Mental Toughness and Physiological Function: An Exploratory Analysis of Multisystem Correlates in Healthy Adults

Mental Toughness (MT) is associated with a mindset of purposefulness, efficiency, and flexibility under stress. Although traditionally conceptualized as a psychological construct, emerging frameworks in psychophysiological toughness and mind-body integration suggest that MT may also be associated with or reflect variation in physical systems. This study explores whether MT can be meaningfully modeled within a multisystem framework of physiological and metabolic function. PURPOSE: To examine the extent to which physiological performance, metabolic health, and body composition predict 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. Participants underwent Bruce Protocol treadmill testing for VO₂max, DEXA scans for body composition, and comprehensive metabolic and lipid panels. Resting heart rate and bilateral handgrip strength were also assessed. A multiple linear regression in Python predicted MTtotal from VO₂max, % body fat, grip strength, BMI, age, sex, and resting HR. Correlation and quartile comparisons complemented regression modeling. RESULTS: The regression model was not statistically significant, F(8, 29) = 1.47, p = .212, but explained 28.8% of the variance in MT scores, R² = .29, adj. R² = .09. VO₂max (β = 0.18, p = .37) and handgrip strength (β = 0.04, p = .83) showed positive trends. Participants in the top quartile of MT had higher VO₂max (M = 39.0 ml/kg/min) and grip strength (M = 57.5 kg) compared to the bottom quartile (M = 33.6 ml/kg/min; M = 48.6 kg, respectively). MTtotal was positively correlated with VO₂max (r = .47) and grip strength (r = .31). CONCLUSION: In this exploratory, hypothesis-generating study, aerobic capacity and neuromuscular strength were positively associated with self-reported MT. These findings offer preliminary support for conceptualizing MT within a multisystem framework that includes physiological function. Future research should examine whether longitudinal or experimental designs can clarify the direction and nature of this relationship, particularly in contexts where both MT and physical fitness contribute to stress resilience.