Reliability and Validity of Muscle Size and Quality Analysis Techniques.

OBJECTIVE: This study investigated reliability and validity of muscle cross-sectional area and echo intensity using an automatic image analysis program. METHODS: Twenty-two participants completed two data collection trials consisting of ultrasound imaging of the vastus lateralis (VL) at 10 and 12 MHz. Images were analyzed manually and with Deep Anatomical Cross-Sectional Area (DeepACSA). Reliability statistics (i.e., intraclass correlation coefficient [ICC] model 2,1, standard error of measure expressed as a percentage of the mean [SEM%], minimal differences [MD] values needed to be considered real) and validity statistics (i.e., constant error [CE], total error [TE], standard error of the estimate [SEE]) were calculated. RESULTS: Automatic analyses of ACSA and EI demonstrated good reliability (10 MHz: ICC2,1 = 0.83 - 0.90; 12 MHz: ICC2,1 = 0.87-0.88), while manual analyses demonstrated moderate to excellent reliability (10 MHz: ICC2,1 = 0.82-0.99; 12 MHz: ICC2,1 = 0.73-0.99). Automatic analyses of ACSA presented greater error at 10 (CE = -0.76 cm2, TE = 4.94 cm2, SEE = 3.65 cm2) than 12 MHz (CE = 0.17 cm2, TE = 3.44 cm2, SEE = 3.11 cm2). Analyses of EI presented greater error at 10 (CE = 3.35 a.u., TE = 2.70 a.u., SEE = 2.58 a.u.) than at 12 MHz (CE = 3.21 a.u., TE = 2.61 a.u., SEE = 2.34 a.u.). CONCLUSION: The results suggest the DeepACSA program may be less reliable compared to manual analysis for VL ACSA but displayed similar reliability for EI. In addition, the results demonstrated the automatic program had low error for 10 and 12 MHz.

Effects of Hormonal Contraception and the Menstrual Cycle on Fatigability and Recovery From an Anaerobic Exercise Test.

ABSTRACT: Cabre, HE, Ladan, AN, Moore, SR, Joniak, KE, Blue, MNM, Pietrosimone, BG, Hackney, AC, and Smith-Ryan, AE. Effects of hormonal contraception and the menstrual cycle on fatigability and recovery from an anaerobic exercise test. J Strength Cond Res XX(X): 000-000, 2024-This study sought to evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with a eumenorrheic (EUM) cycle, on fatigability and recovery between hormone the phases. Peak power (PP), average power (AP), fatigue index (FI), blood lactate, vessel diameter, and blood flow (BF) were measured from a repeated sprint cycle test (10 × 6 seconds) in 60, healthy, active women (mean ± SD; age: 26.5 ± 7.0 years, BMI: 22.5 ± 3.7 kg·m-2) who used monophasic OC (≥6 months; n = 21), had a H-IUD (≥6 months; n = 20), or had regular naturally occurring menstrual cycle (≥3 months) or had a nonhormonal IUD (EUM; n = 19). Subjects were randomly assigned to begin in either the low-hormone phase (LHP) or high-hormone phase (HHP) and were tested once in each phase. Separate univariate analyses of covariances assessed the change from HHP to LHP between the groups, covaried for progesterone, with significance set at p ≤ 0.05. All groups demonstrated similar changes in PP, AP, FI, blood lactate, vessel diameter, and BF between the phases (p > 0.05). Although not significant, AP was higher in LHP for OC (Δ -248.2 ± 1,301.4 W) and EUM (Δ -19.5 ± 977.7 W) and higher in HHP for H-IUD (Δ 369.3 ± 1,123.0 W). Oral contraceptive group exhibited a higher FI (Δ 2.0%) and reduced blood lactate clearance (Δ 2.5%) in HHP. In recreationally active women, hormonal contraception and hormone phases may minimally impact fatigue and recovery. Individual elite female athletes may benefit from understanding hormonal contraception type as performance and recovery may slightly vary across the cycle.

Ultrasound-based measurement of central adiposity: Key considerations and guidelines.

Central adiposity, which is visceral and subcutaneous adiposity in the abdominal region, is a known risk factor for developing chronic cardiometabolic diseases. Central adiposity can be measured relatively inexpensively using ultrasound. Ultrasound has been shown to be precise and reliable, with measurement accuracy comparable to computed tomography and magnetic resonance. Despite the advantages conferred by ultrasound, widespread adoption has been hindered by lack of reliable standard operating procedures. To consolidate the literature and bring clarity to the use of ultrasound-derived measures of central adiposity, this review outlines (i) the [patho]physiological importance of central adiposity to cardiometabolic disease risk; (ii) an overview of the history and main technical aspects of ultrasound methodology; (iii) key measurement considerations, including transducer selection, subject preparation, image acquisition, image analysis, and operator training; and (iv) guidelines for standardized ultrasound protocols for measuring central adiposity.

