Abstract
BACKGROUND/OBJECTIVES: Loss of muscle strength and mass is common in patients with chronic lung disease (CLD) and contributes to functional decline. Resistance training and adequate protein intake improve muscle function in healthy adults, but data for this patient population are limited. METHODS: In this prospective, non-randomized controlled study, 16 patients with CLD (51-85 years) participated in three six-week intervention phases: phase 1-usual diet, phase 2-daily protein intake according to recommendations (1.2-1.5 g/kg bodyweight), and phase 3-additional protein supplementation immediately after training. Combined strength and endurance training was performed throughout the entire intervention period. The main outcome was maximum strength and body fat, while secondary outcomes included physical capacity, weight, activity, and quality of life (QoL). Data were analyzed using linear mixed-effect models to evaluate interaction effects between time points and phases with an intention-to-treat analysis. RESULTS: In the patients' usual diets, daily protein intake was below the recommended levels; during the intervention, protein intake increased significantly but did not reach the recommended target range. Maximum strength was increased marginally significantly by 4.6 kg during the intervention time without an interaction effect. Body fat reduction was significantly modeled using the interaction effect, whereas body weight remained unchanged. These enhancements are remarkable given that the training intensity was very low (less than once weekly), and protein consumption was below recommended levels. CONCLUSIONS: Targeted resistance training, combined with increased protein intake, led to measurable improvements in strength and body composition. These findings demonstrate that low-effort interventions can be implemented in real-life settings, providing a practical strategy to improve strength (a significant prognostic indicator) and increase protein consumption among this vulnerable population.