Changing body composition and anthropometry
Body composition changes with growth and maturation, and due to influences such as diet and exercise. Anthropometry is the comparative study of sizes and proportions of the human body. This chapter provides an overview of body composition, anthropometric methods used to assess body composition, and how body composition can be modified through diet and exercise.
LEARNING OUTCOMES
Upon completion of this chapter you will be able to:
• provide a definition of body composition
• outline techniques used to assess body composition
• describe how body composition can be modified.
Body composition is a term that is commonly used when referring to the amount of fat relative to muscle you have in your body. However, this technically is total body fat and fat-free mass (FFM), which includes muscle, water and bone. Body composition is, therefore, the relative proportions of fat, protein, water and mineral components in the body. Almost 99 per cent of the human body mass is composed of six elements: oxygen, carbon, nitrogen, hydrogen (and smaller quantities of their stable isotopes), calcium and phosphorus.
Isotope
Atoms that have the same number of protons and electrons but a different number of neutrons.
Body density
The compactness of a body, defined as the mass divide by its volume.
Body composition varies among individuals due to differences in body density and degree of obesity. Bone is more dense than muscle, which is more dense than fat. If there is relative loss of bone density (osteoporosis) or decrease in muscle mass (with reduced training), fat mass may be overestimated when using densitometry techniques to calculate the ratio of fat mass to fat-free mass. Densitometry techniques include underwater (hydrostatic) weighing and air displacement plethysmography (Bod Pod®).
TECHNIQUES USED TO ASSESS BODY COMPOSITION
Extracellular water
Water that is outside the cells, including the water between the cells and the plasma.
Visceral adipose tissue
The adipose tissue within the abdominal cavity, which is wrapped around the organs.
Subcutaneous adipose tissue
Adipose tissue directly under the skin.
Intermuscular adipose tissue
Adipose tissue located within the skeletal muscle.
Ectopic fat depots
Excess adipose tissue in locations not usually associated with adipose tissue storage, such as in the liver or around the heart.
Anthropometry is the comparative study of sizes and proportions of the human body. We most commonly use surface anthropometry techniques to assess body composition.
However, there are a variety of body composition (physique assessment) techniques that can be selected. Assessment of body composition may be conducted using non-imaging (surface anthropometry, air displacement plesthmyography, three-dimensional body scanning, doubly-labelled water, bioelectrical impedance, new innovations), and imaging techniques (dual energy X-ray absorptiometry, ultrasound, computed tomography and magnetic resonance imaging). See the recently published guidelines for more information on how to use selected physique assessment methods and report data to athletes and coaches (Hume et al. 2017).
Combinations of techniques allow measurement of fat, fat-free mass, bone mineral content, total body water, extracellular water, total adipose tissue and its subdepots (visceral, subcutaneous and intermuscular), skeletal muscle, select organs, and ectopic fat depots (Lee & Gallagher 2008). Clinicians and scientists can quantify a number of body components and can track changes in physique with the aim of determining efficacy of training, nutrition and clinical interventions.
Selection of techniques to assess body composition is dependent upon factors including the validity, reliability, cost, safety, time for data collection and analysis, skill required for the practitioner and accessibility of the technology. It is important to consider:
• why you measure body composition using the techniques and technologies
• precision and accuracy, validity, practicality, and sensitivity to monitor changes in body composition using the technique
• advantages and disadvantages of the technique
• the equipment/hardware, calibration, software, skills required, training and accreditation for techniques
• client presentation and preparation protocols for the techniques.
Athlete presentation for measurement is important, as hydration levels will affect the results. Factors such as time of day, prior food or fluid intake, exercise, body temperature, hydration status and gastrointestinal tract contents should be standardised wherever possible prior to any physique assessment. Given the diurnal variation in body mass, fasted early morning assessments following bladder and possibly bowel evacuation are the most reliable where practical.
Diurnal
The 24-hour period or daily cycle, such as being active during the day and resting at night.
