The inability to achieve a full-depth squat, where the crease of the hip descends below the top of the knee, is a common source of frustration for many people. This “below parallel” position is often a goal because it demonstrates a full range of motion, promotes greater muscle recruitment in the glutes and hamstrings, and builds functional strength. The reasons for this limitation are diverse, ranging from fixed anatomical structures to correctable issues in mobility and movement mechanics. Understanding the root cause is the first step toward improving performance.
Unchangeable Limitations: Skeletal Anatomy
The shape of your hip joint is the first limiting factor and one that no amount of stretching can change. The hip is a ball-and-socket joint, and the depth of the socket, or acetabulum, varies significantly among individuals. A person with a deep hip socket will experience a physical, bone-on-bone “hard stop” much sooner than someone with a shallow socket, limiting hip flexion and preventing an extremely deep squat.
The orientation of the hip socket and the angle of the femur’s neck determine your most comfortable squat stance. For example, a forward-facing socket (anteversion) may favor a narrower stance, while an outward-facing socket (retroversion) may require a wider stance with toes pointed out. Forcing a stance that conflicts with your bone structure can lead to early impingement, causing a pinching sensation in the hip. This bony collision (FAI) is a structural limit, not a soft-tissue tightness that can be stretched away.
The Mobility Equation: Ankle and Hip Restrictions
Beyond fixed bone structure, the most common roadblocks to depth are restrictions in the ankle and hip joints due to soft tissue limitations. The ankle joint requires sufficient dorsiflexion, the motion of the shin moving forward over the foot, to allow the knees to travel forward in the squat. When dorsiflexion is restricted, the body compensates by forcing the torso to lean excessively forward to maintain balance, preventing the hips from descending fully before the heels lift off the ground.
The hips require full mobility in the surrounding soft tissues to reach maximum depth. Tightness in hip flexors, such as the iliopsoas, can pull the pelvis into an anterior tilt, restricting the necessary hip flexion. The adductors (inner thigh muscles) must also lengthen to accommodate the hip flexion and outward movement at the bottom of a deep squat. If the adductors are tight, they limit depth or contribute to the lower back rounding known as “butt wink.”
Technique and Form Mistakes
Even with adequate mobility, poor movement patterns or technique errors can prevent an individual from reaching their full depth potential. A frequent mistake is adopting a stance that does not match the lifter’s anatomy, such as squatting with feet too narrow or pointed straight forward when a wider, toes-out stance would better accommodate their hip structure. Choosing the wrong stance restricts the hip’s ability to rotate and flex fully.
Another common error is in the initiation of the movement, such as bending the knees too soon or pushing the hips back too aggressively. An optimal squat involves the simultaneous breaking of the hips and knees, allowing the bar to track over the mid-foot. Initiating only by pushing the hips backward can turn the movement into a “good morning,” requiring a greater forward lean and prematurely limiting depth.
The “butt wink,” the rounding of the lower back at the bottom of the squat, is a major depth limiter. It can be caused by mobility issues or a lack of core bracing. When the core fails to maintain a neutral spine, the pelvis tucks under to achieve extra depth, which increases compressive forces on the lumbar spine.
Actionable Steps to Improve Depth
Addressing the fixable limitations involves specific, targeted drills for mobility and motor control. To improve ankle mobility, the “knee-to-wall” drill is highly effective, where you repeatedly drive your knee forward toward a wall while keeping your heel flat, gradually moving your foot further back as range increases. For the hips, the “90/90 stretch” targets both hip internal and external rotation capabilities, which are essential for maximizing the space in the hip socket during the deep squat.
To correct technique and improve stability, the box squat is an excellent tool. It allows the lifter to practice reaching a consistent, safe depth without relying on the stretch reflex, reinforcing the motor pattern of “sitting back” while maintaining core tightness. Using a resistance band looped above the knees provides a tactile cue to actively push the knees outward, correcting the common mistake of the knees caving inward. Elevating the heels onto small plates or wearing weightlifting shoes also compensates for limited ankle dorsiflexion, allowing the lifter to practice the deep squat pattern with a more upright torso.