A cross-sectional study of the relationship between physical activity, diet quality, and high-sensitivity C-reactive protein in US adults.

BACKGROUND AND AIMS: High-sensitivity C-reactive protein (hs-CRP) is associated with many diseases, especially cardiovascular disease (CVD). Research into the independent and integrated relationships of physical activity and diet quality with hs-CRP across sex-specific cohorts is lacking. METHODS AND RESULTS: National Health and Nutrition Examination Survey data (2015-2018) was used to examine the relationship between physical activity and diet quality with hs-CRP and hs-CRP classified CVD risk using multiple multinormal logistic regression adjusted for covariates including demographics. Physical activity was measured using a self-reported survey and further categorized to those who met (MPAR) or did not meet (NPAR) national recommendations. Diet quality was measured using the Healthy Eating Index-2015, and further categorized to higher (HDQ) and lower (LDQ) diet quality. hs-CRP was also categorized as low, average, and high CVD risk using established cut-points. Physical activity was inversely related to hs-CRP in males (p < 0.001) whereas diet quality was inversely related to hs-CRP in females (p = 0.031). Compared to those with NPAR and LDQ, the hs-CRP for males with NPAR and HDQ and females with MPAR and HDQ was 1.18 mg/L and 0.75 mg/L lower respectively. Although, diet quality was inversely associated with high CVD risk in both sexes (p < 0.05), the lowest proportion of high and average CVD risk was observed in males and females with MPAR and HDQ. CONCLUSION: Physical activity and diet-quality lowered CVD risk regardless of sex. However, the independent effects of physical activity and diet quality on hs-CPR differs between sexes.

The relationship between fat distribution and diabetes in US adults by race/ethnicity.

Introduction: This study examined the relationship between fat distribution and diabetes by sex-specific racial/ethnic groups. Methods: A secondary data analysis of National Health and Nutrition Examination Survey 2011-2018 data (n = 11,972) was completed. Key variables examined were visceral adipose tissue area (VATA), subcutaneous fat area (SFA), diabetes prevalence, and race/ethnicity. The association of VATA and SFA and diabetes prevalence was examined separately and simultaneously using multiple logistic regression. Bonferroni corrections were applied to all multiple comparisons between racial/ethnic groups. All analyses were adjusted for demographics and muscle mass. Results: VATA was positively associated with diabetes in both sexes (p < 0.001) and across all racial/ethnic groups (p < 0.05) except Black females. No statistically significant relationships were observed between SFA and diabetes while accounting for VATA with the exception of White females (p = 0.032). When comparing racial/ethnic groups, the relationship between VATA and diabetes was stronger in White and Hispanic females than in Black females (p < 0.005) while the relationship between SFA and diabetes did not differ between any racial/ethnic groups. Conclusion: This study found that VATA is associated with diabetes for both sexes across almost all racial/ethnic groups independent of SFA whereas the only significant relationship between SFA and diabetes, independent of VATA, was observed in White females. The findings indicated that visceral fat was more strongly associated with diabetes than subcutaneous. Additionally, there are health disparities in sex-specific racial/ethnic groups thus further study is warranted.

Does insulin-like growth factor 1 genotype influence muscle power response to strength training in older men and women?

The CA-repeat polymorphism in the insulin-like growth factor 1 (IGF1) gene promoter region has been associated with strength and circulating IGF-I protein levels. The purpose of the study was to determine if the IGF1 CA-repeat polymorphism influences muscle power at baseline and in response to ST in older adults. Knee extensor peak power (PP) was measured at 50, 60, and 70% of 1-RM strength before and after 10 weeks of unilateral knee extensor ST in older adults, aged 50-85 years, to determine the changes in absolute and relative PP with ST. Subjects (N = 114) were genotyped for the IGF1 CA-repeat polymorphism and grouped as homozygous for the 192 allele, heterozygous, or non-carriers of the 192 allele. The 192 homozygotes had significantly lower baseline PP at 50, 60, and 70% of 1-RM strength than the non-carriers when age, sex, and baseline fat-free mass were covaried (all P < 0.05). This same relationship was observed when the highest PP within these ranges was compared (e.g., 317.6 ± 13.5 for 192 homozygotes and 380.2 ± 16.3 for non-carriers of the 192 allele, P < 0.05). Both absolute and relative PP increased significantly with ST in all genotype groups as expected, but there were no significant relationships among IGF1 genotypes and any of the PP changes. Despite a significant relationship between IGF1 genotype and knee extensor peak power at baseline, IGF1 genotype does not appear to influence changes in knee extensor peak power with ST.