Validity of total body water measured by multi-frequency bioelectrical impedance devices in a multi-ethnic sample.

BACKGROUND & AIMS: Total body water (TBW) is the largest component of fat free mass and therefore is commonly used in multi-compartment body composition models and as a stand-alone method to assess body composition. Previous literature has not validated bioelectrical impedance spectroscopy device estimates of TBW in racial and ethnic minority populations; previous studies have focused on bioelectrical impedance analysis devices that rely on proprietary algorithms and participant characteristics for accuracy. The purpose of this study was to assess the validity of two bioelectrical impedance spectroscopy devices for measures of TBW compared to a deuterium dilution criterion in a multi-ethnic sample. METHODS: 109 individuals (55% female, Age: 26.6 ± 6.9 yrs, BMI: 25.3 ± 4.0 kg/m2) identifying as Asian, African American/Black, Caucasian/White, Hispanic, and Multi-racial were enrolled. After a 12 h fast, participants provided a saliva sample for the criterion baseline TBW measure and completed two bioelectrical impedance device (BIS, IB) measurements of TBW. Participants then ingested deuterium oxide (D2O). After an equilibration period, participants provided a second saliva sample for analysis of TBW. RESULTS: For the total multi-ethnic sample, BIS estimates demonstrated good to fairly good agreement (Total error [TE] = 2.56 L, R2 = 0.951) and IB estimates were excellent to very good (TE = 1.95 L, R2 = 0.975). Validity results did not vary meaningfully between race and ethnicity. CONCLUSIONS: The results suggest the BIS and IB devices evaluated can produce valid TBW estimates compared to D2O in a multi-ethnic sample. TBW estimates from the IB may have better agreement with D2O compared to the BIS when using the default settings.

Characterization and prevalence of obesity among normal weight college students.

Normal weight obesity (NWO) describes individuals who have a normal weight body mass index (BMI), but have an unhealthy amount of body fat. Based on the life-long habits that develop during college, exploring NWO among a college-aged population may be essential in identifying and preventing obesity that develops in early adulthood. This study aimed to characterize NWO among young adults with normal weight BMI. 94 college students (Mean ± SD: Age: 19.6 ± 1.5 yrs; BMI: 21.9 ± 1.8 kg/m2) enrolled during the Fall semester (Aug-Oct) were assessed for body composition by dual energy X-ray absorptiometry to determine body fat percentage, fat mass, lean mass and trunk fat; lifestyle habits were characterized from validated questionnaires. Mean arterial pressure and metabolic biomarkers [total cholesterol, high density lipoproteins, non-high density lipoproteins, and glucose] were evaluated for cardiometabolic health. NWO was defined using data from the National Health and Nutrition Examination Survey (NHANES) for body fat percentage. Data was analyzed by group (NWO vs NWL) and sex. with independent t-tests to investigate continuous data, and chi-square test of independence for categorical data. Rates of NWO for the total sample were 13.8%. Males (n=30) had a higher rate of NWO (26.7%) compared to females (n=64; 7.8%). NWO individuals had higher fat mass (p=0.024), trunk fat (p<0.001), and larger waist to hip ratio (p<0.001) than normal weight lean. NWO also engaged in less vigorous physical activity (p=0.043). The occurrence of NWO among otherwise healthy college students is evident. Identification of these individuals may be an effective component for obesity prevention and treatment. Determining feasible methods to measure body fat in this population is essential, as BMI may mask obesity in a young adult population.

Effects of Essential Amino Acids on High-Intensity Interval Training Performance, Fatigue Outcomes, and Workload Progression.

