The PreCor EFX546 Elliptical Trainer Over Predicts Energy Expenditure

Abstract

1722 In the United States, the prevalence of obesity has risen at an epidemic rate during the past 20 years. Results from the 1999 National Health and Nutrition Examination Survey (NHANES) indicate that an estimated 61 percent of US adults are either overweight or obese. In an attempt to correct the current trends, fitness professionals encourage dietary modification (caloric restriction) along with physical activity as the best strategy for weight loss. The American College of Sports Medicine recommends as part of weight loss therapy that a minimum of 300 kilocalories be expended during each exercise session for a minimum of three to five days per week. Fitness facilities have various types of exercise equipment that use prediction equations to compute caloric expenditure. A popular piece of equipment found in these facilities is the PreCor EFX546 elliptical trainer. The PreCor EFX546 provides an aerobic mode of exercise with less impact on joints than treadmill jogging or walking. The PreCor also provides an individual with an estimate of caloric expenditure during the workout. However, there is no evidence in the scientific literature validating the accuracy of the caloric expenditure calculations used in the PreCor trainers. PURPOSE: To determine the accuracy of the PreCor EFX546 elliptical trainer caloric expenditure prediction equation. METHODS: Fifteen subjects (9 females), age 21.7 ± 3.6 years (mean ± SD), body fat of 20.6 ± 5.8% were asked to complete a maximal oxygen uptake test on the PreCor EFX546. On a subsequent day, subjects performed a ten-minute sub maximal test at ∼70% VO2max. Caloric expenditure (assessed using a Parvo Medics 2400 metabolic cart) was compared to the PreCor predicted caloric expenditure. RESULTS: The caloric expenditure predicted by the PreCor EFX546 was 33.4 ± 7.7% higher than the caloric expenditure determined using oxygen consumption and respiratory exchange ratio data from the metabolic cart. A strong correlation (r = 0.81) was found between the overestimation of caloric expenditure and the absolute oxygen consumption (L/min) during the submaximal exercise test. CONCLUSION: The PreCor EFX546 Elliptical trainer overestimated caloric expenditure on all tested subjects. Knowledge of this overestimation may be particularly important for individuals attempting to fulfill a certain caloric expenditure prescription for weight loss.