Reliability of Testing of the Electrical Activity of Muscles during Isometric Contractions in Archery

Abstract

BACKGROUND. The archery sport needs a high level of accuracy and coordination between muscle forces. Electromyography is a useful and effective method in studding the electrical activity of muscles in archery. Resulting in a great variation in EMG data repeatability, the results regarding a theory of test reliability should be studied. PURPOSE. The research aims to develop a method of determination concerning reliability of testing of the electrical activity of muscles during isometric contractions in archery. METHODS. The electrical activity of rectus femoral muscle during isometric contractions with the maximal effort in bending of a thigh from −15º to 70º is tested in a sample of twenty skilled male archers of 23–28 years old. ANOVA for repeated measures, ICC and regression models are used. RESULTS. The electrical potential is found to be maximal (7.15 mV), when the joint angle equals −8.9º and minimal (1.44 mV), when the joint angle equals 62.8º. A ratio of sum of squares due interaction between subjects’ and joint angles’ variability to the total sum of squares variability of all measures is accepted as a measure of the error in a hypothetical function of dependence of the electrical activity of muscles on joint angles (23.3%, p < 0.001). A single measure test after elimination of trends in test–retest results shows a sufficient level of reliability: ICC(1,1)=0.745. Corresponding mean scores reliability of the test with five trials is estimated as good: ICC(1,k)=0.936, (k = 5). CONCLUSION. A method of determination concerning reliability of testing of the electrical activity of muscles during isometric contractions specifically to the archery sport is recommended to the practical employment.