During training and rehab, I often utilize unstable split squats to enhance lower body strength and balance. Beyond the impact on the lower extremity, I value the need for sufficient trunk control and core stability necessitated by this exercise.

The BOSU® NexGen™ Pro Balance Trainer is the ideal training tool to introduce an unstable environment for the lead leg in this exercise. It poses a challenge to lower extremity dynamic stability.

Execution: Begin in a split squat position with the left foot on top of the BOSU® NexGen™ Pro Balance Trainer. The right foot will be positioned on a 6-8 inch box/step with the heel up. The front leg will be flexed between 45 and 90 degrees, while maintaining an upright torso. The goal is to avoid lateral trunk displacement and medial collapse of the front knee.

Initially, I begin with isometric split squats for 30 seconds, taking note of how many times there is a loss of balance. Once the client masters good isometric form the following progression can implemented:

1. Increase the depth of flexion for the lead knee

2. Lengthen the duration of the isometric split squat

3. Add light perturbations to the shoulders, torso or legs

4. Isotonic split squat for time or repetitions

5. Isotonic split squat with horizontal chest press

The client is instructed to maintain a stable trunk and lower body position with a steady cadence during the isotonic version of the exercise.


1. Use light upper body support to maintaining balance/stability

2. Decrease the amount of knee flexion in the lead leg

3. Position the rear foot on the ground

Application: Training the core, hips and lower extremity in a split squat stance is a very functional way to train and improve a client’s ability to maintain proper body alignment for activities such as running, cutting, jumping, etc.

You will often see an overactive quadratus lumborum (QL) on the front side so it may be necessary to cue out of this pattern until the client understands the proper alignment and muscle activation patterns. Clients should be able to master split squats with perturbations on the floor prior to progressing to the version with the BOSU® NexGen™ Pro Balance Trainer. The perturbations do not need to be significant to be effective, so grade them carefully as you work to train the desired neuromuscular patterns. In addition, cue the client to place the lead foot on the center of the dome.

Precautions: I suggest spotting all clients in case there is a sudden loss of balance. For those with recent sprains, ankle instability or pain related to tendinopathy, it may be necessary to start with stable split squats first based on client response and form.