The Sex and Race/Ethnicity-Specific Relationships of Abdominal Fat Distribution and Anthropometric Indices in US Adults.

The purpose of this study was to examine demographic-specific relationships between direct abdominal fat measures and anthropometric indices. A cross-sectional study was conducted utilizing abdominal fat measures (visceral fat area, VFA; visceral to subcutaneous adipose area ratio, VSR) and anthropometrics (body mass index, BMI; waist circumference, WC) data from the 2011-2018 National Health and Nutrition Examination Survey. Linear or polynomial linear regression models were used to examine the relationships of abdominal fat measures to anthropometrics with adjustment for demographics. The results revealed that while VFA was linearly related to BMI and WC across all demographics (p < 0.001), the relationships between VSR and both BMI and WC were concave in men and convex in women. The relationships between VFA, VSR, and BMI, WC varied by sex and race/ethnicity. In conclusion, increasing BMI and WC were linearly associated with increased VFA, but their relationships with VSR were nonlinear and differed by sex.

The Demographic Specific Abdominal Fat Composition and Distribution Trends in US Adults from 2011 to 2018.

Despite the rising awareness of abdominal adiposity associated health problems and demographic health disparities, research is lacking about abdominal fat trends using a national representative sample of US adults. Our purpose was to examine national demographic specific abdominal fat composition and distribution trends from 2011 to 2018. This trend analysis was using National Health and Nutrition Examination Survey data (n = 13,163). Visceral adipose percent (VAT%), visceral adipose tissue area (VAA) and visceral to subcutaneous adipose area ratio (VSR) were utilized in data analyses. Multiple polynomial linear regression was utilized with adjustment for confounding variables. Our findings revealed that VAT%, VAA and VSR trends were concave among all demographic groups. The VAT%, VAA and/or VSR changes were observed in most demographic groups (p < 0.05) except younger, White and Black respondents. The pattern was consistent with biennial increases up to 2014 or 2016 followed by decreases in 2017-2018. There were demographic disparities, with middle-aged respondents and Hispanics having the most evident VAT%, VSR and/or VAA changes biennially when compared to their counterparts (p < 0.05). In conclusion, abdominal fat composition and distribution increased before 2014 or 2016 but decreased afterwards with variations by age and/or race/ethnicity. Further research is needed to explore the possible causes of abdominal fat changes overtime.

AKT1 polymorphisms are associated with risk for metabolic syndrome.

Converging lines of evidence suggest that AKT1 is a major mediator of the responses to insulin,insulin-like growth factor 1 (IGF1), and glucose. AKT1 also plays a key role in the regulation of both muscle cell hypertrophy and atrophy. We hypothesized that AKT1 variants may play a role in the endophenotypes that makeup metabolic syndrome. We studied a 12-kb region including the first exon of the AKT1 gene for association with metabolic syndrome-related phenotypes in four study populations [FAMUSS cohort (n = 574; age 23.7 ± 5.7 years), Strong Heart Study (SHS) (n = 2,134; age 55.5 ± 7.9 years), Dynamics of Health, Aging and Body Composition (Health ABC) (n = 3,075; age 73.6 ± 2.9 years), and Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE)(n = 175; age 40­65 years)]. We identified a three SNP haplotype that we call H1, which represents the ancestral alleles eles at the three loci and H2, which represents the derived alleles at the three loci. In young adult European Americans (FAMUSS), H1 was associated with higher fasting glucose levels in females. In middle age Native Americans (SHS), H1 carriers showed higher fasting insulin and HOMA in males, and higher BMI in females. Inolder African-American and European American subjects(Health ABC) H1 carriers showed a higher incidence of metabolic syndrome. Homozygotes for the H1 haplotype showed about twice the risk of metabolic syndrome in both males and females (p < 0.001). In middle-aged European Americans with insulin resistance (STRRIDE) studied by intravenous glucose tolerance test (IVGTT), H1 carriers showed increased insulin resistance due to the Sg component (p = 0.021). The 12-kb haplotype is a risk factor for metabolic syndrome and insulin resistance that needs to be explored in further populations.

