Quadriceps weakness is one of the most common causes of anterior knee pain. Clients recovering from injuries and even surgery often struggle to regain girth and functional quad strength. It is important to use single leg training to optimize patellofemoral mechanics and knee function.

Since many clients will not be able to perform a pistol squat with good form, the single leg box squat is an effective alternative to improve quadriceps strength and teach proper form.

Execution: Utilize a box at an appropriate height that will challenge the strength/control of the client, but not allow for a sudden drop or loss of control on the descent. Stand on the left leg with the heel about 2-3 inches away from the box. The right leg will be unsupported and out in front of the body. The arms can be extended out in front of the body during the squat to help maintain balance.

Now, slowly squat down until the glutes softly touch the top of the box. Pause momentarily, and then return to the start position. Perform 8-10 repetitions on each side, and repeat for 2-3 sets. It may be necessary to use a mirror or tactile/verbal cues to avoid values collapse.


1. Increase the height of the box

2. Use external support for the upper body to increase balance/stability


1. Decrease the height of the box

2. Increase the cadence (especially the eccentric phase)

Application: This exercise will strengthen the quadriceps and help eliminate any asymmetry or imbalances between limbs. In addition, it will improve proximal hip stability, proprioception and balance. If you do not have access to adjustable boxes, consider using a weight bench or chair and augmenting the height with foam pads.

Precautions: Do not force range of motion or push to a depth where there is any anterior knee pain.