Comparison of different VO2max scaling models in male and female non-obese and obese adults.

BACKGROUND: The aim of this paper was to identify the most appropriate allometric scaling model for expressing aerobic fitness, determined by maximal oxygen consumption (VO2max), that would allow comparisons across differing body types. METHODS: VO2max and body composition data were collected from untrained non-obese and obese participants (N.=126). Allometric models were created using body mass (BM), fat-free mass (FFM), and leg FFM (LFFM) to determine the goodness-of-fit using the Akaike Information Criterion (AIC). RESULTS: Allometric scaled exponents adjusted for BM, FFM and LFFM were 0.67, 0.68 and 0.55, respectively. VO2max scaled to BM was 22% higher in non-obese individuals. Scaled to LFFM, V VO2max was only 7.5% higher in non-obese individuals as compared to obese individuals. Data showed a positive correlation (r=0.28; P=0.009) between VO2max and BM for non-obese participants and a negative correlation (r=-0.39; P=0.014) for obese participants. AIC values showed the LFFM model as the best fit (AICc = 0 "substantial support) and the AIC differences for FFM and BM were both >10 "no support" for the model (12.1 and 28.2, respectively). CONCLUSIONS: Interpretation of aerobic power and comparisons would be most appropriate when allometrically scaled to the metabolically active tissue (LFFM). Bias is introduced when scaling to BM and comparing individuals of various body compositions.

Prediction and Cross-validation of an Energy Expenditure Equation in Walking or Running in Asian Adults.

The prevalence of obesity is increasing across the world. Knowledge of the actual energy expenditure (EE) of walking and running can lead to a more precise exercise prescription which may contribute to obesity reduction or avoidance. Limited research has focused on EE prediction during walking or running in Asian adults. So, the aims of this study included developing an EE prediction equation and cross-validating the equation for Asian adults. METHODS: A total of 85 Asians participated to test EE through indirect calorimetry. Linear regression analysis was employed for EE prediction, and a dependent t-test and Chow statistical test were used to cross-validate the equation. RESULTS: Predicting EE during walking or running, corrected for one mile, yielded the following equation: EE = 0.933 * (Body Weight) - 4.127 * Gender (M = 1, F = 2) + 44.256 (standard error of estimate, SEE = 12.1 kcal·mile-1). A dependent t-test revealed no significant difference between measured EE (101.4 ± 4.3 kcal) and predicted EE (100.0 ± 2.8 kcal) (p = 0.546). Also, the coefficients for body weight and gender between the development prediction equation and the predicted equation in the cross-validation group were not significantly different (p = 0.365). CONCLUSION: The cross-validation results supported the validity of our predicted equation in Asians. In a practical field setting, exercise professionals could apply this equation for assessing EE during walking or running, corrected for one mile, in normal weight (body fat percentage ≤ 22 for males, ≤ 35 for females) and overweight (body fat percentage > 22 for males, > 35 for females) Asian adults.

Comparison and predicted equation of energy expenditure during walking or running among Caucasians, African Americans and Asians.

Knowledge of measured energy expenditure (EE) during walking and running is important for exercise prescription. Further, research on the EE comparison and EE predicted equation during walking or running among different ethnicities is limited. The purpose of the current study was to compare EE to walk or run 1 mile in Caucasian, African American and Asian adults and to develop a regression equation to predict EE to walk or run 1 mile. Two hundred and twenty-four participants were included (71 Caucasians, 68 African Americans and 85 Asians) with 3 groups (normal weight walking, overweight walking and running). EE was measured via indirect calorimetry. Analysis of variance was used to compare EE across groups. Multiple regression analysis was employed for EE prediction, and the prediction equation was cross-validated. A significant EE difference was found between walking and running among three ethnicities. The prediction equation was: EE â€‹= â€‹0.978 Body Weight - 4.571 Gender (male=1; female=2) â€‹+ â€‹3.524 Ethnicities (Caucasians=1, African Americans=2, Asians=3) â€‹+ â€‹32.447 (standard error of estimate=12.5 â€‹kcal·mile-1). The equation was valid through cross-validation, so it is recommended to apply for calculating EE during walking or running 1 mile among Caucasians, African Americans and Asians.