Surface anthropometry assessment
The International Society for the Advancement of Kinanthropometry (ISAK) provides international standards for surface anthropometry assessment, using basic measures of skinfolds, girths, lengths and breadths. A restricted profile includes two basic measures (body mass, height), eight skinfolds (triceps, biceps, subscapular, iliac crest, supraspinale, abdominal, front thigh, calf), five girths (upper arm relaxed, upper arm tensed, waist, hips, calf) and two breadths (elbow, knee). A full profile includes all the restricted profile measures plus additional measures, resulting in a total of four basic measures, eight skinfolds, 13 girths, eight lengths and nine breadths.
The advantages of ISAK surface anthropometry methods are that assessments take approximately ten minutes for a restricted profile and up to 30 minutes for a full profile, and the equipment is readily available and easily calibrated. The methods are valid and reliable if ISAK training is undertaken to ensure correct use of anatomical bony landmarks (Hume & Marfell-Jones 2008) and correct use of calipers. The disadvantage of the ISAK surface anthropometry technique is that skinfold calipers compress the adipose (fat) tissue, resulting in variation in measurements. To help reduce the effects of skinfold compressibility, a complete set of skinfold measurements is obtained before repeating the measurements.
Air displacement plethysmography (Bod Pod®)
Air displacement plethysmography is used to measure body volume and calculate estimates of body density. The Bod Pod® (COSMED USA Inc., Concord, CA) device consists of a measurement pod of two isolated chambers to measure body volume, a calibratable set of scales and a computer attached to each measurement device. The Bod Pod® is easy to use and non-invasive. Completion of the test including accurate body mass, multiple measures of body volume, and either measurement or estimation of lung gas volume, takes approximately ten minutes from stepping on the scales to stepping out of the Bod Pod®.
During measurement the client sits quietly in the measurement chamber, breathing normally and minimising movement. The chamber has a magnetically locking door with a clear window. Within the measurement pod, the technology allows estimation of lung volume. Two measurements of body volume are undertaken, with a third required if the first two measures are not within 150 millilitres. Once body volume has been calculated the software provides body-fat percentage and absolute values of fat mass and fat-free mass. The Bod Pod® will underestimate fat mass compared to other physique assessment techniques if there are poor standardisation practices in athlete presentation.
Bioelectrical impedance analysis (BIA)
Bioelectrical impedance analysis (BIA) allows measurement of total body water, which is used to estimate fat-free body mass and, by difference with body mass, body fat. BIA assessment devices are readily available and assessment is quick compared to other methods. A client appointment of 15 minutes is needed for body mass and standing stature measurement, electrode placement and then one minute of data collection. The technique is client-friendly as it is non-invasive and there is low health risk. The procedure is simple and there is good portability of the equipment. BIA is relatively low cost compared to other methods of body composition analysis. However, precision and validity is low.
Sensitivity to monitor change of physique is low given that variation in client presentation for testing can affect the results (for example, levels of hydration) (Kerr et al. 2017). The techniques to collect the data are simple; however, interpretation of the data is impeded given that the formulas used by the equipment to calculate body-fat/fat-free mass are not readily available and instead only a final figure/figures are displayed. Client preparation for measurement is important given the effect of hydration on results. Training of the technician is needed to ensure correct preparation of the skin and reliable placement of electrodes on the ankle and the wrist. Regional body assessment is possible but is invalid.
Deuterium dilution–doubly-labelled water technique
The doubly-labelled water technique (commonly known as deuterium dilution) is used to measure body water and total energy expenditure. The technique requires the client to consume a stable isotope water (known as doubly-labelled water) and then provide urine samples for several days after the initial ingestion. The technique is a non-invasive way of measuring the rate of carbon dioxide production in clients over a period of seven to 14 days. The most sensitive means of measuring the isotopes of deuterium and oxygen-18 in the samples is by isotope ratio mass spectroscopy. Due to the technical nature, cost and lack of availability of the equipment, the use of the technique is uncommon. The reliability of the technique is high. Regional body assessment is not possible; instead, total body water, fat-free mass and fat mass are calculated. The time commitment for clients is approximately six hours given the repeat samples required.
