Efficacy of aerobic exercise following concussion: a narrative review

Identifying the Cerebral Physiologic Response to Aerobic Exercise Following Concussion: A Scoping Review

OBJECTIVE

The purpose of this study was to identify the cerebral physiologic response to aerobic exercise in individuals with a symptomatic concussion, highlighting available knowledge and knowledge gaps in the literature.

DESIGN

A systematic scoping review was conducted and reported in keeping with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews. A search of EMBASE, MEDLINE, SCOPUS, BIOSIS, and Cochrane libraries was conducted on June 15, 2023 (from database inception). An online systematic/scoping review management system was used to remove duplicates, and the remaining articles were screened for inclusion by 2 researchers. Inclusion criteria required articles to be original research published in peer-reviewed journals. Additionally, studies were required to have an aerobic exercise component, include a measure of cerebral physiology during a bout of aerobic exercise, exclude moderate and/or severe traumatic brain injury (TBI) populations, and be in the English language. Both human and animal studies were included, with participants of any age who were diagnosed with a mild TBI/concussion only (ie, Glasgow Coma Scale score ≥ 13). Studies could be of any design as long as a measure of cerebral physiologic response to a bout of aerobic exercise was included.

RESULTS

The search resulted in 1773 articles to be screened and data from 3 eligible studies were extracted.

CONCLUSIONS

There are currently too few studies investigating the cerebral physiologic response to aerobic exercise following concussion or mild TBI to draw definitive conclusions. Further research on this topic is necessary since understanding the cerebral physiologic response to aerobic exercise in the concussion and mild TBI populations could assist in optimizing exercise-based treatment prescription and identifying other targeted therapies.

Response of Central Nervous System Biomolecules and Systemic Biomarkers to Aerobic Exercise Following Concussion: A Scoping Review of Human and Animal Research

The purpose of this study was to identify the response of biomolecules and biomarkers that are associated with the central nervous system to aerobic exercise in human and pre-clinical models of concussion or mild traumatic brain injury (TBI), and to highlight the knowledge gaps in the literature. A systematic scoping review was conducted following a search of EMBASE, MEDLINE, SCOPUS, BIOSIS, and Cochrane Libraries performed on September 8, 2023 (from data base inception). The scoping review was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews. Duplicates were removed and article screening was performed using an online systematic review management system. The search resulted in a total of 2,449 articles being identified, with 14 articles meeting the inclusion/exclusion criteria and having their data extracted. One study was conducted in humans, while the remainder of identified studies utilized murine models. The current literature is limited and evaluated many different biomolecules and biomarkers with brain-derived neurotrophic factor being the most researched. Further studies on this topic are needed to better understand the biomarker response to exercise after concussion and mild TBI, especially in the human population.

Differences in Volatile Organic Compounds Between Concussed and Non-concussed Division I Athletes

Introduction Diagnosing a concussion is challenging because of complex and variable symptoms. Establishing a viable biomarker of injury may rely on physiologic measurements rather than symptomology. Volatile organic compounds (VOCs) such as breath acetone have been identified as potential physiological markers that can capture changes in the utilization of energy substrates post-concussion. Here, we aimed to explore whether differences in VOCs exist between concussed and non-concussed athletes at the initial and later stages of injury recovery. Methods Six (N=6) non-concussed athletes were enrolled as control participants prior to the competitive season. Control participants' breath acetone, heart rate, and anthropometric measures were obtained at rest and throughout a single exercise challenge by breathalyzer. Six (N=6) athletes diagnosed with concussion during the competitive season had breath acetone measured daily until cleared to return to activity or approximately four weeks following enrollment where they participated in an exit exercise challenge having breath acetone, heart rate, and anthropometric measures obtained. Comparisons were made between at-rest measures of concussed and non-concussed participants at multiple time points during the recovery period. Paired t-test comparisons with individuals serving as their own control were used to determine individual differences in recovery. Visual graphs were used to demonstrate differences in obtained measures amongst individuals and between groups during the exercise challenges. Results Results demonstrated statistically significant differences in breath acetone between concussed and control participants when the highest day measured during the first week of concussion was compared to the control participant's resting values (P=0.017). Additionally, when the concussed participants served as their own control and their highest measured day of the first week post-concussion was compared to values when cleared to return to activity or at 26 days post-concussion, there was a significant difference in breath acetone (P=0.028). Comparing breath acetone during exercise between non-concussed and cleared concussed participants or four weeks post-injury, demonstrated no significant differences throughout the challenge or at rest prior. Visual graph comparisons in a single participant before and after concussion suggest differences may appear following exercise during the recovery period. Discussion These results suggest VOCs, particularly breath acetone, have the potential to serve as diagnostic markers of concussion. However, longitudinal research within larger cohorts and with equipment able to expel VOCs other than acetone from measures are needed to make informed recommendations.

