Effects of Covert Subject Actions on Percent Fat by Air Displacement Plethsymography

Abstract

Athletes in weight classification sports may engage in rapid weight loss methods to "make weight“ prior to competition. Distance runners and endurance athletes, where there is a perception of improved performance at a lower body weight, may also engage in excessive weight loss methods prior to competition. Such practices may cause poor athletic performance and can be harmful to the body. Some trainers and coaches, and in the case of wrestling, the NCAA have adopted programs aimed at reducing unhealthy weight loss behaviors by measuring body fat using hydrostatic weighing, skinfolds or air-displacement plethysmography (ADP). Athletes, however, may use covert methods during body composition testing to artificially increase their percent body fat allowing them to reach a lower minimum weight. PURPOSE: The goal of this study was to examine the accuracy of ADP under altered conditions. This study examined the susceptibility of the Bod Pod ADP instrumentation to intentional manipulation of body composition measures by subjects. METHODS: Subjects underwent body composition analysis in the Bod Pod following the standard procedure previously validated. They then underwent eight more measurements while performing the following: four breathing patterns altering lung volume, foot movement, hand cupping to trap air, and heat and cold exposure. RESULTS: Increasing and decreasing lung volume during thoracic volume measurement and during body density measurement altered the apparent percent body fat assessment (p<0.001). High lung volume during thoracic gas measures (HLV-TG) overestimated fat by 3.7±2.1%. Lowered lung volume during body volume measures (LLV-BV) overestimated body fat by an additional 2.2±2.1%. The summation effect of the covert manipulation resulted in an overestimation of the athletes‘ body composition by 5.9 percent body fat. The heat and cold exposure, tapping and cupping treatments were not significantly different from control. CONCLUSION: These results demonstrate that athletes can covertly alter their body composition measurement to obtain a lower competition weight when measured by ADP. It is therefore important that technicians monitor for intentionally altered breathing when using ADP that could artificially increase percent body fat and invalidate the test result.