Effect of moderate intensity resistance training during weight loss on body composition and physical performance in overweight older adults.

The impact of resistance training has not been thoroughly examined in overweight older adults undergoing weight loss. Subjects (n = 27) were overweight and obese (BMI 31.7 +/- 3.6 kg/m(2)) older (age 67 +/- 4 years) adults and were randomized into either a 10-week Dietary Approaches to Stop Hypertension for weight loss diet (DASH, n = 12) or DASH plus moderate intensity resistance training (DASH-RT, n = 15). Outcomes included weight loss, total body and mid-thigh composition, muscle and physical function. There were no significant weight loss differences between the DASH-RT and DASH groups (-3.6 +/- 0.8 vs. -2.0 +/- 0.9%, p = 0.137). The DASH-RT group had a greater reduction in body fat than the DASH group (-4.1 +/- 0.9 vs. -0.2 +/- 1.0 kg, p = 0.005). The DASH-RT group had greater changes in lean mass (+0.8 +/- 0.4 vs. -1.4 +/- 0.4 kg, p = 0.002) and strength (+60 +/- 18 vs. -5 +/- 9 N, p = 0.008) than the DASH group. There were favorable changes in mid-thigh composition variables in the DASH-RT group that were different than the lack of changes observed in the DASH group, except for intermuscular adipose tissue. Both groups experienced decreases in 400-m walk times showed (DASH -36 +/- 11 s, DASH-RT -40 +/- 7 s) with no differences between groups. Moderate intensity resistance training during weight loss appears to improve fat mass and thigh composition, but weight loss only does not. However, global measures of physical functioning may improve with a weight loss-only program.

A polymorphism near IGF1 is associated with body composition and muscle function in women from the Health, Aging, and Body Composition Study.

Previous studies have reported associations of polymorphisms in the IGF1 gene with phenotypes of body composition (BC). The purpose of this study was to identify phenotypes of BC and physical function that were associated with the IGF1 promoter polymorphism (rs35767, -C1245T). Subjects from the Health, Aging, and Body Composition Study, white males and females (n = 925/836) and black males and females (533/705) aged 70-79 years were genotyped for the polymorphism. Phenotypes of muscle size and function, bone mineral density, and BC were analyzed for associations with this polymorphism. To validate and compare these findings, a cohort of young (mean age = 24.6, SD = 5.9) white men and women (n = 173/296) with similar phenotypic measurements were genotyped. An association with BC was identified in elderly females when significant covariates (physical activity, age, smoking status, body mass index) were included. White women with C/C genotype had 3% more trunk fat and 2% more total fat than those with C/T (P < 0.05). Black women with C/C genotype had 3% less total lean mass and 3% less muscle mass than their T/T counterparts (P < 0.05). Associations were identified with muscle strength in white women (P < 0.01) that were in agreement with the C/C genotype having lower muscle function. Thus, in an elderly population but not a young population, a polymorphism in the IGF1 gene may be predictive of differences in body composition, primarily in black females.

Longitudinal Sex-Specific Physical Function Trends by Age, Race/Ethnicity, and Weight Status.

BACKGROUND: There is a need to assess longitudinal trends in physical function and to understand the prevalence of physical function status in the older population using objectively measured physical function. Therefore, the primary purpose of this study was to examine longitudinal sex-specific physical function trends and prevalence of physical function status by age, race/ethnicity, and weight status in older adults, aged 65 years and older. METHODS: The present study used longitudinal data from the National Health and Aging Trends Study. Physical function was measured annually from 2011 to 2018 using the Short Physical Performance Battery, and classified as poor (0-6), fair (7-9), or good (10-12). Mixed effect regression and generalized estimating equation models were used to estimate unadjusted trends and annual changes in physical function, adjusting for confounders and accounting for complex sampling. RESULTS: Respondents' physical function declined over time regardless of sex, age, race/ethnicity, and weight status (P < .001). Respondents aged 75 to 84 years (males: ß = -.18; 95% confidence interval (CI) = -.22 to -.13; females: ß = -.23; 95% CI = -.27 to -.20) and 85 years and older (males: ß = -.39; 95% CI = -.47 to -.30; females: ß = -.33; 95% CI = -.39 to -.28) had a greater annual physical function rate of decline than respondents aged 65 to 74 years. Respondents aged 75 years and older also had a greater annual increase in the proportion classified as having poor physical function than respondents aged 65 to 74 years (P < .001), regardless of sex. Compared with non-Hispanic whites, Hispanic females had a lower annual physical function rate of decline (ß = .14; 95% CI = 0.07-0.20), and Hispanic and/or non-Hispanic blacks had slower annual changes in the proportion classified as having good physical function (P < .05). Compared with normal weight males, overweight males had lower annual changes in physical function (P = .003) and proportion of those with poor physical function (P = .004), but no differences between weight status were observed in females. CONCLUSIONS: Physical function declines with age, but temporal changes in physical function and physical function status varied by sex, age, race/ethnicity, and weight status. J Am Geriatr Soc 68:2270-2278, 2020.

