Background Successful performers in weight-sensitive sports are characterised by low body mass (BM) and fat content. This often requires chronic energy restriction and acute weight loss practices.
Aim To evaluate current use of body composition (BC) assessment methods and identify problems and solutions with current BC approaches.
Methods A 40-item survey was developed, including demographic and content questions related to BC assessment. The survey was electronically distributed among international sporting organisations. Frequencies and χ2 analyses were computed.
Results 216 responses were received, from 33 countries, representing various institutions, sports and competitive levels. Of the sample, 86% of respondents currently assess BC, most frequently using skinfolds (International Society for the Advancement of Kinanthropometry (ISAK): 50%; non-ISAK, conventional: 40%; both: 28%), dual energy X-ray absorptiometry (38%), bioelectrical impedance (29%), air displacement plethysmography (17%) and hydrostatic weighing (10%). Of those using skinfolds, more at the international level used ISAK, whereas conventional approaches were more reported at regional/national level (p=0.006). The sport dietitian/nutritionist (57%) and physiologist/sports scientist (54%) were most frequently the professionals assessing BC, followed by MDs and athletic trainers, with some reporting coaches (5%). 36% of 116 respondents assessed hydration status and more (64%) did so at international than regional/national level (36%, p=0.028). Of 125 participants answering the question of whether they thought that BC assessment raised problems, 69% said ‘yes’, with most providing ideas for solutions.
Conclusions Results show high use of BC assessment but also a lack of standardisation and widespread perception of problems related to BM and BC in sport. Future work should emphasise standardisation with appropriate training opportunities and more research on BC and performance.
- Body composition methodology
- Exercise and/or caloric restriction effects on body weight/composition
- Injury Prevention
- Eating disorders
- Sports and nutrition
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- Body composition methodology
- Exercise and/or caloric restriction effects on body weight/composition
- Injury Prevention
- Eating disorders
- Sports and nutrition
In response to concerns regarding adverse health outcomes resulting from extreme dieting and weight loss practices, the Medical Commission of the International Olympic Committee (IOC) established an ad hoc Research Working Group on Body Composition Health and Performance of Athletes (BCHP) in 2010. Of particular concern was the potential for irreversible loss of bone mass and loss of reproductive function secondary to disruptions of pituitary and gonadal function.1 The aim of the group was to
Identify medical problems due to unhealthy practices in sports leading to extremes of underweight or overweight, short-term weight reduction, dehydration or other body composition (BC) disturbances.
Identify research needs in the field of BC, health and performance in sport, aiming to develop a scientific foundation upon which strategies for improving the health of athletes can be based.
Develop suggestions for practical strategies capable of solving BC and underweight problems in sports.
Determine whether an optimum BC and minimum values for body fat (BF) content, body water content and other parameters can be established.
The first outcome of the group was to review methods used for BC assessment of athletes, and in particular the limitations to the reliability of these methods.2 It became apparent from this review that few sports organisations had a coherent strategy for the management of BC issues in their sport. A diverse range of methods for BC assessment are in use, limiting the possibility of making meaningful comparisons between sports and even within sports. More significantly, uncertainties over the reliability of measurements of BF levels preclude the possibility of establishing cut-off points that can reasonably be applied. There has been no systematic collection of information on the anthropometric and BC measurements made on elite athletes or on the roles of the various sports medicine and sport science team members involved in collecting this information and managing BC issues. The aim of the present study, therefore, was to collate this information with a view to exploring the feasibility of establishing a database of BC assessment practices and strategies for the management of this information in elite sport. A second aim was to use this analysis of the status quo as the basis for recommendations on BC assessment practices.
This study was an exploratory study. A survey was developed to assess current methods used among international practitioners, scientists and medical and health professionals for the assessment of the BC of athletes. The survey contained 24 questions, many of which had subquestions, resulting in a 40-item questionnaire. The survey included questions relating to demographics (eg, country of residence, institution or organisation, level of competition, sports, position within institution/organisation) and content questions related to BC methods and applications. Questions addressed whether respondents assessed BC, who in the organisation/institution assessed BC, what BC methods were used, and why, when and how often they were used within the annual training/competition cycle. Questions also focused on the pathways from referral for measurement to data dissemination. Further questions pertained to whether practitioners used standardisation approaches, including hydration testing, to increase validity and reliability of measures. Several questions pertained to norms and the use and application of minimum/maximum BC or body mass (BM) values for health and performance reasons. Finally, several questions related to the problems participants encountered concerning the current focus on BC in sport, whether solutions had been identified and successfully implemented, and what barriers to implementation, if any, were identified.