Ultrasound
The ultrasound technique for measurement of subcutaneous adipose tissue and embedded fibrous structures employs image capture from any standard-brightness mode ultrasound machine, followed by an image-analysis procedure. The technique avoids compression of the tissues and movement that occurs when using skinfold calipers. As with skinfolds, the ultrasound technique only samples the subcutaneous adipose tissue and does not measure the fat stored in deeper depots. It is an accurate and reliable technique for measurement of subcutaneous adipose tissue provided the practitioner has had certified training in the data collection and use of the analysis software
All participants must be marked prior to measurement. Measurements are taken from eight standard measurement sites: upper abdomen, lower abdomen, erector spinae, distal triceps, brachioradialis, lateral thigh, front thigh, medial calf. The operator places the centre of the ultrasound probe over the marked site to capture an ultrasound image.
Magnetic resonance imaging (MRI) and computed tomography (CT)
Magnetic resonance imaging and computed tomography are imaging techniques that provide highly accurate measures of body composition at the tissue-organ level. Computed tomography works through measuring the attenuation of X-rays through body tissues, whereas magnetic resonance imaging uses a strong magnetic field to align positively charged protons in the body’s tissues which are then digitised to provide an image. Magnetic resonance imaging is a safer method than computed tomography as it does not expose participants to radiation. Due to high cost and low availability, these techniques are generally only used for clients as part of a medical assessment or for research purposes. Both techniques are considered reference methods for body composition assessment due to their high precision and validity.
Dual energy X-ray absorptiometry (DXA)
Dual energy X-ray absorptiometry (DXA) is regarded as the current gold standard for determining body-fat percentage and lean mass. The DXA machine emits sources of X-ray energies which pass through the body, enabling determination of bone mineral content, lean mass and fat mass for the whole body and for regional areas. Given the use of X-rays (exposure to radiation), the International Society for Clinical Densitometry has established clinical practice guidelines relating to the collection and analysis of DXA data. Standardisation of how athletes present for scanning is important. Ideally it should be done in the morning and they should be well hydrated (urine specific gravity (USG) measurements may be taken), glycogen replete (not having exercised heavily the day before), overnight-fasted and in minimal clothing (such as singlet and underwear). They should be correctly positioned on the scanning bed, being centrally aligned in a standard position using custom-made positioning aids (foam blocks). Following the scan, images should be reviewed so that the automatic segmentation of body regional areas of the scan can be checked and adjusted manually if required. Body composition assessment using such a protocol will ensure a high level of precision, while still being practical for clients. An assessment can usually be completed within ten minutes.
Three-dimensional body scanning
Three-dimensional body scanning is used to determine surface anthropometry characteristics such as body volume, segment lengths and girths. Three-dimensional scanning systems use laser, light or infra-red technologies to acquire shape and software to allow manual or automatically extracted measures. Body posture during scanning is important to ensure accurate measures can be made from the images. The images vary depending on the configuration, resolution and accuracy of the scanner. Training is required to ensure successful use of three-dimensional scanning hardware and software. The hardware for full body scanning is expensive, so the technique is not commonly available yet. Three-dimensional body scanning protocols (Stewart & Hume 2014) are available at the J.E. Lindsay Carter Kinanthropometry Archive <https://www.aut.ac.nz/study/study-options/sport-and-recreation/research/j.e.-lindsay-carter-clinic-for-kinanthropometry>.
Three-dimensional body scanning systems integrated with other imaging modalities to create multifaceted digital human profiles, and artificial intelligence techniques such as deep learning and artificial neural networks, are set to revolutionise the physique assessment landscape over the coming decade. Using computer vision techniques, it is now possible to register an individual’s DXA-derived body composition with the mesh exported by the same individual’s three-dimensional body scan. Technological and computing innovations are rapidly transforming the tools we employ for measuring, recording, collating and interpreting body dimension and composition assessments.