OBJECTIVE: To explore the effects of essential amino acid (EAA) supplementation on high-intensity interval training (HIIT) fatigue, perceived exertion, and training progression in overweight and obese adults. A secondary aim was to explore potential sex-differences on these outcomes. METHODS: Thirty-seven untrained adults (51% female; 36.2 ± 5.9 yrs; 35.5 ± 6.7% body fat) completed eight weeks of HIIT, 2d/wk on a cycle ergometer, either with EAA supplementation (HIIT + EAA; 3.6 g of EAA twice daily, 30 minutes pre and post HIIT) or without supplementation (HIIT). Heart rate (HR) and ratings of perceived exertion (RPE) were recorded throughout each session as indices of within training fatigue. Time to exhaustion (TTE) was recorded for the final interval of each session. Workload progression was determined by change in watts. Differences between groups (with and without EAA) were evaluated at 1wk, 4wks, and 8wks by repeated measure ANOVAs (α = 0.05). RESULTS: There were no differences in TTE (p = 0.983) or workload progression (p = 0.655) with EAA supplementation at any time point. HR and RPE within HIIT sessions were not significantly different with EAA supplementation at any time point (p > 0.05). Results were similar when evaluating males and females separately, but in females, RPE was significantly lower with EAA supplementation at 4wks (Δ: 1.1-2.2; p = 0.016). CONCLUSION: EAA supplementation did not extend TTE during exercise or enhance workload progression across eight weeks of HIIT in untrained, overweight and obese adults. However, EAA consumed 30 minutes before exercise may reduce perceived exertion during the first four weeks of training in women, which may have implications for overall exercise enjoyment and long-term adherence.

Reliability and accuracy of ultrasound image analyses completed manually versus an automated tool.

Analysis of Brightness-mode ultrasound-captured fascicle angle (FA) and fascicle length (FL) can be completed manually with computer-based programs or by automated programs. Insufficient data exists regarding reliability and accuracy of automated tools. Therefore, the purpose of this study was to determine the test-retest reliability of automatic and manual ultrasound analyses, while determining accuracy of the automatic tool against the manual equivalent. Twenty-three participants (mean ± SD; age = 24 ± 4 years; height = 172.2 ± 10.5 cm; body mass = 73.1 ± 16.1 kg) completed one laboratory visit consisting of two trials where vastus lateralis muscle architecture was assessed with ultrasound. Images were taken at both lower (10 MHz) and higher frequency (12 MHz). Images were analyzed manually in an open-source imaging program and automatically using a separate open-source macro function. Test-retest reliability statistics were calculated for automatic and manual analyses. Accuracy was determined with validity statistics and were calculated for automatic analyses. The results show that manual ultrasound analyses for FA and FL for both lower and higher frequency displayed good reliability (ICC2,1 = 0.75-0.86). However, automatic ultrasound analyses for FA and FL revealed moderate reliability (ICC2,1 = 0.61-0.72) for the lower frequency images and poor reliability (ICC2,1 = 0.16-0.27) for higher frequency images. When assessed against manual techniques, automatic analyses presented greater total error (TE) and standard error of the estimate (SEE) for FA at lower frequency (constant error (CE) = -3.91°, TE = 5.57°, SEE = 3.45°) than higher (CE = -2.78°, TE = -4.54°, SEE = 2.45°). For FL, the higher frequency error (CE = 0.92 cm, TE = 2.12 cm, SEE = 1.15 cm) was similar to lower frequency error (CE = 1.98 cm, TE = 3.66 cm, SEE = 1.57 cm). The findings overall show that manual analyses had good reliability and low absolute error, while demonstrating the automated counterpart had poor to moderate reliability and large errors in analyses. These findings may be impactful as they highlight the good reliability and low error associated with manually analyzed ultrasound images and validate a novel automatic tool for analyzing ultrasound images. Future work should focus on improving reliability and decreasing error in automated image analysis tools. Automated tools are promising for the field as they eliminate biases between analysts and may be more time efficient than manual techniques.

Body composition of NCAA division I football players pre- and post-COVID-19 stay-at-home advisory.

BACKGROUND: The COVID-19 pandemic forced collegiate athletes to train at home, without access to facilities. The purpose of this study was to evaluate the effect of the COVID-19 stay-at-home order on body composition of Division I Football Players, with a secondary aim to evaluate these changes between players with "higher" (>25 kg/m2) and "lower" (<25 kg/m2) Fat-Free Mass Index (kg/m2). METHODS: Body composition of 29 NCAA Division I Football Players (age=21.0±10 yr, Ht=186.7±5.6 cm, body mass=110.5±22.8 kg) were measured spring season (February) and prior to preseason (June). Whole body dual-energy X-ray absorptiometry scans were used to determine regional (arms, legs, trunk) and total body fat mass (FM), lean mass (LM), and fat-free mass (FFM). Fat-Free Mass Index (FFMI) was calculated as (LM+bone mineral content [BMC])/height2); participants were stratified by FFMI higher (N.=16) and lower (N.=13). RESULTS: Total LM (mean difference±standard error: 0.80±1.65 kg, P=0.016) increased from pre- to post-COVID stay-at-home. No significant changes in total FM were seen. Players with lower FFMI showed a significant decrease in trunk FM (-0.55±0.19 kg, P=0.016). Players with higher FFMI showed a significant increase in total LM (0.96±0.42 kg, P=0.038). CONCLUSIONS: These results suggest no detrimental effect on body composition.