The questions were developed by one member of the Ad Hoc Working Group on BCHP of the IOC Medical Commission, and content validity was obtained through the review of the survey by the other members (n=7), all of whom are internationally recognised experts in BC research and practice. The survey was finalised using features which excluded forced completion of each question, allowing respondents to opt out from questions they did not want to answer. Finally, the survey was prepared for electronic distribution using Survey Monkey (http://www.surveymonkey.com). The survey link was distributed among a convenience sample of national and international sport science, medicine and nutrition listserves, organisation member email lists, by word of mouth and through established contacts of the working group. The study was approved by the University of Colorado, Colorado Springs Institutional Review Board and all respondents provided informed consent by completing the survey.
Data were analysed using descriptive statistics. Continuous variables are expressed as means±SD and categorical variables as frequencies (%). Several categorical variables were recoded and used as filters to describe the data (ie, competitive levels, geographical region (continents), weight-sensitive sports). Data reflect overall respondents as well as the n-size of responding participants for each specific question. Where applicable, data were analysed using χ2 analysis. The type I error rate was set at α=0.05 for all tests.
Qualitative responses (open ended) were analysed according to Creswell.3 Data were first examined by highlighting significant statements which were then assigned to categories of meaning. These categories of meaning were then expressed as emerging themes using scientific terminology according to the current scientific topic. All working group members, except for the lead author, were involved in the qualitative data analysis process. In addition, a graduate sport nutrition student also assisted with the qualitative analysis.
Two hundred and sixteen participants initially logged on to begin the survey, with 188 participants from 33 countries completing it. Most respondents were from North America, Europe and Oceania (figure 1). The sample comprised a variety of health professionals (figure 2) with variable experience. Professional experience ranged from 0.2 to 48 years, with an average of 9.2±8.6 years. Sport dietitians had 6.4±6.2-year experience, sports scientists 7.4±7.4 years, medical doctors 12.5±9.6 years, professors 13.5±11.4 years, athletic trainers (ATC) or physical therapists (PTs) 13.8±8.8 years, coaches (including strength and conditioning coaches) 11.9±11.9 years, and students 3.8±4.9 years. About half of the participants (51%) reported they were currently involved in research of BC in sport. The distribution of professionals working with athletes was equally spread among regional, national and international levels. Most professionals worked with a variety of sports, including weight-sensitive sports. There were 109 professionals (58%) working partly or exclusively with weight-sensitive sports (eg, endurance, gravitational, weight category, aesthetic; table 1), with 55 (30%) working with other sports. Twenty-four individuals did not respond (12%) as to the sport with which they are currently working. Of 159 respondents, 86% (n=137) reported regularly assessing BC in athletes. Of those not assessing BC directly, 48% (n=11) reported that someone else in their organisation assessed BC. Thus, 79% (n=148) of professionals completing the survey confirmed measuring BC in athletes in their organisation.
For the following analysis, all responses (ie, from those measuring directly and those reporting on behalf of their measuring team) were included. The methods most commonly used to assess BC are shown in figure 3. Of those using skinfold methods, more reported using the International Society for the Advancement of Kinanthropometry (ISAK) protocol at the international (67%) than at the regional/national level (33%; p<0.0001). Skinfold approaches other than the ISAK method, hereafter referred to as ‘conventional’ skinfold approaches, were reported at both regional/national (56%) and international level (44%). The use of dual energy X-ray absorptiometry (DXA) was more commonly reported at international (60%) than regional/national level (40%; p=0.015), with all other methods similarly used among competitive levels. Table 2 shows the distribution of the most common BC methods across continents (ie, Europe, Americas, Oceania and Other). Significant group (by continent) differences were found for ISAK and conventional skinfold approaches, bioelectrical impedance (BIA) and DXA (p<0.05). The use of ultrasound was reported exclusively in Europe (n=4; 7%). The use of DXA and ISAK was more commonly reported by professionals working with weight-sensitive sports (p<0.05) than professionals working with non-weight-sensitive sports.
