Improving the Reliability of V-Wave Responses in the Soleus Muscle

Abstract

Purpose: The V wave is an electrophysiologic variant of the H reflex that is evoked with supramaximal stimulus intensity. In this study, we explored whether the between-day reliability of V-wave normalized amplitude varies as a function of the number of intrasession measurement trials. We also determined whether the reliability of the V wave improves after the exclusion of the initial testing trials. Methods: Eighteen healthy, young participants (10 men and 8 women) were included in this study. Test–retest reliability was assessed using intraclass correlation coefficients and the standard error of the measurement (1.96*SEM). Results: The intraclass correlation coefficient values of the V-wave normalized amplitude increased in a progressive fashion with the inclusion of more than two measurement trials (from 0.41 to 0.75). The 1.96*SEM scores also decreased from 12.47% to 7.60% after calculating the V-wave normalized amplitude from five versus two measurement trials. After excluding the first two trials from V-wave calculations, the intraclass correlation coefficient and the 1.96*SEM score attained values of 0.88 and 6.54%, respectively. Conclusions: Our findings indicate that the test–retest reliability of the V-wave response increases in a progressive fashion with more than two intrasession measurement trials (up to five trials). It also shows that to ensure maximal reliability, the first two measurement trials should be discarded from V-wave computations.

Effects of acute sleep deprivation on H reflex and V wave

“…Testing was performed as reported in previous research (Mendonca et al., 2019). All assessments were made on the participants’ right lower limb, using a Biodex System 3 Pro isokinetic dynamometer (Biodex Medical System 3).…”

“…Participants were instructed to exert their maximum force as fast and hard as possible and subsequently were allowed to rest for 60 s between trials. This protocol is highly reliable for torque measurements during a plantarflexor MVC (the intraclass correlation coefficient and 95% confidence interval of standard error of the measurement corresponding to 0.99 and 2.86, respectively) (Mendonca et al., 2019). The highest peak torque value obtained during plantarflexion was used to determine the individual torque output compatible with 10% MVC.…”

“…Participants performed five MVCs, with 1 min of rest between trials. V waves were elicited via supramaximal electrical stimulation (150% of the current needed to evoke a maximal M wave; 1‐ms single square pulse) delivered to the tibial nerve at the instant the torque exceeded 90% of the MVC (Mendonca et al., 2019).…”

“…Although H waves were normalized to the corresponding M max , V waves were normalized to the M wave (M sup ) elicited concomitantly with the V wave (V/M sup ). V waves with concomitant M sup < 90% of the highest M sup were excluded from further analyses to ensure stable conditions (exclusion of 37 from a total of 140 V‐wave trials; valid trials for analysis: 3.8 ± 0.9) (Mendonca et al., 2019). A general squares model was fitted to the ascending part of the H‐reflex recruitment curve and the following parameters were then extracted (Klimstra & Zehr, 2008): (a) current intensity at H‐reflex threshold, (b) current intensity at 50% of H max , (c) current intensity at H max and (d) slope of the ascending limb of the recruitment curve at 50% of H max (using >9 data points for slope determination).…”

The Effects of Spinal Manipulation on Motor Unit Behavior

“…2021, 11, 105 2 of 19 as N20 and N30, significantly decreased after cervical spinal manipulation in a relatively healthy population [12][13][14]. These early cortical SEP peaks are thought to represent the arrival of the afferent signals at the primary somatosensory cortex and early sensorimotor integration, respectively [15,16]. Interestingly, in a chronic stroke population, who are known to have a reduced amplitude of early SEP peaks [17], a recent study showed an increase in N30 SEP peak amplitude following chiropractic care [18].…”