The validation of contemporary body composition methods in various races and ethnicities.

Few investigations have evaluated the validity of current body composition technology among racially and ethnically diverse populations. This study assessed the validity of common body composition methods in a multi-ethnic sample stratified by race and ethnicity. One hundred and ten individuals (55 % female, age: 26·5 (sd 6·9) years) identifying as Asian, African American/Black, Caucasian/White, Hispanic, Multi-racial and Native American were enrolled. Seven body composition models (dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), two bioelectrical impedance devices (BIS, IB) and three multi-compartment models) were evaluated against a four-compartment criterion model by assessing total error (TE) and standard error of the estimate. For the total sample, measures of % fat and fat-free mass (FFM) from multi-compartment models were all excellent to ideal (% fat: TE = 0·94-2·37 %; FFM: TE = 0·72-1·78 kg) compared with the criterion. % fat measures were very good to excellent for DXA, ADP and IB (TE = 2·52-2·89 %) and fairly good for BIS (TE = 4·12 %). For FFM, single device estimates were good (BIS; TE = 3·12 kg) to ideal (DXA, ADP, IB; TE = 1·21-2·15 kg). Results did not vary meaningfully between each race and ethnicity, except BIS was not valid for African American/Black, Caucasian/White and Multi-racial participants for % fat (TE = 4·3-4·9 %). The multi-compartment models evaluated can be utilised in a multi-ethnic sample and in each individual race and ethnicity to obtain highly valid results for % fat and FFM. Estimates from DXA, ADP and IB were also valid. The BIS may demonstrate greater TE for all racial and ethnic cohorts and results should be interpreted cautiously.

Abdominal Adiposity in Collegiate Football Linemen: A Study of Race and Position.

American football linemen are at an increased risk for developing obesity-related diseases. This study evaluated the impact of race and position on abdominal fat (visceral adipose tissue and android fat percentage) in football linemen. Thirty-four offensive and defensive linemen (%fat: 27.1±7.2%) completed a total body dual-energy X-ray absorptiometry scan to estimate visceral fat and android fat percentage. Participants were stratified by race [Black: n=23; White: n=11] and position (Offense: n=18; Defense: n=16). Two separate two-way ANOVA tests [race × position] were completed. For visceral adipose tissue, there was no interaction (p=0.056), but there was an effect of race (Black: 0.57±0.34 kg; White: 1.51±0.56 kg; p <0.001) and position (Offense: 1.22±0.60 kg; Defense: 0.49±0.34 kg; p<0.001). For android fat percentage, there was no interaction (p=0.855) or race effect (Black: 31.5±11.3%; White: 40.9±8.6%; p=0.123); there was a position effect (Offense: 42.1±5.6%; Defense: 26.0±9.9%; p<0.001). Offensive linemen, regardless of race, had greater visceral adipose tissue and android fat percent compared to defensive linemen. White linemen had greater visceral adipose tissue, regardless of position. These results suggest football linemen, especially offensive linemen with increased abdominal adiposity, may benefit from tracking metabolic health during their collegiate career to mitigate obesity-related disease risk once retired from sport.

Effects of adiposity and body composition on adjusted resting energy expenditure in women.

OBJECTIVES: Fat-free mass (FFM) accounts for ~80% of the variance in resting energy expenditure (REE), and this relationship is complicated by adiposity. The objective was to compare adjusted REE and contributions of skeletal lean mass and fat mass (FM) to adjusted REE in women with varying adiposity levels using a novel approach. METHODS: Women were divided into tertiles by body fat percent (%fat): Tertile 1 (T1): %fat = 18.5%-28.4%; Tertile 2 (T2): %fat = 28.5%-33.8%; Tertile 3 (T3): %fat = 34.0%-61.0%. Outcome measures were measured and adjusted REE, body composition (skeletal lean mass, FM, %fat) from dual-energy X-ray absorptiometry, and percent contribution of skeletal lean mass and FM to adjusted REE. RESULTS: The main effect for tertiles (T1 vs. T2 vs. T3) was significant (p = .001); REE was significantly higher in T3 versus both T1 by 281 kcal/day (p = .001) and T2 by 215 kcal/day (p = .001). Expenditure from skeletal lean mass in T1 was significantly higher than T3 by 3.2% (p = .001). T3 had a significantly higher FM contribution than T1 by 5.1% (p = .001) and T2 by 3.9% (p = .001). CONCLUSIONS: Women with elevated %fat experienced lower skeletal lean mass contribution and higher FM contribution to adjusted REE. FM may explain more of the variance in REE between women of different levels of adiposity.

