The Influence of Throwing Height on Muscle Fatigue in Repetitive Snow-shoveling Movements

[Purpose] The purpose of this study was to examine the changes in muscle fatigue caused by different throwing heights in repetitive snow-shoveling movements. [Subjects and Methods] The subjects were 8 healthy male adults, and the muscles examined were the upper trapezius, lumbar erector spinae (LES), and rectus femoris (RF). A weight was placed on the shovel, and shoveling action to clear a bar set at 50, 75 and 100% of subjects’ height was repeated for 10 minutes. The values of mean power frequency (MPF) were calculated during the movements. [Results] The MPF of RF of both sides decreased at all shoveling heights. The activity of the non-throwing side LES at rest increased simultaneously or immediately after MPF showed a decrease in RF. [Conclusion] The fatigue of RF causes activity increase in LES. Because lower back pain may be caused, the increase of the activity of LES needs periodical rest.