the foot to clear toe (foot not in neutral yet). - Extensors also extend toes

Initial contact (heel-strike or heel contact/RLA): Knee

- When the heel hits the ground, the quads concentrically contract to extend the knee and prepare for load. - Hamstrings coactivate to stabilize the knee.

Loading response (foot flat): Ankle/Foot

. - Dorsiflexors overcome plantar torque which causes the tibia to lean forward relative to the talus, creating momentum and the knee to flexes. - Tibialis posterior controls ankle pronation. - Fibularis muscles plantar flex and counteract strong tib posterior inversion torque.