Influences on Body Size Perceptions Among Black Women in the Mississippi Delta.

PURPOSE: To identify factors that influence Black women's body size perceptions. DESIGN: Interviews (cognitive mapping exercise) with 25 women; focus group with 7 additional women. SETTING: Mississippi Delta. PARTICIPANTS: Thirty-two black women. MEASURES: Influences on body size perceptions, body mass index, and body satisfaction. ANALYSIS: Interviewee maps were combined and condensed, using matrix addition and qualitative aggregation, to create a social map. The social map was presented to a focus group. A paired sample t test and descriptive statistics were run to assess weight perception accuracy and body satisfaction. RESULTS: The initial social map contained 27 variables. Male preferences (87.5%) and appearance (64%) were believed by most participants to influence perceptions of body size. The focus group identified lack of encouragement, stress, and substance use as factors worth adding to the map. A statistically significant proportion of interviewees possessed an inaccurate weight perception, t(24) = 2.741, P < .05. Furthermore, 76% were dissatisfied with their current weight status and 80% desired a healthy body size. CONCLUSION: These findings provide practitioners with leverage points, beyond diet and physical activity, that may improve the efficacy of weight reduction interventions among black women. Considering the paucity of research regarding influences on body size perceptions, this study also provides researchers with participant-defined variables worthy of further examination.

A Randomized Study of Exercise and Fitness Trackers in Obese Patients After Total Knee Arthroplasty.

Functional limitations persist in obese patients after total knee arthroplasty (TKA). This study assessed the effect of an exercise program (EP) and fitness trackers (FT) in obese patients with TKA. Sixty patients 1 year after orthopedic surgery were recruited and received a 16-week tailored EP; half were randomized to receive an FT. FT had no measurable effect compared with EP alone. EP improved knee range of motion, strength, and quality-of-life scores. This study provides preliminary evidence that a 16-week EP in obese individuals 1 year post TKA is feasible and effective in improving function and quality of life.

The Bigger the Hand, the Bigger the Difference? Implications for Testing Strength With 2 Popular Handgrip Dynamometers.

CONTEXT: Studies developed the frail elderly handgrip strength (HGS) diagnostic criteria using multiple types of handgrip dynamometers. If different handgrip dynamometers report different values, then this would have the potential to misclassify people into the wrong diagnostic category. OBJECTIVE: To examine the characteristics of HGS measured by 2 standard handgrip dynamometers and to investigate the influence of hand size on HGS. SETTING: University research laboratory. PARTICIPANTS: A total of 87 young and middle-aged adults between the ages of 20 and 60 years participated in this study. MAIN OUTCOME MEASURES: Standard methods of HGS measurements were used for hydraulic and Smedley spring-type dynamometers, although the participants were instructed to maintain an upright standing position in both tests. RESULTS: Test-retest reliability of hydraulic and Smedley dynamometers provided comparable results to that observed with previous studies. However, the difference in HGS between the 2 dynamometers (Hydraulic-Smedley difference) was positively associated (r = .670, P < .001) with the mean of the 2 dynamometers. The participants who had relatively low HGS (at least <35 kg) produced similar HGS values when the 2 dynamometers were compared, whereas persons who had relatively higher HGS (at least >45 kg) produced greater strength values with the hydraulic compared with the Smedley. The hand and palm lengths were weakly correlated (r = .349 and r = .358, respectively, both Ps < .001) with the difference in HGS between the 2 dynamometers. CONCLUSIONS: Test-retest reliability of hydraulic and Smedley dynamometers provides comparable results to previous studies. However, the difference in HGS between the 2 dynamometers was positively associated with the mean of the 2 dynamometers. This Hydraulic-Smedley difference would not affect persons who have relatively low HGS (at least <35 kg), while when HGS is relatively high, the comparison between dynamometers should be done with caution.

