Search

Cerebral autoregulation (CA) refers to the control of cerebral tissue blood flow (CBF) in response to changes in perfusion pressure. Due to the challenges of measuring intracranial pressure, CA is often described as the relationship between mean arterial pressure (MAP) and CBF. Dynamic CA (dCA) can be assessed using multiple techniques, with transfer function analysis (TFA) being the most common. A 2016 white paper by members of an international Cerebrovascular Research Network (CARNet) that is focused on CA strove to improve TFA standardization by way of introducing data acquisition, analysis, and reporting guidelines. Since then, additional evidence has allowed for the improvement and refinement of the original recommendations, as well as for the inclusion of new guidelines to reflect recent advances in the field. This second edition of the white paper contains more robust, evidence-based recommendations, which have been expanded to address current streams of inquiry, including optimizing MAP variability, acquiring CBF estimates from alternative methods, estimating alternative dCA metrics, and incorporating dCA quantification into clinical trials. Implementation of these new and revised recommendations is important to improve the reliability and reproducibility of dCA studies, and to facilitate inter-institutional collaboration and the comparison of results between studies.

Currently, the standard approach for restricting exercise prior to cerebrovascular data collection varies widely between 6 and 24 h. This universally employed practice is a conservative approach to safeguard physiological alterations that could potentially confound one’s study design. Therefore, the purpose of this systematic review was to amalgamate the existing literature examining the extent and duration of postexercise alterations in cerebrovascular function, measured via transcranial Doppler ultrasound. Furthermore, an exploratory aim was to scrutinize and discuss common biases/limitations in the previous studies to help guide future investigations. Search strategies were developed and imported into PubMed, SPORTDiscus, and Medline databases. A total of 595 records were screened and 35 articles met the inclusion criteria in this review, which included assessments of basic cerebrovascular metrics ( n = 35), dynamic cerebral autoregulation (dCA; n = 9), neurovascular coupling (NVC; n = 2); and/or cerebrovascular reactivity (CVR-CO2; n = 1) following acute bouts of aerobic exercise. Across all studies, it was found that NVC was impacted for 1 h, basic cerebrovascular parameters and CVR-CO2 parameters for 2 h, and dCA metrics for 6 h postexercise. Therefore, future studies can provide participants with these evidence-based time restrictions, regarding the minimum time to abstain from exercise prior to data collection. However, it should be noted that other physiological mechanisms could still be altered (e.g., metabolic, hormonal, and/or autonomic influences), despite cerebrovascular function returning to baseline levels. Thus, future investigations should seek to control as many physiological influences when using cerebrovascular assessments, immediately following these time restraints. The main limitations/biases were lack of female participants, cardiorespiratory fitness, and consideration for vessel diameter.

The systematic review evaluated the evidence related to how physical activity affects recovery following a sport-related concussion (SRC) in adolescents. Databases indexed were PUBMED, MEDLINE, and SPORTDiscus. Inclusion criteria included 1) original research article, 2) ≥66% have an SRC diagnosed by a clinician, 3) human research, and 4) evaluated the effect of an SRC on physical activity in adolescents only (

Standard practices for quantifying neurovascular coupling (NVC) with transcranial Doppler ultrasound (TCD) require participants to complete one-to-ten repetitive trials. However, limited empirical evidence exists regarding how the number of trials completed influences the validity and reliability of temporally derived NVC metrics. Secondary analyses was performed on 60 young healthy participants (30 females/30 males) who completed eight cyclical eyes-closed (20-seconds), eyes-open (40-seconds) NVC trials, using the “Where’s Waldo?” visual paradigm. TCD data was obtained in posterior and middle cerebral arteries (PCA and MCA, respectively). The within-day (n = 11) and between-day ( n = 17) reliability were assessed at seven- and three-time points, respectively. Repeat testing from the reliability aims were also used for the concurrent validity analysis ( n = 160). PCA metrics (i.e., baseline, peak, percent increase, and area-under-the-curve) demonstrated five trials produced excellent intraclass correlation coefficient (ICC) 95% confidence intervals for validity and within-day reliability (>0.900), whereas between-day reliability was good-to-excellent (>0.750). Likewise, 95% confidence intervals for coefficient of variation (CoV) measures ranged from acceptable (

