Big Picture

Question 1

How could the inclusion of neuroimaging data have contributed to the study?

Answer 1

• The inclusion of neuroimaging data, such as functional magnetic resonance imaging (fMRI) or positron emission tomography (PET), could have provided valuable insights into the exercise-induced changes in brain activation patterns, functional connectivity, and cerebral metabolism that may be associated with the improvements in antisaccade performance.

However, the current study was limited by practical and financial constraints, and the use of transcranial Doppler ultrasound to estimate cerebral blood flow provided a reasonable proxy for evaluating the potential physiological mechanisms.

Question 2

Why was it important to control for body weight and cardiovascular fitness in the study? Justify why you only controlled for age and sex.

Answer 2

• Controlling for body weight and cardiovascular fitness would have been important to ensure that any observed differences in cerebral blood flow and executive function between the SRC and healthy control (HC) groups were not simply due to differences in physical characteristics, exercise capacity, or exercise intensity on the BCBT.
• By matching the SRC and HC groups on age and sex, we aimed to minimize the potential confounding effects of these demographic factors on the dependent variables of interest. However, we did not control for body weight and cardiovascular fitness due to the higher screening failure rate, the relatively small sample size and the potential for over-controlling, which could have reduced the statistical power to detect group differences.
• Future studies with larger sample sizes should consider including these additional covariates to further isolate the effects of the concussion injury on the physiological and cognitive responses to exercise.

Question 3

How could the inclusion of concussion history and severity as covariates have improved the study? Justify why you didn’t include history as a covariate.

Answer 3

• Incorporating concussion history and severity as covariates could have provided valuable insights into how these factors may modulate the physiological and cognitive responses to exercise in the SRC group.
• Individuals with a more extensive concussion history or more severe initial injury may exhibit different patterns of cerebral blood flow and executive function changes following exercise compared to those with a single, less severe concussion. Including these factors as covariates could have helped elucidate the potential moderating role of concussion history and severity on the primary outcome measures.
• However, due to the relatively small sample size in the current study, we did not have sufficient statistical power to reliably examine the influence of these factors. Additionally, the inclusion of concussion history and severity as covariates may have further reduced the degrees of freedom and statistical power to detect the main effects of interest.

Question 4

How might the results differ if the sample were older adults with a history of sport-related concussion?

Answer 4

Older adults typically exhibit age-related declines in cognitive function and cerebrovascular regulation, which could interact with the effects of concussion and exercise in complex ways.

• Older adults may show a diminished or delayed postexercise improvement in executive function compared to the younger adults in the current study. Additionally, older adults with a history of concussion may have more persistent cognitive deficits and altered cerebrovascular responses that could influence their ability to benefit from a single bout of exercise. Furthermore, older adults may have a higher risk of exercise-induced symptom exacerbation due to potential comorbidities and reduced exercise tolerance.

Exploring the interactive effects of age, concussion history, and exercise on cognitive and physiological outcomes in older adults would be an important avenue for future research to better understand the generalizability of the current findings and the potential clinical implications for this population.

Question 5

Why is it important to explore potential sex/gender differences in the physiological and cognitive responses to exercise following concussion? Justify why you did not conducted a sex and gender analysis.

Answer 5

• Examining potential sex and gender differences in the physiological and cognitive responses to exercise following concussion is important for several reasons.
• Differences in brain structure, function, and neurochemistry between males and females may lead to differential vulnerability and recovery patterns following a concussive injury. Additionally, hormonal fluctuations and menstrual cycle phase in females can influence cerebrovascular regulation and cognitive performance, which may interact with the effects of exercise and concussion.
• In the current study, we did not conduct a formal analysis of sex and gender differences due to the relatively small sample size and the potential for reduced statistical power.
• With a larger sample, future studies should aim to investigate the moderating role of sex and gender on the physiological and cognitive outcomes following exercise in the context of sport-related concussion. This would provide a more comprehensive understanding of the factors that influence the recovery process and the potential benefits of exercise-based interventions.

Question 6

If you were making sex and gender analysis, how would you control for hormonal changes in females, and what kind of analysis would you do

Answer 6

• Controlling for Hormonal Changes in Females:
• 1. Menstrual cycle phase monitoring: We would ask female participants to track and report their menstrual cycle phase (e.g., follicular, ovulatory, luteal, or menstrual) at the time of each assessment.
• 2. Hormonal contraceptive use: We would collect information on the use of hormonal contraceptives by female participants.
• 3. Saliva or blood sampling: We could measure the levels of relevant hormones (e.g., estradiol, progesterone, testosterone) through saliva or blood samples.
• Proposed Analysis Plan:
• 1. Separate analyses by sex and concussion status:
• We would conduct the primary analyses (e.g., cerebral blood flow, executive function) separately for male and female SRC groups, as well as male and female healthy control groups.
• 2. Menstrual cycle phase as a covariate (for females):
• For the female participants, we would include menstrual cycle phase as a covariate in the analyses to control for the potential influence of hormonal fluctuations.
• 3. Hormonal status as a moderator:
• We could explore the moderating role of hormonal status (e.g., hormonal contraceptive use, hormone levels) on the relationship between exercise, cerebral blood flow, and executive function, separately for the SRC and healthy control groups.
• 4. Interaction analyses:
• We could conduct interaction analyses to examine the complex interplay between sex, hormonal factors, concussion status, and the effects of exercise.

Question 7

Use the results of your study to make clinical recommendations for sports physicians seeing SRC patients

Answer 7

• 1. Incorporate sub-symptom threshold aerobic exercise into the rehabilitation protocol:
• The findings demonstrate that a single bout of sub-symptom threshold aerobic exercise can elicit a transient improvement in executive function, as evidenced by the reduced antisaccade reaction times in the SRC group.
• This exercise intervention was shown to be safe and did not exacerbate concussion symptoms, suggesting it can be a beneficial addition to the current standard of care.
• Sports physicians should consider prescribing sub-symptom threshold aerobic exercise, such as stationary cycling at 80% of the individual’s heart rate threshold, as part of the early rehabilitation process (within 3-14 days post-injury).
• Sports physicians should consider factors such as concussion history, symptom severity, and individual differences in exercise capacity when prescribing the appropriate exercise intensity and duration for each patient.
• 2. Monitor executive function using oculomotor assessments:
• The study found that the SRC group exhibited impaired executive function, as evidenced by longer antisaccade reaction times and increased directional errors compared to healthy controls.
• The antisaccade task, in particular, appears to be a sensitive measure of the persistent executive function deficits associated with SRC, even after medical clearance for return to play.
• Sports physicians should consider incorporating oculomotor assessments, such as pro- and antisaccade tasks, as part of the comprehensive evaluation and monitoring of cognitive recovery in patients with SRC.
• 3. Educate patients on the potential benefits of sub-symptom exercise:
     Patients should be informed that carefully prescribed sub-symptom threshold aerobic exercise can be a safe and effective way to facilitate recovery and improve executive function during the early stages of SRC.

Question 8

If you had used the entire SCAT-5 test, and not just the symptom checklist portion what data would you want to further analyze in the context of your current study

Answer 8

• The SCAT-5 includes a standardized assessment of cognitive function, such as the Standardized Assessment of Concussion (SAC). This evaluates orientation, immediate memory, concentration, and delayed recall.
• We could analyze the performance on the cognitive assessment before and after the exercise intervention, and compare the changes to the oculomotor performance of the SRC and healthy control groups.
• The SCAT-5 includes a Balance Error Scoring System (BESS) test, which assesses postural stability and balance.
  We could analyze the BESS scores before and after the exercise intervention, and compare the changes between the SRC and healthy control groups.