Approximately 65% to 75% of the US population is overweight or obese. Overweight (body mass index [BMI] = 25-29 kg/m2) individuals make up approximately 30% to 40% of this total number, and the obese (BMI > 30) population comprises 35% (CDC, 2012). BMI is an indirect method of assessing body fatness and is a useful tool to indicate risk of various chronic diseases such as cardiovascular diseases (CVD), hypertension, stroke, type 2 diabetes, certain cancers, osteoarthritis, gall stones, and renal disease in the general population. BMI is a poor indicator of body fatness, however, since it does not account for body composition.
Another anthropometric measurement is waist circumference, which is useful in measuring fat distribution. The criteria for waist circumference cutoffs from the National Heart, Lung, and Blood Institute (NHLBI) are gender and ethnicity based; the gender-based cutoffs of greater than 35 in (88 cm) for women and greater than 40 in (102 cm) for men are considered high risk for diseases associated with obesity. According to the NHLBI treatment guidelines for obesity, waist circumference provides a higher prediction of risk for diseases associated with obesity compared to BMI. A high waist circumference increases the risk for hypertension, dyslipidemia, type 2 diabetes, sleep apnea, respiratory illnesses, and CVD. If the BMI is 35 or higher, however, waist circumference does not have better predictive power than BMI (NHLBI, 1998). BMI and waist circumference should be used together to classify obesity and estimate risk for disease (Seagle, 2009).
Body composition measurement is the best method for identifying fatness and lean tissue in athletes. There are several different methodologies for assessment. The position paper on nutrition and athletic performance from the Academy of Nutrition and Dietetics used the Evidence Analysis Library to rate body composition techniques for the level of accuracy. Indirect assessment methods (Level II = fair amount of evidence; Level III = limited evidence) are the only methods used in clinical practice. Level II assessment methodologies include hydrostatic weighing (underwater weighing), dual-energy X-ray absorptiometry, and air displacement plethysmography. Body composition methods rating Level III include bioelectrical impedance analysis and skinfold measurements (Rodriguez, 2009).
A widely used practical method for body fat composition is skinfold calipers. The International Society for the Advancement in Kinanthropometry (ISAK) is a standardized anthropometric method that is utilized globally to aid in predicting body composition. This method is favored by many sports dietitians who work with collegiate, professional, and Olympic athletes. The ISAK methodology includes a seven skinfold landmarks technique. Skinfold measures of several sites is useful to assess body composition. It is not appropriate to convert skinfold measures into body fat percentage due to errors in measurement. The suggested skinfold measure for male athletes is 40 to 60 mm (excellent body fat level) with the average for male athletes being 81 to 100 mm; for female athletes 50 to 70 mm is considered excellent with 86 to 110 mm as average for athletes (ISAK, 2012).
Measuring body composition in athletes is a multifactorial process that should involve BMI, waist circumference, and body composition analysis. Athletes who fit the criteria for obesity are in danger of the chronic diseases previously mentioned as well as musculoskeletal conditions like osteoarthritis, rheumatoid arthritis, fibromyalgia, soft tissue injury, and joint replacement surgery. Obesity also compromises these athletes’ cardiorespiratory system, ultimately impairing their athletic performance and overall health (Anandacoomarasamy, 2009).