Low Relative Muscle Research Articles

Low Relative Lean Mass is Associated with Increased Likelihood of Abdominal Aortic Calcification in Community-Dwelling Older Australians.

Age-related loss of skeletal muscle is associated with increased risk of functional limitation and cardiovascular (CV) mortality. In the elderly abdominal aortic calcification (AAC) can increase CV risk by altering aortic properties which may raise blood pressure and increase cardiac workload. This study investigated the association between low muscle mass and AAC in community-dwelling older Australians. Data for this cross-sectional analysis were drawn from a 2010 sub-study of the Melbourne Collaborative Cohort Study in the setting of community-dwelling older adults. Three hundred and twenty-seven participants [mean age=71±6years; mean BMI=28±5kg/m(2); females n=199 (62%)] had body composition determined by dual-energy x-ray absorptiometry (DXA) and AAC determined by radiography. Participants were stratified into tertiles of sex-specific BMI-normalised appendicular lean mass (ALM). Those in the lowest tertile were considered to have low relative muscle mass. Aortic calcification score (ACS) was determined visually as the extent of calcification on the aortic walls between L1 and L4 vertebrae (range: 0-24). Severe AAC was defined as ACS≥6. Prevalence of any AAC was highest in participants with low relative muscle mass (74%) compared to the middle (65%) and upper (53%) tertiles (p trend=0.006). The lower ALM/BMI tertile had increased odds (Odds ratio=2.3; 95% confidence interval: 1.1-4.6; p=0.021) of having any AAC; and having more severe AAC (2.2; 1.2-4.0; p=0.009) independent of CV risk factors, serum calcium and physical activity. AAC is more prevalent and severe in community-dwelling older adults with low relative muscle mass. Maintaining muscle mass could form part of a broader primary prevention strategy in reducing AAC.

Biomechanics of Locomotion in Antarctic Sea Spiders (Pycnogonida)

Eight‐legged locomotion within chelicerates and other arthropod groups allows a diverse array of maneuvers (e.g. variable speeds; forwards, sideways and backwards walking; low turning radius turns) on uneven substrate. During straight path locomotion, an alternating tetrapod gait cycle (R1, R3, L2, L4 to L1, L3, R2, R4) is characteristic in terrestrial eight‐legged species. However, far less is known about octopod locomotion in aquatic or marine arthropods which, like their terrestrial relatives, face highly uneven and variable substrates, but also live in a highly resistant fluid medium. While aboard the RV Laurence M. Gould, we investigated the walking kinematics of Antarctic sea spiders (Pycnogonida) in the genera Pallenopsis, Colossendeis, Nymphon, and Austropallene collected from the Southern Ocean near the Antarctic Peninsula. In all groups, absolute and relative walking speeds were comparatively slow, with absolute walking speed ranging from 0.05 to 0.2 cm/sec, and relative walking speed ranging from 0.07 to 0.11 body lengths/sec. While footfall patterns sometimes approximated an alternating tetrapod gait, the gait pattern was variable and often non‐symmetrical, with leg pairs commonly transitioning from out of phase to in phase within the same individual. Extremely cold temperatures, low relative muscle mass, and a resistant fluid medium likely contribute to the extremely slow walking speeds of sea spiders, while their variable gait patterns compared to those of terrestrial spiders suggest that aquatic and terrestrial habitats impose different selective pressures on central pattern generators controlling leg movements and walking.Support or Funding InformationA.R.M. and S.P.R. were supported by research grant ANT‐1043670 by the US National Science Foundation (NSF). K.M.H. was supported by research grant ANT‐1043745 by the NSF.

Relationship Between Low Relative Muscle Mass and Coronary Artery Calcification in Healthy Adults.

Sarcopenia or low muscle mass is related to cardiovascular risk factors; however, the association between low muscle mass and subclinical atherosclerosis has been largely unexplored. We investigated whether muscle mass is related to coronary artery calcification (CAC) in a large sample of middle-aged asymptomatic adults. We performed a cross-sectional study of 31 108 asymptomatic adults without cancer, diabetes mellitus, or known cardiovascular disease who underwent a health checkup examination including cardiac tomography estimation of CAC scores between 2012 and 2013. Skeletal muscle mass index (SMI) [SMI (%)=total skeletal muscle mass (kg)/body weight (kg)×100] was estimated using a bioelectrical impedance analyzer. We assessed the relationship between SMI and CAC scores using both multivariate-adjusted Tobit models and multinomial logistic regression models. Of the 31 108 subjects, 3374 subjects (10.9%) had a CAC score 1 to 100, and 628 subjects (2.0%) had a CAC score >100. SMI was inversely associated with CAC score ratios. Specifically, in a multivariable-adjusted model adjusting for potential confounders, CAC score ratios (95% confidence intervals) of SMI for quartiles 1, 2, and 3 compared with quartile 4 were 2.27 (1.70-3.05), 1.46 (1.15-1.85), and 1.24 (0.98-1.55), respectively (P for trend <0.001). Adjusting for insulin resistance reduced the magnitude of the associations, but they remained statistically significant. Relative muscle mass was negatively associated with the prevalence of coronary calcification, supporting low muscle mass as an independent risk factor of coronary heart disease.

