The effects of acute training status on reliability of integrated electromyographic activity and "efficiency of electrical activity" during isometric contractions: a case study.
"Efficiency of electrical activity" (EEA) is the measure of muscular force production per unit of neuromuscular electrical activity as measured by integrated electromyographic (IEMG) activity. To determine the effects of acute training status on day-to-day and within test reliability for both IEMG activity and EEA, one experienced weight trained male was observed on three separate days (age = 33 yrs., height = 172.7 cm, body weight = 81.4 kg). The first (I) and third (III) test days were preceded by 1-2 days rest from weight training, while the second test day (II) was preceded by 4 days of rest from weight training. Two external electrodes were placed on the right biceps brachii. EMG signals were rectified by an amplifier, while a signal gain of 5000 was utilized. Three different levels of isometric muscle activity using a dumbbell, were performed at 25.0 N (2.55 kg), 87.3 N (8.90 kg), and 157.9 N (15.90 kg) of force. These resistances represented 12%, 42% and 76% respectively, of the subject's maximum capabilities. Five trials were performed at each resistance on each of the test days. Repeated measures ANOVAs (3 x 3) were used to determine differences between test days and loads (p < or = 0.05). Within day variations were determined by coefficient of variation (CV = SD/mean x 100%). The EEA for each test day was curvilinear, with greater forces exhibiting lower EEA. Test day II exhibited the greatest EEA, which may have been related to the acute training status of the subject.(ABSTRACT TRUNCATED AT 250 WORDS)
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Center for Sports Medicine, Pennsylvania State University, University Park 16802.
D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D010806:Physical Education and Training; D015203:Reproducibility of Results; D014891:Weight Lifting / Q000502:physiology*