Exercise Intensity Estimation via Normalized T Wave Amplitude
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Solution Overview
Problem
Existing wearable ECG waveform measurement devices face challenges in accurately estimating exercise intensity due to variations in amplitude levels, which affect the evaluation of T wave changes, making it difficult to correctly assess heart load and blood flow during physical activity.
Innovation Solution
The method involves normalizing the T wave amplitude by the RS amplitude and combining it with heart rate to generate indices that accurately reflect exercise intensity, thereby accounting for amplitude variations and providing a reliable estimation of exercise intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If T wave amplitude is used to estimate exercise intensity, then exercise intensity can be estimated based on ventricular diastole changes, but the estimation becomes inaccurate when ECG waveform amplitude varies due to electrode wetting or contact conditions
Solution Approach 1:
The patent transforms the T wave amplitude parameter from an absolute value to a relative value by calculating the ratio of T wave amplitude to RS wave amplitude. This parameter transformation makes the measurement independent of electrode contact conditions and amplitude variations, thereby resolving the contradiction between measurement precision and reliability.
2Ease of operation
If wearable ECG measurement devices are used for convenience, then ease of operation is improved, but amplitude level variations occur due to electrode wetting or contact conditions
Solution Approach 1:
The patent converts the harmful effect of amplitude variations caused by electrode wetting or contact issues into a beneficial feature. By using the RS wave amplitude (which varies similarly to the T wave) as a reference for normalization, the system eliminates the impact of contact conditions on the final T wave/RS wave ratio measurement, maintaining measurement precision while preserving wearable device convenience.
3Device complexity
If absolute T wave amplitude is measured, then the measurement process is simple, but it cannot distinguish between amplitude changes due to exercise intensity and those due to contact conditions
Solution Approach 1:
The patent introduces the RS wave amplitude as an intermediary reference parameter to mediate between the T wave amplitude and the final exercise intensity estimation. This intermediary allows the system to distinguish between amplitude changes caused by exercise intensity and those caused by contact conditions, as the RS wave varies similarly to the T wave under contact variations but independently under exercise conditions.
Data Source
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Figure 2
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AI summary
An exercise intensity estimation apparatus includes an RS wave calculation unit (3) configured to calculate an RS amplitude from a peak value of an R wave to a peak value of an S wave in an ECG waveform of a target person, a T wave calculation unit (4) configured to calculate an amplitude of a T wave of the ECG waveform, a heart rate calculation unit (5) configured to calculate a heart rate from the ECG waveform, an index calculation unit (6) configured to calculate, as a first index indicating exercise intensity of the target person, the amplitude of the T wave normalized by the RS amplitude, and an index calculation unit (7) configured to calculate, as a second index indicating the exercise intensity of the target person, a value obtained by multiplying the first index by the heart rate.