The sport dietitian/nutritionist (57%) and physiologist/sports scientist (54%) were most frequently the professionals assessing BC, followed by MDs (14%), ATCs (13%) and PTs (4%), with smaller numbers reporting that strength/conditioning coaches, other allied health professionals and coaches undertook the assessment of BC (multiple answers were possible). The sports scientist/physiologist was reported to perform measures of BC more frequently at the international (p<0.0001) versus regional/national level, while the sport dietitian/nutritionist was equally mentioned to perform measures at all competitive levels. By continent, sport dietitians/nutritionists and exercise scientists/physiologists working in Oceania were more frequently reported to perform measures of BC in athletes than in Europe and the Americas (p<0.05). Forty-two sport dietitians/nutritionists (70% of responding sport dietitians) and 42 physiologists/sports scientists (69% of responding physiologists/sports scientists) reported assessing BC in weight-sensitive sports, while this number dropped to 18 sport dietitians/nutritionists (30%) and 19 physiologists/sports scientists (31%) in non-weight-sensitive sports. These differences were not statistically significant. Further, 13 sports medicine physicians (81% of responding physicians) reported assessing BC in weight-sensitive sports, with three (19%) assessing BC in non-weight-sensitive sports. Eight ATCs (57% of responding ATCs) and two PTs (40% of responding PTs) reported assessing BC in weight-sensitive sports, while six ATCs (43%) and three PTs (60%) reported assessing BC in non-weight-sensitive sports. Two coaches (33% of responding coaches) assessed BC in weight-sensitive sports, while there were four (67%) assessing BC in non-weight-sensitive sports.
Frequency of BC measures ranged from weekly to once per annual training/competition season. Figure 4 shows the frequency of BC testing of athletes. A large number of respondents chose to respond under the open-ended ‘Other’ category for the question of how often they were assessing BC. Most ‘Other’ responses included notes, which are qualitatively summarised in box 1. For all filters (eg, competitive levels, continents and weight-sensitive sports), the open-ended ‘Other’ category appeared more prevalent, but this was statistically significant only for respondents working primarily with weight-sensitive sports compared with those working with non-weight-sensitive sports (p=0.003).
Responses provided under ‘other’ for frequency of body composition (BC) assessment in sport
Common themes identified
Depends on the individual athlete and the sport
Determined by goals, health status, training season and weight management needs
Depends on research protocols (every 6 months)
Depends on methods: skinfolds taken monthly and DXA five times/season/year
Based on seasonal monitoring in certain sports (ie, more frequent assessment when in-season vs off-season)
“While it varies, we don't believe in overdoing it, as it can do harm if the athlete focuses on BC. They put too much emphasis on BC than on smart training and nutrition to improve performance.”
“Athletes who are asked to make or self-initiate BM/BC changes are offered BC assessment if consulting with a nutritionist.”
Standardisation of BC methods
Most common approaches to standardisation were the choice of BC method and use of the same protocol (eg, standardised preparation prior to testing, test protocol and tester training). Using the ISAK certification scheme, population-specific equations for body density and % BF, calibrated and well-maintained equipment, high-quality equipment (eg, type of calliper and tape), quality assurance testing (DXA) and establishing intratester reliability (ISAK) were also common responses.
Hydration status assessment prior to BC measures was reported by 36% (n=42) of professionals (116 responded): more reported doing so at international (n=27; 64%) than regional/national level (n=15; 36%; p=0.028) and hydration testing was more commonly reported in weight-sensitive sports (p=0.009). Common hydration assessment methods are shown in table 3. In addition to hydration status, 81% (n=113) of professionals reported using other parameters in combination with BC testing, and this was more common in weight-sensitive sports (74%; n=65) than non-weight-sensitive sports (26%; n=23; p=0.006), with no difference among competitive levels or continent. Other parameters commonly assessed and standardisation procedures employed are qualitatively summarised in table 4.
From requests for BC assessment to data dissemination
Table 5 shows who makes BC requests and the rationale for those BC requests. Table 5 also shows what data are reported and to whom data are reported. It was apparent that respondents used a variety of referral and dissemination processes. When giving back BC data, the majority of respondents did not identify the person to whom they pass on the collected data. At the international level, the sum of skinfolds was more commonly reported than at regional/national level (p<0.0001), with no other differences. Sum of skinfolds was more commonly reported by professionals working in Oceania than Europe and the Americas (p<0.0001). Further, there was a trend for greater use of sum of skinfolds for reporting purposes in Europe than in the Americas (p=0.05), although %BF was also commonly reported in Europe. There were no differences for reporting BC data (fat vs lean variables) among continents or between weight-sensitive and non-weight-sensitive sport.
Nearly half (48%; n=63) of the respondents (n=132) reported using a minimum value (eg, BM; %BF) when evaluating BC or BM in sport, of whom 76% (n=48) responded with further details. Reported minimum values for %BF ranged from 4% to 10% for men and 9% to 15% for women. Of those who provided further details, 50% (n=24) reported using minimum %BF values of 5% and 12% for men and women, respectively. A further 25% (n=12) of respondents reported using a sum of skinfold (mm) minimum value: four used both mm and %BF. Professionals using sum of skinfold minimum values reported sex-specific and sport-specific ranges for the sum of 6, 7 and 8 sites. Frequently reported sum of skinfold minimum values, were 30 mm for men and 40 mm for women using six sites. However, most responses were sport specific and specific to the number of skinfold sites measured. Finally, a BM index ranging from 18 to 21 kg/m2 was also mentioned as a minimum value. Using minimum values was reported 53% of the time for Americas (n=32); 35% for Europe (n=22), 8% for Oceania (n=5) and 6% for ‘others’ (n=4). Minimum values were used with similar frequency in those working with weight-sensitive versus non-weight sensitive sports. Twenty-six per cent reported using a maximum value, with no differences among competitive levels, continents or sports.
