Squat technique: common mistakes
The squat is one of the most effective movements for the legs and the whole body, but also one of those where technique most often «drifts». Most mistakes have clear causes: limited mobility, weakness of certain muscles, incorrect setup or excessive weight. Our editorial team examined the most common mistakes, explained their biomechanics and offered ways to correct each one.
The biomechanics of the squat: what should happen
The squat is simultaneous flexion at the hip, knee and ankle joints while maintaining a neutral position of the spine. The center of mass of the «person plus barbell» system should remain roughly over the middle of the foot throughout the movement. When this rule is broken, the body compensates for the imbalance, and mistakes appear.
A review by Schoenfeld (2010) on the kinematics and kinetics of the squat emphasizes: there is no single «ideal» technique for everyone. The length of the thighs and shins, the structure of the hip joints and ankle mobility determine how vertical the torso will be, how wide you should set your feet and how far the knees will come forward. So you should be careful comparing yourself with another person on video.
At the same time there are universal principles. The foot is flat on the floor, the weight distributed between the heel and the front of the foot. The knees move in the direction of the toes. The spine keeps its natural shape without excessive rounding or arching. The movement is smooth and controlled, without «dropping» into the bottom position.
The variant of squat also matters. In a front squat the torso stays more vertical, and the load shifts to the quadriceps. In a «low bar» position on the back the torso leans more, and the glutes and hamstrings work more. The mistakes described below occur in all variants.
Knees: caving inward and «knees past the toes»
Caving of the knees inward, which in biomechanics is called dynamic valgus, is the best-known mistake. During the ascent from the bottom position the knees «gather» toward the middle, especially under heavy weight. This position increases the load on the medial structures of the knee joint and is considered undesirable, especially under repeated loads.
The causes vary: weakness of the hip abductors and the glutes, limited ankle mobility, when the body seeks depth through pronation of the foot, or simply habit. Valgus often appears only in the last reps of a set, when the muscles tire — a signal that the weight is at the limit of your capabilities.
Another popular «mistake» is the knees going past the line of the toes. In fact this is largely a myth. A study by Fry, Smith and Schilling (2003) showed that if you artificially restrict the forward movement of the knees, the load on the knee decreases, but the torque on the hip joint and lower back rises substantially. That is, by «protecting» the knee we overload the back.
A review by Escamilla (2001) on the biomechanics of the knee joint in squatting concluded that the squat is a safe exercise for a healthy knee, and the compression and shear forces in the joint stay within acceptable limits with correct technique. The knees going past the toes is, for people with long thighs, a natural part of the movement as long as the heels stay on the floor.
Back and pelvis: rounding and «butt wink»
«Butt wink» is the tucking of the pelvis and flexion of the lumbar spine at the bottom of a deep squat. A small pelvic tilt at the end of the range happens to almost everyone and is not in itself a problem. The question arises when the rounding is pronounced and occurs under heavy weight: then the intervertebral discs receive extra load.
The causes of the «wink» are the anatomy of the hip joint, restrictions in its mobility, a lack of ankle mobility and insufficient core control. The practical approach is to squat to the depth you can reach with a controlled lower-back position and to gradually work on mobility.
Another mistake is excessive forward lean of the torso, when the squat turns into a kind of «good morning». The pelvis rises faster than the shoulders at the start of the ascent, and the load shifts to the back extensors. This often indicates weak quadriceps relative to the posterior chain, or excessive weight.
