Single Leg Squats: 4 Fatal Errors…

The Single Leg Squat (SLS) is an advanced exercise for the lower body. Although it is advanced there are a number of errors in it’s performance as people rush to master this advanced exercise while still not having enough lower body strength to complete the movement succesfully. If you are a regular reader you will know that I place a massive emphasis on good form- indeed if it’s not in good form then you are performing the wrong exercise.

Problem 1: Poor Hip Range of Motion- Firstly, the question is why can some one not get the depth on the lowering portion of the movement? Simply, they are not strong enough to have control of the hip stabilisers during the lowering portion of the movement.

Problem 2: Lower Back Position- Typically this is due to problem 1. In order to acheive more movement often people will flex their lower back to acheive more range. Now when training a stable lower back it is unnecessary to emphaise flexion at the lower back just to get a bit more range. Individuals who generally have good strength levels can usually cheat the movement this way while beginners will often look to get range from the knee first (as explained in problem 3).

Problem 3: Forward Knee Position: Often the knee will push forward if there is not enough strength and stability around the hip. This gives a feeling of getting more range in the squat but instead emphasises the muscles in the anterior chain such as the quadraceps. A lot of the time I consider this “moving towards your strengths”. If you have poor hip extensor strength and stability through the muscles such as the hamstrings and the gluteals then this will happen. It highlights that often this movement needs to be taught with hip flexion being initiated first which will also limit unnecessary patella and knee joint issues.

Problem 4: Poor Ankle Stability- Often on this exercise people will shift their weight to their forefoot to compensate for forward knee position and a more quad dominant movement. This often means that the heel may lift. Having a good mix of stability and mobility is vital at the ankle for this exercise- if there is insufficnet range at the ankle then you may also fall forward on to your toes. Similarly if there is poor multidirectional stability at this joint then you may fall over.

This post highlights that although some exercises look cool they may be beyond some people no matter there fitness levels. As always making sure the leverages are right around an exercise are right before progression is suggested.

Published by ianmellis

Ian Mellis MSc. CSCS is the co-founder of Results FAST ( in Ware, Hertfordshire. Specialising in athletic development, physique improvement and injury rehabilitation he provides personal training, strength and conditioning and nutrition coaching for motivated exercisers and those looking to make a long term change to their health, fitness and performance.

One thought on “Single Leg Squats: 4 Fatal Errors…

  1. I have never considered doing pistol squats (1 legged squats) on a box. Definitely giving that a try on Monday

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