Progressive aerobic exercise treatment of post concussion syndrome
Kozlowski, Karl F.
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Post-concussion Syndrome (PCS) is defined as three or more symptoms from a concussion checklist persisting at least three weeks post concussion. The most common treatment of PCS is rest and medication, with anti-depressants at the top of the list. To date, there is no evidence that medications have any efficacy. Patients often end up fatigued, depressed and deconditioned. Investigators at the University at Buffalo have developed a model of treatment based on a physiologic explanation of concussion. Intense exercise exacerbates symptoms and is the current recommended test of readiness for return to sport. This treatment plan establishes the patient's threshold for exercise induced symptoms and then creates an exercise program that is 80% of this heart rate threshold. Thus the patient is encouraged to become reconditioned without symptom exacerbation. The central hypotheses of the work was that a structured aerobic exercise program reduces the occurrence and frequency of symptoms related to PCS and that this program will alter the physiologic response to exercise of individuals with PCS such that they can exercise to volitional fatigue without symptom exacerbation. Methods . Participants with PCS (n=14) with their age and gender matched controls (n=10) underwent an extensive interview to assist in the identification of background symptoms using validated checklists, mechanisms, and concerns. Resting measures of blood pressure (BP), heart rate (HR) and heart rate variability (HRV) were taken. The Balance Error Scoring System (BESS) test was conducted to evaluate clinical postural stability. An incremental exercise test on a treadmill was performed. During the exercise test, HR, BP and Ratings of Perceived Exertion (RPE) were recorded. The test was continued until the subject could no longer maintain the appropriate intensity, or they felt as though there would have been a return of symptoms if they continued any further. Presence of symptoms was recorded daily using the Graded Symptom Checklist (GSC) and the Head Injury Scale (HIS) for two weeks to establish a baseline. No exercise was prescribed during this time thereby allowing for a recording of daily variability in baseline symptoms for each individual. After the second week a second incremental exercise test was performed as described. Data recorded from this test were used to determine sub-symptom threshold (SST) training intensity. The subjects then exercised every other day at SST over the next three weeks. Subjects completed the GSC and HIS daily, and HR measurements pre and post exercise. Protocols for PCS participants focused on maintaining SST-HR for the calculated duration. Control participants participated in three weeks of exercise matched to the average duration and intensity as prescribed to the PCS group (8 minutes at 60% age predicted maximal heart rate (APMHR)). Mode of exercise was independently determined by the participant. After three weeks of training, a third incremental exercise test was performed following the previously stated protocol in both groups. A new SST was calculated for the PCS group from the new incremental test. The PCS subjects continued to train for the next three weeks at the new SST. This process was repeated until the participant completed a full incremental exercise test without the return of symptoms. At this time participants were re-evaluated for the presence of post-concussion syndrome by the participating physician. Data from the exercise tests were analyzed using repeated measures ANOVA with contrasts for most values. Individual regression slopes were computed for symptom report data. A priori t-tests were used post-hoc to determine individual group differences where appropriate. Results . No differences at baseline for HRV, BESS or resting measures were detected between the PCS participants and their matched controls. However, there were differences in maximal HR during exercise testing and RPE (p<0.05). Repeat administration of the exercise test was reliable in both groups (p<0.05). Following three weeks of treatment, there was no significant change in either group for any variables except SBP in the PCS participants. However, after prolonged exercise intervention (10 week average), the PCS group reported fewer symptoms that were less intense. They were also able to exercise maximally and closely resemble their matched control group in outcomes. No changes in HRV, BESS test scores or resting physiologic parameters were detected over treatment. Conclusion . Individualized progressive aerobic exercise reduces symptom reports in patients with PCS and allows them to tolerate increased workloads without the exacerbation of symptoms. It is remains unknown whether the mechanism for prolonged PCS symptoms is related to autonomic nervous system (ANS) control functions at this time. Key Words: post-concussion syndrome, exercise test, symptom response, aerobic