Exploring the "Athlete's Paradox": Division I Cross-Country Runners Demonstrate Similar Muscle Characteristics to Recreationally Trained Young Adults.

ABSTRACT: Cabre, HE, Greenwalt, CE, Gould, LM, Hirsch, KR, Blue, MNM, and Smith-Ryan, AE. Exploring the "Athlete's Paradox": Division I cross-country runners demonstrate similar muscle characteristics to recreationally trained young adults. J Strength Cond Res 35(11): 3213-3217, 2021-Endurance training can influence body composition and muscle characteristics. Endurance athletes have demonstrated elevated intramuscular fat (IMF), yet individuals with greater body fat also demonstrate elevated IMF. The purpose of this study was to examine differences in muscle characteristics (echo intensity [EI] and muscle cross-sectional area [mCSA]) and body composition between Division I collegiate athletes and college-age adults matched for percent fat (%fat). Thirty cross-country athletes (XC) and 30 normal-weight (NW) recreationally active college students (male athletes: n = 30; female athletes: n = 30; mean ± SD: age: 19.2 ± 1.1 years; body mass: 61.7 ± 8.7 kg; %fat: 18.0 ± 5.2%) underwent a panoramic ultrasound scan of the vastus lateralis to evaluate EI and mCSA. A full-body dual-energy x-ray absorptiometry scan was used to assess fat mass (FM), lean mass (LM), and %fat. Independent t-tests were used to evaluate mCSA, EI, and body composition. Significance level was set at ≤ 0.05. There were no significant differences between the XC and NW cohorts in mCSA (mean difference [MD; XC - NW], -1.30 ± -0.40 cm3; p = 0.340) or EI (MD: 3.97 ± 2.66 a.u.; p = 0.478). Body composition was not different between the groups: FM (MD: -0.14 ± -0.54 kg; p = 0.848), LM (-3.07 ± 1.25 kg; p = 0.268), or bone mineral content (-0.21 ± 0.03 kg; p = 0.120). There were also no significant differences for any outcome variables when stratified by male athletes (p = 0.097-0.468) or female athletes (p = 0.055-0.700). These results suggest that XC athletes may have similar muscle characteristics to NW individuals when matched for %fat. Understanding and tracking muscle characteristics in XC athletes may be important for performance, injury prevention, and the transition to retirement.

Acute feeding has minimal effect on the validity of body composition and metabolic measures: dual-energy X-ray absorptiometry and a multi-compartment model.

Understanding the effects of acute feeding on body composition and metabolic measures is essential to the translational component and practical application of measurement and clinical use. To investigate the influence of acute feeding on the validity of dual-energy X-ray absorptiometry (DXA), a four-compartment model (4C) and indirect calorimetry metabolic outcomes, thirty-nine healthy young adults (n 19 females; age: 21·8 (sd 3·1) years, weight; 71·5 (sd 10·0) kg) participated in a randomised cross-over study. Subjects were provided one of four randomised meals on separate occasions (high carbohydrate, high protein, ad libitum or fasted baseline) prior to body composition and metabolic assessments. Regardless of macronutrient content, acute feeding increased DXA percent body fat (%fat) for the total sample and females (average constant error (CE):-0·30 %; total error (TE): 2·34 %), although not significant (P = 0·062); the error in males was minimal (CE: 0·11 %; TE: 0·86 %). DXA fat mass (CE: 0·26 kg; TE: 0·75 kg) and lean mass (LM) (CE: 0·83 kg; TE: 1·23 kg) were not altered beyond measurement error for the total sample. 4C %fat was significantly impacted from all acute feedings (avg CE: 0·46 %; TE: 3·7 %). 4C fat mass (CE: 0·71 kg; TE: 3·38 kg) and fat-free mass (CE: 0·55 kg; TE: 3·05 kg) exceeded measurement error for the total sample. RMR was increased for each feeding condition (TE: 1666·9 kJ/d; 398 kcal/d). Standard pre-testing fasting guidelines may be important when evaluating DXA and 4C %fat, whereas additional DXA variables (fat mass and LM) may not be significantly impacted by an acute meal. Measuring body composition via DXA under less stringent pre-testing guidelines may be valid and increase feasibility of testing in clinical settings.

Metabolic effects of high-intensity interval training and essential amino acids.

