Toward Measuring Cognitive Endurance Capacity: A Proof-of-Principle Study in a Healthy Population

Occupational health professionals increasingly encounter workers who complain about a decrease in cognitive endurance, yet standardized tools to objectively assess this decrease are lacking. Cognitive endurance, the ability to sustain cognitive performance during prolonged mental effort, is critical for sustainable employability.

In this proof-of-principle study, 101 healthy working adults (M_age = 35.7, SD = 13.6) completed neuropsychological assessments and fatigue questionnaires at the start and end of a regular workday. Cognitive endurance was operationalized as within-day change scores across six cognitive domains. Analyses included paired t-tests, Wilcoxon signed-rank tests, Spearman correlations, and multiple regression.

Over the course of a workday, cognitive performance improved in language, attention/executive functioning, and information processing speed (all p < 0.001), despite a significant increase in subjective fatigue (Z = -6.34, p < 0.001). Nearly half of the neuropsychological tests showed improvement. Fatigue measures explained only a small part of the variance in language change (R² = 0.122), and no individual fatigue predictors were significant in that model. Higher subjective fatigue was associated with less improvement in processing speed (p = 0.040).

Cognitive performance remained stable or improved over the course of the day, even as subjective fatigue levels increased. Fatigue measures showed limited predictive value for changes in cognitive outcomes, with only subjective fatigue significantly related to performance in one domain. These findings suggest that in healthy working adults, subjective complaints alone do not reliably indicate reduced cognitive functioning. Incorporating objective cognitive data may therefore be important when assessing endurance capacity and informing occupational health evaluations.