Sex-specific associations between bouted moderate-to-vigorous physical activity and cardiorespiratory fitness—Results from the Paracelsus 10,000 study

Physical activity recommendations of 150 min week⁻¹ have shifted from bouted (≥10-min increments) to ‘every step counts’ (sporadic). This study analysed the distribution of bouted and sporadic moderate to vigorous physical activity (MVPA) by sex and cardiorespiratory fitness (CRF). Objective data from 720 individuals (338 females) from the Paracelsus 10,000 study with valid cardiopulmonary exercise testing and accelerometry measurements were analysed. MVPA total (min week −1 ) combined accelerometry measurements (MVPA bouted , MVPA sporadic ) with self-reported cycling activity (MVPA nr-bouted ). Males were more active (542 ± 296 min week⁻¹) than females (350 ± 204 min week⁻¹). MVPA sporadic contribution decreased significantly from CRF-low to CRF-high groups, while MVPA bouted and MVPA nr_bouted increased significantly. Regression analyses showed that MVPA bouted significantly associated with relative VO 2peak in females ( R 2 Adj. = 0.30) and males ( R 2 Adj. = 0.35). Adding MVPA nr_bouted further improved model fit, with all three MVPA patterns explaining variance in females ( R 2 Adj. = 0.34), but only MVPA bouted and MVPA nr_bouted in males ( R 2 Adj. = 0.47). BMI, age, and smoking status were additional significant predictors. These findings indicate sex-specific associations between MVPA patterns and CRF. In females, all physical activity patterns—including MVPA sporadic —were independently associated with CRF, whereas in males the association was driven mainly by MVPA bouted and MVPA nr_bouted . Given the cross-sectional design, these findings should be interpreted as hypothesis-generating for future longitudinal and intervention studies.