When addressing the question of whether there are problems (eg, potentially unhealthy practices such as restrictive/disordered eating, excessive dehydration and additional exercise) encountered that may be associated with the focus on BM and/or BC in sport, 125 responded, with the majority (69%) perceiving problems with the focus on BM and/or BC in sport. Emerging themes that were reported as problems (80 responses qualitatively analysed) and how organisations currently deal with these problems (79 responses) were qualitatively analysed and are reported in box 2 and table 6.
Perceived problems associated with the focus on body mass (BM) and composition (BC) in sport
Common themes identified
Disordered eating/eating disorders; female athlete triad, body image issues; injuries
In weight-category sports, extreme BM loss through pathogenic methods; dehydration
Lack of knowledge; misperception that changes in BM/BC always improve performance
Lack of guidance in goal setting for BM/BC
Measures occur too frequently
Coaches encourage athletes to weigh themselves; coaches assess BM/BC
Personnel lack training to evaluate risk, and a lack of policy and procedures
Striving for peak performance and enhancing physical appearance through changes in BM/BC, both advertently and inadvertently
The Ad Hoc Research Working Group on Body Composition, Health and Performance was asked by the IOC Medical Commission to address several areas related to unhealthy weight control practices in sport leading to extremes in underweight and overweight, short-term weight reduction, dehydration or other BC disturbances and to develop suggestions for practical strategies capable of solving BC and underweight problems in sport. Among other activities1 this working group developed a survey to assess the use of BC methods, standardisation and perceptions of problems associated with BM and BC in an international sample of nutrition, sport science and medicine professionals and coaching staff. This study found that respondents use a variety of BC methods with a multitude of approaches to standardisation, referral and data dissemination, and reported a general lack of personnel training to identify at-risk athletes. Further, this research showed that the majority of the respondents perceived the focus on BM and BC in sport to be problematic, leading to issues of extreme underweight, eating disorders and misperceptions of the way altered BC affects performance (box 2).
The most commonly used BC methods were skinfolds (with and without %BF formulae). Owing to the low-cost, convenient data collection of skinfolds as a field method,2 it is not surprising that this method was used more than any other method. Measuring skinfolds is practical and requires limited equipment, but reliable scores can be expected only if technicians are well trained and protocols are standardised.2 ,4 The paper by Lohman4 illustrates that for one BC method, large interinvestigator variation and investigator measurement error occur due to calliper and equation employed. Skinfold measurements produce more variability if %BF is calculated using one of the numerous equations available, which often can lead to confusion, even though the %BF figure may be easier for athletes and coaches to grasp. Equations are population-specific2 and because much of the developmental work was carried out several decades ago using densitometry as the criterion, it is likely there is no equation available for the current sample of interest. An alternative to these approaches includes that which is currently followed by ISAK. Indeed, ISAK has carefully controlled landmarking for locating measurement sites and provides training in technique in an effort to constrain measurement error as far as possible. While the ISAK methodology does not preclude the use of the raw data in estimating density and %BF, it emphasises the value of raw data as individual skinfolds, skinfold sum or skinfold ratios. As a result, this approach eliminates the additional error associated with converting skinfolds into body density and %BF. Further, ISAK training is mandatory at each of its levels, with more stringent error targets for both intratester and intertester error at higher levels. While intratester error is frequently reported as justification for the precision of measurements from a laboratory, in practice, ISAK is the only approach which systematically reports intertester error—where a candidate technician's data are compared with those of an anthropometry instructor or criterion anthropometrist.5 At any rate, skinfolds remain limited in validity when used to predict %BF both by the reference method used and its assumptions, and also by how representative the sites chosen are of total body adiposity. The method and skill of technicians in acquiring skinfolds is pivotal, and while many laboratories report low intratester errors, intertester errors are more important, and standardisation of technique is fundamental. In the current study, ISAK methodology was reported to be used as frequently as other skinfold methods overall, but ISAK appeared to be used significantly more often in Oceania and Europe than in the Americas (including Canada, the USA and South America) and ISAK was also more often used in weight-sensitive sports than non-weight-sensitive sports. ISAK was first established in 1986, and to date has provided training to more than 5000 anthropometrists in over 50 countries, and remains the only internationally recognised certification scheme for anthropometry. While ISAK training and certification are offered world-wide, the availability of courses may be limited by certified ISAK specialists, and thus not all countries offer courses at the same frequency. The observation that the ISAK method is more frequently used in weight-sensitive sports is encouraging, as standardisation of BC methods is especially critical where the risks associated with extremes of BC are high.
