Not all Unilateral Exercises are Created Equally!

The content in this article is based on concepts from:

  • Alex Natera’s “Load Comparison Ratio in Single and Double Leg Movements for UKSCA while at Aspire in Dohar, Qatar” 
  • Mike Boyle’s explanation of these concepts in “Mike Boyle – Unilateral Training Revisited (MBSC Thrive Summit 2021)”

Unilateral Squat Variations and Progressions

Among other findings, the work of Alex Natera and Mike Boyle demonstrated the effective contribution of the back/assisting leg in various unilateral squat and deadlift movements.  The findings can be used to provide guidance for progressing athletes through various squat variations.  The findings can be summarized as follows:


Front Leg (% of Load)  Back Leg (% of Load) 
Bilateral Squat N/A N/A
Step-Up 50% 50%
Split Squat 65% 35%
RFESS 78% 22%
Single Leg Squat   100% 0%
Skater Squats   100% 0%
Single Leg RDLs   100% 0%


This supports our general progression model: 

  1. Start athletes off by developing strength and competence in the bilateral squat
  2. Progress to single leg training by starting with Split Squats.  For cases where the split squat is still too challenging regress to Step-Ups
  3. Progress from split squats to Rear Foot Elevated Split Squats (RFESS)
  4. Progress from RFESS to “true” single leg exercises – uns-suppoorted unilateral exercises where the back lag does not provide any assistance. These exercises include squat and hinge variations including:
    • Single Leg Squat Variations
    • Single Leg RDLS
    • Skater Squats 

High level athletes training using this methodology have shown to be able to progress to Single Leg Squats PLUS 50% Bodyweight external load which has been shown mathematically and in the lab to be equivalent load on the legs as a 2x BW external load bilateral back squat!  

What are you waiting for?  Start building single leg strength and serious athleticism now! 

Here’s some videos from our exercise library to help you get started with the right form on each of these exercises:

Bilateral Squat Variations

Goblet Squat

Unilateral – Supported Squat Variations


Split Squats

Rear Foot Elevated Split Squats (RFESS)



Unilateral – Unsupported Squat and Hinge Variations


Single Leg Squat



Skater Squat


Single Leg RDL