The cerebral pressure-flow relationship has directional sensitivity, meaning the augmentation in cerebral blood flow is attenuated when mean arterial pressure (MAP) increases vs MAP decreases. We employed repeated squat-stands (RSS) to quantify it using a novel metric. However, its within-day reproducibility and the impacts of diurnal variation and biological sex are unknown. Study aims were to evaluate this metric for: 1) within-day reproducibility and diurnal variation in middle (MCA; ∆MCAvT/∆MAPT) and posterior cerebral arteries (PCA; ∆PCAvT/∆MAPT); 2) sex differences. ∆MCAvT/∆MAPT and ∆PCAvT/∆MAPT were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv or PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Relative metric values were also calculated (%MCAvT/%MAPT, %PCAvT/%MAPT). Intraclass correlation coefficient (ICC) evaluated reproducibility, which was good (0.75-0.90) to excellent (>0.90). Time-of-day impacted ∆MCAvT/∆MAPT (0.05 Hz: p = 0.002; 0.10 Hz: p = 0.001), %MCAvT/%MAPT (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.009), and ∆PCAvT/∆MAPT (0.05 Hz: p = 0.024), albeit with small/negligible effect sizes. MAP direction impacted both arteries' metric at 0.10 Hz (all p < 0.024). Sex differences in the MCA only (p = 0.003) vanished when reported in relative terms. These findings demonstrate this metric is reproducible throughout the day in the MCA and PCA and is not impacted by biological sex.

To determine the stability of the Sport Concussion Assessment Tool (SCAT) 5 between consecutive seasons in uninjured collision and combative varsity athletes.Thirty-six athletes (19 females) were recruited to participate (wrestling [n = 12], rugby [n = 14], and hockey [n = 10]). The SCAT5 was administration at the start of the 2017 and 2018 seasons. Median baseline demographics for 2017 were as follows: age (19 years [range: 17-24 years]), height (174 cm [range: 149-195 cm]), and weight (76 kg [range: 57-118 kg]). Outcome metrics included subcomponents of the SCAT5: symptom reporting, standardized assessment of concussion (SAC), neurological screening, and balance performance measured with the modified balance error scoring system (mBESS). Wilcoxon signed-rank tests and Cronbach's alpha (α) values were calculated to determine the stability between consecutive years for the SCAT5 variables in the same cohort of athletes. Bonferroni corrections were applied for Wilcoxon signed-rank tests, where alpha = Between the 2017 and 2018 seasons, no differences were noted in symptom reporting (While no statistical differences were present for all SCAT5 subcomponent metrics between 2017 and 2018 baselines, all but one displayed unacceptable to questionable stability (α ≤ 0.70) when retested one year later. Further research is needed to understand the appropriate time duration baseline SCAT5 values can reliably be utilized within longitudinal studies; as well as the normal variation of SCAT5 reporting/scoring.

Background: Near point of convergence (NPC) assesses the vergence ability of the visuo-oculomotor system; however, little is known regarding: the extent and duration exercise impacts NPC and the be...

New findings What is the central question of this study? What are the characteristics of cerebral blood flow (CBF) regulation following a single SCUBA dive to a depth of 18 m sea water with a 47 min bottom time. What is the main finding and its importance? Acute alterations in CBF regulation at rest, including extra-cranial vasodilatation, reductions in shear patterns and elevations in intra-cranial blood velocity were observed at rest following a single SCUBA dive. These subtle changes in CBF regulation did not translate into any functional changes in cerebrovascular reactivity to hypoxia or hyperoxia, or neurovascular coupling following a single SCUBA dive. Abstract Reductions in vascular function during a SCUBA dive - due to hyperoxia-induced oxidative stress, arterial and venous gas emboli and altered endothelial integrity - may also extend to the cerebrovasculature following return to the surface. This study aimed to characterize cerebral blood flow (CBF) regulation following a single SCUBA dive to a depth of 18 m sea water with a 47 min bottom time. Prior to and following the dive, participants (n = 11) completed (1) resting CBF in the internal carotid (ICA) and vertebral (VA) arteries (duplex ultrasound) and intra-cranial blood velocity (v) of the middle and posterior cerebral arteries (MCAv and PCAv, respectively) (transcranial Doppler ultrasound); (2) cerebrovascular reactivity to acute poikilocapnic hypoxia (i.e. F I O 2 , 0.10) and hyperoxia (i.e. F I O 2 , 1.0); and (3) neurovascular coupling (NVC; regional CBF response to local increases in cerebral metabolism). Global CBF, cerebrovascular reactivity to hypoxia and hyperoxia, and NVC were unaltered following a SCUBA dive (all P > 0.05); however, there were subtle changes in other cerebrovascular metrics post-dive, including reductions in ICA (-13 ± 8%, P = 0.003) and VA (-11 ± 14%, P = 0.021) shear rate, lower ICAv (-10 ± 9%, P = 0.008) and VAv (-9 ± 14%, P = 0.028), increases in ICA diameter (+4 ± 5%, P = 0.017) and elevations in PCAv (+10 ± 19%, P = 0.047). Although we observed subtle alterations in CBF regulation at rest, these changes did not translate into any functional changes in cerebrovascular reactivity to hypoxia or hyperoxia, or NVC. Whether prolonged exposure to hyperoxia and hyperbaria during longer, deeper, colder and/or repetitive SCUBA dives would provoke changes to the cerebrovasculature requires further investigation.

