Complex, but not simple, motor tasks assessment improves detection of motor-cognitive interaction in midlife

Executive and motor function are bidirectionally linked and decline as we age, yet motor-cognitive links are predominantly studied in older adults, while studies focused on midlife report mixed results. We aimed to evaluate whether motor tasks of varying complexity reflect executive function in midlife, a sensitive window for identifying early cognitive-functional risks that are otherwise undetected, thus informing timely intervention strategies. Using a cross-sectional study design, we assessed executive function with the trail making test and the stroop color-word test, calculating a composite cognitive score. Motor function was assessed by low complexity unipedal stance test and three-min step test, and the complexity by the one-minute Burpee test and the four step square test (FSST). A total of N = 181 participants completed all tasks (48.8 ± 5.6 years, 53% women). Only complex motor tasks were significantly associated with the composite cognitive score (Burpee rho = 0.28, p = 0.005; FSST rho = -0.29, p < 0.001). In a multiple linear regression model predicting the composite cognitive score based on motor task performance, FSST and age were the only significant contributing variables (adjusted R² = 0.17, p < 0.001; FSST B = -0.29, 95% confidence interval (-0.41, -0.11), controlling for age, sex, BMI, and education). Associations between motor performance and executive function emerged only during complex motor tasks, suggesting that midlife functional reserves must be challenged to unmask subtle cognitive-motor changes. Widely used motor assessments often exhibit ceiling effects that mask midlife heterogeneity. We advocate for integrating graded, age-adjusted complex tasks into the intrinsic capacity framework, improving early risk stratification and informing personalized interventions for promotion of healthy aging.