The relationship between muscle strength and quality with functional performance in women mid- to long-term after Roux-en-Y gastric bypass

BACKGROUND: The reduction of muscle mass and strength commonly observed after bariatric surgery might negatively affect the individual physical function. Muscle quality is also of functional relevance in different populations, but its significance in patients who underwent bariatric surgery has yetto be explored. OBJECTIVE: To examine the association between muscle strength and quality with physical function in women mid- to long-term after Roux-en-Y gastroplasty (RYGB). METHODS: In this cross-sectional study, 133 women (43.7± 9.9 years) who have undergone RYGB at least two years before the study were included. All participants underwent body composition evaluation using DEXA and knee extensors peak moment (PM) using an isokinetic dynamometer. Muscle quality (MQ) was obtained through the ratio between absolute PM and dominant leg fat-free mass. Physical function was measured through the 30-second sit-to-stand (30-STS), 6-minute walking (6-MWT), and timed up-and-go (TUG) tests. RESULTS: Differences between PM tertiles were observed for 30-STS and 6-MWT tests. However, statistical significance disappeared when adjusting for age. Regarding PM relative to body weight, all functional tests were significantly different between tertiles. Comparing functional performance according to MQ tertiles, differences were found for 30-STS and 6-MWT tests, but significance disappeared when adjusting for age. Absolute PM was correlated to the 30-STS performance and 6-MWT, while PM relative to body mass and MQ were correlated with all functional tests. CONCLUSIONS: Muscle strength and quality seem to be associated with physical function in women mid-to-long-term after RYGB, but strength relative to bodyweight outperformed absolute strength and MQ.