Leg Skeletal Muscle Mass Research Articles

Validity of ultrasound muscle thickness measurements for predicting leg skeletal muscle mass in healthy Japanese middle-aged and older individuals

BackgroundThe skeletal muscle mass of the lower limb plays a role in its mobility during daily life. From the perspective of physical resources, leg muscle mass dominantly decreases after the end of the fifth decade. Therefore, an accurate estimate of the muscle mass is important for the middle-aged and older population. The present study aimed to clarify the validity of ultrasound muscle thickness (MT) measurements for predicting leg skeletal muscle mass (SM) in the healthy Japanese middle-aged and older population.FindingsMTs at four sites of the lower limb and the bone-free lean tissue mass (LTM) of the right leg were determined using brightness-mode ultrasonography and dual-energy X-ray absorptiometry (DXA), respectively, in 44 women and 33 men, 52- to 78-years old. LTM was used as a representative variable of leg skeletal muscle mass. In the model-development group (30 women and 22 men), regression analysis produced an equation with R2 and standard error of the estimate (SEE) of 0.958 and 0.3 kg, respectively: LTM (kg) = 0.01464 × (MTSUM×L) (cm2) - 2.767, where MTSUM is the sum of the product of MTs at four sites, and L is length of segment where MT is determined. The estimated LTM (7.0 ± 1.7 kg) did not significantly differ from the measured LTM (7.0 ± 1.7 kg), without a significant systematic error on a Bland-Altman plot. The application of this equation for the cross-validation group (14 women and 11 men) did not yield a significant difference between the measured (7.2 ± 1.6 kg) or estimated (7.2 ± 1.6 kg) LTM and systematic error.ConclusionThe developed prediction equation may be useful for estimating the lean tissue mass of the lower extremity for the healthy Japanese middle-aged and older population.

Visceral fat mass is associated with daily physical activity, leg skeletal muscle mass and fiber intake in healthy men

Visceral fat mass is associated with daily physical activity, leg skeletal muscle mass and fiber intake in healthy men

Postoperative loss of skeletal muscle mass, complications and quality of life in patients undergoing cardiac surgery

Objective The objective of this study was to describe postoperative undernutrition in terms of postoperative losses of appendicular skeletal muscle mass (ASMM) with respect to complications, quality of life, readmission, and 1-y mortality after cardiac surgery. Methods Patients undergoing cardiac surgery were prospectively followed. ASMM was measured 2 wk before and 2 mo after surgery using dual-energy X-ray absorptiometry. ASMM consists of arm skeletal muscle mass (SMM) and leg SMM. The association between ≥5% of ASMM decrease and postoperative outcome was analyzed using the chi-square test. A similar approach was used to analyze arm SMM and leg SMM decreases separately. Results Twenty-nine patients were included (23 male, 34.5% ≥65 y old). Postoperatively, seven patients (24.1%) lost ≥5% ASMM. When analyzed separately, a ≥5% decrease in leg SMM was associated with a decrease in experienced vitality (odds ratio 13.0, 95% confidence interval 1.32–128.11, P = 0.03). In contrast, a ≥5% loss of arm SMM was associated with fewer in-hospital complications (odds ratio 0.20, 95% confidence interval 0.04–0.98, P = 0.04). These patients were characterized by a higher preoperative fat-free mass index (kilograms per meter squared; P = 0.01). Conclusions The results suggest that a preoperatively higher fat-free mass index indicates better ability to cope with operative stress, resulting in fewer complications. In addition, postoperative loss of muscle mass was associated with decreased vitality. We advocate further research investigating the effect of preoperative and postoperative nutritional intervention combined with physical exercise programs to increase lean body mass and thereby improve postoperative recovery after cardiac surgery.

Development of nonexercise prediction models of maximal oxygen uptake in healthy Japanese young men

The present study developed nonexercise models for predicting maximal oxygen uptake (VO2max) using skeletal muscle (SM) mass and cardiac dimensions and to investigate the validity of these equations in healthy Japanese young men. Sixty healthy Japanese men were randomly separated into two groups: 40 in the development group and 20 in the validation group. VO2max during treadmill running was measured using an automated breath-by-breath mass spectrometry system. Left ventricular internal dimensions at end-diastole (LVIDD) and at end-systole (LVIDS) were measured using M-mode ultrasound with a 2.5 MHz transducer. Stroke volume (SV) was calculated based on the Pombo rule. SM mass was predicted by B-mode ultrasound muscle thickness. Correlations were observed between VO2max and predicted thigh (r = 0.74, P < 0.001) and lower leg SM mass (r = 0.55, P < 0.001). Furthermore, there were correlations between VO2max and LVIDD (r = 0.74, P < 0.001) and SV (r = 0.72, P < 0.001). Stepwise regression analysis was applied to thigh SM mass and SV for prediction of VO2max in the development group, and these parameters were closely correlated with absolute measured VO2max (R2 = 0.72, P < 0.001) by multiple regression analysis. When the VO2max prediction equations were applied to the validation group, significant correlations were also observed between the measured and predicted VO2max (R2 = 0.83, P < 0.001). These results suggested that nonexercise prediction of VO2max using thigh SM mass and cardiac dimension is a valid method to predict VO2max in young Japanese adults.

