A squat is a fundamental human movement, but the question of how low to go remains a frequent source of debate in fitness. “Going all the way down” often refers to achieving an “Ass to Grass” (ATG) position, where the hips descend well below the knees, past parallel. This deep range of motion is frequently contrasted with the parallel squat, where the crease of the hip aligns with the top of the knee. Determining the optimal depth requires balancing the effectiveness of the exercise with individual safety. The answer is not universal, but depends on anatomical limitations, specific training goals, and the ability to maintain proper form.
Biomechanical Factors Determining Squat Depth
An individual’s maximum safe squat depth is dictated by their unique skeletal and joint structure. A primary limiting factor is insufficient ankle dorsiflexion—the ability of the shin to move forward over the foot while the heel remains grounded. If the ankle cannot flex enough, the body compensates by shifting the torso forward or forcing movement from other joints, often leading to a breakdown in form or premature end to the descent.
Hip anatomy also plays a substantial role. The depth and orientation of the hip socket (acetabulum) and the shape of the femoral head naturally restrict the range of motion. Individuals with deeper hip sockets may experience a pinching sensation, or “hip impingement,” when attempting to squat past a certain depth. This anatomical limit cannot be forced and indicates the end of an individual’s safe range of motion.
The “butt wink” is a visible sign that the body has reached its biomechanical limit for maintaining a neutral spine. This occurs when the pelvis tucks under, causing the lower back (lumbar spine) to round at the bottom of the squat. This rounding happens because the hips and ankles have run out of available range, forcing the pelvis to tilt backward. Allowing significant lumbar rounding under heavy load can increase shear stress on the spinal discs. Therefore, squat depth must stop immediately before the lower back loses its neutral position, as this mechanical boundary is far more important than achieving any arbitrary depth standard.
Benefits of Achieving Full Depth
For individuals with the requisite mobility and anatomical structure, descending into a deep squat offers advantages for muscle development and joint function. Training through a complete range of motion is associated with increased muscle hypertrophy and strength gains. Research indicates that quadriceps activation is greater when performing a full-range squat compared to a partial squat.
Achieving full depth means muscles, particularly the quadriceps, spend greater time working at longer lengths, which promotes muscle growth. The adductor magnus is also strongly engaged in the deepest ranges of motion. This muscle acts as a powerful hip extensor, contributing significantly to lower body strength.
Training to full depth improves functional mobility in the hips and ankles, a quality that carries over into everyday movements. Moving the joints through their full capacity allows surrounding tissues to adapt and enhances the nervous system’s control in deep positions. This enhanced range of motion contributes to long-term joint health and stability.
Training the lift-off from the deepest position develops greater force production capabilities at the weakest point of the movement. This enhanced strength in the bottom position translates to stronger lifts overall and builds resilience across the full range of motion.
When to Prioritize Safety Over Depth
The decision to squat deep must always be secondary to maintaining a stable and controlled posture. If an individual cannot maintain a neutral spine, stable knee position, and heels flat on the floor, the depth should be immediately reduced. Loss of form under load significantly increases the risk of injury, regardless of the depth achieved.
For those with a history of knee or lower back issues, limiting the range of motion can be a necessary modification. People with patellofemoral pain or a meniscal injury may find that squatting only to a pain-free depth, often above parallel, is advisable. Training at a partial range allows for strength gains without irritating compromised joint structures.
For healthy individuals, deep squats are not inherently dangerous and can be beneficial for knee health. The highest compressive forces on the knee joint occur around 90 degrees of flexion (the parallel position). As the squat descends past this point, the contact area between the thigh and shin bones increases, distributing the force more favorably and reducing pressure on the joint surfaces.
Training goals also dictate the necessary depth. In powerlifting, the required depth is achieved when the hip crease is below the top of the knee. Going significantly deeper than this standard is often unnecessary and may reduce the total weight lifted. Therefore, a powerlifter’s goal is to hit the minimum effective depth.
Techniques for Safely Increasing Squat Depth
For those limited by mobility who wish to safely increase their squat depth, improving ankle dorsiflexion is often the most direct path. This can be addressed through regular mobility drills, such as the knee-to-wall drill, where the knee is driven forward over the foot while keeping the heel down to gradually increase the available range of motion.
Adjusting Stance
Adjusting the foot position offers an immediate way to accommodate anatomical limitations. A wider stance or turning the toes out slightly reduces the demand on ankle mobility and hip flexion, allowing the lifter to descend further before encountering restriction. This personalized stance allows for better alignment and control.
Using Heel Elevation
Temporary aids, such as weightlifting shoes with an elevated heel or placing small plates under the heels, can instantly improve squat depth. This elevation mechanically reduces the required ankle dorsiflexion, which is useful for lifters with stiffness. Using a heel lift allows training the deeper range of motion with better posture while working on long-term mobility.
Gradual Progression
Progression must be gradual, focusing on consistency rather than forcing depth in a single session. Incorporating deep goblet squat holds, where a light weight acts as a counterbalance, helps the body adapt to the end-range position. Practicing the deep position without heavy load allows joints and tissues to adapt slowly, which is the safest method for increasing depth.