Hips Don’t Lie: Why the Psoas Matters in Sprint Performance

When therapists think about sprinting, the hamstrings and calves often receive most of the attention. This makes sense: hamstring strains are common in running sports, and the calf–Achilles complex is essential for force transfer during ground contact. But a recent MRI-based study of collegiate American football players suggests that maximal sprint speed may depend strongly on a different region: the muscles around the hip and pelvis.

The study measured lower-body muscle volumes using MRI and compared them with peak sprinting speed. Among 35 muscles, the psoas major showed the strongest relationship with sprint speed. Its relative size explained about half of the variation in peak speed between athletes. This is a striking finding because sprinting speed is influenced by many factors, including technique, tendon stiffness, limb length, fibre type, coordination, strength, training history and fatigue. Yet one deep hip flexor muscle still accounted for a large part of the difference between faster and slower players.

The next strongest muscles were also mostly located around the hip: gluteus medius, gluteus maximus, pectineus, rectus femoris, piriformis, adductor magnus, gluteus minimus and obturator internus. This pattern suggests that faster sprinting is not simply about having bigger legs. It is more specifically associated with better-developed proximal muscles — the muscles that control the pelvis, move the thigh, and transfer force between the trunk and lower limb.

The best three-muscle combination was psoas major, gluteus medius and piriformis, which explained about 57–59% of the variation in sprint speed. However, this was only a modest improvement over the psoas major alone. For therapists, this means the psoas may be important in two ways. It may contribute directly to fast hip flexion during the swing phase, helping the athlete recover the leg quickly for the next stride. It may also act as a marker of broader hip development, indicating a strong and well-integrated hip flexor–extensor–rotator system.

This does not mean the hamstrings, quadriceps or calves are unimportant. The hamstrings remain critical for late swing control, hip extension and injury prevention. The calves and Achilles tendon are essential for stiffness, propulsion and elastic energy return. But the study suggests that, when looking at maximal sprint speed, therapists should pay closer attention to the deep hip and pelvic muscles, not only the more visible posterior-chain muscles.

The gluteus maximus contributes to powerful hip extension. The gluteus medius and minimus help stabilise the pelvis and control frontal-plane movement during high-speed running. The psoas major and rectus femoris assist with hip flexion and rapid thigh recovery. The adductors, pectineus, piriformis and obturator muscles help control hip position, rotation and force direction. Together, these muscles form a functional hip system that allows the athlete to generate, redirect and absorb force at high speed.

For assessment, this means therapists should look beyond isolated hamstring length or calf strength. A sprinting athlete may need evaluation of hip flexor strength, gluteal capacity, pelvic control, hip rotation, adductor function and trunk–pelvis coordination. Weakness, inhibition, stiffness or poor timing in this region may affect stride mechanics and increase load elsewhere, including the hamstrings.

For rehabilitation and performance work, the practical message is not simply to “strengthen the psoas”. The better goal is to restore and train the whole hip complex. This may include progressive hip flexor loading, gluteal strengthening, adductor capacity work, pelvic control drills, sprint-specific mechanics, and high-speed exposure when appropriate. The hip muscles need to be strong, but they also need to work together at speed.

The main takeaway for therapists is clear: sprinting is not just a hamstring problem or a calf-power problem. It is a hip-driven, pelvis-controlled movement. The psoas major, gluteal muscles, deep rotators and adductors appear to be strongly linked with maximal sprint speed. For athletes returning to sprinting, therapists should assess and train the proximal hip system as carefully as they assess the hamstrings and lower leg.