The Boston Exercise Symptom Threshold Test for Mild Traumatic Brain Injury Rehabilitation

Research Objectives: To provide preliminary data on the feasibility of the newly designed Boston Exercise Symptom Threshold Test (BESTT) in community-dwelling (CD) individuals with mTBI and to test the efficacy of the test on thresholding subsequent aerobic exercise intervention sessions as part of an ongoing pilot randomized control trial (NCT06494592).

Design: During the BESTT, heart rate (HR) and symptoms are collected every two minutes. HR at 60-85% of symptom threshold (the point at which symptoms increase beyond +3 baseline symptoms) is then calculated and used to threshold 30-minute aerobic exercise sessions delivered three-times per week.

Setting: The BESTT was implemented in the Center for Cognitive and Brain Health on the campus of Northeastern University. Subsequent exercise intervention sessions would be completed online via zoom.

Participants: 24 CD adults 29.79 (11 yrs.) diagnosed with mTBI within the last 12 months

Interventions: The BESTT test involves a seven-minute warm-up without resistance or restrictions. A six-minute sub-maximal cardiorespiratory fitness test (Modified Astrand Rhyming Cycle Test - phase one) is administrated followed by a progressive increase in cadence and resistance (phase two) until stopping criteria is reached (+3 symptoms or safety/physical exhaustion). Subsequent exercise intervention sessions involved 30-minute floor based exercise sessions three-times a week for 12 weeks.

Main Outcome Measures: Adverse events, HR at symptom threshold, and symptom severity

Results: No adverse events were reported during the test nor any of the subsequent exercise intervention sessions. All 24 participants completed phase one of the BESTT allowing for the estimation of cardiorespiratory fitness. 45.8% of participants ended the BESTT due to symptom increase, while 37.5% were due to exhaustion. On average, the test lasted 9.56 (3.24) minutes. Data from the first two-weeks of aerobic exercise intervention sessions showed that 91.6% of participants were able to exercise within, or above, 65 – 80% of their symptom threshold without experiencing symptom exasperation. The correlations between ratings of perceived exertion (Borg) and heart rate revealed a significant effect of HR (Beta = 0.038, p < 0.001, CI = 0.018 – 0.058) and time point (Beta = 1.023, p = < 0.001, CI = 0.780 – 1.265) was observed. Meaning, a positive association of HR and RPE occurred over time.

Conclusions: The BESTT is a feasible exercise exertion test for CD individuals and provides accurate information to allow prescribers to threshold aerobic exercise sessions without increasing mTBI-related symptoms. The BESTT systematically reduces exercise-induced symptoms and allows exercise as medicine interventions to reach many more individuals recovering from mTBI, beyond SR concussion populations.

Author(s) Disclosures: All authors declare no conflicts of interest.