Besides skinfolds, DXA, BIA and air displacement plethysmography (ADP) were other frequently reported BC methods. Of those measuring BC in our sample, 38% reported using DXA, with significantly more practitioners using DXA in Oceania than on other continents. The use of DXA for BC assessment was also reported more at the international level and in weight-sensitive sports. This is probably due to the fact that DXA technology is expensive and is often not accessible to athletes at the regional and national level. For athletes competing at the international level, national sport institutes may have DXA available on campus. In the case of DXA, both fat and bone mass can be assessed, and fat-free soft tissue mass predicted by subtraction from total mass. DXA also enables BC to be ascertained in each body segment or separate region of interest, making it one of the most appealing approaches to measuring BC in athletes.2 Against a four-component model, DXA accurately measures BF within 1% of error in ethnically diverse male and female athletes participating in various sports, with errors likely to be greatest at extremes of body fatness and lean tissue hydration.6 Recently, Nana et al7 examined various protocols reported in the literature in DXA studies over the past 15 years. These authors found a lack of standardisation for DXA positioning of participants, giving rise to error. In their article, they present a detailed positioning procedure others may adopt for future studies to allow for improved positioning of arms and legs on the DXA table. Further, DXA measures are thought to be less sensitive to changes in total body water than other measures,2 ,8 although new research suggests a significant influence of food intake, exercise and hydration status on DXA reliability and concludes that to achieve a minimum technical error and to estimate BC changes over time, all DXA measurements should be made in the fasted, euhydrated and rested state following a standardised positioning protocol by the same operator.9 In addition, there can be a loss of accuracy at the extremes of leanness (less than 10% BF), and in the heavier, more muscular individuals10 although software settings (eg, thin mode) may minimise discrepancies in %BF estimates from DXA in very lean individuals.
In the current study, the use of BIA was reported as widespread with 29% of those measuring BC in athletes choosing this method. There was a significant difference in the reported frequency of BIA use among continents, with Europe employing BIA more frequently than any other continent. BIA technology varies greatly: some units use single frequency and some use only upper extremities, lower extremities, while others use the whole body. Some devices incorporate multifrequency using the whole body. In addition, there are many BIA equations and only a limited number have been cross-validated in specific athletic populations.11 Currently, there is no evidence that BIA methodology is valid in athletes, especially considering the lack of generalised equation using a total body water-based, multiple component method.11 Furthermore, limited research supports BIA's validity to track changes in BC over time.12 Most importantly, the sensitivity of BIA to hydration status is much greater than any other BC method2 and variation in hydration status, due to sweat loss and dehydration from exercise in athletes has a significant effect on its validity. As with other BC methods, BIA may produce acceptable results if standardised protocols and raw data scores are used in the appropriate equation by body type, sex, age and sport.11
Of those measuring BC, 17% also reported the use of ADP. For this two-component method, body density depends on the given athlete having both normal BMD as well as a normal hydration status at the time of measurement. Variation in both areas can influence the fat free component and this is well documented in athletes,13 ,14 thus limiting the use of ADP and other densitometry techniques such as underwater weighing for the athletic population.2
Assessing BC over time is a common practice of those working with athletes. The results of this study showed that most practitioners select the frequency of BC measures based on individual circumstances (figure 4), but many also reported making 2–4 measurements/year, and some reported more frequent assessments. However, changes in BF content of 1–3% are not reliably detected by any method, so measuring changes by any method more than three or four times a year in the same individual is not recommended. Measurement of BM can be performed more often, where BM loss or gain is expected and needs to be monitored. As previously mentioned, most of the respondents to the survey reported that problems can arise with the focus on BM and BC in sport. Frequent BM and BC assessments were highlighted as a problem, as this can undoubtedly encourage the athlete to focus more on BM and BC than on performance. While some sports require frequent BM and BC assessment even during competitions, measuring BC on or close to the day of competition is discouraged as this could affect an athlete's mental make-up and negatively influence performance.
Standardisation of BC methods
Measuring hydration status is one element of standardisation among others (eg, pretesting protocol, calibrated equipment, certified tester; see tables 3 and 4) reported by survey participants. It was surprising to find that only 42 respondents reported the use of hydration measures prior to BC assessment. Considering the likelihood of non-responders to this question also not assessing hydration status, in all probability, less than one-fifth of our sample reported measuring hydration status prior to BC assessment. While data show that hydration status at the time of BC measurement has a smaller effect on skinfolds and DXA8 ,15 ,16 for BIA and ADP, hydration status can decrease the accuracy of BC estimates17 and is a major limiting factor when applying these methods to athletes.
