Estimation Of Energy Expenditure During Resistance Training Using Accelerometry.

Abstract

PURPOSE: The purpose of this investigation was to (a) estimate energy expenditure during resistance training using accelerometry (ActiGraph GT1M) and (b) to determine the optimal location for the accelerometer for assessment of energy expenditure. METHODS: Thirty subjects, (15 males, 15 females), mean age 21.6 years, performed 2 sets of a 10 repetition maximum (10RM) for each of 8 exercises. Subjects wore 3 accelerometers (wrist, waist, and ankle) and these data were compared to energy expenditure assessed with a portable metabolic system (CosMed K4b2). RESULTS: Activity counts from accelerometers worn on the waist were more strongly associated with net kilocalories expended (r=0.77; p<0.001) than activity counts from wrist (r=0.31; p=0.10) and ankle (r=0.50; p=0.01) accelerometers. A forward stepwise regression analysis was conducted to develop an equation to predict energy expended during resistance training based on waist counts from the accelerometer. Total counts of activity alone explained 59% of the variance (R2 = 0.59) in net kilocalories expended. To improve the accuracy of the prediction equation for net kilocalories expended during the workout, a forward stepwise regression analysis was conducted using the following variables: Total counts at the waist, gender, height, body mass, body mass index, body fat percentage, fat free mass, circumference of the neck, shoulder, chest, waist, abdomen, hip, thigh, ankle, calf, ankle, arm, wrist, and forearm, upper and lower body limb length, and training volume (training volume = (weight * reps)1 + (weight * reps)2). The final equation included gender, fat free mass, and waist counts, and explained 0.90% of the variance (R2=0.90) in energy expended during resistance training. CONCLUSION: It was concluded that energy expended during resistance training can be estimated using an accelerometer worn on the waist.