Total And Regional Skeletal Muscle Mass In Middle-aged And Elderly Japanese Men And Women

PURPOSE To examine the influence of age and gender on total and regional (arm, trunk and leg) skeletal muscle (SM) mass in middle-aged and elderly Japanese men and women. METHODS 395 middle-aged (183 men and 212 women, aged42.4±4.2yr [35–49yr]) and 168 elderly subjects (79 men and 89 women, mean age 73.5±3.5yr [70–91yr]) were volunteered for the study. All subjects were free of orthopaedic abnormalities and diagnosed neurological or cardiovascular disease. Muscle thickness was measured by B-mode ultrasound (5 MHz scanning head) at 6 sites on anatomical SM belly (anterior and posterior upper arm, abdomen, subscapular, anterior and posterior thigh). Total and regional (arm, trunk and leg) SM mass were estimated using prediction equations (MSSE 36(5): S74, 2004), which was developed based on the relationship between ultrasound-measured muscle thickness and MRI-measured SM mass. RESULTS Total SM mass in elderly men and women was 17.1±2.6and 11.4±1.8 kg, which was lower (P < 0.01) than in middle-aged men (21.5±2.3kg) and women (14.1±1.6kg), respectively. The ratio of total SM mass to body mass in elderly subjects (men 32.0±3.3%, women 24.3±2.3%) was lower (P < 0.01) than in middle-aged subjects (men 34.1 ±2.5%, women 26.0±2.4%). The difference of total SMmass between middle-aged and elderly subjects was 4.4kg in men and 2.7kg in women. Arm, trunk and leg SMmass in elderly subject (men 1.8±0.4, 7.4±1.1 and 8.0±1.6kg; women 1.2±0.2, 5. 1±0.7 and 5.0±1.2kg, respectively) was lower (P < 0.01) compared with middle-aged subjects (men 2.5±0.3, 8.5±1.1 and 10.5±1.4kg; women 1.5±0.2, 5.6±0.6 and 7.0±1.1kg, respectively). The difference of arm, trunk and leg SMmass between middle-aged and elderly subjects was 0.7 (17%), 1.1 (25%) and 2.5kg (58%) in men and 0.3 (10%), 0.5 (17%) and 2.0kg (73%) in women. CONCLUSIONS These results indicated that 1) elderly subjects possessed about 25% less total SM than middle-aged subjects in both men and women, and 2) about 60–70% of this difference in whole body SM loss may be attributable to loss of leg SM mass.

Skeletal muscle mass and muscle strength in relation to lower-extremity performance in older men and women.

Low muscle strength is associated with poorer physical function, but limited empirical evidence is available to prove the relationship between muscle mass and physical function. We tested the hypothesis that persons with lower muscle mass or muscle strength have poorer lower-extremity performance (LEP). A cross-sectional, population-based study. A cohort of 449 men and women aged 65 years and older living in Amsterdam and its surroundings participating in the second examination (1995-1996) of the Longitudinal Aging Study Amsterdam. Leg skeletal muscle mass was measured using dual-energy X-ray absorptiometry (DXA). Grip strength was used as an indicator of muscle strength. Timed functional performance tests, including walking and repeated chair stands, were used to assess LEP. After adjustment for body height and age, leg muscle mass was positively associated with LEP in men (regression coefficient 0.178 [95% confidence interval 0.013-0.343], P = .035). In women an inverse association was observed, which became positive after additional adjustment for body mass index (BMI) (0.202 [-0.001-0.405], P = .052). Grip strength was positively associated with LEP in men and women. After additional adjustment for behavioral, physiological, and psychological variables, the associations between leg muscle mass and LEP disappeared, whereas grip strength remained to be independently associated with LEP in men (0.079 [0.042-0.116], P = .0001), with a tendency in women (0.046 [-0.009-0.101], P = .11). Results were similar when quartiles of leg muscle mass or grip strength were used. These results suggest that low muscle strength, but not low muscle mass, is associated with poor physical function in older men and women. However, prospective studies are needed to investigate the association between loss of muscle mass and physical function.

Appendicular skeletal muscle mass: prediction from multiple frequency segmental bioimpedance analysis

Bioimpedance analysis (BIA) methods have potential to predict appendicular skeletal muscle mass (SM), although available 50 kHz prediction models include, in addition to impedance (Z), an independent age term. An age term in models is undesirable as it reflects incomplete understanding of underlying conduction physiology. This study tested the hypothesis, based on fluid distribution models related to aging, that appendicular SM bioimpedance analysis (BIA) prediction models would no longer include an independent age term, after first controlling for stature-adjusted appendicular impedance (height2/Z), at injected frequencies greater than 50 kHz. Cross-sectional evaluation of adults who had segmental Z and phase angle (phi) measured with multiple frequency BIA, and arm and leg SM with dual-energy X-ray absorptiometry (DXA). Skeletal muscle prediction models were developed with appendicular SM as dependent variable and height2/Z, gender, age and phi as potential independent variables. Examination of hypothesis in 49 subjects indicated: both arm and leg SM were highly correlated with height2/segmental Z at frequencies ranging from 1-300 kHz; gender was significant covariate in prediction models only at 1 kHz; age remained a significant covariate after controlling for height2/segmental Z at all frequencies; phi did not add significantly to models; and SM prediction models gave maximum R2 at 50 kHz for arm but R2 continued to rise up to 300 kHz for leg. Although multifrequency BIA did not eliminate SM prediction model age term, our findings suggest injected frequencies up to 300 kHz may have advantages for evaluating leg SM over conventional 50 kHz method.