Appendicular Body Composition Analysis: Validity of Bioelectrical Impedance Analysis Compared With Dual-Energy X-Ray Absorptiometry in Division I College Athletes.

Brewer, GJ, Blue, MNM, Hirsch, KR, Peterjohn, AM, and Smith-Ryan, AE. Appendicular body composition analysis: Validity of bioelectrical impedance analysis compared with dual-energy x-ray absorptiometry in Division I college athletes. J Strength Cond Res 33(11): 2920-2925, 2019-The purpose of this study was to evaluate validity of appendicular body composition measurements measured from a multifrequency bioelectrical impedance analysis (MF-BIA) compared with a dual-energy x-ray absorptiometry (DXA) criterion in Division I athletes. One hundred sixty male (n = 44) and female (n = 116) collegiate athletes were enrolled: Men's Cross Country (n = 15), football linemen (n = 29), Women's Soccer (n = 27), Women's Field Hockey (n = 27), Women's Cross Country (n = 13), Women's Gymnastics (n = 16), and Women's Lacrosse (n = 33). Appendicular fat mass (FM) of the arms (AFM, right AFM, left AFM) and legs (LFM, right LFM, left LFM), appendicular fat-free mass (FFM) of the arms (AFFM, RAFFM, LAFFM) and legs (LFFM, RLFFM, LLFFM), total body FM and FFM, and total body %fat were collected from both devices. MF-BIA significantly underestimated appendicular FFM of the arms (AFFM mean difference [MD]: -0.7 kg; RAFFM: -0.4 kg; LAFFM: -0.4 kg, p < 0.001) and legs (LFFM MD: -3.8 kg; RLFFM: -1.9 kg; LLFFM: -1.9 kg, p < 0.001), and FM of the legs (LFM MD: -2.5 kg; RLFM: -1.3 kg; LLFM: -1.3 kg, p < 0.001). There was no significant difference in appendicular FM measures of the arms (p = 0.174). All measures held true for male subjects and female subjects. Female subjects produced smaller differences compared with male subjects. The lack of validity, from raw and relative error, between the devices for most appendicular measures (FFM of arms and FFM and FM legs) and all total body measures (FM, FFM, and %fat) suggest that this MF-BIA may not be accurate in measuring a lean, athletic, population compared with DXA.

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.

The effects of nutrient timing on training adaptations in resistance-trained females.

OBJECTIVES: The purpose of this study was to determine the effects of pre- vs. post-workout nutrition on strength, body composition, and metabolism in trained females over 6 weeks of high intensity resistance training (HIRT). DESIGN: Forty-three trained females (mean±SD; age: 20.5±2.2 yrs; height: 165.2±5.7cm; body mass: 66.5±11.4kg) were measured for strength, body composition, and metabolic variables before and after a HIRT intervention. Participants were randomized using a 2:2:1 matched block randomization scheme by baseline leg press strength into a group that consumed a 1:1.5 carbohydrate-protein supplement (16g CHO/25g PRO) pre-training (PRE), post-training (POST), or no supplement (CON). METHODS: Dual-energy X-ray absorptiometry was used to evaluate fat mass (FM), lean mass (LM), and percent fat (%fat). Strength was analyzed using a one repetition max on the leg and bench press (LP1RM and BP1RM, respectively). Participants completed HIRT twice per week for 6 weeks. At the first and last trainings, metabolic variables [resting energy expenditure (REE) and respiratory exchange ratio, RER] were measured. RESULTS: There were no significant differences between groups for any changes in body composition variables or LP1RM (p=0.170-0.959). There were significant differences for BP1RM (p=0.007), with PRE and POST experiencing greater increases than CON (p=0.010 and 0.015, respectively). REE changes were not significant between groups (p=0.058-0.643). PRE demonstrated greater fat oxidation (RER) at 30min post-exercise (p=0.008-0.035). CONCLUSION: Peri-workout nutrition is potentially important for upper body strength and metabolism. PRE may be more effective for promoting fat utilization immediately post-workout.