Also critical to standardisation is the tester. It is apparent from the survey that sports scientists and dietitians were the professionals most commonly assessing BC, with the sports scientists more often measuring athletes competing at the international level and especially in Oceania. This may be due to the interdisciplinary approach to sport science and medicine at the elite level. Sport dietitians and sports scientists were also more likely to measure BC in weight-sensitive sports. Currently, BC certification exists only for ISAK, and thus there is concern regarding the various approaches to standardisation, even within one method such as DXA. Thus, publications such as the one by Nana et al9 appear essential and are needed also for other BC methods. The finding that others, including coaches, undertake measurement of BC was seen by some respondents as a major concern because of the potential for problems related to BM and BC testing in sports (box 2). While coaches, including strength and conditioning staff, may be equally trained in BC assessment as others in the sport science team, there is still a concern if BC is measured by the coaching staff. Ideally, BC assessment should be part of sport science assessment and best be linked to a sport dietitian who can directly follow-up with the athlete to assist with nutritional strategies if data indicate BC manipulations (see box 1). If coaches are directly involved with BC/BM assessment there must be careful consideration given to the sensitivity of such an environment and possible risks should be minimised. Further, BC is more often regarded as a performance-modifying tool than as a factor also affecting general health. There is no doubt that BC is a performance-determining factor in many sports; however, the dialogue less likely includes possible health risks associated with the focus on BC manipulation in sports. In addition, BC does not assume equal prominence with other physiological tests of athletes, especially those that are sport-specific and conducted frequently across the periodised training plan. Health professionals and coaching staff should treat each athlete's BC assessment, and subsequent goal setting and training/nutrition-related strategies as unique and a mindful risk assessment each time BC is measured is necessary by those testing the athlete's BC to reduce risk. Finally, integrating BC data with other performance-related parameters as well as subjective input from the athlete will likely offer the most diverse feedback to the interdisciplinary team working towards the common goal of athlete success.
From referral for BC assessment to data dissemination
Another aspect of standardisation relates to the process of BC requests and data dissemination. Various scenarios were reported from initiation of BC requests to what data get reported and to whom. Almost half of the respondents did not answer the question related to the dissemination of results. It may be that this depends on each situation or that those testing are also the practitioners reporting the information back to the athlete. However, it may also mean that there is no clearly identified pathway for providing a report of results to the athlete.
Both the sum of skinfolds (ISAK) and percentage of fat from selected skinfold equations that have been cross-validated are widely used to determine BC and associated minimum weight. Since the minimum %BF that is appropriate for both optimum performance and health varies between and within athletes, either approach (a minimum level of sum of skinfolds or a minimum %BF) may be appropriate, provided certain safeguards of equipment and professional training are followed. Limitations in current practice, including a lack of training in skinfold measurements and using generalised or inappropriate %BF formulae for a given athlete, appear prevalent in the field. Much of the current variation could be minimised with appropriate (ISAK) training, use of discrete skinfolds or use of combinations including all eight ISAK sites18 or for %BF to be derived from skinfolds using a formula validated on athletes such as the Jackson-Pollock sum of four or seven skinfold equations with a certified Lange calliper.19
This survey set out to identify BC methods in current use and their standardisation, and to gather information on data dissemination pathways in the sports medicine/science community around the world. It is apparent from the results that great variability exists in all of these constructs worldwide. Almost all respondents felt that problems exist with respect to the focus on BM and BC in sport. Several respondents were, at the time of the survey, working for national institutes of sport, Olympic training centres, universities and professional sport clubs. Box 2 and table 6 show the most frequent problems and solutions identified by the participants. Several also mentioned that there were barriers to implementation. Some of these barriers included economic, personnel (if coach and medical personnel are not committed) and regulatory issues.
While this original research assists with formulating conclusions about the current use of BC methods around the world, the Ad Hoc Research Working group proposes recommendations based on this and previously published papers2 related to BC, health and performance in sport, and these are summarised below.
