Body Composition & The Elite Athlete I: Fundamentals

Body composition is a pivotal marker in high performance sport of the athlete’s nutritional status. However, there are a litany of assessment methods, and each has its own advantages and limitations. So, how do we separate the good from the unethical? And what does it matter anyway?

What is Body Composition?

It helps to know what the hell we’re talking about first of all. Body composition (BC) partitions the body into fat-free mass (FFM) and adipose tissue – or in essence fat versus not fat. Because we all know that in the fitness realm all that matters is that ratio, certainly if you want to land a high-waisted legging sponsorship with a questionable fast-fashion label.

The prime focus of BC is often body fat percentage (BF%). Often demonised, body fat is shockingly not a negative, and is indeed essential for our survival. BF is used to provide energy, assist hormonal regulation and cushion our internal organs (Stefan, 2020). Take that, dieting industry.

However, excessive body fat poses several health risks (increased cardiovascular disease, obesity and generally poorer health outcomes [Lee et al., 2018]). The distribution of our body fat also affects health, with increased visceral fat (around your organs) linked to the aforementioned negative health effects. Indeed, Stefan (2020) found that even individuals with lower BF% that had elevated visceral fat had increased risk of cardiovascular disease. Not the vibe. Therefore, assessing body fat can be a vital indicator of health.

We also like to monitor athletes FFM. In terms of general health, increased FFM is associated with lower cardiovascular disease risk, sarcopenia and improved lifespan.

Is there anything gains can’t do?

Why Do We Care About Body Composition For Elite Athletes?

All-Ireland’s aren’t awarded for the best delts (however, I for one believe this should be considered). What does it matter if an athlete carries more fat if they can perform?

I’m glad you asked, dear reader.

Within elite sport, body composition plays a vital role beyond general health assessment, and is an invaluable performance metric.

Nunes et al. (2020) found a higher BF% was associated with decreased sprinting performance, jump height and speed amongst rugby players. In addition, increased skeletal muscle mass leads to an increase in muscular strength and output. Pasin et al. (2017) noted an increase in FFM led to increased muscle strength, jumping ability and high-intensity capacity. This may also be due to an overall reduction in body mass. Crewther et al. (2012)’s more widely-cited study identified a correlation between a reduction in overall body mass and individual players’ force and power output.

However, there is no “ideal” body composition that best suits every player, every position and every sport. Body composition varies hugely between athletes, even players within the same sport. This is well-demonstrated in elite rugby.

Within rugby, positions are loosely grouped into forward and backs. Brazier et al. (2020) demonstrated that forwards tend to be heavier and stronger. Similarly, amongst female elite rugby players, forwards tend to be heavier with a greater FFM and BF% overall than backs. Backs were also expected to be quicker, more agile and exhibit greater jumping ability (Jones et al., 2016).

Therefore, by identifying these characteristics in the elite athlete, BC can be used to guide training/nutritional strategies for the athlete, and help identify performance criteria (Ackland et al., 2012).

BC assessments may identify an excess BF% that can predispose the athlete to various health conditions mentioned above. Similarly, BC assessments may identify athletes whose BF% is insufficient to support health and performance. Falling below the essential BF% can impair physiological function. Within males, this range is 2-5% (Fidanza, 2003). BF% of below 12% within females has been linked with amenorrhea and a reduction in bone mass (Hulmi et al., 2016).

Using BC to assess health can be advantageous over bodyweight alone for athletes. Calculations such as Body Mass Index (BMI), which charts bodyweight against height, can be useful in assessing the general adiposity of populations (Lee et al., 2018). However, BMI does not consider the FFM of the individual, nor the distribution of body fat. Both of these factors are powerful influences on the health status of the individual (Lee et al., 2018). Furthermore, elite athletes do not exhibit the same characteristics/BC as the general population.

So, Where Do We Go From Here?

Straight into Part II of this series obviously.

Body composition hugely influences the athletic capacity of elite athletes. BF% can be a key marker of health, but is only one of many factors in performance. The need to assess FFM is also pivotal. We use body composition to guide nutrition protocols, training programmes and as a key indicator of health for elite athletes.

This had led to the development of a number of assessment techniques that vary in accuracy, and Part II will discuss the key BC assessment methods (and rip them to shreds).


  • Ackland, T.R., Lohman, T.G., Sundgot-Borgen, J., Maughan, R.J., Meyer, N.L., Stewart, A.D., Muller, W. (2012) ‘Current Status of Body Composition Assessment in Sport’, Sports Medicine, 42, pp. 227-249
  • Brazier, J., Antrobus, M., Stebbings, G.K., Day, S.H., Callus, P., Erskine, R.M., Bennett, M.A., Kilduff, L.P., Williams, A.G. (2020) ‘Anthropometric and Physiological Characteristics of Elite Male Rugby Athletes’, 34(6), pp. 1790-1801.
  • Crewther, B.T., Kilduff, L.P., Cook, C.J., Cunningham, D.J., Bunce, P.J., Bracken, R.M., Gaviglio, C.M. (2012) ‘Scaling strength and power for body mass differences in rugby union players’, Journal of Sports Medicine and Physical Fitness, 52(1), pp. 27-32.
  • Fidanza, F. (2003) ‘Body fat in adult man: semicentenary of fat density and skinfolds’, Acta Diabetologica, 40, pp. 242-245
  • Hulmi, J.J., Isola, V., Suonpaa, M., Jarvinen, N.J., Kokkonen, M., Wennerstrom, A., Nyman, K., Perola, M., Ahtiainen, J.P., Hakkinen, K. (2016) ‘The Effects of Intensive Weight Reduction on Body Composition and Serum Hormones in Female Fitness Competitors’, Frontiers in Physiology, 7(689).
  • Jones, B., Emmonds, S., Hind, K., Nicholson, G., Rutherford, Z., Till, K. (2016) ‘Physical Qualities of International Female Rugby League Players by Playing Position’, Journal of Strength and Conditioning Research, 30(5), pp. 1333-1340.
  • Lee, D.H., Keum, N., Hu, F.B., Orav, E.J., Rimm, E.B., Willett, W.C., Giovannucci, E.L. (2018) ‘Predicted lean body mass, fat mass, and all cause and cause specific mortality in men: prospective US cohort study’, British Medical Journal, 362.
  • Nunes, H., De Souza, E., Orssatto, L.B., Moreno, Y.M., Loturco, I., Duffield, R., Silva, D.A., Guglielmo, L.G. (2020) ‘Assessing body composition in rugby players: agreement between different methods and association with physical performance’, Journal of Sports Medicine and Physical Fitness, 60(5), pp.733-742.
  • Pasin, F., Caroli, B., Spigoni, V., Dei Cas, A., Volpi, R., Galli, C., Passeri, G. (2017) ‘Performance and anthropometric characteristics of Elite Rugby Players’, Acta Biomedica, 88(2), pp. 172-177.
  • Stefan, N. (2020) ‘Causes, consequences, and treatment of metabolically unhealthy fat distribution’, The Lancet Diabetes & Endocrinology, 8(7), pp. 616-627

Published by Michelle Carroll

I am an online coach (MSc Sports & Exercise Nutrition, EQF Level 4 Personal Trainer, PN Level 1) and radiographer (BSc). I believe in empowering others to make better choices for their health through education. I think that the fitness industry has created a disconnect between best practices and “evidence-based” practices. I hope by chronicling my experience as a healthcare professional and my education as a fitness professional I can assist others on the path to bettering themselves.

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