Background:
Aerobic exercise has emerged as a useful treatment to improve outcomes among individuals who experience a concussion. However, compliance with exercise recommendations and the effect of ...exercise volume on symptom recovery require further investigation.
Purpose:
To examine (1) if an 8-week aerobic exercise prescription, provided within 2 weeks of concussion, affects symptom severity or exercise volume; (2) whether prescription adherence, rather than randomized group assignment, reflects the actual effect of aerobic exercise in postconcussion recovery; and (3) the optimal volume of exercise associated with symptom resolution after 1 month of study.
Study Design:
Cohort study; Level of evidence, 2.
Methods:
Individuals randomized to an exercise intervention (n = 17; mean age, 17.2 ± 2.0 years; 41% female; initially tested a mean of 11.3 ± 2.8 days after injury) or standard of care (n = 20; mean age, 16.8 ± 2.2 years; 50% female; initially tested a mean of 10.7 ± 3.2 days after injury) completed an aerobic exercise test within 14 days of injury. They returned for assessments 1 month and 2 months after the initial visit. The aerobic exercise group was instructed to exercise 5 d/wk, 20 min/d (100 min/wk), at a target heart rate based on an exercise test at the initial visit. Participants reported their exercise volume each week over the 8-week study period and reported symptoms at each study visit (initial, 1 month, 2 months). Because of low compliance in both groups, there was no difference in the volume of exercise between the 2 groups.
Results:
There were no significant symptom severity differences between the intervention and standard-of-care groups at the initial (median Post-Concussion Symptom Inventory, 15 interquartile range = 10, 42 vs 20 11, 35.5; P = .26), 1-month (4 0, 28 vs 5.5 0.5, 21.5; P = .96), or 2-month (6.5 0, 27.5 vs 0 0, 4; P = .11) study visits. Exercise volume was similar between groups (median, 115 54, 225 vs 88 28, 230 min/wk for exercise intervention vs standard of care; P = .52). Regardless of group, those who exercised <100 min/wk reported significantly higher symptom severity at the 1-month evaluation compared with those who exercised ≥100 min/wk (median, 1.5 0, 7.5 vs 12 4, 28; P = .03). Exercising ≥160 min/wk successfully discriminated between those with and those without symptoms 1 month after study commencement (classification accuracy, 81%; sensitivity, 90%; specificity, 78%).
Conclusion:
Greater exercise volume was associated with lower symptom burden after 1 month of study, and an exercise volume >160 min/wk in the first month of the study was the threshold associated with symptom resolution after the first month of the study. Because our observation on the association between exercise volume and symptom level is a retrospective and secondary outcome, it is possible that participants who were feeling better were more likely to exercise more, rather than the exercise itself driving the reduction in symptom severity.
Reduced middle cerebral artery blood velocity (MCAv) and flow pulsatility are contributors to age-related cerebrovascular disease pathogenesis. It is unknown whether the rate of changes in MCAv and ...flow pulsatility support the hypothesis of sex-specific trajectories with aging. Therefore, we sought to characterize the rate of changes in MCAv and flow pulsatility across the adult lifespan in females and males as well as within specified age ranges. Participant characteristics, mean arterial pressure, end-tidal carbon dioxide, unilateral MCAv, and flow pulsatility index (PI) were determined from study records compiled from three institutional sites. A total of 524 participants 18-90 yr; females 57 (17) yr,
= 319; males 50 (21) yr,
= 205 were included in the analysis. MCAv was significantly higher in females within the second (
< 0.001), fifth (
= 0.01), and sixth (
< 0.01) decades of life. Flow PI was significantly lower in females within the second decade of life (
< 0.01). Rate of MCAv decline was significantly greater in females than males (-0.39 vs. -0.26 cm s
·yr,
= 0.04). Rate of flow PI rise was significantly greater in females than males (0.006 vs. 0.003 flow PI,
= 0.01). Rate of MCAv change was significantly greater in females than males in the sixth decade of life (-1.44 vs. 0.13 cm s
·yr,
= 0.04). These findings indicate that sex significantly contributes to age-related differences in both MCAv and flow PI. Therefore, further investigation into cerebrovascular function within and between sexes is warranted to improve our understanding of the reported sex differences in cerebrovascular disease prevalence.