HOW BODY COMPOSITION CAN BE MODIFIED
Body composition changes with growth and maturation, and due to influences such as diet and exercise. Body characteristics such as stature (height), skeletal lengths and breadths are not adaptable except during the growth periods, but body mass, lean mass and fat mass are more modifiable and can be manipulated. The influence of a person’s genetic profile impacts on their presenting body shape (morphology), as well as their responsiveness to interventions that aim to change body composition and shape (Ivey et al. 2000) and the associated physique capacity (Kouri et al. 1995).
Morphology
The body shape.
Morphological prediction
The prediction of the adult body shape from a growing child or adolescent.
Morphological prototype
The best body shape and distribution of soft tissue to maximise performance in a given sport.
Anticipating adult physique in a growing child (morphological prediction) has implications for athlete talent identification and development for sports performance (Hume & Stewart 2012). During growth, segment breadths are most useful for prediction of adult dimensions because they remain stable in relation to stature throughout adolescence. Changes in soft tissue for maximum functional effectiveness (morphological prototype) respond to training. Alignment of morphology to performance, and recognition of the wide individual variability in maturation rate, helps avoid biasing athlete selection or overlooking individuals with athletic potential.
Body composition information can be used to monitor the effectiveness of physique manipulation via exercise or nutrition (Cole et al. 2005) interventions. Physique assessment allows identification of clients who require additional support to restore or maintain physique status (for example, at-risk clients who have lost or gained weight rapidly). Monitoring the progress of clients in meeting their physique goals (such as strength and conditioning goals to increase muscle mass) provides motivation to continue in the intervention.
Dietary approaches to change body composition
Gaining weight
When an athlete is interested in weight gain, in most cases muscle gain is desired. For muscle gain to occur, two key things need to be present: excess energy intake to provide energy for anabolism, and a good training program to activate the muscle tissue and encourage growth and development.
From a dietary perspective, an excess of 2000–4000 kJ/day is usually required to generate consistent muscle gain. This is best achieved by eating regular meals and snacks that are high in energy and nutrients. It is realistic to expect muscle gain of 2–4 kilograms per month; however, rates of muscle gain vary between individuals and genetics can play a considerable role. Consistency, in terms of both diet and training program, is key for successful muscle gain. Excessive energy intake without appropriate training will result in fat gain instead of muscle gain.
As an example, the following foods combinations can provide an additional 2000 kJ:
• full-fat fruit yoghurt (200 g) plus 25 almonds plus medium banana OR
• half a large avocado spread on two slices of toast and an apple.
Eating enough food to obtain the additional energy can be challenging for some athletes, so simple meal and snack ideas can make a big difference. In recent times, the popularity of ‘shakes’ and smoothies has been helpful for athletes trying to gain weight, as some find it easy to throw ingredients in the blender, mix and drink versus eating.
Working with individual athletes to put together a realistic eating plan is very important; if a plan is not followed consistently, results are likely to be slow. Additionally, prioritising real foods over weight-gain supplements is highly recommended, as the nutrient density of wholesome real foods is likely to outweigh commercial protein powder-based products.
Losing weight
Generally, when weight loss is desired it is ‘fat’ loss people think about; while fat is the most common form of weight athletes may want to lose, there are circumstances—such as in weight category sports—where athletes may not be concerned about what weight type they lose as long as they weigh in below the cut-off (see Chapter 17).
Nutrition professionals generally recommend that weight is lost slowly, aiming for about 500 grams weight loss per week. This can be achieved through a 2000 kJ/day energy restriction—that is, reducing energy intake by 2000 kJ every day below total requirements. This should be planned based on current dietary intake and on what the individual’s body composition has been over the last 2–3 months, as well as any planned changes in training. If training is to remain consistent and weight has been stable, then reducing the athlete’s usual diet by 2000 kJ per day can often be effective. This can be done by reducing portion sizes at each meal time or by cutting out unnecessary items and discretionary foods.
