Comparison Of Two Portable Devices For Assessing Energy Expenditure During High-intensity Running

Abstract

One of the main challenges of exercise nutrition is to ensure that athletes keep their energy intake and energy expenditure (EE) within healthy limits. Therefore, correct methods to quantify EE are necessary. Exercise-induced EE can be measured reliably with indirect calorimetry (IC) under laboratory conditions but the quantification of EE in the field is more challenging. Portable devices such as the Sensewear Pro3 armband (SENS; BodySense, USA) and the Actiheart monitor (ACTI; CamNtech, UK) have been designed for simple EE assessment on a daily basis. These devices have been validated in the general population but their performance has not been studied adequately during high-intensity exercise. PURPOSE: To compare energy expenditure measured with SENS and ACTI with an accepted reference method (IC) during high-intensity running. METHODS: Twenty-nine male participants (27.2 ± 1.9 y, 184 ± 7 cm, 79.8 ± 7.6 kg) performed a running test, which started at 2.8 m/s. Every 5 minutes, velocity was increased by 0.4 m/s until 4.8 m/s or voluntary exhaustion. During the test, the participants simultaneously wore SENS and ACTI. IC was performed with a ZAN 600 spirograph (Zan, Germany). RESULTS: EE measured with SENS was moderately correlated with IC values (r = 0.68). For running speeds greater or equal 3.2 m/s EE obtained with SENS was significantly smaller than reference data. The difference increased from 1.0 ± 1.0 METs at 3.2 m/s to 4.8 ± 1.7 METs at 4.8 m/s (p < 0.001). Underestimation was minimal before the test (0.2 ± 0.9 METs) but significant post-exercise (3.7 ± 2.9 METs, p < 0.001). For ACTI, there was also a moderate correlation with IC values (r = 0.77). ACTI underestimated EE between 0.9 ± 1.2 METs (2.8 m/s) and 4.3 ± 1.9 METs (4.8 m/s) and also during rest periods (before: 0.5 ± 0.4 METs, after: 4.1 ± 3.0 METs). The level of underestimation grew significantly with increasing EE (p < 0.001). CONCLUSIONS: Both devices performed similarly during the high-intensity running trial. SENS and ACTI underestimated ExEE and the level of underestimation increased significantly with increasing running velocities. However, the correlation with the IC data indicates that the application of exercise-specific should improve the validity of both devices.