The Mental Strength Scale®  (MSS-9) is a validated psychological instrument developed by the Combat Sports Psychology Lab as a simple tool for field applications for coaches and mental performance practitioners to determine strategic plans to improve a person's mental strength and overall goal optimization.

Mental Strength is operationally defined as a person's behavioral ability to persist through obstacles and overcome failures. 

The MSS-9 is free to use in clinical practice and research when accompanied by its citation (Lorenco-Lima, L., Waterbury, E.M., & Gaines, S.A. (2025) Mental Strength Scale (MSS-9): Factor Structure and Reliability. Journal of Human Sport and Exercise, 20(4), 1413-1426. https://doi.org/10.55860/4zqnaq61 )