Background While previous studies have demonstrated a complex visual scene search elicits a robust neurovascular coupling (NVC) response, it is unknown how the duration of visual stimuli presentation influences NVC metrics. This study examined how stimuli duration, in addition to biological sex and self‐reported engagement impact NVC responses. Methods Participants (n = 20, female = 10) completed four visual paradigms. Three involved simple visual shapes presented at 0.5‐, 2‐, and 4‐s intervals in randomized orders. The fourth paradigm was a complex visual scene search (“Where's Waldo?”). Participants completed eight cycles of 20‐s eyes‐closed followed by 40‐s eyes‐open. Transcranial Doppler ultrasound indexed posterior and middle cerebral artery velocities (PCA and MCA). Participants self‐reported their engagement following each task (1 [minimal] to 10 [maximal]). Results The “Where's Waldo?” task evoked greater PCA percent increase (all p, A simple shapes task elicited a modest neurovascular coupling (NVC) response, regardless of image presentation duration (4‐, 2‐, or 0.5‐s). Conversely, a complex “Where's Waldo?” search produced a robust response that maximized the NVC response. While absolute cerebral blood velocity metrics were higher in females, no differences were found between biological sexes regarding the NVC response. However, subjective task engagement had a greater correlation within males, highlighting the need for researchers to use more engaging tasks for males to elicit a similar NVC response compared to females.

We recently employed repeated squat-stands (RSS) to quantify directional sensitivity of the cerebral-pressure flow relationship (i.e. hysteresis) using a novel metric. Within-day reproducibility and diurnal variation impacts of this metric are unknown. We evaluated this metric for: 1) within-day reproducibility and the extent diurnal variation has in middle (MCA; ΔMCAvT/ΔMAPT) and posterior cerebral arteries (PCA; ΔPCAvT/ΔMAPT); 2) sex differences. Absolute (ΔMCAvT/ΔMAPT ; ΔPCAvT/ΔMAPT) and relative (%MCAvT/%MAPT, %PCAvT/%MAPT) metrics were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv/PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Reproducibility was evaluated with intraclass correlation coefficient (ICC). For all metrics, reproducibility was good (0.75-0.90) to excellent (>0.90). The metric in both arteries was impacted by MAP direction at 0.10 Hz (all p < 0.024). Time-of-day influenced ΔMCAvT/ΔMAPT (0.05 Hz: p = 0.0028; 0.10 Hz: p = 0.0009), %MCAvT/%MAPT (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.0087), and ΔPCAvT/ΔMAPT (0.05 Hz: p = 0.0236). Sex differences in the MCA (p = 0.0028) vanished in relative terms and was absent in the PCA. These findings demonstrate within-day reproducibility of this metric in both arteries. Moreover, hysteresis is not impacted by sex.