Temporal Association between Abdominal Weight Status and Healthy Aging: Findings from the 2011-2018 National Health and Aging Trends Study.

BACKGROUND/OBJECTIVES: The longitudinal effect of abdominal weight status (AWS) defined by waist circumference (WC) on healthy aging has not yet been comprehensively examined. Therefore, the purpose of the present study was to examine the temporal association between WC-defined AWS and a comprehensive assessment for healthy aging. SUBJECTS/METHODS: This study utilized data from 5211 respondents aged 65+ who participated in the National Health and Aging Trends Study from 2011 to 2018. Mixed effects regression models were used to examine the association between baseline AWS and the annual change rate in healthy aging score (HAS) via interaction terms (AWS*round) adjusting for confounding effects. Further multiple mixed models examined the relationship of AWS and HAS over an 8-year period. RESULTS: There were no annual change rate differences in HAS by baseline AWS, regardless of sex. However, males with abdominal obesity were more likely to have a lower HAS than males with normal AWS (ß = -0.20, 95% CI: -0.30, -0.10, p < 0.001) but no difference in HAS was observed between males with overweight and normal AWS. A similar pattern was observed among females. CONCLUSIONS: Study results indicate that AWS was associated with HAS but it did not modify annual HAS change rate over time.

The Relationships between Total Protein Intake, Protein Sources, Physical Activity, and Lean Mass in a Representative Sample of the US Adults.

BACKGROUND: Although dietary protein and physical activity play essential roles in developing and preserving lean mass, studies exploring these relationships are inconsistent, and large-scale studies on sources of protein and lean mass are lacking. Accordingly, the present study examined the relationship between total protein intake, protein sources, physical activity, and lean mass in a representative sample of US adults. METHODS: This cross-sectional study analyzed data from 2011-2016 US National Health and Nutrition Examination Survey and corresponding Food Patterns Equivalents Database (n = 7547). Multiple linear regression models were performed to examine the sex-specific associations between total protein intake, protein sources (Dairy, Total Protein Foods, Seafood, and Plant Proteins), physical activity, and lean mass adjusting for demographics, weight status, and total daily energy intake. RESULTS: Total protein intake was inversely related to lean mass in females only (Lean mass index: ß= -0.84, 95%CI: -1.06--0.62; Appendicular lean mass index: ß= -0.35, 95%CI: -0.48--0.22). However, protein sources and physical activity was positively associated with lean mass in males and/or females (p < 0.05). CONCLUSION: Study results suggest that consuming more protein daily had a detrimental influence on lean mass in females whereas eating high-quality sources of proteins and being physically active are important for lean mass for men and women. However, the importance of specific protein sources appears to differ by sex and warrants further investigation.

Relationships of Physical Activity and Diet Quality with Body Composition and Fat Distribution in US Adults.

