Objective: This paper presents a tail-worn sensor-equipped heart rate measurement apparatus to quantify the effect of exercise preconditioning on the physical disability of rats due to ischemic stroke. So far, physiological measurements in the literature are mostly conducted in an invasive manner, meaning that sensor implant surgery is a necessity, and result in the risk of infection and the problem of interrupted data capture. Nonetheless, most existing noninvasive physiological measurement apparatus are designed for animals at rest, not on the move. For this sake, this heart rate measurement apparatus was developed as an easy-touse, but high performance, non-invasive tool for long-term physiological monitoring on rats, particularly in the running state.
Methods: The presented non-invasive measurement apparatus comprises a front-end PPG sensor array and a back-end digital signal processor. A PPG signal was chosen for back-end signal extraction, using an adaptive filer and Hilbert-Huang Transform (HHT). This work was experimentally validated by the heart rate variability due to the epinephrine administration to rats in the conscious and unconscious states, and a heart rate monitoring in the running state was performed at the end of this work.
Results: Rats under test were equally divided into two groups for comparison purposes, one as the control group and the other as the exercise group, and each member in the latter needs to take a 3-week physical training program as a preconditioning. In weeks 1–3, the exercise (control) group members demonstrated an average pre-exercise heart rate of 358.31 (356.89), 328.21 (360.1) and 312.91 (361.68) BPM, respectively. The exercise group members clearly have a much slower preexercise average heart rate than the control group in weeks 2–3, indicating a negative correlation
between the heart rate and the slide angle result of an inclined plane test.
This paper presents a novel physiological measurement apparatus as a non-invasive alternative to a typical inclined plane test for quantifying the benefit of exercise preconditioning to ischemic stroke prevention. Featuring low physical confinement on animals and long-term monitoring, it was experimentally validated herein as an easy-to-use, but high performance, tool, and is expected to be employed in futuristic clinical research.