Abstract
Introduction: The BOD POD uses air displacement plethysmography to determine an individual’s body composition as percentages of fat mass and fat free mass. Based on ethnicity, it uses either the Siri or Shutte equation to calculate body composition via gas laws and the volume of air and pressure differences exerted within a confined space. Objective: The purpose of this study was to determine if the BOD POD protocol, as set forth by Life Measurement, Inc., needs to be followed in its entirety to ensure validity of body composition results. Our hypothesis was that breaking the established protocol would not have any statistically significant effects on body composition results. This study examined two components of the BOD POD protocol: urination prior to testing and fluid consumption prior to testing. Methods: 32 soccer athletes as a dividion 1 University participants were asked to follow the established pretesting protocol which included refraining from eating or drinking, as well as not exercising four hours prior to testing. An additional stipulation was added that participants refrain from urinating two hours prior to testing to ensure presence of urine content in the bladder upon testing. Four separate measurements of body composition were taken: the first being pre-urination, the second and third followed standard LMI protocol for BOD POD testing, and the fourth consisted of the participants consuming an amount of water equal to 10% of their body weight in ounces of water prior to this final measurement. Results: A Pearson moment correlation ran between the second condition (post urination) and the third condition (post urination retest) yielded a p value =0.977, signifying a good to excellent relationship between the standard test and the retest conditions. Analyses ran comparing the pre-urination test and the post-urination test/retest yielded a p value = 0.322/0.452 respectively, indicating that not urinating prior to testing had little to no effect on the body composition measurement (test/re-test p values = 0.322/0.452 respectively) Interestingly, the act of consuming water did have a significant effect on the results of the body composition measurements (Male/Female p value = 0.002/0.000 respectively). The study results did not support the need to empty the bladder prior to testing while supporting the need to refrain from water consumption directly prior to testing. Discussion: It is thought that excess fluids in the body will be inappropriately categorized as fat mass when using the BOD POD for body composition measurements. The LMI protocol requires participants to urinate prior to testing in attempts to remove any excess fluids that may skew the results of the fat mass versus fat free mass compositions. All participants in this study acknowledged that they followed the no urination for two hours prior to testing requirement. The major finding of the present study was that breaking protocol for BOD POD testing resulted in a significant difference on body composition measurements. Compared with standard protocol testing, consumption of water provided significantly different results in body composition testing (p = 0.002), meanwhile voiding before testing did not have a significant difference (p = 0.322). This is the first study, to our knowledge, that examined the consumption of water and its effects on body composition as measured by the BOD POD, as well as contents of urine in the bladder. Conclusion: It appears that excess fluid in the body and its effects on body composition using ADP, are dependent on fluid location. This study did not support the need to empty the bladder prior to testing while supporting the need to refrain from water consumption directly prior to testing. Future studies may look to determine how much consumed fluid results in a statistically significant difference between body composition measurements. This can be accomplished by measuring the input output ratio to determine if there is a critical level of fluid that should be avoided, and also if there is a time factor to consider when accounting for the interval between consumption and testing.