OBJECTIVE: This study aimed to investigate the relationships among physical activity (PA), diet quality, body composition, and fat distribution in a representative sample of US adults. METHODS: A cross-sectional analysis was conducted using publicly accessible data from the 2011 to 2016 National Health and Nutrition Examination Survey and the Food Patterns Equivalents Database (n = 7,423). Variables from the data sets were analyzed for this study, including PA, two 24-hour dietary recalls, and dual-energy x-ray absorptiometry outputs. RESULTS: For men, PA and diet quality were inversely associated with the percentage of body fat (ß = -0.0042, 95% CI: -0.0084 to -0.0001; ß = -0.28, 95% CI: -0.42 to -0.14) and fat mass index (ß = -0.0125, 95% CI: -0.0209 to -0.0041; ß = -0.56, 95% CI: -0.81 to -0.32); meeting the PA recommendation and having good diet quality provided an additive effect on body fat. A similar pattern was observed in women. Additionally, diet quality was inversely associated with all fat distribution measures in both sexes, whereas PA was positively associated with lean mass measures in men only. CONCLUSIONS: Increased PA and/or better diet quality were associated with reduced body fat, a healthier fat distribution, and increased lean mass. Further research examining how changes in PA or diet quality influence body composition and fat distribution in adults is warranted.

Effects of strength training on physical function: influence of power, strength, and body composition.

The purpose of this study was to determine (a) the effects of strength training (ST) on physical function and (b) the influence of strength, power, muscle volume (MV), and body composition on physical function. Healthy, inactive adults (n = 50) aged 65 years and older underwent strength, power, total body composition (% fat and fat free mass [FFM]), and physical function testing before and after 22 weeks of ST. Physical function testing consisted of tasks designed to mimic common physical activities of daily living (ADL). To improve internal validity of the assessment of mid-thigh intermuscular fat, subcutaneous fat, and knee extensors MV, a 10-week unilateral ST program using the untrained leg as an internal control preceded 12 weeks of whole-body ST. Strength, power, and FFM increased significantly with ST (all p < 0.05), whereas rapid walk, 5 chair stands, and get up and go time decreased significantly with ST in the overall group (all p < 0.05). Women improved significantly in both walking test times (both p < 0.05) but not in the stair climb test, whereas men improved in the stair climb test (p < 0.05) but not in walking test times. Multiple regression analysis revealed the highest R (0.28) for the change in chair stands time, followed by stair climb and usual walk at 0.27 and 0.21, respectively. ST improves performance in functional tasks important for ADLs. Changes in strength, power, and FFM are predictors of ST-induced improvements in these tasks.

Association of the ACTN3 genotype and physical functioning with age in older adults.

OBJECTIVE: The purpose of this study was to examine the association of the alpha-actinin-3 (ACTN3) R577X polymorphism on muscle function and physical performance in older adults. METHODS: We measured knee extensor torque, midthigh muscle cross-sectional area, muscle quality, short physical performance battery score, and 400-meter walk time at baseline and after 5 years in white older adults aged 70-79 years in the Health, Aging and Body Composition Study cohort (n = 1367). Incident persistent lower extremity limitation (PLL) over 5 years was additionally assessed. We also examined white men in the Osteoporotic Fractures in Men Study, a longitudinal, observational cohort (n = 1152) of men 65 years old or older as a validation cohort for certain phenotypes. RESULTS: There were no significant differences between genotype groups in men or women for adjusted baseline phenotypes. Male X-homozygotes had a significantly greater adjusted 5-year increase in their 400-meter walk time compared to R-homozygotes and heterozygotes (p =.03). In women, X-homozygotes had a approximately 35% greater risk of incident PLL compared to R-homozygotes (hazard ratio = 0.65, 95% confidence interval = 0.44-0.94). There were no other significant associations between any of the phenotypes and ACTN3 genotype with aging in either cohort. CONCLUSIONS: The ACTN3 polymorphism may influence declines in certain measures of physical performance with aging in older white adults, based on longitudinal assessments. However, the influence of the ACTN3 R577X polymorphism does not appear to have a strong effect on skeletal muscle-related phenotypes based on the strength and consistency of the associations and lack of replication with regard to specific phenotypes.

Effects of physical activity on strength and skeletal muscle fat infiltration in older adults: a randomized controlled trial.

