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.

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.

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.

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.

Comparison of energy expenditure to walk or run a mile in adult normal weight and overweight men and women.

We compared the energy expenditure to walk or run a mile in adult normal weight walkers (NWW), overweight walkers (OW), and marathon runners (MR). The sample consisted of 19 NWW, 11 OW, and 20 MR adults. Energy expenditure was measured at preferred walking speed (NWW and OW) and running speed of a recently completed marathon. Body composition was assessed via dual-energy x-ray absorptiometry. Analysis of variance was used to compare groups with the Scheffe's procedure used for post hoc analysis. Multiple regression analysis was used to predict energy expenditure. Results that indicated OW exhibited significantly higher (p < 0.05) mass and fat weight than NWW or MR. Similar values were found between NWW and MR. Absolute energy expenditure to walk or run a mile was similar between groups (NWW 93.9 ± 15.0, OW 98.4 ± 29.9, MR 99.3 ± 10.8 kcal); however, significant differences were noted when energy expenditure was expressed relative to mass (MR > NWW > OW). When energy expenditure was expressed per kilogram of fat-free mass, similar values were found across groups. Multiple regression analysis yielded mass and gender as significant predictors of energy expenditure (R = 0.795, SEE = 10.9 kcal). We suggest that walking is an excellent physical activity for energy expenditure in overweight individuals that are capable of walking without predisposed conditions such as osteoarthritis or cardiovascular risk factors. Moreover, from a practical perspective, our regression equation (kcal = mass (kg) × 0.789 - gender (men = 1, women = 2) × 7.634 + 51.109) allows for the prediction of energy expenditure for a given distance (mile) rather than predicting energy expenditure for a given time (minutes).

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.

Energy expenditure and influence of physiologic factors during marathon running.

This study examined energy expenditure and physiologic determinants for marathon performance in recreational runners. Twenty recreational marathon runners participated (10 males aged 41 +/- 11.3 years, 10 females aged 42.7 +/- 11.7 years). Each subject completed a V(.-)O2max and a 1-hour treadmill run at recent marathon pace, and body composition was indirectly determined via dual energy X-ray absorptiometry. The male runners exhibited higher V(.-)O2max (ml x kg(-1) x min(-1)) values (52.6 +/- 5.5) than their female counterparts (41.9 +/- 6.6), although ventilatory threshold (T-vent) values were similar between groups (males: 76.2 +/- 6.1 % of V(.-)O2max, females: 75.1 +/- 5.1%). The male runners expended more energy (2,792 +/- 235 kcal) for their most recent marathon as calculated from the 1-hour treadmill run at marathon pace than the female runners (2,436 +/- 297 kcal). Body composition parameters correlated moderately to highly (r ranging from 0.50 to 0.87) with marathon run time. Also, V(.-)O2max (r = -0.73) and ventilatory threshold (r = -0.73) moderately correlated with marathon run time. As a group, the participants ran near their ventilatory threshold for their most recent marathon (r = 0.74). These results indicate the influence of body size on marathon run performance. In general, the larger male and female runners ran slower and expended more kilocalories than smaller runners. Regardless of marathon finishing time, the runners maintained a pace near their T-vent, and as T-vent or V(.-)O2max increased, marathon performance time decreased.

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.

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.

Associations of body size and composition with physical activity in adolescent girls.

PURPOSE: To examine whether components of body composition (size, fat mass, and fat-free mass) were related to physical activity. METHODS: A random sample of 60 eligible sixth grade girls at each of 36 schools (six schools per region and six regions in total sample); complete measurements on 1,553 girls. Physical activity was assessed over 6 d in each girl using an accelerometer, and body composition was assessed using a multiple regression equation using body mass index and triceps skinfold. Minutes of moderate-to-vigorous and vigorous physical activity were estimated from accelerometer counts per 30 s above threshold values determined from a previous study. RESULTS: Significant inverse relationships were found for all measures of body size and composition and all physical activity indices. The combination of fat and fat-free mass expressed as a weight and as an index (divided by height squared) along with race, SES, site, and school were most highly associated with physical activity in multiple regression analysis, accounting for 14-15% of the variance in physical activity. Fat mass was more closely related to moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) than fat-free mass with higher standardized regression coefficients. CONCLUSION: We conclude that both fat mass or fat mass index as well as fat-free mass or fat-free mass index make independent contributions in association with physical activity levels. These indices are recommended for future studies.

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.

Comparison of oxygen uptake kinetics and oxygen deficit in severely overweight and normal weight adolescent females.