High-intensity interval training (HIIT) promotes positive cardiometabolic and body composition changes. Essential amino acids (EAA) may support changes associated with HIIT, but evaluation of potential synergistic effects is lacking. The purpose of this study was to compare independent and combined effects of HIIT and EAA on total body composition and metabolism in men and women considered overweight/obese; an exploratory aim was to evaluate the modulatory effects of sex. Sixty-six healthy adults (50% female; Age: 36.7 ± 6.0 years; BMI: 32.0 ± 4.2 kg/m2) completed 8 weeks of: (1) HIIT, 2 days/weeks; (2) EAA supplementation, 3.6 g twice daily; (3) HIIT + EAA; or (4) control. Body composition, resting metabolic rate (RMR), substrate metabolism (respiratory exchange ratio; RER), and cardiorespiratory fitness were measured at baseline, 4 weeks, and 8 weeks; cardiometabolic blood markers were measured at baseline and 8 weeks. Differences between groups were assessed by linear mixed models covaried for baseline values, followed by 95% confidence intervals (CI) on adjusted mean change scores. There were no significant changes in body composition (p > 0.05) for any group. Changes in RER, but not RMR, occurred with HIIT (mean change; [95% CI]: - 0.04; [- 0.07, - 0.02]) and EAA (- 0.03; [- 0.06, - 0.01]) after 8 weeks. Cardiorespiratory fitness increased following 8 weeks of HIIT (+ 5.1 ml/kg/min [3.3,6.8]) and HIIT + EAA (+ 4.1 ml/kg/min [1.0,6.4]). Changes with HIIT + EAA were not significantly different from HIIT. There were no changes in cardiometabolic markers (p > 0.05) and no sex interaction (p > 0.05). HIIT is efficacious for promoting positive changes in cardiorespiratory fitness and resting substrate metabolism in adults considered overweight/obese. Addition of EAA did not significantly enhance HIIT-induced adaptations. ClinicalTrials.gov ID#NCT04080102.

Promoting Exercise and Healthy Diet Among Primary Care Patients: Feasibility, Preliminary Outcomes, and Lessons Learned From a Pilot Trial With High Intensity Interval Exercise.

Physical activity and healthy diet are recognized as effective approaches for disease prevention. Controlled laboratory clinical trials support these approaches, yet minimal data exists supporting implementation of exercise as medicine within a healthcare setting. Objectives: To understand perception and barriers to exercise and nutrition from patients and physicians from a family medicine clinic (FMC) to inform the implementation of a laboratory-based exercise and nutrition lifestyle intervention (Phase I), and to determine the feasibility, adherence, and preliminary outcomes of implementing this lifestyle intervention into a FMC (Phase II). Methods: In phase I 10 patients and 5 physicians were interviewed regarding perceptions of exercise and nutrition practices. In phase II patients at risk for cardiovascular disease were enrolled into a lifestyle intervention (n = 16), within a FMC, manipulating diet and exercise. Cardiorespiratory fitness (CRF), body composition, and metabolic blood markers were completed at baseline, after the 12-week intervention, and at 24 weeks. Feasibility was defined by patients who completed the intervention and number of sessions vs. total available. Results: Prescribing high-intensity interval training and a meal replacement for 12 weeks in patients with at least one risk factor for cardiovascular disease, was shown to have moderate feasibility with 62.5% (n = 10) for patients completing the 12 week intervention, and poor feasibility for assessing effects 12 weeks after cessation of the intervention, with 50% (n = 5) participants returning. Tracking exercise electronically via FitBit had moderate fidelity (n = 9), with hardcopy logs yielding poor compliance (n = 6). This pilot study demonstrated preliminary effectiveness of this home-based approach for improving cardiorespiratory fitness with an average 4.31 ± 5.67 ml·kg·min-1 increase in peak oxygen consumption. Blood triglycerides and insulin were improved in 70% and 60% of the patients, respectively. Conclusions: Despite moderate feasibility, a home-based exercise and nutrition has the potential to be used as an effective approach for managing and mitigating cardiovascular disease risk factors. There were key lessons learned which will help to develop and adapt a larger scale lifestyle intervention into a clinical setting. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/study/NCT02482922, identifier NCT02482922.

High-Intensity Interval Training for Knee Osteoarthritis: A Pilot Study.