Prediction and Validation of DXA-Derived Appendicular Fat-Free Adipose Tissue by a Single Ultrasound Image of the Forearm in Japanese Older Adults.

OBJECTIVES: To develop regression-based equations for estimating dual-energy x-ray absorptiometry (DXA) derived appendicular fat-free adipose tissue (FFAT) using a single ultrasound image in the forearm, and to investigate the validity of those equations to calculate FFAT-free appendicular lean mass (aLM-minus-FFATappendicular ) in 311 Japanese adults aged 60 to 79 years. METHODS: Subjects were randomly separated into two groups: 215 in the model-development group (91 men and 124 women) and 96 in the cross-validation group (42 men and 54 women). Appendicular fat mass and aLM were measured by the DXA, and subcutaneous adipose tissue (AT-forearm) and muscle (MT-ulna) thicknesses were measured by ultrasound. Appendicular FFAT was calculated based on the results of a previous study (appendicular FFAT = appendicular fat mass/0.85 x 0.15). The aLM was estimated from MT-ulna using a previously published equation (aLM = 4.89 x MT-ulna x body height - 9.15). Stepwise linear regression analysis was used to determine predictive models for DXA-derived appendicular FFAT from AT-forearm, sex, age, and anthropometrical variables. The best ultrasound prediction equation for estimation of appendicular FFAT was developed and then cross-validated in a subsample of older adults. RESULTS: There was no significant difference between the DXA-derived and ultrasound-predicted aLM-minus-FFATappendicular . A strong correlation was observed between the DXA-derived and ultrasound-predicted aLM-minus-FFATappendicular (r = 0.935, P < .001). Bland-Altman analysis did not indicate a bias in the prediction of the aLM-minus-FFATappendicular for the validation group. CONCLUSIONS: Our results indicated that a single ultrasound forearm measurement can be used to accurately estimate DXA-derived aLM-minus-FFATappendicular in Japanese older adults, which may be advantageous for community-based physical examinations.

A Prospective Study Comparing Distance-based vs. Time-based Exercise Prescriptions of Walking and Running in Previously Sedentary Overweight Adults.

Prior work has reported that the declines observed in body mass index (BMI) and circumference measurements in their cross-sectional data were twice as large when calculated from distance energy expenditure estimations compared to energy expenditure estimations based on time and intensity. The primary purpose of this study was to compare walking/running for distance to walking/running for time as part of an exercise intervention. This study followed a between-subjects, repeated measures design. Fifteen overweight, but otherwise healthy participants completed the study. The time-based group walked/ran for self-reported time while the distance-based group walked/ran for self-reported distance. A mixed-factor repeated-measures ANOVA was used to compare all dependent variables both within-subjects and between-subjects. Weekly adherence rates to the exercise program did not exhibit a significant difference (p > 0.05). Significant interactions were shown for mean body mass loss between groups as well as mean blood glucose level (p < 0.05). Distance-based group exhibited a decline in body mass and blood glucose while the time-based group exhibited an increase in both variables. To the best of the authors' knowledge, the present study is the first to directly compare a distance-based vs. a time-based exercise program for walking and running for improvement of risk factors of cardiovascular disease. The results of this study would suggest that a distance-based exercise prescription of walking or running should provide a clinician or researcher with a closer estimation of overall accumulated exercise and resultant weight loss.

Physical Function and Physical Activity in Obese Adults After Total Knee Arthroplasty.

Obese patients are more likely to have osteoarthritis and total knee arthroplasty (TKA). This investigation sought to evaluate physical function, activity level, and quality of life (QOL). Obese participants near 1-year postsurgical follow-up appointment were recruited. Evaluation included QOL and activity questionnaire, medical histories, anthropometrics, strength, and aerobic capacity. Sixty participants completed assessments. Obese TKA patients have physical performance limitations and low physical activity levels 1 year after surgery and completion of postoperative rehabilitation.

Expression of VO2peak in Children and Youth, with Special Reference to Allometric Scaling.

