Understanding physical activity through physical fatigue, mental fatigue, and physical effort tendencies: a two-study investigation including the Italian Physical Effort Scale (PES) validation and a longitudinal study.

The present research comprised two distinct studies. Study 1 validated the Italian version of the Physical Effort Scale (PES) among 675 participants (375 males, 297 females, 3 not reported; Mage = 24.8, SD = 8.93). A subsample of 266 participants completed the scale twice over two weeks to assess PES test-retest reliability. Confirmatory factor analyses supported the original two-factor structure (i.e., physical effort approach and avoidance), and results demonstrated satisfactory internal consistency, construct validity, and test-retest reliability, thus confirming its suitability for Italian-speaking populations. Study 2 included 424 participants (211 males, 212 females, 1 not reported; Mage = 25.2, SD = 9.54) and employed a three-month longitudinal design to test two separate mediation models in which, physical and mental fatigue predicted physical activity through the intervening effects of the tendency to approach and the tendency to avoid physical effort, respectively. Different patterns emerged. Physical fatigue was associated with lower approach and higher avoidance tendencies toward physical effort, which in turn predicted physical activity, especially vigorous physical activity. Conversely, mental fatigue was not associated with these tendencies but directly predicted light and moderate physical activity. The validated Italian PES provides a reliable instrument for assessing tendencies to approach or avoid physical effort in research and applied settings. Overall, these findings suggest that physical and mental fatigue, together with such tendencies, could be important factors influencing physical activity and that targeting them may help increase population activity levels, thereby improving public health.