Validity of the Sensewear Pro Armband during Outdoor Cycling

Abstract

Understanding the energy expenditure (EE) of different types of physical activity is important for exercise prescription. New systems such as the Sensewear Pro Armband (SWA) have been developed to provide simple methods of evaluating EE in free-living subjects. The armband has been validated for indoor cycling, however, no information is available on the armband for outdoor cycling, which has greater environmental factors which may influence the assessment of EE. PURPOSE: The purpose of this study was to evaluate the validity of the SWA s a method of measuring energy expenditure in trained cyclists compared to indirect calorimetry (IC). METHODS: Five trained cyclists (age=38.6 + 6.5 yrs., wt=71.0 + 9.6 kg, ht=1.8 + 0.1 m, VO2max= 43.7 + 6.8 ml/kg/min) performed two 1609 m continuous laps outdoors while wearing the SWA and a portable metabolic system (Viasys, Hoechberg, Germany). Subjects were instructed to complete the first lap at a preferred (moderate) intensity and the second lap at a faster self-selected pace. Minute by minute EE was calculated and summed for each lap for both the SWA and IC. On a separate day subjects also completed a VO2max test on a cycle ergometer while wearing the portable metabolic system. The data collected during the outdoor cycling was expressed as a percentage of each subject's VO2max. RESULTS: Mean speed for the first and second laps was 466.3 ± 37.5 and 514.6 ± 42.9 m/min, respectively. Relative oxygen uptake and % HRmax were 57.5 ± 19.6% and 74.5 ± 4.9% during lap one. These values increased to 76.2 ± 22.4 % VO2max and 89.5 ± 3.1% HRmax during lap 2. Using an independent t-test, predicted EE was significantly different between the SWA (132.3 + 37.0) and IC (76.2 + 20.5) for the first lap, p < 0.05. However, no significant difference in EE was found between the SWA (81.9 + 40.5) and IC (98.0 + 29.9) for the second lap, p > 0.05. CONCLUSIONS: Results suggest the SWA may be more accurate at predicting EE at higher exercise intensities. However, exercise specific algorithms are necessary to accurately assess EE during outdoor cycling at various intensities. Further research is needed to improve the prediction of energy expenditure in free living individuals using objective devices.