Considerable evidence suggests that the loss of strength and muscle mass appear to be inevitable consequences of aging. Moreover, aging is associated with an increase in body fat. This study examined whether increased physical activity could prevent or reverse the losses of strength and skeletal muscle mass as well as the gain in fat in older adults. Eleven men and 31 women completed a randomized trial consisting of either a physical activity (PA; n = 22) or successful aging health educational control (SA; n = 20) group. Isokinetic knee extensor strength and computed tomography-derived midthigh skeletal muscle and adipose tissue cross-sectional areas (CSA) were assessed at baseline and at 12 mo following randomization. Total body weight and muscle CSA decreased in both groups, but these losses were not different between groups. Strength adjusted for muscle mass decreased (-20.1 +/- 9.3%, P < 0.05) in SA. The loss of strength was completely prevented in PA (+2.5 +/- 8.3%). In addition, there was a significant increase (18.4 +/- 6.0%) in muscle fat infiltration in SA, but this gain was nearly completely prevented in PA (2.3 +/- 5.7%). In conclusion, regular physical activity prevents both the age-associated loss of muscle strength and increase in muscle fat infiltration in older adults with moderate functional limitations.

ACE genotype and the muscle hypertrophic and strength responses to strength training.

PURPOSE: Previous studies have linked an insertion/deletion polymorphism in the angiotensin-converting enzyme (ACE) gene with variability in muscle strength responses to strength training (ST), though conclusions have been inconsistent across investigations. Moreover, most previous studies have not investigated the influence of sex on the association of ACE I/D genotype with muscle phenotypes. The purpose of this study was to investigate the association of ACE genotype with muscle phenotypes before and after ST in older men and women. METHODS: Eighty-six inactive men and 139 inactive women, ages 50-85 yr (mean: 62 yr), were studied before and after 10 wk of unilateral knee extensor ST. The one-repetition maximum (1RM) test was used to assess knee extensor muscle strength, and computed tomography was used to measure quadriceps muscle volume (MV). Differences were compared among ACE genotype groups (II vs ID vs DD). RESULTS: Across the entire cohort at baseline, ACE genotype was significantly associated with total lean mass and body weight, with higher values in DD genotype carriers (both P < 0.05). At baseline, DD genotype carriers exhibited significantly greater MV compared with II genotype carriers for both the trained leg (men: 1828 +/- 44 vs 1629 +/- 70; women: 1299 +/- 34 vs 1233 +/- 49; P = 0.02) and untrained leg (men: 1801 +/- 46 vs 1559 +/- 72; women: 1268 +/- 36 vs 1189 +/- 51; P = 0.01), with no significant genotype x sex interaction. No ACE genotype associations were observed for the 1RM or MV adaptations to ST in either men or women. CONCLUSIONS: In the present study, ACE genotype was associated with baseline differences in muscle volume, but it was not associated with the muscle hypertrophic response to ST.

Do sex or race differences influence strength training effects on muscle or fat?

PURPOSE: To examine the influence of sex and race on the effects of strength training (ST) on thigh muscle volume (MV), midthigh subcutaneous fat (SCF), and intermuscular fat (IMF). METHODS: One hundred eighty-one previously inactive healthy Caucasian (N = 117) and African American (N = 54) men (N = 82) and women (N = 99), aged 50-85 yr, underwent about 10 wk of unilateral knee extension ST. Ten subjects were neither Caucasian nor African American and were, therefore, not included in the race analysis. Quadriceps MV and midthigh SCF and IMF cross-sectional area were measured with computed tomography before and after ST. Sex and race comparisons were made with a 2 x 2 (sex by race) analysis of covariance. RESULTS: Training-induced increases in absolute MV were significantly greater (P < 0.001) in men than in women, though both sex groups increased MV significantly with ST (P < 0.001), and the relative (%) increases were similar. There were significant increases in MV within race groups (P < 0.001), but no significant differences between races. There were no significant changes in SCF or IMF, whether sex and racial groups were separated or combined. In addition, there was no sex by race interaction for changes in MV, SCF, or IMF with ST. CONCLUSION: Strength training does not alter subcutaneous or intermuscular fat, regardless of sex or racial differences. Although men exhibit a greater muscle hypertrophic response to strength training than do women, the difference is small. Race does not influence this response.

Estimation of Skeletal Muscle Mass Relative to Adiposity Improves Prediction of Physical Performance and Incident Disability.