The best approach will vary from athlete to athlete, and hence should be planned in a collaborative way. However, if weight has not been stable over the last 2–3 months (either increasing or decreasing) and/or training is about to change considerably, then more care will need to be taken to determine a suitable total dietary intake to enable healthy weight loss to occur.
ISSUES TO CONSIDER FOR BODY COMPOSITION ASSESSMENT
Data interpretation
Physique assessment provides valuable information; however, taken in isolation physique assessment can easily be misinterpreted or misused. Additional information, such as dietary intake and training load, and input from exercise and health professionals, is required to fully interpret findings and make recommendations.
Physique and sport
Profiling of athletes at all levels of participation in sport can help determine potential suitability for sport and effectiveness of interventions such as diet and training. As scientists and clinicians, we ask what physique characteristics are important for athletes in the sports we work with to help improve performance (Keogh et al. 2009) or reduce injury risk; what should we measure and monitor? Athletes, and their coaches, often ask how the athletes’ physique compares to elite athletes in their sport. Accessing normative data for athletes at all levels of participation from development to elite can be difficult. Consideration of population trends for physique characteristics in normative databases is needed. Where possible, current research data should be gained to enable comparisons of physique characteristics for athletes of similar age, gender, ethnicity and sports participation level.
Large-scale surveys of world-class athletes have been conducted at Olympic Games (Kerr et al. 2007) and world championship events for over 60 years. These projects have provided data for identifying unique physique characteristics for selected sports that aim to optimise power, leverage or have a high metabolic demand. Physique characteristics play an important role in the self-selection of individuals for competitive sport. However, as a large number of factors are involved in the physical make-up of a champion sportsman or sportswoman, there is not necessarily one perfect body shape for a particular sport or event within that sport. Anthropometric tools have been used in profiling athletes’ trajectory to optimising the trainable parameters at the times that matter most. This is important for weight category sports, where athletes may be at risk of employing unsafe weight control practices in order to ‘make weight’. Rowing and powerlifting are two sports that require body mass to meet weight class categories for competition. Gymnastics is a sport that has pressure for leanness due to aesthetic reasons (see Chapter 17). We need to understand what physique characteristics are important for athletes to help improve performance or reduce injury risk.
Body image
The concept of body image includes how we perceive, think, feel and, ultimately, behave due to our own conception of our physical image. Body-image dissatisfaction is when there is a difference between our perceived body image and our desired body image. The prevalence of body-image disorders in athletic populations remains worryingly high. The assessment of body image in people may progress with the use of modern three-dimensional scanning technology together with volumetric assessment. The novel iPad SomatoMac application may be useful for estimates of body-image dissatisfaction and distortion, especially in athletes (Macfarlane et al. 2016).
Body-image disorder
A mental disorder in which an individual continually focuses on one or more perceived flaws in appearance that are minor or not observable to others.
Somatotype
Classification of the human physical shape according to the body build or shape.
The SomatoMac application uses male and female somatotype photographs that allow more comprehensive estimates of body-image dissatisfaction than existing figural silhouettes and pictorial scales.
TRAINING OF PHYSIQUE ASSESSMENT PROVIDERS
Training, accreditation and quality-assurance schemes ensure appropriate levels of professionalism and safety for the public who utilise physique assessment programs. There are only two international training and certification programs for surface anthropometry and ultrasound techniques. Manufacturers’ training on equipment is provided for three-dimensional scanning, Bod Pod®, bioelectrical impedance analysis, dual energy X-ray absorptiometry, magnetic resonance imaging and computed tomography. Ethical considerations in assessing anthropometry profiles for clients are important. Practitioners need to maintain professional objectivity and integrity and respect the client during physique assessment. Client safety and wellbeing are paramount in assessments, and practitioners must ensure the client understands all procedures and that consent is gained to conduct the physique assessment.
