Effect of Graded Aerobic Exercise in Mild Traumatic Brain Injury

There is a paucity of knowledge about mechanisms behind mild traumatic brain injury (mTBI) subgroup's sustained problems, and effective interventions that can alleviate this disabling condition. Persistent Post-concussive Symptoms (PCS) affect between 20% and 30% of individuals after mTBI.

This Randomized Controlled Trial (RCT) will investigate whether graded aerobic exercise has a positive effect on symptom burden (including exercise intolerance) and Autonomic Nervous System (ANS) dysfunction in patients with PCS.

This study will expand upon previous work on adolescents with sport-related concussion in the acute phase. It will cover a wider age group and will include patients with persisting symptoms, thus providing knowledge on whether a sub-symptom threshold aerobic exercise program will alleviate symptom burden in adult patients with PCS.

Furthermore - looking into the relationship between mTBI and ANS function, this study is expected to contribute to a better understanding of the neurobiological factors involved in PCS. The results may also help developing targeted interventions to specific characteristics in persistent symptoms after mTBI.

Background: TBI is a public health challenge of considerable, but insufficiently recognized proportions. Therefore, a concerted effort should be made to reduce the burden and impact of TBI. Health care providers are in need of standardization of the medical examination and targeted individual interventions with potential to treat PCS.

Main purpose: The main purpose of this study is to evaluate whether a progressive, sub-symptom threshold aerobic exercise program in addition to ordinary rehabilitation will lead to clinically meaningful reduction in symptom burden, normalize exercise tolerance and improve health-related quality of life compared to a control group that only receives ordinary rehabilitation. In addition, changes in ANS function will be assessed in both the intervention and the control group.

Design: Randomized, controlled, single-blind parallel-group study with two measurement points; T0 at baseline and T1 after the intervention.

Method: The Buffalo Concussion Treadmill Test (BCTT) will be used to expose exercise intolerance, and participants with exercise intolerance will be randomized to the intervention group or the control group. Both groups will receive ordinary rehabilitation. The intervention group will in addition receive an individualized (based on BCTT) sub-symptom threshold aerobic exercise program for 12 weeks. To assess ANS function, Arterial spin labeling (ASL) MRI and Cold Pressor Test (CPT) will be performed at T0 and T1. Symptom burden will be assessed by Rivermead Post-concussion Symptom Questionnaire (RPQ) and other patient reported outcomes measurements including self-reported autonomic symptoms (the Composite Autonomic Symptom Score 31) will also be used.

Clinical relevance: Self-reported ANS, exercise intolerance testing, the CPT and ASL-MRI could prove to be useful clinical assessment tools to confirm the PCS-diagnosis and to determine readiness to return to preinjury level of day-to-day activities.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of mild TBI as defined by the World Health Organization (WHO)
* Diagnosis of PCS based on ICD-10 criteria for a minimum of 3 months to a maximum of 2 years
* Age 18-60 years.
* Reduced tolerance to physical activity/exercise intolerance (self-reported worsening of symptoms such as dizziness, nausea or headache during physical activity and exercise). Or have not yet tried physical activity/exercise after the injury.

Exclusion Criteria:

* Other neurological or severe psychiatric conditions listed in the medical record.
* Heart-lung disease.
* Extremity injuries that prevent physical exercise
* Drug addiction
* Insufficient understanding of the Norwegian language (unable to follow instructions and/or fill in forms).
* Normal BCTT.