Anatomy of running: GLUTES & HIP
The hip joint's range of motion (ROM) during running varies depending on the phase of the gait cycle and the runner's speed. As running is predominantly a sagittal plane sport (forward & back), we will primarily be looking at this plane of motion rather than rotation or lateral movements of the hip.
During stance phase the hip may be flexed to 40° at heel strike. Foot strike pattern may influence this measure, as a mid foot or forefoot pattern would accompany a lesser degree of hip flexion. The hip extends throughout the duration of stance phase up to about 10° at toe-off during easy running. The hip reaches maximal extension at initial swing phase. Throughout swing phase the hip is flexing up to about 55° at terminal swing to drive the leg forward. As running speed increases the total arc of motion at the hip joint also increases from 40-50° up to 70-80°. The majority of this increased motion comes from greater hip extension, suggesting a positive correlation between speed and hip extension.
Gluteus maximus is the largest and most powerful muscle in the lower extremity, the prime mover of hip extension and is responsible for a strong push-off and hip drive during running. As a hip extensor, the glute max propels the body forward with each stride. It additionally contributes to deceleration of the swing leg and limits trunk flexion on the stance leg to help stabilize the lower limb in addition to stabilizing the lower back and lumbo-sacral region
Dysfunction in the gluteus maximus can lead to excessive forward lean or instability at the trunk, and weakness may limit power and stride length. It is critical to strengthening the glute max to improve speed and force production. Exercises like squats, lunges, deadlifts, and glute bridges can help train the hip extensors.
Gluteus medius is the prime mover of hip abduction, driving the hip outward laterally. The posterior fibers of this muscle also contribute to external rotation of the hip, while the anterior fibers contribute to internal rotation. With running being a sagittal plane, forward and back movement of the ower limb, the gluteus medius primarily functions to stabilize. During running, this muscle stabilizes the pelvis, helping to maintain a level pelvis and prevents it from dropping toward the swing leg. Gluteus minimus assists with providing this stability. Additionally, it helps absorb the force of the ground pushing back against your leg as your foot hits the ground. The stability provided by the lateral glute muscles prevent your knee from collapsing inwards, or adducting, while running. Lastly the gluteus medius generates power, producing peak muscle force during mid-stance phase of gait.
An inactive or weak gluteus medius allows energy to leak out of the system. If this muscle does not effectively stabilize and absorb shock, it can lead to misalignment of the femur, which can cause the knee and ankle to drop inwards. This can increase the risk of injuries like medial tibial stress syndrome, achilles tendinitis, patellofemoral injuries or "runner's knee", and other overuse syndromes.
Strengthening the gluteus medius can help improve single leg stability during stance phase of the running gait, and subsequently prevent injuries down the chain. Some exercises that can help strengthen the gluteus medius include clams, side plank, lateral stepping with resistance bands, and fire hydrants.