To evaluate how an exertional field-test impacts the Sport Concussion Assessment Tool 5 (SCAT5) subcomponents in uninjured athletes.Prospective case-series.Sports medicine setting.A total of 37 rugby and wrestling athletes (76% female) with a median age of 19 years (range: 18-23). Twenty-one (57%) had a history of concussion.The SCAT5 was administered prior-to and following a volitionally fatiguing, field-based 30-15 Intermittent Fitness Test. The primary outcome measures included: total symptom scores and severity, standardized assessment of concussion, neurological screening, and balance errors during the modified balance error scoring system. Wilcoxon signed-rank tests examined differences in ordinal data between pre- and post-exertion with Bonferroni corrections (alpha = 0.006). Data were also stratified into time to SCAT5 administration post-exertion and compared via Cliff's Delta (d).The SCAT5 was administered a median of 20-min (interquartile range: 14-26-min) following exertion. No differences were found pre- and post-exertion across all SCAT5 metrics (p 0.048). Within the post-exertion 0-10-min stratification, total symptoms and severity scores appeared to be elevated with a large effect size (d ≥ 0.64).While SCAT5 metrics were not statistically altered when quantified a median of 20-min following high-intensity exertion; greater symptom reporting may occur 10-min following exertion.

While cardiac pulsations are widely present within physiological and neuroimaging data, it is unknown the extent this information can provide valid and reliable heart rate and heart rate variability (HRV) estimates. The objective of this study was to demonstrate how a slight temporal shift due to an insufficient sampling frequency can impact the validity/accuracy of deriving cardiac metrics.Twenty-two participants were instrumented with valid/reliable industry-standard or open-source electrocardiograms. Five-minute lead II recordings were collected at 1000 Hz in an upright orthostatic position. Following artifact removal, the 1000 Hz recording for each participant was downsampled to frequencies ranging 2-500 Hz. The validity of each participant's downsampled recording was compared against their 1000 Hz recording ("reference-standard") using Bland-Altman plots with 95 % limits of agreement (LOA), coefficient of variation (CoV), intraclass correlation coefficients, and adjusted r-squared values.Downsampled frequencies of ≥ 50 and ≥ 90 Hz produced highly robust measures with narrow log-transformed 95 % LOA (±0.01) and low CoV values (≤3.5 %) for heart rate and HRV metrics, respectively. Below these thresholds, the log-transformed 95 % LOA became wider (LOA range: ±0.1-1.9) and more variable (CoV range: 1.5-111.6 %).These results provide an important consideration for obtaining cardiac information from physiological data. Compared to the "reference-standard" ECG, a seemingly negligible temporal shift of the systolic contraction (R wave) greater than 11-milliseconds (90 Hz) away from its true value, lessened the validity of the HRV. Further research is warranted to determine the minimum sampling frequency required to obtain valid heart rate/HRV metrics from pulsatile waveforms.

Context After concussion, a multifaceted assessment is recommended, including tests of physical exertion. The current criterion standard for exercise testing after concussion is the Buffalo Concussion Treadmill Test (BCTT); however, validated tests that use alternative exercise modalities are lacking. Objective To evaluate the feasibility and concurrent validity of a universal cycling test of exertion compared with the BCTT in adults who sustained a sport-related concussion. Design Crossover study. Setting University sports medicine clinic. Patients or Other Participants Twenty adults (age = 18–60 years) diagnosed with a sport-related concussion. Intervention(s) Participants completed the BCTT and a cycling test of exertion in random order, approximately 48 hours apart. Main Outcome Measure(s) The primary outcome of interest was maximum heart rate (HRmax; beats per minute [bpm]). Secondary outcomes of interest were the total number of symptoms endorsed on the Post-Concussion Symptom Scale, whether the participant reached volitional fatigue (yes or no), the symptom responsible for test cessation (Post-Concussion Symptom Scale), maximum rating of perceived exertion, symptom severity on a visual scale (0–10), and the time to test cessation. Results Of the 20 participants, 19 (10 males, 9 females) completed both tests. One participant did not return for the second test and was excluded from the analysis. No adverse events were reported. The median HRmax for the BCTT (171 bpm; interquartile range = 139–184 bpm) was not different from the median HRmax for the cycle (173 bpm; interquartile range = 160–182 bpm; z = −0.63; P = .53). For both tests, the 3 most frequently reported symptoms responsible for test cessation were headache, dizziness, and pressure in the head. Of interest, most participants (64%) reported a different symptom responsible for cessation of each test. Conclusions On the novel cycling test of exertion, participants achieved similar HRmax and test durations and, therefore, this test may be a suitable alternative to the BCTT. Future research to understand the physiological reason for the heterogeneity in symptoms responsible for test cessation is warranted.