We present the largest dataset (
= 524) pooled from three institutions to study how age and sex affect middle cerebral artery blood velocity (MCAv) and flow pulsatility index (PI) across the adult lifespan. We report the rate of MCAv decline and flow PI rise is significantly greater in females compared with in males. These data suggest that sex-specific trajectories with aging and therapeutic interventions to promote healthy brain aging should consider these findings.
High-intensity interval training (HIIE) may present unique challenges to the cerebrovascular system in individuals post-stroke. We hypothesized lower middle cerebral artery blood velocity (MCAv) in ...individuals post-stroke: 1) during 10 minutes of HIIE, 2) immediately following HIIE, and 3) 30 minutes after HIIE, compared to age- and sex-matched controls (CON). We used a recumbent stepper submaximal exercise test to determine workloads for high-intensity and active recovery. Our low volume HIIE protocol consisted of 1-minute intervals for 10 minutes. During HIIE, we measured MCAv, mean arterial pressure (MAP), heart rate (HR), and end tidal carbon dioxide (PETCO2). We assessed carotid-femoral pulse wave velocity as a measure of arterial stiffness. Fifty participants completed the study (25 post-stroke, 76% ischemic, 32% moderate disability). Individuals post-stroke had lower MCAv during HIIE compared to CON (p = 0.03), which remained 30 minutes after HIIE. Individuals post-stroke had greater arterial stiffness (p = 0.01) which was moderately associated with a smaller MCAv responsiveness during HIIE (r = −0.44). No differences were found for MAP, HR, and PETCO2. This study suggests individuals post-stroke had a lower MCAv during HIIE compared to their peers, which remained during recovery up to 30 minutes. Arterial stiffness may contribute to the lower cerebrovascular responsiveness post-stroke.
Background
Reduced cerebral blood flow (CBF) along with vascular risk factors (e.g., dyslipidemia) are prevalent in Alzheimer’s disease (AD) and related dementias. Considering the lack of ...disease‐modifying therapies, targeting modifiable vascular risk factors is imperative. Statins are one of the most effective pharmacologic treatments for vascular risk reduction, which may increase CBF in individuals with an increased risk for AD. Despite widespread statin use in both sexes, sex specific statin effects on CBF is not completely understood.
Method
Cross‐sectional analysis of 194 older adults with a family history of dementia. Heart rate via electrocardiogram, mean arterial pressure (MAP) via plethysmograph, end‐tidal CO2 via capnograph, and CBF velocity at the middle cerebral artery (MCAv) via transcranial Doppler ultrasound were collected following 20‐minutes of supine rest. Mean MCAv (cm/s) was measured within each cardiac cycle and averaged over an 8‐minute duration.
Result
114 females (68 ± 5 years; 49 statin) and 80 males (70 ± 6 years; 46 statin) were included in analyses. There were no significant differences between vasodilator medication use, heart rate, end‐tidal CO2, or MAP between sexes. MCAv was significantly higher in females compared to males. There was a significant interaction effect between statin use and sex (p = 0.03). Post‐hoc analyses suggest that the female statin group had significantly higher MCAv than female non‐statin group (59.0 ± 12.1 vs. 52.7 ± 12.1; p = 0.02) and female statin group had significantly higher MCAv than male statin group (59.0 ± 12.1 vs. 47.5 ± 10.4 cm/s; p < 0.001). Males were significantly older than females; however, we report that age was not a significant covariate in the model.
