Mental Toughness and Neuromuscular Strength: A Parsimonious Model from a Multisystem Perspective

Mental Toughness (MT) is a trainable capacity that supports consistent performance under pressure. Conceptually grounded in purposefulness, efficiency, and flexibility, MT is increasingly examined through a multisystem lens, including physiological function. Yet, specific physical indicators that meaningfully relate to MT remain unclear. PURPOSE: To identify physiological predictors of MT in healthy adults. METHODS: Eighty-four adults (M = 84; 44.7 ± 14.8 years; BMI = 26.8 ± 5.2; %BF = 24.2 ± 7.2) completed the Mental Toughness Index (MTI). Candidate predictors included VO₂max (Bruce Protocol), resting heart rate (RHR), % body fat and BMI (via DEXA), right-hand grip strength (dynamometer), and age. Standardized predictors were entered into an AIC-based stepwise linear regression to model MTtotal in MATLAB. RESULTS: The final model retained two predictors: grip strength and age, F(2, 45) = 2.64, p = .082, adj. R² = .064. Grip strength was significantly associated with MTtotal (β = 0.30, p = .037); age was not (β = -0.19, p = .166). No other variables improved model fit. CONCLUSION: Neuromuscular strength emerged as a significant predictor of self-reported MT, independent of cardiovascular fitness and body composition. While modest in variance explained, this relationship suggests that functional strength may signal or support adaptive stress responses. These findings contribute to a growing view of MT as a multisystem construct. Future studies should examine whether enhancing neuromuscular performance can positively influence MT in high-stakes or stress-laden environments.