A one size fits all methodological approach to quantify HRV metrics appears to be inappropriate, where study design considerations need to be conducted upon a variable-by-variable basis. The present results found 60 s (heart rate), 240 s (time-domain parameters), and 300 s (relative frequency-domain parameters) were required to obtain accurate and reproducible metrics. The lower validity/reliability of the ultra-short-term metrics was attributable to measurement error and/or confounding from extraneous physiological influences (i.e., respiratory and hemodynamic variables).

There is growing concern repetitive head contacts sustained by soccer players may lead to long-term health ramifications. Therefore, this preliminary investigation examined the impact an acute soccer heading bout has on dynamic cerebral autoregulation (dCA) metrics.In this preliminary investigation, 40 successful soccer headers were performed in 20 min by 7 male elite soccer players (24.1 ± 1.5 years). Soccer balls were launched at 77.5 ± 3.7 km/h from JUGS soccer machine, located 35 m away from participants. Linear and rotational head accelerations impacts were measured using an accelerometer (xPatch). The SCAT3 indexed concussion symptom score and severity before and after: soccer headers, sham (body contact only), and control conditions. Squat-stand maneuvers were performed at 0.05 Hz and 0.10 Hz to quantity dCA through measures of coherence, phase, and gain.Cumulative linear and rotational accelerations during soccer headers were 1574 ± 97.9 g and 313,761 ± 23,966 rads/sThese preliminary results indicate an acute bout of soccer heading resulted in alterations to dCA metrics. Therefore, future research with larger sample sizes is warranted to fully comprehend short- and long-term physiological changes related to soccer heading.

Purpose Studies examining neurovascular coupling (NVC) require participants to refrain from exercise for 12–24 hours. However, there is a paucity of empirical evidence for this restriction. The objectives for this study were to delineate the time‐course recovery of NVC metrics following exercise and establish the NVC within‐ and between‐day reliability. Methods Nine participants completed a complex visual search paradigm to assess NVC via transcranial Doppler ultrasound of the posterior cerebral artery blood velocity (PCA). Measurements were performed prior to and throughout the 8‐hour recovery period following three randomized conditions: 45 minutes of moderate‐intensity exercise (at 50% heart‐rate reserve), 30 minutes high‐intensity intervals (10, 1‐minute intervals at 85% heart‐rate reserve), and control (30 minutes quiet rest). In each condition, baseline measures were collected at 8:00am with serial follow‐ups at hours zero, one, two, four, six, and eight. Results Area‐under‐the‐curve and time‐to‐peak PCA velocity during the visual search were attenuated at hour zero following high‐intensity intervals (all p 0.13). Conversely, baseline PCA velocity, peak PCA velocity, and the relative percent increase were not different following high‐intensity intervals compared to baseline (all p > 0.26). No NVC metrics differed from baseline following both moderate exercise and control conditions (all p > 0.24). The majority of the NVC parameters demonstrated high levels of reliability (intraclass correlation coefficient: >0.90). Conclusion Future NVC assessments can take place a minimum of one hour following exercise. Moreover, all metrics did not change across the control condition, therefore future studies using this methodology can reliably quantify NVC between 8:00am and 7:00 pm., Previous studies examining neurovascular coupling (NVC) metrics, required participants to refrain from exercise for 4‐24 hours prior to data collection, despite a lack of objective evidence for this time restriction. The results in the current investigation demonstrated that the NVC response was attenuated immediately following high‐intensity exercise within the posterior cerebral artery (PCA); however, the NVC response was comparable to baseline values one‐hour following exercise. Additionally, NVC metrics displayed high levels of within‐ and between‐day reliability across the control condition (8:00am – 7:00pm) when using a complex visual scene search paradigm (“Where’s Waldo”).