OBJECTIVE: To assess the feasibility and changes in outcomes of a 12-week high-intensity interval training (HIIT) program in individuals with symptomatic knee osteoarthritis (OA). METHODS: The single-arm trial included 29 participants (mean ± SD age 63 ± 7 years; 66% women; 66% obese). Measures of participant flow, adherence, and tolerability were collected. Pain, function, and balance were assessed at baseline, 6 weeks, and 12 weeks using the Western Ontario and McMaster Universities Osteoarthritis Index, 20-m fast-paced walk test, 30-second chair-stand test, stair-climb test, timed up and go test, and single leg stance. Cardiorespiratory fitness, strength, and body composition were evaluated using peak oxygen consumption (VO2 peak), isometric knee extensor/flexor strength, and dual-energy x-ray absorptiometry, respectively. HIIT was completed two times/week (cycling or treadmill) and consisted of 10 repetitions of 1-minute bouts at 90% VO2 peak, with 1-minute rest periods. Separate multivariable-adjusted linear mixed models were fit for each outcome with fixed effects of time, age, sex, body mass index, and random effects of baseline values to estimate mean changes and 95% confidence intervals (CIs) between baseline and 12-week assessments. RESULTS: Recruitment aligned with the anticipated enrollment rate, adherence was 70%, and no adverse events were reported. At 12 weeks, improvements were observed for most outcomes, with notable mean changes for the 20-m fast-paced walk (-1.13 [95% CI -1.61 to -0.64] seconds), 30-second chair-stand (2.6 [1.8-3.4] stands), and VO2 peak (0.14 [0.03-0.24] liters/minute). CONCLUSION: In this 12-week pilot study, HIIT improved multiple aspects of health in individuals with knee OA; larger studies are needed.

Impact of Follicular Menstrual Phase on Body Composition Measures and Resting Metabolism.

PURPOSE: This study aimed to identify the effects of early follicular (EF) and midfollicular (MF) menstrual phases on body composition, resting metabolic rate (RMR), and respiratory quotient (RQ) assessment accuracy to identify an optimal testing period. METHODS: Body composition was obtained from a four-compartment (4C) criterion model (fat mass (FM), fat-free mass, body fat percent, and dual-energy x-ray absorptiometry (DXA; FM, lean mass (LM), trunk FM, and trunk LM) in 19 eumenorrheic females (mean ± SD: age, 21.3 ± 3.1 yr, body mass index, 23.6 ± 1.8 kg·m-2). RMR (kcal·d-1) and RQ (a.u.) were measured via indirect calorimetry for 25 min. Body composition, RMR, and RQ were measured during the EF and MF phases. Dependent-samples t-tests were used to compare outcomes between EF and MF. RESULTS: 4C outcomes were similar between phases (P > 0.05). During EF, the following 4C components were significantly greater (P < 0.05): body volume (mean difference (MD) ± SD, 0.70 ± 1.05 L), extracellular fluid (MD ± SD, 0.27 ± 0.51 L), and body mass (MD ± SD, 0.56 ± 0.80 kg). DXA-measured LM, body fat percent, trunk LM, and trunk FM were similar (P > 0.05); however, DXA FM was significantly greater during EF (MD ± SD, 0.29 ± 0.40 kg; P = 0.005), yet within measurement error of the device. Although RMR was not significantly different between phases (MD ± SD, 6.0 ± 190.93 kcal·d-1; P > 0.05), RQ was significantly higher during EF (mean ± SD, 0.03 ± 0.06 a.u.; P = 0.029) compared with MF. CONCLUSIONS: Body composition from 4C and DXA do not seem to be affected beyond measurement error as a result of compartmental changes from the menstrual cycle. During MF, women oxidized more fat as demonstrated by a lower RQ. Researchers should aim to be more inclusive and schedule testing for females within 11-12 d from the onset of menstruation.

Validation of InBody 770 bioelectrical impedance analysis compared to a four-compartment model criterion in young adults.

BACKGROUND: Multi-frequency bioelectrical impedance analysis (MF-BIA) offers enhanced body composition outcomes in a time-efficient manner. The accuracy of stand-up MF-BIA compared against a four-compartment (4C) criterion lacks evidence. OBJECTIVES: To validate a stand-up MF-BIA compared to a 4C criterion for fat mass (FM), fat-free mass (FFM) and body fat percentage (%fat). SUBJECTS/METHODS: Eighty-two healthy (32% men) normal-weight (BMI: 18.5-24.9 kg/m2 ) young adults were measured for body composition determined from a stand-up MF-BIA and 4C model. Validity statistics included total error (TE) and standard error of the estimate (SEE) to examine prediction error between methods. RESULTS: For the total sample, prediction error was the highest for %fat (TE = 4.2%; SEE = 3.9%) followed by FM (TE = 2.4 kg; SEE = 2.2 kg) and FFM (TE = 2.4 kg; SEE = 2.2 kg). In men, %fat (TE = 2.5%; SEE = 2.2%) and FM (TE = 1.9 kg; SEE = 1.6 kg) were ideal; FFM was similar to FM (TE = 1.9 kg; SEE = 1.6 kg). In women, %fat (TE = 4.7%; SEE = 4.4%) ranged from good to fairly good, and FM was very good to excellent (TE = 2.6 kg; SEE = 2.4 kg); FFM was similar to FM (TE = 2.6 kg; SEE = 2.3 kg). CONCLUSIONS: Stand-up MF-BIA may overestimate %fat and FM, and underestimate FFM compared to a 4C model. FM and FFM estimates from MF-BIA demonstrate good agreement to a 4C model and may be a practical measure of body composition in normal-weight adults. The highest error was seen in %fat for both sexes, with greater error in women.