SUMMARY AND KEY MESSAGES
After reading this chapter, you should understand what body composition is, understand the importance of the validity and reliability of methods used to assess body composition, and be familiar with how body composition can be modified. You will have identified anthropometric methods that can help you to monitor your ability to achieve goals of modifying body composition.
Key messages
• Body composition is the relative proportions of fat, protein, water and mineral components in the body.
• Anthropometry is the comparative study of sizes and proportions of the human body.
• There are valid and reliable techniques used to assess body composition; however, practitioner training is required and client presentation for assessment can affect results.
• Body composition can be modified via growth and development, diet and exercise.
• Athletes aiming to gain muscle mass need to make sure they consistently eat appropriate foods containing the required amount of additional energy (excess of 2000–4000 kJ/day) and exercise appropriately.
• Athletes aiming to lose fat mass need to make sure they consistently have an energy deficit of 2000 kJ/day.
• Physique assessment provides an objective measure of body composition status in relation to physical performance, health status and diet.
REFERENCES
Cole, C.R., Salvaterra, G.F., Davis, J.E.J et al., 2005, ‘Evaluation of dietary practices of national collegiate athletic association division I football players’, Journal of Strength and Conditioning Research, vol. 19, no. 3, pp. 490–4. Hume, P. & Marfell-Jones, M., 2008, ‘The importance of accurate site location for skinfold measurement’, Journal of Sports Science, vol. 26, no. 12, pp. 1333–40. Hume, P.A., Kerr, D. & Ackland, T. (eds), 2017, Best Practice Protocols for Physique Assessment in Sport, Singapore: Springer Nature Singapore. Hume, P.A. & Stewart, A.D., 2012, ‘Body composition change’, in Stewart, A.D. & Sutton, L. (eds), Body Composition in Sport, Exercise and Health, London, UK: Taylor and Francis, pp. 147–165. Ivey, F.M., Roth, S.M., Ferrell, R.E. et al., 2000, ‘Effects of age, gender, and myostatin genotype on the hypertrophic response to heavy resistance strength training’, Journal of Gerontology, vol. 55, no. 11, pp. M641–8. Keogh, J.W.L., Hume, P.A., Mellow, P. et al., 2009, ‘Can absolute and proportional anthropometric characteristics distinguish stronger and weaker powerlifters?’, Journal of Strength and Conditioning Research, vol. 23, no. 8, pp. 2256–65.
Kerr, A., Slater, G. & Byrne, N., 2017, ‘Impact of food and fluid intake on technical and biological measurement error in body composition assessment methods in athletes’, British Journal of Nutrition, vol. 117, no. 4, pp. 591–601.
Kerr, D.A., Ross, W.D., Norton, K.P. et al., 2007, ‘Olympic lightweight and open-class rowers possess distinctive physical and proportionality characteristics’, Journal of Sports Sciences, vol. 25, no. 1, pp. 43–5.
Kouri, E.M., Pope, H.G., Katz, D.L. et al., 1995, ‘Fat-free mass index in users and nonusers of anabolic-androgenic steroids’, Clinical Journal of Sports Medicine, vol. 5, no. 4, pp. 223–8.
Lee, S.Y. & Gallagher, D., 2008, ‘Assessment methods in human body composition’, Current Opinion in Clinical Nutrition and Metabolic Care, vol. 11, no. 11, pp. 566–72.
Macfarlane, D.J., Lee, A., Hume, P. et al., 2016, ‘Development and reliability of a novel iPad-based application to rapidly assess body image: 3776 Board# 215’, Medicine & Science in Sports & Exercise, vol. 48, no. 6, p. 1056.
Stewart, A.D. & Hume, P.A., 2014, Bideltoid Breadth Measurement [Online], J.E. Lindsay Carter Kinanthropometry Archive 3D Scanning Protocols, available at: www.sprinz.aut.ac.nz/clinics/j.e.-lindsay-carter-kinanthropometry-clinic/archive.