Biomechanical Evaluation of the Air Stretcher as an Alternative for the Carpet Knee Kicker

摘要

The knee kicker is a must have tool used by carpet installers. Carpet installers had high knee injury compensation claims. The use of the knee kicker is an essential reason. The air stretcher is a new tool (Lee's Custom Floors, British Columbia, Canada) designed to replace the knee kicker. 9 professional carpet installers were recruited to join the experiment to evaluate the air stretcher. Muscle activity, impact force and changes of segment angles were collected by EMG electrodes (Delsys DE-3.1 Surface EMG Sensors, Delsys Inc. Boston, MA, 02215); load cell (ST_1, Fabrication Company, Ann Arbor, MI) and motion capture system (Northern Digital Inc., Ontario, Canada) respectively. Biceps femoris (P=0.009), right deltoid (P=0.006) muscle activities decreased significantly; rectus femoris (0.077) and left deltoid muscle (0.101) activities decreased board line significantly. The impact force of the knee kicker was as high as 1.24 times of mean body weight. The new tool does not produce the impact force. The air stretcher decreased changes of hip and knee angle also prevented extreme high and low angles. From perspective of Biomechanics, the air stretcher is a good alternative for the knee kicker.