Changes in lower extremity muscle mass and muscle strength after weight loss in obese men: A prospective study.

Obesity is not only associated with internal diseases but also with surgical problems. Surgical diseases related to obesity frequently occur in the load bearing joints of the lower limbs. To decrease the occurrence of surgical diseases related to obesity, weight loss has been recommended. It is important for obese men to maintain muscle mass and muscle strength after weight loss because low muscle mass and muscle strength are also related to the occurrence of surgical diseases. To date, the importance of muscle mass and muscle strength after weight loss in obese men has been underappreciated. The purpose of this study was to investigate changes in lower extremity muscle mass and muscle strength resulting from a weight loss programme consisting of caloric restriction and exercise. All participants concurrently attended a 12-week diet class 1day/week and a 12-week exercise class 3days/week. Body weight and body composition by dual-energy X-ray absorptiometry and knee extensor strength by dynamometry were assessed. The weight loss programme led to a 14.1% weight loss accompanied by significant loss of leg muscle mass, static maximal muscle strength, dynamic maximal muscle strength and dynamic muscle endurance but not with significant loss of dynamic muscle power. Decline of muscle strength was related to a decrease in muscle mass, but not completely dependent on a decrease in muscle mass. Body weight-normalised muscle strength increased significantly. We recommend utilising resistance exercise to restore muscle mass and muscle strength in the legs after substantial weight loss.

Kim B ，Tsujimoto T ，So R ，Tanaka K ... -  《Obesity Research & Clinical Practice》

Lower extremity muscle size and strength and aerobic capacity decrease with caloric restriction but not with exercise-induced weight loss.

Weiss EP ，Racette SB ，Villareal DT ，Fontana L ，Steger-May K ，Schechtman KB ，Klein S ，Ehsani AA ，Holloszy JO ，Washington University School of Medicine CALERIE Group ... -  《-》

Changes in lower extremity muscle mass and muscle strength after weight loss in obese patients with knee osteoarthritis: a prospective cohort study.

To investigate the effects of low-energy diet-induced weight loss on lower-extremity muscle mass and knee muscle strength in obese patients with knee osteoarthritis (OA), and the associations of these effects. We studied 159 obese patients with knee OA and available data from body composition analysis that had been performed using dual x-ray absorptiometry scanning and isometric muscle strength testing of the knee in extension and in flexion. The data had been obtained as part of a randomized controlled trial, with measurements performed before and after a supervised low-energy diet-induced weight loss intervention lasting 16 weeks. The patients lost an average of 12.9 kg (95% confidence interval [95% CI] 10.2, 15.7) (13% of baseline weight). The weight loss consisted of 10.9 kg fat mass (95% CI 8.9, 12.9), of which 3.8 kg (95% CI 2.7, 4.9) was leg fat mass. Total lean body mass was reduced by 1.9 kg (95% CI 0.05, 3.8), of which 0.785 kg (95% CI 0.09, 1.476) was leg lean mass. Absolute muscle strength decreased by ∼3-4% after the weight loss, whereas body mass-normalized muscle strength increased by 11-12%. At baseline, leg lean mass was significantly related to muscle strength, but changes in these measurements at followup were not related. Weight loss induced by a low-energy diet led to independent losses of leg muscle tissue and strength. The weight loss was accompanied by increased normalized muscle strength along with improved self-reported disability and pain--all of which are beneficial to patients with knee OA. The present results suggest that significant weight loss in patients with knee OA should be followed by an exercise regimen to restore or increase muscle mass.

Henriksen M ，Christensen R ，Danneskiold-Samsøe B ，Bliddal H ... -  《-》

Contribution of isokinetic muscle strengthening in the rehabilitation of obese subjects.

Ghroubi S ，Kossemtini W ，Mahersi S ，Elleuch W ，Chaabene M ，Elleuch MH ... -  《-》

Reduced body weight or increased muscle quality: Which is more important for improving physical function following exercise and weight loss in overweight and obese older women?

The purpose of this study was to examine the relative contributions of changes in muscle quality and body composition to changes in lower-extremity physical function (LEPF) following a 6-month exercise and weight loss intervention in overweight and obese older women. Thirty-eight overweight and obese (BMI = 30.0 ± 4.4 kg/m2) older (age = 69.3 ± 4.1 y) women completed 6 months of multicomponent exercise (cardiorespiratory, resistance, balance and flexibility training) and weight loss (hypocaloric diet that reduced energy intake by ~500 kcal/d). Body composition was measured via dual-energy X-ray absorptiometry and muscle quality (N-m/kg) was defined as maximal concentric isokinetic knee torque divided by upper-leg lean mass. The standardized scores of four objective measures of physical function were summed to yield a composite LEPF Z-score. At 6 months, there were significant reductions in body weight (-9.6 ± 3.5%, p < 0.01), absolute fat mass (-6.8 ± 2.4 kg, p < 0.01) and relative adiposity (-4.9 ± 2.1%, p < 0.01). There were also improvements in both muscle quality (+1.6 ± 1.8 N-m/kg, p < 0.01) and individual measures of LEPF (11-57%, p < 0.01). Multivariate linear regression indicated that increased muscle quality was the strongest independent predictor of an improvement in LEPF Z-score (standardized β = 0.64, p < 0.01) and explained 34% of the variance. A reduction in body weight also predicted an improvement in LEPF, independent of the change in muscle quality. In conclusion, muscle quality can be increased in the presence of clinically meaningful weight loss, and is the primary determinant of improved physical function in overweight/obese older women.

Straight CR ，Berg AC ，Reed RA ，Johnson MA ，Evans EM ... -  《-》