Physical activity is not associated with feelings of mental energy and fatigue after being sedentary for 8 hours or more

Boolani, Ali Bahr Brandon Milani Italia Caswell Shane Cortes Nelson Smith Matthew Lee Martin Joel

The objective of this study was to examine the associations between physical activity (PA) and sedentary behavior (SB) on feelings of: 1) mental energy (ME), 2) physical energy (PE), 3) mental fatigue (MF) and 4) physical fatigue (PF) in participants who report sitting for less than 8 h (<8 h) compared to those who report sitting for greater than 8 h (>8 h) during the initial lockdown phase of the COVID-19 pandemic. Using a longitudinal study design, we measured PA and SB using the International Physical Activity Questionnaire-Short Form (IPAQ0SF) and feelings of ME, PE, MF, PF and fatigue using the Trait-State Mental and Physical Energy and Fatigue Questionnaire. Participants were then split into 2 groups, <8hr and >8hr. A series of step-wise regression models were used controlling for demographic factors and other lifestyle factors (e.g. sleep, mental workload, diet). Among the 473 participants in the <8hr group, PA was associated with increased PE and ME and decreased MF. However, of the 366 participants in the >8hr group PA was only associated with increased PE and decreased PF. We found PA was not significantly associated with ME and MF for participants who reported sitting >8hr. Our results suggest that sitting for >8hr may negate the positive benefits of PA on ME and MF. We recommend that individuals with low levels of ME and MF and who sit for >8hr to prioritize reducing their sitting time. For individuals with low levels of PE or PF, increasing PA is likely beneficial regardless of SB.