title: Test-Retest Cross-Reliability of Tests to Assess Neuromuscular Function as a Multidimensional Concept.
abstract: The purpose of this investigation was to estimate the test-retest cross-reliability of peripheral and central changes with respect to nonlinear and linear measures of a surface electromyography (EMG) signal measured during isometric maximal voluntary contraction (MVC) combined with superimposed electrical stimulation during a brief and fatiguing task involving the ankle plantar flexors over 2 follicular phases of menstrual cycle. Ten healthy female adults underwent 1 familiarization session and 5 identical test-retest sessions. The results showed that the decrease in plantar flexor EMG components (root mean square [RMS], mean frequency [MnF], wavelet packet entropy [WPE]) for soleus and gastrocnemius muscles, central activation ratio (CAR) and MVC, and contractile properties (P20, P100, PTT-100, and half-relaxation time) of the plantar flexor muscles at the end of 2-minute MVC were similar (time effect; p < 0.001, η(p)² > 0.7, statistical power [SP] > 99%) and exhibited high stability over 5 trials (trial effect; p > 0.05; η(p)² < 0.2, SP < 30%). High reliability between trials was found for 5-second MVC (intraclass correlation coefficient [ICC] > 0.82, p < 0.001) and meaningful reliability for 2-minute MVC (ICC > 0.66, p < 0.01). In conclusion, in young healthy women, measurements of neuromuscular function, such as RMS, MnF, and WPE of a surface EMG signal, MVC, and CAR from a brief and sustained MVC of the ankle plantar flexors, are reliable, and multidimensional stability was found with respect to both high and low correlation outcomes across the 5 identical test-retest trials of any 2 properties measured during brief and sustained MVC.
authors: 1Sports Science and Innovation Institute, Lithuanian Sports University, Kaunas, Lithuania; and 2Department of Rehabilitation, Siauliai State College, Siauliai, Lithuania.
authors: Vaida
authors: V
authors: Bernecke
authors: Kazimieras
authors: K
authors: Pukenas
authors: Daiva
authors: D
authors: Imbrasiene
authors: Dalia
authors: D
authors: Mickeviciene
authors: Neringa
authors: N
authors: Baranauskiene
authors: Nerijus
authors: N
authors: Eimantas
authors: Marius
authors: M
authors: Brazaitis
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D015203:Reproducibility of Results; D055815:Young Adult