Relationship between bioelectrical impedance–derived muscle quality and physical activity, sedentary behavior, or sleep using compositional data analysis (CoDA)

The association between exercise behaviors-including physical activity (PA), light-intensity PA (LPA), moderate-to-vigorous-intensity PA (MVPA), sedentary behavior (SB), and sleep-and muscle quality remains unclear. This study aimed to examine the association between 24-h movement behaviors and muscle quality, as assessed by bioelectrical impedance spectroscopy (BIS). A total of 294 participants were enrolled in the cross-sectional study. LPA, MVPA, and SB were objectively measured using a tri-axial accelerometer. Sleep duration was assessed through a validated self-reported questionnaire. Muscle quality, based on electrical properties, was evaluated using a BIS device including parameters such as phase angle, intracellular-to-extracellular water ratio, membrane capacitance, characteristic frequency. Associations between 24-h movement behaviors and muscle quality derived from electrical properties were examined using compositional multiple linear regression. Additionally, hypothetical time reallocations among different movement behaviors in relation to muscle quality were evaluated using compositional isotemporal substitution. The same analyses were also conducted among participants classified as non-regular exercisers. Longer durations of MVPA were significantly associated with better indicators of muscle quality. Theoretical time reallocation analyses suggested that 30 min from SB, LPA, or sleep to MVPA was associated with approximately 0.5-3.8% higher values of BIS-derived muscle quality indices. This association remained consistent among non-regular exercisers. These cross-sectional findings indicate that greater daily MVPA is associated with a more favorable BIS-derived muscle-quality profile. MVPA is a key component of daily movement that contributes to the maintenance and potential improvement of muscle quality, as evaluated through electrical properties measured using BIS in both regular and non-regular exercisers.