Conclusion
Our findings suggest a sex specific statin effect on MCAv, with females having had a significantly higher MCAv from statin use. Further investigation is warranted into other components of cerebrovascular function, as differences between sexes may have implications for brain health and disease pathogenesis.
After a cerebrovascular accident (CVA) aerobic deconditioning contributes to diminished physical function. Functional electrical stimulation (FES)-assisted cycling is a promising exercise paradigm ...designed to target both aerobic capacity and locomotor function. This pilot study aimed to evaluate the effects of an FES-assisted cycling intervention on aerobic capacity and locomotor function in individuals post-CVA.
Eleven individuals with chronic (>6 months) post-CVA hemiparesis completed an 8-wk (three times per week; 24 sessions) progressive FES-assisted cycling intervention. V˙O2peak, self-selected, and fastest comfortable walking speeds, gait, and pedaling symmetry, 6-min walk test (6MWT), balance, dynamic gait movements, and health status were measured at baseline and posttraining.
Functional electrical stimulation-assisted cycling significantly improved V˙O2peak (12%, P = 0.006), self-selected walking speed (SSWS, 0.05 ± 0.1 m·s, P = 0.04), Activities-specific Balance Confidence scale score (12.75 ± 17.4, P = 0.04), Berg Balance Scale score (3.91 ± 4.2, P = 0.016), Dynamic Gait Index score (1.64 ± 1.4, P = 0.016), and Stroke Impact Scale participation/role domain score (12.74 ± 16.7, P = 0.027). Additionally, pedal symmetry, represented by the paretic limb contribution to pedaling (paretic pedaling ratio PPR) significantly improved (10.09% ± 9.0%, P = 0.016). Although step length symmetry (paretic step ratio PSR) did improve, these changes were not statistically significant (-0.05% ± 0.1%, P = 0.09). Exploratory correlations showed moderate association between change in SSWS and 6-min walk test (r = 0.74), and moderate/strong negative association between change in PPR and PSR.
These results support FES-assisted cycling as a means to improve both aerobic capacity and locomotor function. Improvements in SSWS, balance, dynamic walking movements, and participation in familial and societal roles are important targets for rehabilitation of individuals after CVA. Interestingly, the correlation between PSR and PPR suggests that improvements in pedaling symmetry may translate to a more symmetric gait pattern.
Aerobic exercise has become a useful method to assist with postconcussion management. Exercise can exacerbate concussion symptoms even when symptoms are not apparent at rest. Few studies have ...examined the reasons for symptom exacerbation during exercise following a concussion. We had 2 primary objectives: (1) to delineate cardiopulmonary and cerebrovascular responses to exercise in adolescents and young adults with a concussion and healthy controls and (2) to determine the association between cerebrovascular responses and symptom burden.
We recruited participants with a recent concussion from a sport concussion clinic between September 1, 2018, and February 22, 2020. They were included if their concussion occurred <3 weeks before initial testing and if they were symptomatic at rest. Participants were excluded if they sustained a concussion in the past year (excluding index injury), reported history of neurologic disorders, or were using medications/devices that may alter neurologic function. Participants completed a progressive, symptom-limited, submaximal exercise protocol on a stationary bicycle. We assessed heart rate, blood pressure, fraction of end tidal CO
(FETCO
), and middle cerebral artery blood flow velocity (CBF) and cerebrovascular function (vasoactivity and autoregulation) at seated rest and during exercise.
We conducted 107 exercise tests (40 concussed, 37 healthy participants initially; 30 concussed at follow-up). Concussed participants were tested initially (mean 17.6 ± 2.2 SD years of age; 55% female; mean 12.5 ± 4.7 days postconcussion) and again 8 weeks later (mean 73.3 ± 9.5 days postconcussion). Control participants (mean 18.3 ± 2.4 years; 62% female) were tested once. FETCO
increased throughout the exercise protocol as heart rate increased, reached a plateau, and declined at higher exercise intensities. CO
explained >25% of the variation in resting CBF (
> 0.25;
< 0.01) in most (73% individuals). Within the concussion group, resting symptom severity and the heart rate at which FETCO
reached a plateau explained ∼2/3s of variation in exercise-induced symptom exacerbation (
= 0.65; FETCO
β = -1.210 ± 0.517 SE,
< 0.05). There was a moderate, statistically significant relationship between cerebrovascular responses to CO
at rest (cerebral vasoactivity) and cerebrovascular responses to exercise-induced changes in FETCO
(
= 0.13,
= 0.01).
