Enhancing Heart Rate-Based Estimation of Energy Expenditure and Exercise Intensity in Patients Post Stroke
Background: Indirect calorimetry is the gold standard field-testing technique for measuring energy expenditure and exercise intensity based on the volume of oxygen consumed (VO<sub>2</sub>, mL O<sub>2</sub>/min). Although heart rate is often used as a proxy for VO<sub>2...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-12-01
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| Series: | Bioengineering |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2306-5354/11/12/1250 |
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| Summary: | Background: Indirect calorimetry is the gold standard field-testing technique for measuring energy expenditure and exercise intensity based on the volume of oxygen consumed (VO<sub>2</sub>, mL O<sub>2</sub>/min). Although heart rate is often used as a proxy for VO<sub>2</sub>, heart rate-based estimates of VO<sub>2</sub> may be inaccurate after stroke due to changes in the heart rate–VO<sub>2</sub> relationship. Our objective was to evaluate in people post stroke the accuracy of using heart rate to estimate relative walking VO<sub>2</sub> (wVO<sub>2</sub>) and classify exercise intensity. Moreover, we sought to determine if estimation accuracy could be improved by including clinical variables related to patients’ function and health in the estimation. Methods: Sixteen individuals post stroke completed treadmill walking exercises with concurrent indirect calorimetry and heart rate monitoring. Using 70% of the data, forward selection regression with repeated k-fold cross-validation was used to build wVO<sub>2</sub> estimation equations that use heart rate alone and together with clinical variables available at the point-of-care (i.e., BMI, age, sex, and comfortable walking speed). The remaining 30% of the data were used to evaluate accuracy by comparing (1) the estimated and actual wVO<sub>2</sub> measurements and (2) the exercise intensity classifications based on metabolic equivalents (METs) calculated using the estimated and actual wVO<sub>2</sub> measurements. Results: Heart rate-based wVO<sub>2</sub> estimates were inaccurate (MAE = 3.11 mL O<sub>2</sub>/kg/min) and unreliable (ICC = 0.68). Incorporating BMI, age, and sex in the estimation resulted in improvements in accuracy (MAE Δ: −36.01%, MAE = 1.99 mL O<sub>2</sub>/kg/min) and reliability (ICC Δ: +20, ICC = 0.88). Improved exercise intensity classifications were also observed, with higher accuracy (Δ: +29.85%, from 0.67 to 0.87), kappa (Δ: +108.33%, from 0.36 to 0.75), sensitivity (Δ: +30.43%, from 0.46 to 0.60), and specificity (Δ: +17.95%, from 0.78 to 0.92). Conclusions: In people post stroke, heart rate-based wVO<sub>2</sub> estimations are inaccurate but can be substantially improved by incorporating clinical variables readily available at the point of care. |
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| ISSN: | 2306-5354 |