The opposite situation is excessive arching of the lower back at the top, when a person «pushes» the pelvis back and hyperextends the spine. Such overextension loads the spine just as much, only in the other direction. A neutral spine position is the natural curves without exaggeration.
| Mistake | Possible cause | What to try |
|---|---|---|
| Knees caving in | Weak glutes and abductors, fatigue | Reduce the weight, mini-band above the knees in the warm-up, pause at the bottom |
| Heels lifting | Limited ankle mobility | Calf stretching, footwear with a raised heel, goblet squats |
| «Butt wink» | Hip-joint anatomy, weak core control | Squat to the depth you can control, a wider stance |
| Excessive forward lean | Weak quadriceps, too much weight | Front squats, tempo squats |
| Shallow squat | Fear, too much weight, mobility | Box squats, reducing the weight |
Depth, heels and breathing
A shallow squat is probably the most common mistake in the gym, especially when the weight «for ego» is too heavy. A review by Hartmann, Wirth and Klusemann (2013) analyzed the load on the knee joint and spine at different depths. The authors found no evidence that deep squats are harmful to healthy knees, and on the contrary noted that half-squats with heavy weight can load the spine more strongly.
For results, depth also matters. A study by Kubo, Ikebukuro and Yata (2019) showed that full squats produce a greater increase in the volume of the glutes and hip adductors compared with half squats. For the quadriceps the difference between depths was insignificant. So if the goal is to develop the glutes, depth is fundamentally important.
Lifting the heels off the floor is another frequent problem. Its cause is usually limited ankle dorsiflexion, that is, the inability to bring the knee forward over the foot. The body compensates for this by shifting the weight onto the toes, which worsens stability and increases the load on the knee joint. A temporary solution can be footwear with a slightly raised heel.
Breathing is often underrated. Before lowering with a significant weight, experienced athletes take a deep breath «into the belly» and brace the core muscles, creating intra-abdominal pressure that stabilizes the spine. Breath should be held only briefly: in the case of hypertension or cardiovascular disease this technique should be discussed with a doctor, since it sharply raises blood pressure.
How to correct mistakes in practice
The first step is objective assessment. Film several sets from the side and the front with your working weight. Many mistakes a person does not feel are obvious on the recording. If possible, ask an experienced coach to assess your technique live.
- Reduce the weightby 20–30% and drill the movement through the full range with control.
- Goblet squatswith a dumbbell at the chest naturally straighten the torso and teach the correct path.
- Squats with a pause2–3 seconds at the bottom remove the «bounce» and teach control.
- Box squatsset a stable depth and help overcome the fear of the low position.
- Working on mobilityof the ankles and hips — in the warm-up and between workouts.
It is better to change technique gradually, one mistake at a time. If you try to control the knees, heels, back and breathing all at once, the movement becomes stiff and there is little benefit. Choose the most important problem, correct it for 2–4 weeks, then move on to the next.
Pain is an important signal. Minor muscle fatigue after squats is normal, but sharp, shooting pain in the knee, back or hip joint is not. In that case stop the exercise and consult a doctor or physical therapist rather than trying to «work through» the problem.
Editorial conclusions
Most mistakes in squatting have specific causes — limited mobility, weak links or too much weight — and respond well to correction.
Some popular «rules», in particular the ban on letting the knees go past the toes, are not scientifically grounded and can overload the back. On the other hand, caving of the knees inward and pronounced rounding of the lower back under load are worth correcting.
Full range of motion, a controlled tempo and a gradual increase in weight are the foundation of safe and productive squats.
We also recommend reading our materials on back safety in the deadlift, on the bench press and injury risk, and on cooling down and stretching after a workout.
References
- Schoenfeld BJ. Squatting kinematics and kinetics and their application to exercise performance. J Strength Cond Res. 2010;24(12):3497–3506.
- Escamilla RF. Knee biomechanics of the dynamic squat exercise. Med Sci Sports Exerc. 2001;33(1):127–141.
- Fry AC, Smith JC, Schilling BK. Effect of knee position on hip and knee torques during the barbell squat. J Strength Cond Res. 2003;17(4):629–633.
- Hartmann H, Wirth K, Klusemann M. Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load. Sports Med. 2013;43(10):993–1008.
- Kubo K, Ikebukuro T, Yata H. Effects of squat training with different depths on lower limb muscle volumes. Eur J Appl Physiol. 2019;119(9):1933–1942.
- Myer GD, Kushner AM, Brent JL, et al. The back squat: a proposed assessment of functional deficits and technical factors that limit performance. Strength Cond J. 2014;36(6):4–27.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
