Variation in spirometric indices during a 16-week combined exercise training in sedentary workers: a randomized controlled trial

<bold>Background:</bold> Sedentary behavior may accelerate the age-associated decline in lung function. The impact of exercise on spirometric indices of sedentary adults and their relationship with smoking status remains unclear. We aimed to evaluate the longitudinal variation of spirometric indices over a 16-week combined training (CT) in middle-aged adults with sedentary jobs. <bold>Methods:</bold> Participants were randomly allocated (1:1) to a 3 times/week (75 min/session), combined aerobic and resistance exercise training, or a control group. Spirometry was performed using the Spiropalm 6MWT (Cosmed, Italy) before (M1), and after 8 (M2) and 16 weeks (M3) of follow-up. Predicted values were calculated for FEV₁, FVC, FEV_¹/FVC ratio, and FEF_25-75% using prediction equations from the GLI. Latent growth curve modeling was used to estimate interindividual and intraindividual growth paths. Smoking status was considered a predictor of growth. <bold>Results:</bold> Thirty-six adults (age=53.7±6.9 years) completed the trial (n=18 in each group). Smoking had a significant effect on spirometric indices growth in both groups. The non-smokers of the exercise group had higher increases from M1 to M3 in predicted FEV₁% (<italic>β</italic>=.08), FVC% (<italic>β</italic>=.22), FEV₁/FVC ratio (<italic>β</italic>=.19), and FEF_25-75% (<italic>β</italic>=.06) (<italic>p</italic><.05) than those who were smokers. The control group had lower growth in spirometric indices, with lower increases found in smokers compared to non-smokers for predicted FEV₁% (<italic>β</italic>=-.41), FVC% (<italic>β</italic>=-.44), FEV_¹/FVC ratio (<italic>β</italic>=-.98), and FEF_25-75% (<italic>β</italic>=-.52) (<italic>p</italic><.05). <bold>Conclusion:</bold> CT is an effective intervention to improve spirometric indices in sedentary workers. Non-smokers seem to obtain more benefits from training than smokers.