The Reliability of Transcranial Magnetic Stimulation-Derived Corticomotor Inhibition as a Brain Health Evaluation Tool in Soccer Players

Abstract

Background The suitability of corticomotor inhibition and corticospinal excitability to measure brain health outcomes and recovery of sport-related head impact (concussion and subconcussion) depends on good inter-day reliability, which is evaluated in this study. Transcranial magnetic stimulation (TMS) reliability in soccer players is assessed by comparing soccer players, for whom reliability on this measure may be reduced due to exposure to head impacts, to generally active individuals not engaged in contact sport. Methods TMS-derived corticomotor inhibition and corticospinal excitability were recorded from the rectus femoris muscle during two testing sessions, spaced 1–2 weeks apart in 19 soccer players (SOC—age 22 ± 3 years) and 20 generally active (CON—age 24 ± 4 years) healthy volunteers. Inter-day reliability between the two time points was quantified by using intra-class correlation coefficients (ICC). Intra-group reliability and group differences on actual measurement values were also explored. Results Good inter-day reliability was evident for corticomotor inhibition (ICCSOC = 0.61; ICCCON = 0.70) and corticospinal excitability (ICCSOC = 0.59; ICCCON = 0.70) in both generally active individuals and soccer players routinely exposed to sport-related head impacts. Corticomotor inhibition showed lower coefficients of variation than excitability for both groups (InhibSOC = 15.2%; InhibCON = 9.7%; ExcitabSOC = 41.6%; ExcitabCON = 39.5%). No group differences between soccer players and generally active individuals were found on the corticomotor inhibition value (p > 0.05), but levels of corticospinal excitability were significantly lower in soccer players (45.1 ± 20.8 vs 85.4 ± 6.2%Mmax, p < 0.0001). Corticomotor inhibition also showed excellent inter-rater reliability (ICC = 0.87). Conclusions Corticomotor inhibition and corticospinal excitability are stable and maintain good degrees of reliability when assessed over different days in soccer players, despite their routine exposure to head impacts. However, based on intra-group reliability and group differences of the levels of excitability, we conclude that corticomotor inhibition is best suited for the evaluation of neuromuscular alterations associated with head impacts in contact sports.

Test–retest reliability of cortico-spinal measurements in the rectus femoris at different contraction levels

“…The duration of the silent period can provide information about the inhibition at the cortical or spinal level (Inghilleri et al, 1993). Reliability of LS-elicited SP were moderate and good, which were slightly higher than the TMS-elicited SP reported by Di Virgilio et al (2022). Furthermore, CV were similar to those reported previous (CV = 7-15%) (O'Leary et al, 2015;Leung et al, 2018;Di Virgilio et al, 2022).…”

Motor cortical inhibitory deficits in patients with obsessive-compulsive disorder–A systematic review and meta-analysis of transcranial magnetic stimulation literature

“…Cortical silent period is a cortical excitability measure that reflects the duration of the period of suppression in electromyographic activity that typically follows a single TMS pulse delivered to the primary motor cortex while a mild voluntary contraction of the corresponding muscle of interest is being performed ( 49 ). It has good test-retest reliability under different conditions and methodological implementations ( 50 , 51 ), making it a potentially useful marker of disease and/or treatment response for this clinical population. There is evidence that CSP reflects intracortical GABAergic activity, more specifically GABA B receptor activity ( 52 , 53 ), and our results are thus aligned with existing evidence that GABA B receptor function may be impaired in OCD.…”

Enhanced skeletal muscle contractile function and corticospinal excitability precede strength and architectural adaptations during lower-limb resistance training

“…Quadriceps active motor threshold (aMT) was determined by increasing stimulator output in 5% increments, starting from 10%, until a discernible MEP was visible during sustained contraction at an intensity equivalent to 20% of participant MVC achieved during that testing session (Wilson et al 1995 ); contraction intensity was maintained by the participant tracing their contraction force to a template visible on a computer monitor directly in front of them. Subsequent stimulations were delivered at 130% of aMT, this protocol has previously demonstrated a high level of reliability in our laboratories (Di Virgilio et al 2022 ). A study by Temesi et al ( 2014 ) found no differences between VL, RF, and vastus medialis for aMT or resting MT stimulus–response curves; suggesting that one muscle can be considered representative of all three.…”