The aim of this review was to highlight research that has focused on examining expressions of peak oxygen uptake (VO2peak) in children and youth, with special reference to allometric scaling. VO2peak is considered the highest VO2 during an increasing workload treadmill or bicycle ergometer test until volitional termination. We have reviewed scholarly works identified from PubMed, One Search, EBSCOhost and Google Scholar that examined VO2peak in absolute units (L·min(-1)), relative units [body mass, fat-free mass (FFM)], and allometric expressions [mass, height, lean body mass (LBM) or LBM of the legs raised to a power function] through July 2015. Often, the objective of measuring VO2peak is to evaluate cardiorespiratory function and fitness level. Since body size (body mass and height) frequently vary greatly in children and youth, expressing VO2peak in dimensionless units is often inappropriate for comparative or explanatory purposes. Consequently, expressing VO2peak in allometric units has gained increased research attention over the past 2 decades. In our review, scaling mass was the most frequent variable employed, with coefficients ranging from approximately 0.30 to over 1.0. The wide variance is probably due to several factors, including mass, height, LBM, sex, age, physical training, and small sample size. In summary, we recommend that since skeletal muscle is paramount for human locomotion, an allometric expression of VO2peak relative to LBM is the best expression of VO2peak in children and youth.

Validity of ultrasound prediction equations for total and regional muscularity in middle-aged and older men and women.

To test the validity of published equations, 79 Caucasian adults (40 men and 39 women) aged 50-78 y had muscle thickness (MT) measured by ultrasound at nine sites of the body. Fat-free mass (FFM), lean soft tissue mass (LM) and total muscle mass (TMM) were estimated from MT using equations previously published in the literature. Appendicular LM (aLM) was estimated using dual-energy X-ray absorptiometry (DXA) and this method served as the reference criterion. There were strong correlations (range r = 0.85-0.94) between DXA-derived aLM and estimated FFM, leg LM or TMM. Total error between DXA-derived aLM and TMM (∼2 kg) was lower compared with the three other selected equations (6-10 kg). A Bland-Altman plot revealed that there was no systematic bias between aLM and TMM; however, the other three equations included systematic error. Our results suggest that an ultrasound equation for TMM is appropriate and useful for evaluating skeletal muscle mass in the body.

Improving physical activity in daycare interventions.

BACKGROUND: The aim of the study was to objectively determine whether the Nutrition and Physical Activity Self-Assessment for Child Care (NAP SACC) program improved physical activity levels during the school day. METHODS: The study compared the physical activity levels of subjects from 26 daycare centers, randomized into treatment (N=13) and control (N=13) groups. The subjects were 3 to 5 year olds (N=209, 104 males and 105 females; age [years]=3.85±0.8 [mean±standard deviation]), and accelerometry was used to determine the subjects' physical activity levels. Accelerometers were attached to each subject for 2 days before and immediately after a 6-month intervention. Height, mass, and waist were also measured. RESULTS: Regression analyses indicated that the treatment group demonstrated significant increases in moderate and vigorous physical activity, as compared to the control group (F(1, 207)=6.3, p<0.05, Cohen's d=0.30; F(1, 207)=4.7, p<0.05, Cohen's d=0.25, respectively). The treatment group also showed significant increases in total physical activity (F(1, 218)=12.4; p<0.05) from pre- to post-test with significant increases in moderate and vigorous intensity physical activity (F(1, 218)=18.6, p<0.05; F(1, 218)=23.3, p<0.05, respectively). Regression analyses revealed significant increases in height for both groups from pre- to post-tests, but no differences were noted between groups. CONCLUSIONS: Implementation of the NAP SACC program in treatment daycare facilities resulted in significant increases in objectively measured physical activity levels, compared to the control group, demonstrating physical activity improvement in the treatment daycare centers.

Skeletal muscle mass, bone mineral density, and walking performance in masters cyclists.

