Energy Cost and Relative Intensity of a Kettlebell Workout

Abstract

The use of kettlebells as a workout tool originated in Russia and is now becoming increasingly popular in the U.S. A kettle bell is a resistance device that looks like a cannonball with a broad handle on top and is typically made of cast iron. It is used as the resistance when performing a variety of large muscle, multi-joint movements (e.g., snatches). PURPOSE: This study was designed to evaluate the relative exercise intensity and energy expenditure of a typical kettlebell workout. Ten subjects (8 males, 2 females) initially completed a treadmill VO2max test and a kettlebell VO2max test to determine maximal HR and VO2 under each condition. Individual HR/VO2 regression equations were determined from the incremental kettlebell test. Subjects then performed a 20-minute kettlebell workout that consisted of 15 seconds of kettlebell snatches followed by 15 seconds of rest. HR was measured throughout the workout and these values were inserted into the individual HR/VO2 equations to determine VO2 and caloric expenditure. RPE was assessed immediately following the workout using the 6-20 Borg scale. RESULTS: There was a significant difference inVO2max values between the treadmill and kettlebell VO2max tests (49.7+6.6 vs. 40.3+2.2 ml/kg/min). No significant difference was found for maximal HR between the two tests (180+8.5 vs. 176+12.5 bpm). Average HR during the kettlebell workout was 164+14.7 bpm (93+4.5% of HRmax) and estimated VO2 was 31.6+3.71 ml/kg/min (78+8.0% of VO2max). Average caloric expenditure was 13.6+3.08 kcal/min (273+60.6 kcal for the 20-minute workout). RPE for the workout averaged 15.9+2.2, indicating a subjective intensity of "Hard" on the Borg scale. CONCLUSION: These results indicate that the intensity of a typical kettlebell workout is very intense based upon HR, VO2, and RPE criteria and should positively impact cardiorespiratory endurance. Additionally, based upon the caloric expenditure data, performing consistent kettlebell workouts should result in positive changes in body composition.