Objective. Currently, a recording of 300 s is recommended to obtain accurate dynamic cerebral autoregulation estimates using transfer function analysis (TFA). Therefore, this investigation sought to explore the concurrent validity and the within- and between-day reliability of TFA estimates derived from shorter recording durations from squat-stand maneuvers. Approach. Retrospective analyses were performed on 70 young, recreationally active or endurance-trained participants (17 females; age: 26 ± 5 years, [range: 20–39 years]; body mass index: 24 ± 3 kg m−2). Participants performed 300 s of squat-stands at frequencies of 0.05 and 0.10 Hz, where shorter recordings of 60, 120, 180, and 240 s were extracted. Continuous transcranial Doppler ultrasound recordings were taken within the middle and posterior cerebral arteries. Coherence, phase, gain, and normalized gain metrics were derived. Bland–Altman plots with 95% limits of agreement (LOA), repeated measures ANOVA’s, two-tailed paired t-tests, coefficient of variation, Cronbach’s alpha, intraclass correlation coefficients, and linear regressions were conducted. Main results. When examining the concurrent validity across different recording durations, group differences were noted within coherence (F (4155) > 11.6, p F (4155) p > 0.611), gain (F (4155) p > 0.440), or normalized gain (F (4155) p > 0.359) parameters. The Bland–Altman 95% LOA measuring the concurrent validity, trended to narrow as recording duration increased (60 s: Significance. Future studies examining autoregulation should seek to have participants perform 300 s of squat-stand maneuvers. However, valid and reliable TFA estimates can be drawn from 240 s or 180 s recordings if physiological covariates are controlled.

Presently, the literature describing the influence of diurnal variation on dynamic cerebral autoregulation (dCA) metrics is sparse. Additionally, there is little data with respect to dCA comparisons between anterior/posterior circulation beds and biological sexes using squat‐stand maneuvers. Eight male and eight female participants (n = 16) performed 5 min of spontaneous upright rest and squat‐stand maneuvers at 0.05 and 0.10 Hz across seven time points throughout the day. All testing sessions commenced at 8:00 a.m. each day and dCA parameters were quantified across the cardiac cycle (diastole, mean, and systole) using transcranial Doppler ultrasound to insonate cerebral blood velocity within the middle and posterior cerebral arteries (MCA, PCA). No cardiac cycle alternations were seen spontaneous (all p > .207) while a trend was noted in some driven (all p > .051) dCA metrics. Driven dCA produced much lower coefficient of variances (all .096). Between vessels, PCA absolute gain was reduced within all spontaneous and driven measures (all p .099). There appears to be little influence of diurnal variation on dCA measures across the day (8:00 a.m. to 6:00 p.m.). Absolute gain was blunted in the PCA relative to the MCA and consistent with previous literature, driven methods demonstrated vastly improved reproducibility metrics compared to spontaneous methods. Finally, no dCA differences were found between biological sexes, demonstrating that males and females regulate in a harmonious manner, when females are tested within the early follicular phase of the menstrual cycle., Driven dynamic dynamic cerebral autoregulation (dCA) metrics elicited more robust measures compared to spontaneous metrics across the day (8:00–18:00). Additionally, both the middle and posterior cerebral arteries regulated similarly across the day, as well did both males and female participants. Therefore, in the future when feasible, squat‐stand maneuvers should be used to assess dCA in participants, which can be performed in both vessels, across the cardiac cycle and in both biological sexes, as there is minimal influence of diurnal variation across the day within these measures.

To examine how high-intensity physical exertion affects clinical measures of cervical spine (CSp), vestibular/ocular motor screen (VOMS), and vestibulo-ocular reflex (VOR) function.Case series.Sports Medicine Centre.A total of 37 athletes consented to participate (22 rugby, 15 wrestling; 9 men, 28 women; median age = 19 years [range 17-23 years]).Outcome measures included tests of CSp (cervical flexor endurance, head perturbation test, cervical flexion rotation test and anterolateral strength), VOR (head thrust test and dynamic visual acuity [DVA]), and a quantified version of the VOMS. These metrics were assessed prior to and after completing the 30-15 Intermittent Fitness Test. Bland-Altman plots and Wilcoxon signed-rank tests were utilized to analyze the data using an alpha of p 0.004.Cervical anterolateral strength (kg) was reduced post-exertion on the left (z = 3.87; p 0.001), but not on the right between conditions (z = -1.49; p = 0.14). Athletes reported increased dizziness (z = -3.55; p = 0.004) and had reduced DVA following exertion (z = -2.78; p 0.001). All other metrics were not significantly different following exertion (p 0.011).Reduced performance on DVA, decreased left-anterolateral strength, and increased dizziness occurred following high-intensity exertion in varsity collision and combative athletes, which has implications for sideline screening for sport-related concussion.

