Cardiorespiratory fitness in working adults undergoing rehabilitation: the role of lifestyle and body composition- a cross-sectional study

Front Physiol. 2026 May 20;17:1806806. doi: 10.3389/fphys.2026.1806806. eCollection 2026.

ABSTRACT

INTRODUCTION: Cardiorespiratory fitness (CRF) is one of the most important predictors of mortality and morbidity. Lifestyle changes concerning diet, sleep, physical activity (PA), and substance use have a systemic impact and can prevent 80% of premature deaths and chronic diseases. CRF, being a parameter dependent on the functioning of all systems, may therefore be affected by changes in lifestyle.

AIM: To examine the relationship between declared lifestyle (eating habits, alcohol use, smoking, sleep, weekly PA and body composition) and CRF.

METHODS: A sleep questionnaire based on Polish version of the Athens Insomnia Scale, dietary and substance survey from the PaLS study and a PA survey based on the IPAQ-SF were conducted. Body composition was assessed using a bioelectrical impedance analysis device, with particular focus on body fat percentage and skeletal muscle mass. The Åstrand-Rhyming fitness test was used to estimate VO_2max. Spirometry was performed to assess pulmonary function, with results including FVC (% predicted), FEV₁ (% predicted), and the FEV₁/FVC ratio (% predicted).

RESULTS: Self-reported weekly PA was positively correlated with estimated VO_2max (ρ=0.23389; p= 0.0012). Night sleep duration was associated with higher estimated VO_2max (ρ =0.17976; p=0.0155). The frequency of consumption of plant-based protein was positively associated with estimated VO_2max (ρ = 0.18917; p=0.0108).). Body fat percentage was independently associated with VO_2max (B = -0.009, p=0.027). SMM% was independently associated with VO_2max (B = 0.01452, p= 0.0372).

CONCLUSIONS: Self-reported weekly PA, longer sleep duration, and favorable body composition (lower body fat percentage, higher skeletal muscle mass percentage) were associated with higher VO_2max. However, these results should be interpreted with caution due to self-reported data on lifestyle and a submaximal VO2max test.

PMID:42245828 | PMC:PMC13229796 | DOI:10.3389/fphys.2026.1806806