The Ad Hoc Working Group on Body Composition, Health and Performance was established to explore opportunities to reduce unhealthy practices related to weight management in sport. This study aimed to describe current BC practices used around the world and to complement solutions recommended by responding experts. Based on the study's results, standardisation with regard to (1) method, (2) tester, (3) frequency, (4) hydration testing along with other health/performance parameters and (5) pathways of requests for BC assessment to data dissemination is needed. If a minimum weight is set, using targets for %BF and/or sum of eight skinfolds (ISAK), it is essential to align methods and related standardisation protocols regionally, nationally and internationally. How sporting organisations deal with BM and BC assessment and pathways from requests for BC testing to data dissemination, including communication to athletes, should be described in internal policy papers, as these issues appear critical in raising the risk of unhealthy practices related to BM and BC in sport. Further, organisations, on the local and global level, should aim to develop new resources and share existing educational materials to improve knowledge surrounding BM and BC and their impact on performance and health for everyone involved (ie, athlete, coach, parents and sport science and medical personnel). In addition, training of all sports medicine/science and coaching staff should include increased awareness and understanding of risk factors leading to unhealthy weight management behaviours and the ability to identify athletes at risk, as well as to initiate appropriate referral and management processes. Thus, scientists and practitioners in the field of BC have an educational mandate for shifting the focus from the rather troubling weight management approaches to a more robust BC management concept in sport. Facing current challenges and identifying new solutions, and advancing research to identify the validity and reliability of emerging BC assessment field techniques, such as ultrasound, are all part of this BC management concept in the near future.2 ,20 ,21
At present, if all practitioners were certified to use either the skinfold method or DXA method (subject to standardisation of hydration status and other potential errors) to estimate values of %BF or skinfold thickness in athletes, there would undoubtedly be much less variation in the results obtained. However, it should be clear that there is currently no good method for the assessment of BC in the field with better accuracy than 3% under the most standardised conditions. Advancement of field BC methodology today pertains mostly to its standardisation (eg, ISAK) and the development of athlete-specific and sport-specific normative data, as carried out by many national sport institutes. Furthermore, laboratory techniques, such as DXA, can give precise assessments of %BF if used repeatedly with the same system in the same laboratory2 and using a standardised protocol.9 Moreover, the assessment of other parameters pertaining to performance and the general health of the athlete should be included in any assessment to minimise the possibility of misinterpretation of BC results. Progress related to both field and laboratory BC assessments is being achieved world-wide, but practice varies widely among countries and institutions. Thus, provided the limitations of commonly used BC methods are known and appreciated, BC assessment remains highly useful in sport, especially when standardised techniques in lab (ie, DXA) and field (ie, anthropometry) are employed and other data are integrated when interpreting results and developing intervention strategies.
The use of minimum levels of %BF is a critical goal to ensure health and safety in certain sports, but its implementation is complex. Earlier work22 proposing % BF thresholds for athletes to be healthy, has been widely accepted, but several important factors have since become apparent. The tools for BC measurement are neither as precise nor accurate2 as had been assumed, and individual differences inevitably raise concerns about regulations that potentially exclude a healthy athlete from competition. Minimum BF levels of 5–7% in men and 12–14% in women used most often are based on the science of BC methodology and are generally accepted by most practitioners as a condition for participation in competitive sport. However, these numbers are purely arbitrary, because they are not based on an established reference method which would enable investigators to distinguish between these values. At best, the accuracy of the four-component model, as discussed by Ackland et al2 is roughly 1.5% when standardised, while field methods, such as skinfolds or BIA, are worse at 3.5% and when not standardised at 5% and higher. Thus, from a practical point of view, the accuracy of field methods may only be around 4%, which makes it highly problematic when setting minimum values for %BF in any athletic individual or sporting group. An athlete's individual health and performance profile should dictate his/her optimum weight where a minimum value for %BF is appropriate for the athletic event. Thus, 7% BF may be the minimum value estimate for one athlete, while for another 6% or 5% may allow enhanced performance while preserving the health of the athlete. Whereas, in anatomical terms, the physique of an athlete might track the periodisation of the training programme, there is a time-lag to this process, and care must be taken when aligning BC measurements to performance. As the optimal fatness for performance is generally less than that for optimal health, there is room for considerable variability in BF levels throughout the training year. Ultimately, many athletes will be walking the tightrope between optimum training and overtraining, and consider short-term performance to a greater extent than longer term health.
Further, few studies show enhanced performance when athletes reduce BM and fat, due to the often concomitant loss of lean mass.23 However, BM and fat loss can be successfully achieved in the absence of compromised lean mass and performance when using a supervised diet and resistance exercise intervention.24 Thus, BC management in athletes can be achieved effectively and safely, but it usually requires a long-term commitment. In the short term, weight fluctuations are likely to reflect water and glycogen changes in athletes, underscoring the importance of standardising nutrition and hydration status when assessing BC.