Exercise mode and intensity/duration are important factors for influencing muscle morphology and function as well as bone. However, it is unknown whether masters cyclists who undergo regular moderate- to high-intensity exercise maintain lower-body skeletal muscle mass (SM) and function and bone health when compared with young adults. The purpose of this study was to compare SM, areal bone mineral density (aBMD), and gait performance between masters cyclists and young adults. Fourteen male masters cyclists (aged 53-71 years) and 13 moderately active young men (aged 20-30 years, exercising less than twice a week) volunteered. The masters cyclists were all training actively (four to five times per week, ∼200 miles per week) for on average the last 17 years (range 7-38 years). Thigh SM was estimated from an ultrasound-derived prediction equation using muscle thickness (MTH). Appendicular lean mass (aLM) and aBMD were also estimated using dual-energy X-ray absorptiometry. There were no significant differences (p<0.05) in thigh SM, anterior and posterior thigh MTH ratio, or aLM between masters cyclists and young men. Maximum straight and zigzag walking times were also similar between groups. Lumbar spine (L1-L4) aBMD was not different between groups, but femoral neck aBMD was lower (p<0.05) in the cyclists than in the young men. Our results suggest that appendicular as well as site-specific thigh muscle loss with aging were not observed in masters cyclists. This maintenance of muscle mass in masters cyclists may preserve walking performance to similar levels as moderately active young adults. However, long-term cycling does not preserve femoral neck aBMD.

Morphological and functional relationships with ultrasound measured muscle thickness of the upper extremity and trunk.

Unless a subject's muscle is relatively small, a single image from a standard ultrasound can only measure muscle thickness (MT). Thus, it is important to know whether MT is related to morphological and functional characteristics of individual muscles of the extremity and trunk. In this review, we summarize previously published articles in the upper extremity and trunk demonstrating the relationships between ultrasound-measured MT and muscle morphology (cross-sectional area, CSA and muscle volume, MV) and muscular or respiratory function. The linear relationship between MT and muscle CSA or MV has been observed in biceps brachii, triceps brachii, pectoralis major, psoas major, and supraspinatus muscles. Previous studies suggest that MT in the upper arm and trunk may reflect muscle CSA and MV for the individual muscles. Unfortunately, few studies exist regarding the functional relationship with ultrasound MT in the upper extremity and trunk. Future research is needed to investigate these findings further.

Association between site-specific muscle loss of lower body and one-leg standing balance in active women: the HIREGASAKI study.

AIM: To test the hypothesis that static balance is associated with site-specific loss of muscle mass in older adults. METHODS: A total of 57 active women aged 52-83 years had their muscle thickness (MTH) measured by ultrasound at four sites on the anterior and posterior aspects of their upper- and lower-leg. MTH ratios were calculated to assess the site-specific muscle loss. One-leg standing balance with eyes open and maximum isometric knee extension/flexion strength were measured. Daytime physical activity was also measured. The participants were separated into three groups based on achieved timed one-leg balance test: less than 60 s (n = 19, G1), 60-120 s (n = 12, G2) and over 120 s (n = 26, G3). RESULTS: Age was inversely correlated to the upper-leg (A50 : P70) MTH ratios (r = -0.389, P < 0.001), but not lower-leg ratio (r = 0.047), thus site-specific muscle loss was observed in the upper-leg. Total muscle mass was similar among the groups. A50 : P70 MTH ratio and absolute and relative knee flexion strength were lower in G1 than in G3. Step counts and durations of moderate and vigorous exercise were lower in G1 and G2 than in G3. There were significant correlations between one-leg balance and A50 : P70 MTH ratio (r = 0.271, P < 0.05) and physical activity level (r = 0.357-0.481, P < 0.01). After adjusting for step count, one-leg balance was only correlated significantly with duration of vigorous exercise (r = 0.319, P < 0.05). CONCLUSION: Higher physical activity could have more impact on balance regulation, as the influence of site-specific muscle loss was weak in active women.

Prevalence of site-specific thigh sarcopenia in Japanese men and women.

