Validation of Heat Flux Technology to Assess Energy Expenditure During Exercise
There are limitations to current portable technology to estimate energy expenditure (EE), which may limit the accuracy when applied to free-living individuals. The KAL-X SensorTM (Lifechek, LLC, Pittsburgh, PA) uses heat flux technology to estimate EE. The accuracy of this device has not been assessed across levels of body mass index (BMI). The purpose of this study was to examine the validity of the KAL-X SensorTM to measure EE across different modes and intensities of physical activity. Twenty-four subjects (age = 33.8 ± 8.5 yr, BMI = 27.55 ± 3.9 kg/m2) performed two exercise (treadmill walking, stationary cycling) sessions with each lasting 30 minutes. Walking included three 10-minute progressive intervals of 2.5 mph, 0%; 3.0 mph, 0%; and 3.0 mph, 5%. Cycling included three 10-minute progressive intervals of 50 rev/min, 0.5 kg; 60 rev/min, 0.5 kg; and 60 rev/min, 1.0 kg. The criterion measure of EE was indirect calorimetry (IC). A KAL-X SensorTM was placed on the upper arm and at the level of the xyphoid process. EE during 30 minutes of walking for the KAL-X SensorTM (arm sensor = 94.5 kcal, chest sensor = 100.9 kcal) was significantly lower than EE measured using IC (166.5 kcal) (p<0.05). EE during 30 minutes of cycling for the KAL-X SensorTM (arm sensor = 76.4kcal, chest sensor = 90.1 kcal) was significantly lower than EE measured using IC (138.0 kcal) (p<0.05). The level of BMI did not affect the pattern of results, nor did arm circumference or skinfold measured at the bicep or tricep. These results indicate that there are limitations of the KAL-X SensorTM to provide an accurate estimate of EE during walking and cycling exercise. Additional research is needed to determine the accuracy of the KAL-X SensorTM to estimate EE during other forms of exercise, lifestyle activity, and free-living activity.
Advisor:Robert J. Robertson; Amy D. Otto; Bret H. Goodpaster; John M. Jakicic
School:University of Pittsburgh
School Location:USA - Pennsylvania
Source Type:Master's Thesis
Keywords:health physical and recreation education
Date of Publication:12/06/2005