Purpose: We assessed the discrimination of lean mass estimates that have been adjusted for adiposity for physical functioning deficits and prediction of incident disability. Methods: Included were 2,846 participants from the Health, Aging and Body Composition Study with available whole-body dual energy absorptiometry measures of appendicular lean mass index (ALMI, kg/m2) and fat mass index (FMI, kg/m2). Age-, sex-, and race-specific Z-Scores and T-Scores were determined by comparison to published reference ranges. ALMI values were adjusted for FMI (ALMIFMI) using a novel published method. Sex-stratified analyses assessed associations between lean mass estimates and the physical performance score, ability to complete a 400-meter walk, grip strength, and incident disability. Dichotomized definitions of low lean for age and sarcopenia were examined and their performance compared to the ALM-to-BMI ratio. Results: Compared to ALMI T-Scores and Z-Scores, the ALMIFMI scores demonstrated stronger associations with physical functioning, and were similarly associated with grip strength. Greater FMI Z-Scores and T-Scores were associated with poor physical functioning and incident disability. Definitions of low lean for age and sarcopenia using ALMIFMI (compared to ALMI) better discriminated those with poor physical functioning and a greater risk of incident disability. The ALM-to-BMI ratio was modestly associated with grip strength and physical performance, but was not associated with completion of the 400-meter walk or incident disability, independent of adiposity and height. Conclusion: Estimation of skeletal muscle mass relative to adiposity improves correlations with physical performance and prediction of incident disability suggesting it is an informative outcome for clinical studies.

Alternative definitions of sarcopenia, lower extremity performance, and functional impairment with aging in older men and women.

OBJECTIVES: To compare two methods for classifying an individual as sarcopenic for predicting decline in physical function in the Health, Aging and Body Composition Study. DESIGN: Observational cohort study with 5 years of follow-up. SETTING: Communities in Memphis, Tennessee, and Pittsburgh, Pennsylvania. PARTICIPANTS: Men and women aged 70 to 79 (N=2,976, 52% women, 41% black). MEASUREMENTS: Appendicular lean mass (aLM) was measured using dual energy x-ray absorptiometry, and participants were classified as sarcopenic first using aLM divided by height squared and then using aLM adjusted for height and body fat mass (residuals). Incidence of persistent lower extremity limitation (PLL) was measured according to self-report, and change in objective lower extremity performance (LEP) measures were observed using the Short Physical Performance Battery. RESULTS: There was a greater risk of incident PLL in women who were sarcopenic using the residuals sarcopenia method than in women who were not sarcopenic (hazard ratio (HR)=1.34, 95% confidence interval (CI)=1.11-1.61) but not in men. Those defined as sarcopenic using the aLM/ht(2) method had lower incident PLL than nonsarcopenic men (HR=0.76, 95% CI=0.60-0.96) and women (HR=0.75, 95% CI=0.60-0.93), but these were no longer significant with adjustment for body fat mass. Using the residuals method, there were significantly poorer LEP scores in sarcopenic men and women at baseline and Year 6 and greater 5-year decline, whereas sarcopenic men defined using the aLM/ht(2) method had lower 5-year decline. Additional adjustment for fat mass attenuated this protective effect. CONCLUSION: These findings suggest that sarcopenia defined using the residuals method, a method that considers height and fat mass together, is better for predicting disability in an individual than the aLM/ht(2) method, because it considers fat as part of the definition.

Alpha-actinin-3 (ACTN3) R577X polymorphism influences knee extensor peak power response to strength training in older men and women.

BACKGROUND: The alpha-actinin-3 (ACTN3) R577X polymorphism has been associated with muscle power performance in cross-sectional studies. METHODS: We examined baseline knee extensor concentric peak power (PP) and PP change with approximately 10 weeks of unilateral knee extensor strength training (ST) using air-powered resistance machines in 71 older men (65 [standard deviation = 8] years) and 86 older women (64 [standard deviation = 9] years). RESULTS: At baseline in women, the XX genotype group had an absolute (same resistance) PP that was higher than the RR (p =.005) and RX genotype groups (p =.02). The women XX group also had a relative (70% of one-repetition maximum [1-RM]) PP that was higher than that in the RR (p =.002) and RX groups (p =.008). No differences in baseline absolute or relative PP were observed between ACTN3 genotype groups in men. In men, absolute PP change with ST in the RR (n = 16) group approached a significantly higher value than in the XX group (n = 9; p =.07). In women, relative PP change with ST in the RR group (n = 16) was higher than in the XX group (n = 17; p =.02). CONCLUSIONS: The results indicate that the ACTN3 R577X polymorphism influences the response of quadriceps muscle power to ST in older adults.