The purpose of this study was to compare the prevalence of severe sarcopenia detected by total skeletal muscle mass (SM) index and of site-specific thigh sarcopenia for differing age groups in men and women. Japanese nonobese men and women aged 20 to 85 (n = 1,994, 55 % women) had muscle thickness (MTH) measured by ultrasound at six sites on the anterior and posterior aspects of the body. SM was estimated from ultrasound-derived prediction equations. Site-specific thigh sarcopenia was calculated using ultrasound-measured MTH at the anterior and posterior aspects of the thigh (MTH ratio, anterior 50 %/posterior 50 % thigh MTH (A50/P50 MTH)). Sarcopenia was defined as a SM index (SM divided by height(2)) of >2 standard deviations (SD) below the mean for young adults. Site-specific thigh sarcopenia was defined as a ratio of A50/P50 MTH of >2 SD below the mean for young adults. Age was inversely correlated to SM index and A50/P50 MTH in men (r = -0.480 and r = -0.522) and women (r = -0.243 and r = -0.516). The prevalence rate of sarcopenia was less than 3 % for women under the age of 60, 7 % for ages 60-69, and 24 % for ages 70-80. In men, the prevalence rate of sarcopenia was less than 7 % under the age of 50, 18 % for ages 50-59, 33 % for ages 60-69, and 47 % for ages 70-85. Compared to the sarcopenia estimated by SM index, there was a higher prevalence of site-specific thigh sarcopenia observed in both sexes. These results suggest that site-specific thigh sarcopenia appears before it is able to be detected at the whole body level.

Measured versus self-reported physical function in adult survivors of childhood cancer.

PURPOSE: Childhood cancer survivors (CCS) experience late effects that interfere with physical function. Limitations in physical function can affect CCS abilities to actively participate in daily activities. The purpose of this investigation was to evaluate the concordance between self-reported physical performance and clinically evaluated physical performance among adult CCS. METHODS: CCS 18 yr or older and 10 yr or older from diagnosis who are participants in the St. Jude Lifetime cohort study responded to the physical function section of the Medical Outcome Survey Short Form (SF-36). Measured physical performance was evaluated using the Physical Performance Test and the 6-Minute Walk Test. RESULTS: Individuals (N = 1778, 50.8% female) with a median time since diagnosis of 24.9 yr (range = 10.9-48.2) and a median age of 32.4 yr (range = 19.1-48.2) completed testing. Limitations in physical performance were self-reported by 14.1% of participants. The accuracy of self-report physical performance was 0.87 when the SF-36 was compared with the 6-Minute Walk Test or the Physical Performance Test. Reporting inaccuracies most often involved reporting a physical performance limitation. Poor accuracy was associated with previous diagnosis of a bone or CNS tumor, lymphoma, older age, and large body size. CONCLUSIONS: These results suggest that self-report, using the physical performance subscale of the SF-36, correctly identifies CCS who do not have physical performance limitations. In contrast, this same measure is less able to identify individuals who have performance limitations.

Increased plasma levels of soluble vascular endothelial growth factor receptor 1 (sFlt-1) in women by moderate exercise and increased plasma levels of vascular endothelial growth factor in overweight/obese women.

The incidence of breast cancer is increasing worldwide, and this seems to be related to an increase in lifestyle risk factors, including physical inactivity and overweight/obesity. We have reported previously that exercise induced a circulating angiostatic phenotype characterized by increased soluble fms-like tyrosine kinase-1 (sFlt-1) and endostatin and decreased unbound vascular endothelial growth factor (VEGF) in men. However, there are no data on women. The present study determines the following: (a) whether moderate exercise increased sFlt-1 and endostatin and decreased unbound VEGF in the circulation of adult female volunteers and (b) whether overweight/obese women have a higher plasma level of unbound VEGF than lean women. A total of 72 African American and White adult women volunteers ranging in age from 18 to 44 years were enrolled in the exercise study. All the participants walked on a treadmill for 30 min at a moderate intensity (55-59% heart rate reserve), and oxygen consumption (VO(2)) was quantified utilizing a metabolic cart. We obtained blood samples before and immediately after exercise from 63 participants. ELISA assays showed that the plasma levels of sFlt-1 were 67.8±3.7 pg/ml immediately after exercise (30 min), significantly higher than the basal levels, 54.5±3.3 pg/ml, before exercise (P<0.01; n=63). There was no significant difference in the % increase in the sFlt-1 levels after exercise between African American and White (P=0.533) women or between lean and overweight/obese women (P=0.892). There was no significant difference in the plasma levels of unbound VEGF (35.28±5.47 vs. 35.23±4.96 pg/ml; P=0.99) or endostatin (111.12±5.48 vs. 115.45±7.15 ng/ml; P=0.63) before and after exercise. The basal plasma levels of unbound VEGF in overweight/obese women were 52.26±9.6 pg/ml, significantly higher than the basal levels of unbound VEGF in lean women, 27.34±4.99 pg/ml (P<0.05). The results support our hypothesis that exercise-induced plasma levels of sFlt-1 could be an important clinical biomarker to explore the mechanisms of exercise training in reducing the progression of breast cancer and that VEGF is an important biomarker in obesity and obesity-related cancer progression.

