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Fat-Free Mass Changes During Ketogenic Diets and the Potential Role of Resistance Training

Grant M. Tinsley and Darryn S. Willoughby

Low-carbohydrate and very-low-carbohydrate diets are often used as weight-loss strategies by exercising individuals and athletes. Very-low-carbohydrate diets can lead to a state of ketosis, in which the concentration of blood ketones (acetoacetate, 3-β-hydroxybutyrate, and acetone) increases as a result of increased fatty acid breakdown and activity of ketogenic enzymes. A potential concern of these ketogenic diets, as with other weight-loss diets, is the potential loss of fat-free mass (e.g., skeletal muscle). On examination of the literature, the majority of studies report decreases in fat-free mass in individuals following a ketogenic diet. However, some confounding factors exist, such as the use of aggressive weight-loss diets and potential concerns with fat-free mass measurement. A limited number of studies have examined combining resistance training with ketogenic diets, and further research is needed to determine whether resistance training can effectively slow or stop the loss of fat-free mass typically seen in individuals following a ketogenic diet. Mechanisms underlying the effects of a ketogenic diet on fat-free mass and the results of implementing exercise interventions in combination with this diet should also be examined.

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Development of an Anthropometric Prediction Model for Fat-Free Mass and Muscle Mass in Elite Athletes

Erik Sesbreno, Gary Slater, Margo Mountjoy, and Stuart D.R. Galloway

simple calculation, absolute FM, and fat-free mass (FFM; overall mass excluding FM). Some practitioners apply this approach of estimating FFM in athletes in the daily training environment. However, few, if any of these skinfold equations have been validated to quantify body composition change ( Cisar et

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Fat-Free Mass Using Bioelectrical Impedance Analysis as an Alternative to Dual-Energy X-Ray Absorptiometry in Calculating Energy Availability in Female Adolescent Athletes

Ivy Evangelista Ramos, Gabriela Morgado Coelho, Haydée Serrão Lanzillotti, Elisabetta Marini, and Josely Correa Koury

Athletes’ energy requirements depend on the volume, intensity, periodized training, and competition cycle. Some factors, such as exposure to cold, heat, high altitude, stress, physical injuries, and increase in fat-free mass (FFM) increase energy requirements above normal baseline levels ( Thomas

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Cross Validation of Fat-Free Mass Prediction Models for Elite Female Gymnasts

Patricia W. Bauer, James M. Pivarnik, Willa C. Fornetti, Jennifer J. Jallo, and Lawrence Nassar

The purpose of this investigation was to evaluate three bioelectrical impedance analysis (BIA) prediction models for fat-free mass (FFM) using the U.S. National Women’s Gymnastics team (N = 48; age = 15.8 ± 1.8 years). One model had been developed recently using dual-energy x-ray absorptiometry (DEXA) as the criterion measure, whereas the other two used hydrodensitometry. In this investigation, FFM predictions were compared with measures obtained via DEXA. FFM measured by DEXA averaged 40.5 ± 7.4 kg (± SD), whereas values generated using the three BIA models were within 0.8 kg of this actual measure. Validity coefficients for all models were high (Rxy = .95-98). FFM prediction error was lowest with the model using DEXA as the criterion measure (1.3 kg) compared with the other two (1.9 and 2.4 kg). All BIA models underpredicted FFM in the heaviest girls, and the Lohman and Van Loan et al. models overpredicted FFM in the lightest girls. Whereas prediction error was significantly correlated to the girls’ bone mineral density in all BIA models, this relationship was strongest in the two that were developed using hydrodensitometry.

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Evaluating Change in Body Composition and Impact of Menarche Across a Competitive Season in Elite Collegiate Gymnasts

Sam R. Moore, Hannah E. Cabre, Amanda N. Gordon, and Abbie E. Smith-Ryan

female gymnasts have been reported during preseason training ( Chandran et al., 2021 ). Collegiate female gymnasts have demonstrated greater fat-free mass (FFM, LM, and bone mineral content [BMC]) and lower body fat percentage (BF%) than nonathletes ( Falls & Dennis Humphrey, 1978 ). Recent data

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Longitudinal Changes in Body Composition Assessed Using DXA and Surface Anthropometry Show Good Agreement in Elite Rugby Union Athletes

Adam J. Zemski, Shelley E. Keating, Elizabeth M. Broad, and Gary J. Slater

), distinct differences in body composition exist. Forwards have consistently been shown to be heavier, taller, and possess more fat-free mass (FFM) and fat mass (FM), whereas backs display proportionally lower body fat ( Lees et al., 2017 ; Zemski et al., 2015 ). Optimal body composition assists athletes in

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Short-Term Precision Error of Body Composition Assessment Methods in Resistance-Trained Male Athletes

Ava Farley, Gary J. Slater, and Karen Hind

quantify fat-free mass (FFM) and fat mass (FM) ( Ackland et al., 2012 ; Kerr et al., 2017 ). Depending on time and resources, the four most popular methods used on athletic populations are air displacement plethysmography (BOD POD), dual-energy X-ray absorptiometry (DXA), bioelectrical impedance

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Body Composition Over the Menstrual and Oral Contraceptive Cycle in Trained Females

Beatriz Rael, Nuria Romero-Parra, Víctor M. Alfaro-Magallanes, Laura Barba-Moreno, Rocío Cupeiro, Xanne Janse de Jonge, Ana B. Peinado, and on Behalf of the IronFEMME Study Group*

research in this area remain unclear, with some reporting little or no effects of the MC on BC, 9 , 10 whereas others found higher weight and fat-free mass (FFM) during the luteal phase. 11 , 12 Some of these conflicting findings may be related to methodological issues. Most studies in the literature

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Sex-Specific Longitudinal Modeling of Youth Peak Oxygen Uptake

Neil Armstrong and Jo Welsman

single best indicator of youth aerobic fitness, but its interpretation in relation to sex, age, body mass, fat-free mass (FFM), and maturity status is controversial ( 4 ). The vast majority of published data are cross-sectional and, on balance, show that boys’ absolute peak V ˙ O 2 (ie, in L·min −1

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Organ Size Increases With Weight Gain in Power-Trained Athletes

Sakiho Miyauchi, Satomi Oshima, Meiko Asaka, Hiroshi Kawano, Suguru Torii, and Mitsuru Higuchi

The purpose of this study was to determine whether overfeeding and high-intensity physical training increase organ mass. We examined this question using cross-sectional and longitudinal studies in which we measured collegiate male American football players. Freshman (n = 10) and senior players in their second and third years of college (n = 17) participated in the cross-sectional study. The same measurements of the same freshman players (n = 10) were assessed after the one-year weight gain period in the longitudinal study. Fat-free mass (FFM), skeletal muscle, and adipose tissue mass were obtained using dual-energy X-ray absorptiometry. Liver, kidney, brain, and heart volumes were calculated using magnetic resonance imaging or echocardiography. Compared with the freshman players, the senior players had 10.8 kg more FFM, and 0.29 kg, 0.08 kg, and 0.09 kg greater liver, heart, and kidney mass, respectively. In the longitudinal study, FFM, liver, heart, and kidney mass of the freshman players increased by 5.2 kg, 0.2 kg, 0.04 kg, and 0.04 kg, respectively, after one year of overfeeding and physical training. On the other hand, the organ-tissue mass to FFM ratio did not change, except for the brain, in either the cross-sectional or longitudinal studies. Our results indicated that the organtissue masses increased with overfeeding and physical training in male collegiate American football players.