Validity of Body-Composition Methods across Racial and Ethnic Populations.

Multi-compartment body-composition models that divide the body into its multiple constituents are the criterion method for measuring body fat percentage, fat mass, and fat-free mass. However, 2- and 3-compartment body-composition devices such as air displacement plethysmography (ADP), DXA, and bioelectrical impedance devices [bioelectrical impedance analysis (BIA)] are more commonly used. Accurate measures depend on several assumptions, including constant hydration, body proportion, fat-free body density, and population characteristics. Investigations evaluating body composition in racial and ethnic minorities have observed differences in the aforementioned components between cohorts. Consequently, for racial/ethnic minority populations, estimates of body composition may not be valid. The purpose of this review was to comprehensively examine the validity of common body-composition devices in multi-ethnic samples (samples including >1 race/ethnicity) and in African-American, Hispanic, Asian, and Native American populations. Based on the literature, DXA produces valid results in multi-ethnic samples and ADP is valid for Hispanic and African American males when utilizing race-specific equations. However, for DXA and ADP, there is a need for validity investigations that include larger, more racially diverse samples, specifically including Hispanic/Latinx, Asian, Native American adults, and African-American females. Technology has advanced significantly since initial validity studies were conducted; therefore, conclusions are based on outdated models and software. For BIA, body-composition measures may be valid in a multi-ethnic sample, but the literature demonstrates disparate results between races/ethnicities. For BIA and ADP, the majority of studies have utilized DXA or hydrostatic weighing as the criterion to determine validity; additional studies utilizing a multi-compartment model criterion are essential to evaluate accuracy. Validity studies evaluating more recent technology in larger, more racially/ethnically diverse samples may improve our ability to select the appropriate method to accurately assess body composition in each racial/ethnic population.

Post-Exercise Ingestion of Low or High Molecular Weight Glucose Polymer Solution Does Not Improve Cycle Performance in Female Athletes.

ABSTRACT: Mock, MG, Hirsch, KR, Blue, MNM, Trexler, ET, Roelofs, EJ, and Smith-Ryan, AE. Postexercise ingestion of low or high molecular weight glucose polymer solution does not improve cycle performance in female athletes. J Strength Cond Res 35(1): 124-131, 2021-The current study sought to evaluate the effects of postexercise ingestion of a high molecular weight (HMW) glucose polymer solution compared with an isocaloric low molecular weight (LMW) solution or placebo (PLA) on subsequent cycling performance in female athletes. In a randomized, double-blind, placebo-controlled, cross-over design, 10 competitive female cyclists (Mean ± SD; Age = 25.7 ± 5.0 years; V̇o2peak = 49.7 ± 4.3 ml·kg-1·min-1) completed 3 testing sessions separated by 7-10 days. Visits consisted of a ride-to-exhaustion (RTE) at 75% V̇o2peak, followed by immediate consumption of 700 ml containing either: 1.2 g·kg-1 LMW (maltodextrin/dextrose/fructose); 1.2 g·kg-1 HMW (Vitargo); or 0.066 g·kg-1 PLA (noncaloric flavoring). After 2 hours of rest, subjects performed a 15-minute time trial (TT). Respiratory exchange ratio (RER) was assessed via indirect calorimetry during exercise. Total body water (TBW) was measured using bioelectrical impedance to assess fluid balance. When covaried for estrogen, there was no treatment effect on distance (km; p = 0.632) or power output (watts; p = 0.974) during the 15-minute TT. Respiratory exchange ratio was not significantly different during the LMW and HWM TTs (p > 0.999), but both were significantly higher than PLA (p = 0.039, p = 0.001, respectively). Changes in total body water pre-exercise to postexercise were not significantly different between trials (p = 0.777). Despite benefits of HMW on cycling performance previously reported in males, current results demonstrate no ergogenic effect of HMW or LMW in females. Sex differences in substrate utilization may account for the discrepancy, and further research involving performance nutrition for female athletes is merited.