Ultrasound is an appealing tool to assess body composition, combining the portability of a field method with the accuracy of a laboratory method. However, unlike other body composition methods, the effect of hydration status on validity is unknown. This study evaluated the impact of acute hydration changes on ultrasound measurements of subcutaneous fat thickness and estimates of body fat percentage. In a crossover design, 11 adults (27.1 ± 10.5 years) completed dehydration and hyperhydration trials to alter body mass by approximately ±2%. Dehydration was achieved via humid heat (40 °C, 60% relative humidity) with exercise, whereas hyperhydration was via ingestion of lightly salted water. Ultrasound measurements were taken at 11 body sites before and after each treatment. Participants lost 1.56 ± 0.58 kg (-2.0 ± 0.6%) during the dehydration trial and gained 0.90 ± 0.21 kg (1.2 ± 0.2%) during the hyperhydration trial even after urination. The sum of fat thicknesses as measured by ultrasound differed by <0.90 mm across trials (p = .588), and ultrasound estimates of body fat percentage differed by <0.5% body fat. Ultrasound measures of subcutaneous adipose tissue were unaffected by acute changes in hydration status by extents beyond which are rare and overtly self-correcting, suggesting that this method provides reliable and robust body composition results even when subjects are not euhydrated.

Ultrasound Measurements of Subcutaneous Fat Thickness Are Robust Against Hydration Changes

Contemporary sports nutrition guidelines recommend that each athlete develop a personalised, periodised and practical approach to eating that allows him or her to train hard, recover and adapt optimally, stay free of illness and injury and compete at their best at peak races. Competitive triathletes undertake a heavy training programme to prepare for three different sports while undertaking races varying in duration from 20 min to 10 h. The everyday diet should be adequate in energy availability, provide CHO in varying amounts and timing around workouts according to the benefits of training with low or high CHO availability and spread high-quality protein over the day to maximise the adaptive response to each session. Race nutrition requires a targeted and well-practised plan that maintains fuel and hydration goals over the duration of the specific event, according to the opportunities provided by the race and other challenges, such as a hot environment. Supplements and sports foods can make a small contribution to a sports nutrition plan, when medical supplements are used under supervision to prevent/treat nutrient deficiencies (e.g. iron or vitamin D) or when sports foods provide a convenient source of nutrients when it is impractical to eat whole foods. Finally, a few evidence-based performance supplements may contribute to optimal race performance when used according to best practice protocols to suit the triathlete’s goals and individual responsiveness.

/pdf/nutrition-strategies-for-triathlon-22heo84fbf.pdf

Nutrition Strategies for Triathlon

Ultrasound has been demonstrated to be a highly accurate and reliable tool for measuring subcutaneous adipose tissue thickness and is robust against changes in hydration status or acute food or fluid intake. However, the effect of prior acute exercise is unexamined. This study examined the impact of acute an endurance exercise and resistance exercise session on standardised brightness-mode ultrasound measurements of subcutaneous adipose tissue thickness compared to skinfolds and dual-energy X-ray absorptiometry body composition estimates. In a randomised cross over design, 30 active adults (24.2 ± 4.9 y) undertook physique assessment via standardised brightness-mode ultrasound, skinfolds and dual-energy X-ray absorptiometry prior to, immediately and 45 minutes after acute endurance or resistance exercise. Participants completed both exercise sessions. The mean sum of eight subcutaneous adipose tissue thickness measured via standardised brightness-mode ultrasound increased (0.6 mm, p = 0.04) immediately post-endurance exercise but was not meaningful when evaluated against the technical error of measurement of the investigator. A significant (p = 0.01) but not meaningful decrease in the sum of eight skinfolds occurred immediately (-1.1 ± 0.4 mm) and 45 min (-1.3 ± 0.4 mm) post-resistance exercise. Comparatively, endurance exercise elicited a meaning decrease of total mass (460 ± 30 g) and trunk lean mass (680 ± 90 g) dual-energy X-ray absorptiometry estimates. Findings from this study indicate standardised client presentation may be unnecessary when employing either standardised brightness-mode ultrasound or skinfolds for body composition assessment unlike dual-energy X-ray absorptiometry. This article is protected by copyright. All rights reserved.

Acute exercise affects dual-energy X-ray absorptiometry body composition estimates but not standardised ultrasound measurements of subcutaneous adipose tissue.

This study examined long-term changes in body composition and bone mineral characteristics among male long-distance runners from a high-profile university team, focusing on concerns about impaired musculoskeletal development due to extreme leanness and weight management practices in this population. 

Trajectory Analysis of the Four‐Year Changes in Body Composition and Bone Mineral Characteristics Among Highly Competitive Male University Long‐Distance Runners

Body composition is a determinant of performance in soccer. To estimate the body fat percentage (%BF), dual energy X-ray absorptiometry (DXA) is effective though this method is expensive and not readily accessible. This study examines the validity of widely used field methods based on anthropometric data and bioelectrical impedance analysis (BIA). Participants were 21 male Spanish First Division soccer players aged between 22 and 35 years. In each participant, body fat mass was determined by BIA and using 18 anthropometric equations including skinfold (SKF) measurements. DXA was used as reference. Correlation with DXA measurements was excellent for all equations and separate SKF measurements yet only moderate for BIA. However, only the equation recently developed for use in soccer players based on iliac crest and triceps SKFs showed no significant or standardized differences with DXA-derived %BF and these measurements also had the lowest bias. Our findings suggest that when DXA is not available, the best field method for %BF assessment in footballers is the equation based on iliac crest and triceps SKF. As another good option, we propose the sum of triceps, subscapular, supraspinal, and abdominal SKFs, as this combination also showed good correlation with DXA.

https://www.mdpi.com/2076-3417/12/2/727/pdf?version=1641983866

Optimizing Field Body Fat Percentage Assessment in Professional Soccer Players

Physique traits are one of an array of variables known to influence performance of athletes across a wide range of sports. The routine monitoring of physique traits has become common practice amongst athletic populations, affording an opportunity to objectively assess the impact of training and diet and subsequently adjust these variables to optimise adaptations. An array of techniques is available to assess the physique traits of athletes. When selecting the most appropriate technique, a range of factors should be considered, including technical (safety, validity, precision and accuracy of measurement) and practical issues (availability, financial implications, portability, invasiveness, time effectiveness and technical expertise necessary), including the ability of the technique to accommodate the unique physique traits of athletes. Guidelines to assist with facilitating standardisation of athlete presentation prior to assessments are provided, with application to the majority of physique assessment techniques commonly applied amongst athletic populations such as dual-energy X-ray absorptiometry, air displacement plethysmography (i.e. Bod Pod) and bioelectrical impedance analysis. The exception may be surface anthropometry given results are minimally impacted by athlete presentation.

Athlete Considerations for Physique Measurement

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Athlete Considerations for Physique Measurement