The arterial CO
response and symptom exacerbation relationship during postconcussion aerobic exercise may be mediated by increased sensitivity of cerebral vasculature to exercise-related increase in CO
.
To examine if self-reported dizziness is associated with concussion symptoms, depression and/or anxiety symptoms, or gait performance within 2 weeks of postconcussion.
Cross-sectional study.
Research ...laboratory.
Participants were diagnosed with a concussion within 14 days of initial testing (N = 40). Participants were divided into 2 groups based on their Dizziness Handicap Inventory (DHI) score: 36 to 100 = moderate/severe dizziness and 0 to 35 = mild/no dizziness.
Participants were tested on a single occasion and completed the DHI, hospital anxiety and depression scale (HADS), Patient Health Questionnaire-9 (PHQ-9), and Post-Concussion Symptom Inventory (PCSI). Three different postural control tests were use: modified Balance Error Scoring System, single-/dual-task tandem gait, and a single-/dual-task instrumented steady-state gait analysis.
Comparison of patient-reported outcomes and postural control outcomes between moderate/severe (DHI ≥ 36) and mild/no (DHI < 36) dizziness groups.
Participants with moderate/severe dizziness (n = 19; age = 17.1 ± 2.4 years; 63% female) reported significantly higher symptom burden (PSCI: 43.0 ± 20.6 vs 22.8 ± 15.7; P = 0.001) and had higher median HADS anxiety (6 vs 2; P < 0.001) and depression (6 vs 1; P = 0.001) symptom severity than those with no/minimal dizziness (n = 21; age = 16.5 ± 1.9; 38% female). During steady-state gait, moderate/severe dizziness group walked with significantly slower single-task cadence (mean difference = 4.8 steps/minute; 95% confidence interval = 0.8, 8.8; P = 0.02) and dual-task cadence (mean difference = 7.4 steps/minute; 95% confidence interval = 0.7, 14.0; P = 0.04) than no/mild dizziness group.
Participants who reported moderate/severe dizziness reported higher concussion symptom burden, higher anxiety scores, and higher depression scores than those with no/mild dizziness. Cadence during gait was also associated with the level of dizziness reported.
Fluctuating arterial blood pressure during high-intensity interval exercise (HIIE) may challenge dynamic cerebral autoregulation (dCA), specifically after stroke after an injury to the ...cerebrovasculature. We hypothesized that dCA would be attenuated at rest and during a sit-to-stand transition immediately after and 30 min after HIIE in individuals poststroke compared with age- and sex-matched control subjects (CON). HIIE switched every minute between 70% and 10% estimated maximal watts for 10 min. Mean arterial pressure (MAP) and middle cerebral artery blood velocity (MCAv) were recorded. dCA was quantified during spontaneous fluctuations in MAP and MCAv via transfer function analysis. For sit-to-stand, time delay before an increase in cerebrovascular conductance index (CVCi = MCAv/MAP), rate of regulation, and % change in MCAv and MAP were measured. Twenty-two individuals poststroke (age 60 ± 12 yr, 31 ± 16 mo) and twenty-four CON (age 60 ± 13 yr) completed the study. Very low frequency (VLF) gain (
= 0.02, η
= 0.18) and normalized gain (
= 0.01, η
= 0.43) had a group × time interaction, with CON improving after HIIE whereas individuals poststroke did not. Individuals poststroke had lower VLF phase (
= 0.03, η
= 0.22) after HIIE compared with CON. We found no differences in the sit-to-stand measurement of dCA. Our study showed lower dCA during spontaneous fluctuations in MCAv and MAP following HIIE in individuals poststroke compared with CON, whereas the sit-to-stand response was maintained.