Lower body site-specific sarcopenia and accelerometer-determined moderate and vigorous physical activity: the HIREGASAKI study.

BACKGROUND AND AIMS: It is unknown if the site-specific muscle loss of ageing muscle is associated with accelerometer-determined daily step count and/or intensity of physical activity. The purpose of this study was to examine the relationships between accelerometer- determined physical activity and lower body muscle size in women. METHODS: Forty-eight women aged 52 to 76 years had their muscle thickness (MTH) measured by B-mode ultrasound at seven sites on the anterior and posterior aspects of their upper- and lower-leg. Daytime physical activity was measured using an accelerometer on 30 consecutive days and the total duration of each level of exercise intensity (light-PA, moderate-PA and vigorous-PA), average step count, and physical activity-related energy expenditure were calculated. RESULTS: Age was inversely correlated with anterior 30% upper-leg MTH (r=-0.296, p<0.05), but not with other measured MTH sites. Light-PA was not significantly (p>0.05) correlated with measured lower body MTH. However, moderate-PA was correlated (p<0.05) with lower-leg MTH, while vigorous-PA was correlated (p<0.05) with lower-leg and anterior 30% upper- leg MTH. Following adjustment for confounding factors, the anterior and posterior lower-leg MTH was positively correlated (p<0.05) with duration of moderate- PA and vigorous-PA, as well as average step count. CONCLUSIONS: Thus daily moderate and vigorous physical activity was associated with higher muscle mass in the lower leg, but not in the upper-leg muscle, suggesting that the site-specific upper-leg muscle loss may not be prevented or attenuated by daily physical activity.

Relationship between site-specific loss of thigh muscle and gait performance in women: the HIREGASAKI study.

Sarcopenia is observed as a site-specific loss of skeletal muscle mass, however, it is unknown whether the site-specific sarcopenia is associated with development of physical disability. The purpose of this study was to examine the relationship between age-related thigh muscle loss and gait performance. Fifty-three women aged 52-83 years had their thigh muscle thickness (MTH) measured by ultrasound at five sites on the anterior (30%, 50%, and 70% of thigh length) and posterior (50% and 70% of thigh length) aspects of their thigh. Maximum and normal walking speeds, zig-zag walking time, and maximal voluntary isometric knee extension and flexion strength were measured. Age was inversely correlated to the anterior and posterior MTH ratio (e.g., anterior 50%:posterior 70% MTH ratio [r=-0.426, p=0.002]), thus the site-specific muscle loss of the thigh was observed in the present sample. There were no significant correlations between the anterior/posterior MTH ratio and maximum and normal walking speeds. However, the ratios of anterior 50%:posterior 70% MTH (r=-0.430) and anterior 30%:posterior 70% MTH (r=-0.444) were correlated (p=0.001) to zig-zag walking test. After adjusting for age, height and weight, the anterior 30%:posterior 70% MTH (r=-0.292, p=0.040) was inversely correlated to zig-zag walking performance. Isometric knee extension strength was also inversely correlated to zig-zag walking. Our results suggest that an age-related loss of adductor/quadriceps muscles may be associated with a decrease in a relatively difficult task performance such as zig-zag walking.