Late Exercise Tolerance Testing Using a Dynamic High Intensity Interval Multidirectional Movement Protocol

Objective Analyze the utility of a 5-step exertional rehab protocol (ERP) that included High Intensity Interval Multi-Directional Movement (HIIT-MD) or step 5. We assessed the incidence and etiologies of exercise intolerance (EI) during Step 5 in concussed patients who tolerated maximal linear exertion.

Background Exertional testing can be used to determine appropriate levels of exercise tolerance (ET) in concussed patients. Traditionally linear modalities have been used to determine max ET prior to clearance. HIIT-MD protocols can be the next appropriate step to bridge clearance for more dynamic activities.

Design/Methods Retrospective chart review included 130 step 5 trials for EI; of those, 72 had pre/postexercise King Devick (KD) and force plate (FP) testing. Patients were 10–59 years old and clinic visits occurred 2019–2020. EI rate was recorded and failure reason was documented by our clinic's concussion specialist. The difference between pre/post exercise KD and FP was investigated.

Results Of 130 step 5 trials, 21.54% failed due to EI. Reason for EI included the onset of symptoms (82.1%), followed by signs of dysautonomia (39.3%). Symptoms and dysautonomia combined were noted in 35.7% of those with EI. Symptoms appeared in combination with another marker 69.6% of the time. The average change in KD times pre/post exercise testing was +2.52 seconds longer in the EI group compared to −2.45 seconds shorter in the ET group (p = 0.62). The EI group demonstrated an average change of 0.36 deg/sec sway velocity increase after exercise compared to 0.13 deg/sec in the ET group (p = 0.93).

Conclusions There is evidence for the utility of a HITT-MD protocol for dynamic exercise/sports clearance. Exercise testing progression and concussion clearance should include a dynamic HITT-MD protocol to ascertain no late phase dynamic EI. Dysautonomia and/or vestibulocular aggravation may be contributors to late phase EI. If EI exists, identifying and targeting underlying causes can aid optimal recovery.