Obesity-associated metabolic changes influence resting and peak heart rate in women and men

>Objectives: To study the relationship between obesity and heart rate (HR) in women and men. Design: We studied 241 overweight and obese subjects without known heart disease. All subjects underwent ergospirometry during maximal exercise testing on treadmill and recording of body composition, electrocardiogram and clinic and ambulatory blood pressure. Results: Women (n = 132) were slightly older and had higher fat mass, but lower weight, blood pressure and prevalence of metabolic syndrome (MetS) than men (n = 109) (all p < 0.05), while prevalences of obesity and hypertension did not differ. A significant interaction between sex and HR was demonstrated (p < 0.05). In multivariate analysis, female sex (β = 0.99, p < 0.01) predicted higher resting HR independent of confounders. Higher resting HR was particularly associated with presence of MetS, hypertension, higher insulin resistance and lower relative muscle mass in men (all p < 0.05). Female sex also predicted higher peak exercise HR (β = 0.48, p < 0.01) independent of confounders. Higher peak exercise HR was particularly associated with higher exercise capacity and lower age and self-reported physical activity in men, while lower HbA1c and absence of obesity were the main covariates in women in multivariate analyses (all p < 0.05). Conclusions: In our study population, obesity and obesity-associated metabolic changes influenced both resting and peak exercise HR.

Metabolic risk factors in U.S. youth with low relative muscle mass

To examine the association between relative muscle mass (RMM) and nine risk factors for cardiovascular disease and diabetes (CVD/DM) in U.S. youth. We used a sample representative of the U.S. population of youth, aged 8-20 years (NHANES 1999-2004). We compared the prevalence of adverse levels of nine CVD/DM risk factors between youths in the lowest quartile of RMM and their peers in the remaining quartiles, controlling for age, sex, and race/ethnicity. We also examined variations in the adjusted prevalence of these risk factors along the entire range of RMM. The adjusted prevalence of adverse levels of risk factors among youths in the lowest quartile of RMM was significantly higher for seven of the nine risk factors examined compared with their peers in the other quartiles. Over the entire range of RMM, the adjusted prevalence of adverse levels of each of these seven risk factors decreased gradually with increasing RMM values (all p for trend <0.001). RMM and prevalence of adverse risk factors for CVD/DM are highly and inversely associated in U.S. youth. Among youth with low RMM, the risk of these chronic diseases could be significantly high later in life.

AB0211 Sarcopenia in patients with inflammatory arthritis

BackgroundSarcopenia is the progressive generalised loss of skeletal muscle and strength related to age and disease activity and is defined by appendicular skeletal mass/height squared (ASM/h2). Sarcopenia is common in...

Low relative skeletal muscle mass indicative of sarcopenia is associated with elevations in serum uric acid levels: findings from NHANES III.

Sarcopenia may be related to increases in reactive oxygen species formation and inflammation, both of which are associated with elevations in serum uric acid. To test the hypothesis that a reduced skeletal muscle mass index, indicative of sarcopenia, is related to elevations in uric acid. Cross-sectional analysis of nationally representative data. Third National Health and Nutrition Examination Survey, 1988-1994. 7544 men and women 40 years of age and older who had uric acid, skeletal muscle mass, and select covariate information. Skeletal muscle mass assessment was based on a previously published equation including height, BIA-resistance, gender, and age. Absolute skeletal muscle mass was calculated for all study population individuals and compared against the sex-specific mean for younger adults. Serum uric acid data were gathered from the NHANES laboratory file. A logistic regression analysis revealed that elevations in serum uric acid are significantly related to sarcopenia status. For every unit (mg/dL) increase in uric acid, the odds ratio of manifesting a skeletal muscle mass index at least one standard deviation below the reference mean was 1.12. Participants in the highest grouping (> 8 mg/dL) of serum uric acid concentration had 2.0 times the odds of manifesting sarcopenia compared to the lowest grouping (< 6 mg/dL) (p < 0.01) after adjusting for the additional covariates. This study design was limited in its cross-sectional nature. Potential selection, measurement, and recall bias may have occurred, and methodology used to classify sarcopenia status based on skeletal muscle mass index is not validated. This observation provides support for the theory that elevations in uric acid may lead to sarcopenia, although the proposed mechanism needs further experimental support.

Low relative skeletal muscle mass (sarcopenia) in older persons is associated with functional impairment and physical disability.

To establish the prevalence of sarcopenia in older Americans and to test the hypothesis that sarcopenia is related to functional impairment and physical disability in older persons. Cross-sectional survey. Nationally representative cross-sectional survey using data from the Third National Health and Nutrition Examination Survey (NHANES III). Fourteen thousand eight hundred eighteen adult NHANES III participants aged 18 and older. The presence of sarcopenia and the relationship between sarcopenia and functional impairment and disability were examined in 4,504 adults aged 60 and older. Skeletal muscle mass was estimated from bioimpedance analysis measurements and expressed as skeletal muscle mass index (SMI = skeletal muscle mass/body mass x 100). Subjects were considered to have a normal SMI if their SMI was greater than -one standard deviation above the sex-specific mean for young adults (aged 18-39). Class I sarcopenia was considered present in subjects whose SMI was within -one to -two standard deviations of young adult values, and class II sarcopenia was present in subjects whose SMI was below -two standard deviations of young adult values. The prevalence of class I and class II sarcopenia increased from the third to sixth decades but remained relatively constant thereafter. The prevalence of class I (59% vs 45%) and class II (10% vs 7%) sarcopenia was greater in the older (> or = 60 years) women than in the older men (P <.001). The likelihood of functional impairment and disability was approximately two times greater in the older men and three times greater in the older women with class II sarcopenia than in the older men and women with a normal SMI, respectively. Some of the associations between class II sarcopenia and functional impairment remained significant after adjustment for age, race, body mass index, health behaviors, and comorbidity. Reduced relative skeletal muscle mass in older Americans is a common occurrence that is significantly and independently associated with functional impairment and disability, particularly in older women. These observations provide strong support for the prevailing view that sarcopenia may be an important and potentially reversible cause of morbidity and mortality in older persons.