Optimal Volume of Moderate-to-Vigorous Physical Activity Postconcussion in Children and Adolescents

Importance

Determining the optimal volume of early moderate-to-vigorous-intensity physical activity (MVPA) after concussion and its association with subsequent symptom burden is important for early postinjury management recommendations.

Objectives

To investigate the association between cumulative MVPA (cMVPA) over 2 weeks and subsequent symptom burden at 1 week, 2 weeks, and 4 weeks postinjury in children and examine the association between cMVPA and odds of persisting symptoms after concussion (PSAC) at 2 weeks and 4 weeks postinjury.

Design, Setting, and Participants

This multicenter cohort study used data from a randomized clinical trial that was conducted from March 2017 to December 2019 at 3 Canadian pediatric emergency departments in participants aged 10.00 to 17.99 years with acute concussion of less than 48 hours. Data were analyzed from July 2022 to December 2023.

Exposure

cMVPA postinjury was measured with accelerometers worn on the waist for 24 hours per day for 13 days postinjury, with measurements deemed valid if participants had 4 or more days of accelerometer data and 3 or fewer consecutive days of missing data. cMVPA at 1 week and 2 weeks postinjury was defined as cMVPA for 7 days and 13 days postinjury, respectively. Multiple imputations were carried out on missing MVPA days.

Main Outcomes and measures

Self-reported postconcussion symptom burden at 1 week, 2 weeks, and 4 weeks postinjury using the Health and Behavior Inventory (HBI). PSAC was defined as reliable change on the HBI. A linear mixed-effect model was used for symptom burden at 1 week, 2 weeks, and 4 weeks postinjury with a time × cMVPA interaction. Logistic regressions assessed the association between cMVPA and PSAC. All models were adjusted for prognostically important variables.

Results

In this study, 267 of 456 children (119 [44.6%] female; median [IQR] age, 12.9 [11.5 to 14.4] years) were included in the analysis. Participants with greater cMVPA had significantly lower HBI scores at 1 week (75th percentile [258.5 minutes] vs 25th percentile [90.0 minutes]; difference, -5.45 [95% CI, -7.67 to -3.24]) and 2 weeks postinjury (75th percentile [565.0 minutes] vs 25th percentile [237.0 minutes]; difference, -2.85 [95% CI, -4.74 to -0.97]) but not at 4 weeks postinjury (75th percentile [565.0 minutes] vs 25th percentile [237.0 minutes]; difference, -1.24 [95% CI, -3.13 to 0.64]) (P = .20). Symptom burden was not lower beyond the 75th percentile for cMVPA at 1 week or 2 weeks postinjury (1 week, 259 minutes; 2 weeks, 565 minutes) of cMVPA. The odds ratio for the association between 75th and 25th percentile of cMVPA and PSAC was 0.48 (95% CI, 0.24 to 0.94) at 2 weeks.

Conclusions and Relevance

In children and adolescents with acute concussion, 259 minutes of cMVPA during the first week postinjury and 565 minutes of cMVPA during the second week postinjury were associated with lower symptom burden at 1 week and 2 weeks postinjury. At 2 weeks postinjury, higher cMVPA volume was associated with 48% reduced odds of PSAC compared with lower cMVPA volume.

Head Injuries and Emergencies in Sports

Head injuries are a common occurrence in sports and can involve injuries to the brain, skull, and superficial soft tissues. The most commonly discussed diagnosis is a concussion. Head and cervical spine injuries must be considered together at times, due to the overlapping nature of symptoms present during on-field evaluation. This article presents a range of head injuries, along with critical steps in evaluation and management.