Biomechanical effects on lower-body extremities during a maximum effort kettlebell swing protocol
Kettlebell training provides multiple health benefits, including the generation of power. However, previous biomechanical research has been restricted to a few sets or a few repetitions performed in one effort. The primary purpose of this study was to examine the kinematics and kinetics of lower-body joints during a repeated, maximum effort kettlebell swing protocol. Sixteen resistance and kettlebell swing experienced males performed 10 rounds of a kettlebell swing routine (30 s of swings followed by 30 s of rest). Each participant utilized a kettlebell of approximately 20% of their respective body mass and were instructed to perform as many swings as possible each round. Kinematic (i.e., swing duration and angular velocities) and kinetic (i.e., normalized sagittal plane ground reaction force, resultant joint moment [RJM] and power) variables were extracted for the early portion and late portion of the round. Swing duration and normalized ground reaction forces (GRF) increased within a round, while hip joint power decreased. Changes in swing duration were minimal, but consistent due to an increase in overall fatigue. An increase in GRF was observed at the end of the round, which is a potential concern for injury. Hip joint power decreased primarily due to a slower angular velocity. For experienced (both kettlebell and overall resistance trained) individuals, this protocol may be beneficial towards power-training focused routines, as power was not different across rounds while also maintain large RJM values throughout the duration of the exercise.