A common inclusion criterion when assessing cerebrovascular (CVR) metrics is for individuals to abstain from exercise for 12–24 hr prior to data collections. While several studies have examined CVR during exercise, the literature describing CVR throughout post‐exercise recovery is sparse. The current investigation examined CVR measurements in nine participants (seven male) before and for 8 hr following three conditions: 45‐min moderate‐continuous exercise (at ~50% heart‐rate reserve), 25‐min high‐intensity intervals (ten, one‐minute intervals at ~85% heart‐rate reserve), and a control day (30‐min quiet rest). The hypercapnic (40–60 mmHg) and hypocapnic (25–40 mmHg) slopes were assessed via a modified rebreathing technique and controlled stepwise hyperventilation, respectively. All testing was initiated at 8:00a.m. with transcranial Doppler ultrasound measurements to index cerebral blood velocity performed prior to the condition (pre) with serial follow‐ups at zero, one, two, four, six, and eight hours within the middle and posterior cerebral artery (MCA, PCA). Absolute and relative MCA and PCA hypercapnic slopes were attenuated following high‐intensity intervals at hours zero and one (all p .13), aside from a reduced relative hypercapnic MCA slope at hours zero and one following moderate‐continuous exercise (all p, Absolute and relative MCA and PCA cerebrovascular reactivity hypercapnic slopes were attenuated following high‐intensity intervals at hours zero and one (all p .13), aside from a reduced relative hypercapnic MCA slope at hours zero and one following moderate‐continuous exercise (all p

Movement complexity is known to increase reaction time (RT). More recently, transcranial magnetic stimulation (TMS) of the motor cortex has revealed that movement complexity can alter corticospinal excitability. However, the impact of a sequential addition of movement components on corticospinal excitability during the preparatory phase of a simple RT task is unknown. Thus, the purpose of this study was to examine how motor evoked potentials (MEPs) in the premotor period were affected by the complexity of a movement in a simple RT paradigm. Participants (n = 12) completed ballistic movements with their dominant arm, in which they directed a robotic handle to one, two or three targets (32 trials per condition). TMS was delivered prior to movement at 0, 70, 80 or 90% of each participant's mean premotor RT, at the stimulator intensity which yielded a triceps brachii MEP of ~ 10% the maximal M-wave. As expected, premotor RT slowed with increasing task complexity. Although background electromyographic activity (EMG) of the triceps brachii during the preparation phase did not differ among conditions, MEP amplitude increased with movement complexity (i.e., MEPs were greater for the 2- and 3-movement conditions, compared to the 1-movement condition at 80% of premotor RT). We propose the lengthened RTs could be due in part to less suppression of particular motor circuits, while other circuitry is responsible for the increased MEPs. This study demonstrates that, prior to movement, corticospinal excitability increases as a consequence of movement complexity.

Numerous studies have examined heart rate variability (HRV) and cardiac baroreceptor sensitivity (BRS) variables during recovery both acutely (under 3 h) and long-term (24, 48, and 72 h) postexercise. However, there is little literature examining HRV and BRS measures between these timepoints. Spontaneous short-term HRV and cardiac BRS measures were collected in 9 participants before and at zero, 1, 2, 4, 6, and 8 h after 3 separate conditions: moderate-intensity continuous exercise (MICE; 45 min at 50% heart rate reserve), high-intensity interval exercise (HIIE; 25 min including ten 1-min intervals at 85% heart rate reserve), and control (30 min quiet rest). HRV measures in the time domain were only affected immediately following HIIE and MICE at hour zero (all p < 0.043), whereas frequency-domain metrics were unaltered (all p > 0.102). These measures were highly consistent across the control day (all p > 0.420). Cardiac BRS was assessed via low-frequency (LF) gain, and revealed reductions following HIIE at hour zero (p < 0.012). Cardiac BRS LF gain remained consistent following MICE and control interventions (all p > 0.280). The common practice of waiting 12 to 24 h is overly conservative as the current findings demonstrate measures return to baseline at ∼60 min after exercise. Moreover, these metrics demonstrated high levels of within- and between-day reliability. Novelty Previously a 12-h minimum restriction from exercise was required before participation in HRV/BRS studies. Recovery from moderate-intensity exercise for HRV and BRS metrics was