This study provides novel insights into poststroke dynamic cerebral autoregulation (dCA) following an acute bout of high-intensity interval exercise (HIIE). In people after stroke, dCA appears attenuated during spontaneous fluctuations in mean arterial pressure (MAP) and middle cerebral artery blood velocity (MCAv) following HIIE. However, the dCA response during a single sit-to-stand transition after HIIE showed no significant difference from controls. These findings suggest that HIIE may temporarily challenge dCA after exercise in individuals with stroke.
Purpose
It is plausible that statins could improve cerebral blood flow through pleiotropic mechanisms. The purpose of this investigation was to assess the contribution of statins to cerebrovascular ...variables in older adults with dyslipidemia and familial history of dementia. Furthermore, we explored the interaction between statin use and sex due to prevalent bias in statin trials.
Methods
Middle cerebral artery blood flow velocity (MCAv) was measured using transcranial Doppler ultrasound. Continuous supine rest recordings lasted 8 min. Participants included in analyses were statin (
n
= 100) or non-statin users (
n
= 112).
Results
MCAv and cerebrovascular conductance were significantly higher in statin users (
p
= 0.047;
p
= 0.04), and pulsatility index (PI) was significantly lower in statin users (
p
< 0.01). An interaction effect between statin use and sex was present for PI (
p
= 0.02); female statin users had significantly lower cerebrovascular resistance than the other three groups.
Conclusion
In this cross-sectional analysis, statin use was positively associated with cerebrovascular variables in older adults at risk for dementia. Female statin users had significantly higher resting MCAv and cerebrovascular conductance than female non-statin users. The greatest contribution of statin use was the association with reduced cerebrovascular resistance. Given that cerebrovascular dysregulation is one of the earliest changes in Alzheimer’s disease and related dementia pathology, targeting the cerebrovasculature with statins may be a promising prevention strategy.
Objective
To assess acute cerebrovascular function in concussed adolescents (14–21 years of age), whether it is related to resting cerebral hemodynamics, and whether it recovers chronically.
Methods
...Cerebral vasoreactivity and autoregulation, based on middle cerebral artery blood flow velocity, was assessed in 28 concussed participants (≤14 days of injury) and 29 matched controls. The participants in the concussion group returned for an 8‐week follow‐up assessment. Over the course of those 8‐weeks, participants recorded aerobic exercise frequency and duration.
Results
Between groups, demographic, clinical, and hemodynamic variables were not significantly different. Vasoreactivity was significantly higher in the concussed group (p = 0.02). Within the concussed group, 60% of the variability in resting cerebral blood flow velocity was explained by vasoreactivity and two components of autoregulation – falling slope and effectiveness of autoregulation (adjusted R2 = 0.60, p < 0.001). Moreover, lower mean arterial pressure, lower responses to increases in arterial pressure, and lower vasoreactivity were significantly associated with larger symptom burden (adjusted R2 = 0.72, p < 0.01). By the 8‐week timepoint, symptom burden, but not vasoreactivity, improved in all but four concussed participants (p < 0.01). 8‐week change in vasoreactivity was positively associated with aerobic exercise volume (adjusted R2 = 0.19, p = 0.02).
Interpretation
Concussion resulted in changes in cerebrovascular regulatory mechanisms, which in turn explained the variability in resting cerebral blood flow velocity and acute symptom burden. Furthermore, these alterations persisted chronically despite symptom resolution, but was positively modified by aerobic exercise volume. These findings provide a mechanistic framework for further investigation into underlying cerebrovascular related symptomatology. ANN NEUROL 2021;90:43–51
PDF