Leanness is an important performance-determining factor in sports; however, excessive leanness should not be viewed as a performance-enhancing factor by athletes, coaches or staff. There are many examples of athletes, where extreme leanness may have increased performance over the short term, but in many cases resulted in illness when training and competition continued at high levels. In fact, athletes such as those highlighted in the ‘Famous Sufferers: Eating Disorders in Athletes’25 are not exceptions, and there are athletes in many sports (eg, ski jumping, running, gymnastics, figure skating, Nordic skiing, triathlon, cycling) in which specific examples could be named. Having appropriate tools and a professional framework, including standardisation for assessing BC, policies for screening, detection and management of underweight athletes, and educational schemes that de-emphasise excessive leanness and low BM already in young athletes, therefore, represent key elements in the wider domain for both sports performance and athlete well-being.
BC measures are ideally scheduled systematically throughout the year during the planning phases. To avoid a high frequency of measures, a general guideline would include at least 2–6 months between measurements, depending on the method and specific athletic situation, with DXA measurement administered no more than two times per year and preferably not close to or during competition unless needed as part of the qualification process (ie, weight category sports). Further, specific BC requests should not be initiated by the coach or the athlete but rather originate from within an interdisciplinary team and/or preparticipation physicals. Moreover, the interdisciplinary team should also delineate what information (eg, fat and lean variables) is reported back to the athlete and in what format (report, verbal, email) and what information may go to the coach. Finally, the pathway from BC assessment requests to data dissemination should clearly outline who reports the data back to the athlete. In the case of ISAK, we recommend this to be an ISAK-certified sports scientist or sport dietitian, as they may evaluate changes over time based on their known intratester reliability and established sport-specific database. It is important to appreciate individual performance differences in relation to an athlete's optimum BC. Excessive leanness might compromise health and performance in one individual, while the same composition in another individual might enhance performance without adversely affecting health.
Survey research has various limitations, which are acknowledged. First, data were collected from a convenience sample and we recruited those individuals inherently interested in BC assessment in athletes. Second, survey research may also be biased due to the subjective nature of responses. This survey provided an option for respondents not to answer a question and move on to the next area, which affected the number of responses for some questions. Owing to the nature of the topic and the anonymity of the survey, deliberate false answers were not expected. Many respondents added extra information as expert opinion and many respondents expressed encouragement regarding the urgency of this topic. Thus, there is little reason to doubt the validity and reliability of the responses. The results of this study apply the use of BC methods of practitioners working with athletes and are not generalisable to other populations. Finally, this survey was sent out in English only, which may have limited the ability of personnel in some countries to respond.
This study assessed the current use of BC methodology in practitioners from sport organisations around the world. The results show great variability in BC assessment methods and a lack of standardisation. Most respondents also reported that the current focus on BM and BC in sport is problematic and has the potential to increase the risk of unhealthy weight management practices. This study was conducted by the Ad Hoc Working Group on Body Composition, Health and Performance under the auspices of the IOC Medical Commission. We recommend better standardisation of BC methods, more opportunities for training, greater access to resources to increase awareness and understanding of risk factors leading to unhealthy weight control practices and more research related to BC and performance.
What are the new findings
High number of practitioners assess body composition (BC) in sport.
There is a widespread lack of standardisation of BC methods, especially on regional/national level.
Few assess hydration status when measuring BC in sport.
Most practitioners, participating in this study, perceive the focus on BM and BC in sport as problematic due to the increased risk of unhealthy weight management practices.
How might it impact on clinical practice in the near future?
The Ad Hoc Research Working Group on Body Composition, Health and Performance recommends the following to practitioners assessing BC in sport:
Better standardisation with regard to (1) methods, (2) tester, (3) frequency, (4) hydration testing and (5) data dissemination.
More training opportunities for practitioners.
Increasing awareness and understanding of potential risks that may lead to unhealthy weight management practices in sport.
Better understanding and more research related to BC and performance.
We would like to thank the participants for their willingness to contribute to this study. None of the authors have competing interests. This study was conducted under the auspices of the IOC as part of the collaborative efforts of the Ad Hoc Research Working Group of the IOC Medical Commission but was not specifically funded.
Contributors NLM developed the study, collected the data, analysed and interpreted the results. She was also the main author who drafted and revised the manuscript before submission. JS-B, TGL, TRA, ADS, RJM, WM contributed substantially to the development of the survey, assisted with data analysis and interpretation and drafting/revising of the manuscript. TGL also acted as one of the guarantors for the overall content. WM also acted as overall guarantor as leader of the Ad Hoc Working Group. SS was a graduate student who worked on the data collection, analysis and interpretation, and thus contributed significantly to this study.
Competing interests None.
Patient consent Obtained.
Ethics approval University of Colorado, Colorado Springs.
Provenance and peer review Not commissioned; externally peer reviewed.
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