The purpose of this study was to determine if differences in oxygen uptake kinetics and oxygen deficit existed between normal weight and severely overweight adolescent girls. Subjects included 10 normal weight and 8 severely overweight girls. The participants performed a leg cycling VO2 peak test and a constant load leg cycling test at 80% of the ventilatory threshold (T-vent). In the constant workload test O2 kinetics as indicated by Phase I (VO2 L at 20 sec) and Phase II time constants (t) were determined. Also, the O2 deficit (VO2 L) was measured. As expected significant differences were noted in body composition and VO2 peak relative to mass with normal weight body mass averaging 55.3 ± 7.0 kg, severely overweight 90.5 ± 18.0 kg, % fat normal weight 27.3 ± 3.9%, severely overweight 49.7 ± 4.9% and VO2 peak (ml·kg(-1)·min(-1)) normal weight 32.0 ± 2.7 and severely overweight 22.0 ± 5.3. VO2 peak (l·min(-1)) and T-vent (%VO2 max) were similar between groups. Results revealed similar O2 kinetic responses between groups; phase I kinetics normal weight 0.72 ± 0.15 L; severely overweight 0.75 ± 0.13L, phase II (t) normal weight 41.5 ± 21.3 sec; severely overweight 33.9 ± 22.7 sec. However, the O2 deficit was significantly higher in the severely overweight (0.75 ± 0.15L) when compared to the normal weight group (0.34 ± 0.13L). Correlations ranged from r = -0.15 to 0.51 between VO2 peak (L·min(-1)) or fat weight and phase I, t and O2 deficit. These data generally support previous research concerning the independence of O2 uptake response and body size. Key PointsVO2 (L·min(-1) ) similar between the severely overweight and normal weight female youthPhase I and II O2 kinetic responses similar between severely overweight and normal weight female youthO2 deficit was significantly greater in the severely overweight participants.

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.

Association of swim distance and age with body composition in adult female swimmers.

PURPOSE: The purpose of this investigation was to examine the relationship between average weekly swimming distance and age with body composition in adult female endurance swimmers. METHODS: Thirty-five women, aged 21-73 yr, volunteered to participate. Weekly swimming distance was determined from a self-reported exercise log. Body composition was estimated by dual-energy x-ray absorptiometry (DXA), waist circumference, abdominal sagittal diameter, and skinfold thickness measures. Associations between swimming distance and age with body composition were examined using regression analysis. RESULTS: Swimming distance had shared variances as follows: 23% with percent body fat, 26% with waist circumference, 20% with abdominal sagittal diameter, and 20%, 24%, and 22% with subscapular, suprailiac, and triceps skinfolds, respectively. Abdominal sagittal diameter was the only adiposity measure demonstrating a stronger relationship with age (R2 = 0.29, P = 0.00) than with swimming distance (R2 = 0.20, P = 0.03). Bone mineral content was linearly related to swimming distance and age having a negative association with age (r2 = 0.18, P = 0.01) and a positive one with swimming distance (r2 = 0.12, P = 0.05). In addition, there was a negative linear association observed between swimmer age and bone mineral density (r2 = 0.12, P = 0.05). CONCLUSION: In these female adults, endurance swimming was mildly associated with body adiposity. Age was not associated with body fat mass independently from swimming activity except with that measure reflecting abdominal visceral fat deposits. These data suggest that greater fat mass in female swimmers is more strongly related to lower levels of exercise than to age but that there is an additional influence of age on fat accumulation in the intra-abdominal area of the body.

Effect of obesity status on heart rate peak in female youth.

The purpose of this study was to compare heart rate peak in obese (n = 43) and normal weight (n = 45) female youth. Heart rate (HR) peak was significantly lower (p < or = 0.05) in the obese group as compared to the normal weight group (192.3 +/- 9.3, 203.4 +/- 7.6), and VO2 (L x min(-1)) peak similar between groups (1.77 +/- 0.53, 1.97 +/- 0.60). Bivariate correlations for heart rate peak with body weight, percent fat, and body mass index yielded the following: -0.53, -0.54, and -0.57. These findings agree with the adult data indicating low HR peak in obese individuals. Further research is needed to explore physiologic factors that may lead to reduced HR peak in obese female youth.

Comparison of VO2 Peak during Treadmill and Cycle Ergometry in Severely Overweight Youth.

The purpose of this study was to compare peak cardiorespiratory parameters during treadmill and cycle ergometry in severely overweight youth. Twenty-one participants from the Committed to Kids Pediatric Weight Management program at the Louisiana State University Health Sciences Center volunteered. Participants completed peak treadmill and cycle ergometer tests on separate days. In order to examine reliability, six subjects completed a second treadmill test and seven subjects a second cycle test. Physical characteristics included the following: Age (yrs) 12.5 ± 2.8; Body weight (BW) (kg) 78.5 ± 27.0, Height (m) 1.56 ± 0.13; and % fat 42.8 ± 7.5. No statistical significant differences (p ≤ 0.05) were found between treadmill and cycle peak tests. Treadmill VO2 peak (l·min(-1)) averaged 1.57 ± 0.40 and cycle 1.46 ± 0.30 and VO2 peak relative to BW 21.5 ± 4.1 and 20.3 ± 5.5 for treadmill and cycle ergometry, respectively. Therefore treadmill values were 7.0% and 5.6% higher than cycle values. In normal weight or children and adolescents at risk for overweight, treadmill values typically average from 7 to 12% higher than cycle values. Reliability of VO2 peak as indicated by intraclass correlation coefficients ranged from 0.70 to 0.96 for a single or repeated tests. Intra individual variability averaged 0.5% for VO2 peak (l·min(-1)) during treadmill ergometry and 5.7% for cycle ergometry. Also, standard errors of measurement were low (40 to 90 ml min or 1.0 to 1.7 ml.kg(-1). min(-1)) for the peak treadmill or cycle tests. In summary, our data suggest that both treadmill and cycle ergometry provide reliable methods for determining VO2 peak in overweight youth. Key PointsTreadmill peak VO2 higher than cycle ergometry in severely overweight youth.VO2peak test-retest or single trial reliability high in both treadmill and cycle VO2 peak.Standard errors of measure low for both treadmill and cycle VO2peak.

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.