ABSTRACT
BACKGROUND AND PURPOSE: Submaximal graded exercise testing (GXTsubmax) is rarely used during inpatient (IP) rehabilitation, and there is little research supporting its use. Lack of exercise testing limits optimal exercise prescription using target heart rate (HR) zones, which are important for high intensity gait training and rehabilitation. The purpose of this study was to help determine whether GXTsubmax was (1) safe, (2) feasible and (3) able to inform a target training HR zone in people with medically complex diagnoses. CASE DESCRIPTION: Nine patients in IP rehabilitation were identified via therapist referral and chart review (7 males;mean age +/- standard deviation 57 +/- 13 years). Diagnoses were stroke (n = 2), COVID rehab (n=4), limb loss (n=2), and oncology (n= 1). All participants were considered medically complex with significant cardiac and pulmonary disease comorbidities. They received medical clearance to participate in the GXTsubmax. We used the total body recumbent stepper submaximal exercise test (TBRS submax) for the exercise test. Oxygen saturation, heart rate, rate of perceived exertion (RPE) and blood pressure were monitored. Termination criteria included reaching one of the following: 85%HR Max, RPE 17, SpO2 drop,90%, patient requests to stop, or end of test. A target HR zone was chosen through comprehensive performance analysis including HR and RPE. HR zones were identified that correlated with Borg RPE zones 11 to 15/20. Once these HR zones were determined, we compared them to calculated target HR zones using Karvonen's Formula (Moderate exercise intensity 40%-60% HRR) and estimated peak VO2. OUTCOME(S): Nine patients completed 1 or 2 tests during their length of stay, resulting in 15 tests analyzed. There were no serious adverse events. Two tests were terminated at the end of the first stage (3 minutes), 7 tests by the end of the second stage (5-6 minutes), 3 tests by the end of the third stage (7-9 minutes), and 3 tests made it to the fourth stage (11-12 minutes). Reasons for termination were: 11 (73%) reached the RPE 17, 1 SpO2 was 89%, 1 reached 85% HR max, and 2 completed the test. The total duration for set up and completion was less than 30 minutes. Physical therapists (n = 3) reported the TBRS submax was feasible, billable, and provided a valuable opportunity for patient education on exercise intensity. Based on RPE and patient performance, therapists suggested a lower initial target power (15 watts vs 30 watts) and reduce the stepwise workload changes to accommodate complex patients. Seven participants required an extrapolated target HR range because of the brevity of their GXTsubmax. Target HR zone identified based on the GXTsubmax was more than 10% below the target HR derived fromKarvonen's Formula for 7 participants. DISCUSSION: This study suggests the TBRS submax is safe and feasible in IP rehabilitation. Our experience suggests a reduction in both initial watts across stages is needed in complex patients. Future studies should determine whether the target heart rate zones through the TBRS submax are appropriate in IP rehabilitation and contribute to prognosis, quality of life, and discharge planning.