Electrocortical activity during stretch reflex in athletes

Abstract

To evaluate timing and characteristics of electrocortical activity during stretch reflex evocation of the quadriceps femoris at different body postures. Twenty athletes were subjected to reflex hammer percussions on patellar tendon, in a random time sequence, in seated and supine decubitus postures. 745 ms of acquisition were evaluated for data analysis: 200 ms of pre-stimulation, 45 ms relative to the elapsed time from stimulation to the end of the muscular contraction, and 500 ms of post-stimulation. First, a scalp-map analysis, considering channels data, was performed; second, independent component analysis decomposition was applied to all 16 channels. To highlight the differences among two conditions (pre- and post-stimulation) and two sessions (seated and supine decubitus postures), a two-way analysis of variance was used. Time–frequency analysis has been applied to identify the density of the frequencies as a function of the time, instant by instant. Fast alpha, beta, and gamma frequency bands showed a greater electroencephalographic activity after the stimulation. Seated posture showed a greater activation than the decubitus supine posture. Time frequency analysis highlighted an higher electrocortical activation for 160 ms as well as from about 250–300 ms at all frequency bands after the stimulation. Our findings improve the understanding of the neurophysiological dynamics following the stretch reflex after concussion of the patellar tendon, executed in different postures, considering scalp-map, power spectra, and timing of activation. The use of scalp-map and power spectra analysis techniques represents a sophisticated use of advanced signal processing methodologies to analyze brain activity during movement and in specificity in sport science.