Current protocols examining cerebral autoregulation (CA) parameters require participants to refrain from exercise for 12–24 hr, however there is sparse objective evidence examining the recovery trajectory of these measures following exercise across the cardiac cycle (diastole, mean, and systole). Therefore, this study sought to determine the duration acute exercise impacts CA and the within‐day reproducibility of these measures. Nine participants performed squat–stand maneuvers at 0.05 and 0.10 Hz at baseline before three interventions: 45‐min moderate‐continuous exercise (at 50% heart‐rate reserve), 30‐min high‐intensity intervals (ten, 1‐min at 85% heart‐rate reserve), and a control day (30‐min quiet rest). Squat–stands were repeated at hours zero, one, two, four, six, and eight after each condition. Transcranial doppler ultrasound of the middle cerebral artery (MCA) and the posterior cerebral artery (PCA) was used to characterize CA parameters across the cardiac cycle. At baseline, the systolic CA parameters were different than mean and diastolic components (ps 0.079). In the PCA, phase values were affected only following high‐intensity intervals until hour four (ps > 0.055). Normalized gain in all cardiac cycle domains remained different following both exercise protocols (ps, Nine participants performed squat‐stand maneuvers at 0.05 and 0.10 Hz at baseline before three interventions: 45‐min moderate‐continuous exercise (at 50% heart‐rate reserve), 30‐min high‐intensity intervals (ten, one minute at 85% heart‐rate reserve), and a control day (30‐min quiet rest). Squat‐stands were repeated at hours zero, one, two, four, six, and eight after each condition. exercise was shown to affect dynamic CA into recovery up to 4 hr following exercise, with HIIT demonstrating greater affects than MICT (each phase of the cardiac cycle responded differently to exercise, with the systolic component showing impairments for up to 4 hr, compared to diastolic and mean which recovered after 2 hr in all measures).

Accelerometers are being increasingly incorporated into neuroimaging devices to enable real-time filtering of movement artifacts. In this study, we evaluate the reliability of sway metrics derived from these accelerometers in a standard eyes-open balance assessment to determine their utility in multimodal study designs. Ten participants equipped with a head-mounted accelerometer performed an eyes-open standing condition on 7 consecutive days. Sway performance was quantified with 4 standard metrics: root-mean-square (RMS) acceleration, peak-to-peak (P2P) acceleration, jerk, and ellipse area. Intraclass correlation coefficients (ICC) quantified reliability. P2P in both the mediolateral (ICC = 0.65) and anteroposterior (ICC = 0.67) planes yielded the poorest reliability. Both ellipse area and RMS exhibited good reliability, ranging from 0.76 to 0.84 depending on the plane. Finally, jerk displayed the highest reliability with an ICC value of 0.95. Moderate to excellent reliability was observed in all sway metrics. These findings demonstrate that head-mounted accelerometers, commonly found in neuroimaging devices, can be used to reliably assess sway. These data validate the use of head-mounted accelerometers in the assessment of motor control alongside other measures of brain activity such as electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS).

ObjectivesTo determine the effect of heading a soccer ball on serum neurofilament light (NF-L) protein, plasma tau protein and symptom metrics including total number of symptoms reported and symptom severity scores on the Standardized Concussion Assessment Tool— 3rd edition (SCAT3).MethodsEleven male collegiate soccer players were recruited to take part in three experimental conditions including heading, sham and control conditions. Participants were required to perform 40 headers in 20 min in the heading condition, and control 40 soccer balls directed at them with their hands, chest or thigh in the sham condition. No ball contact was made during the control condition. Blood sampling and SCAT3 symptom assessments were completed prior to and 1 hour following conditions. A subset of participants returned 3 weeks following the heading condition for blood sampling.ResultsNF-L was elevated at 1 hour (p=0.004) and 1 month (p=0.04) following the heading condition, and at 1 hour (p=0.02) following the control condition. Tau levels remained unchanged following all conditions. The total number of symptoms (TS) and symptom severity (SS) scores from the SCAT3 were both elevated following the heading condition (p=0.01 and p=0.03, respectively). Both TS and SS decreased following sham (p=0.04 and p=0.04) and control conditions (p=0.04 and p=0.04).ConclusionAn acute bout of soccer heading is associated with increased NF-L concentrations at 1 hour and 1 month following the session and can lead to symptoms commonly reported following sport-related concussion.