JC's Musings

Bilateral Deficit – Bilateral Facilitation

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Single vs double leg isometric assessment

Can somebody help here? Jordan Troester, Director of Performance and Sport Science at University of Oregon shared this observation. When isometric squat assessing their athletes, he typically finds that the single leg peak forces (PF) in the diagram (see Figures B and C ), were at least 80% of double leg PF (see Figure A), sometimes even between 90-100%. In the example on the slide, unilateral isometric PF is ~83% of bilateral PF. Have you seen similar results? Why is that?

We kicked a couple of ideas around about: testing at short and long muscle lengths; differences with bilateral propulsion athletes such as rowers and weightlifters vs unilateral propulsion athletes e.g. runners; ramped vs ballistic assessments; and, settled on thinking it was about neural inhibition. That is, given the safer nature of unilateral isometric maximal squat strength testing in tandem with minimal technique demands), we wondered if there was a lot less neural inhibition (GTO – force feedback) and therefore greater net agonist unilateral force expression.

Are we on the money? Please feel free to share you thoughts with us at info@professorjohncronin.com.

BTW a side plate of thought for you. The right leg signal is interesting. It is of an athlete rehabbing his leg from ACL reconstruction. The PF of both legs pretty much identical but the signals are way different. Looking at the signal in tandem with numbers critical for accurate diagnostics is one take home. Others?