Modelling and regulating of cardio-respiratory response for the enhancement of interval training

Haddad, Azzam; Zhang, Yi; Su, Steven W.; Celler, Branko G.; Nguyen, Hung T.

doi:10.1186/1475-925x-13-9

Cited by 7 publications

(7 citation statements)

References 25 publications

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“…We further explored dynamics in the particular aerobic zone (approximate 70% - 77% of HR max , or 56% - 65% of VO 2 m a x [8]), which has well confirmed the observation reported in literatures [13]. Past works also focused on building a model for estimates of HR and/or VO 2 responses to exercise.…”

Section: Introductionsupporting

confidence: 62%

“…Currently, Azzam et al developed a dual-supply threshold-based solution to simulate HR and VO 2 responses towards the interval training protocols, which employs dual power supplies to set a threshold value for each onset and offset scenario [13]. Figure 7 shows the RC circuit introduced by Azzam et al Although this model can well describe the switching properties during onset and offset of exercise, there are still some limitations since dynamical characteristics (i.e., time constant and steady state gain) of model are not allowed to re-shift back to their original states due to the effect of V off .…”

Section: Resultsmentioning

confidence: 99%

“…Figures 3b and c-1/c-2 are the subcircuits of the proposed model linked by the DPDT switch representing cardiorespiratory behaviors at onset and offset, respectively. The voltage of C 1 with respect to exercise time represents the amplitude of HR and/or VO 2 dynamics during moderate exercise and its subsequent recoveries, since in moderate exercise both HR and VO 2 have similar behaviors [13, 24]. The functionality of D 1 is to configure the resistance amplitude of the onset and offset circuits, which will short R 2 off during the activation of the onset circuit.…”

Section: The Proposed Modeling and Verification Methodsmentioning

confidence: 99%

“…Switching models produce much better results than single non-switching models. The switching resistance-capacitor (RC) circuit introduced by [13] used a dual-supply threshold-based solution to simulate HR and VO 2 responses towards the interval training protocol. Despite a better performance being observed (vs. the non-switching models), particularly for transient behaviors during switching, there are still some limitations since dynamical characteristics (i.e., time constant and steady state gain) of model are not allowed to re-shift back to their original states, especially at the offset of exercise.…”

Section: Introductionmentioning

confidence: 99%

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An equivalent circuit model for onset and offset exercise response

Zhang

Haddad

et al. 2014

BioMedical Engineering OnLine

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BackgroundThe switching exercise (e.g., Interval Training) has been a commonly used exercise protocol nowadays for the enhancement of exerciser’s cardiovascular fitness. The current difficulty for simulating human onset and offset exercise responses regarding the switching exercise is to ensure the continuity of the outputs during onset-offset switching, as well as to accommodate the exercise intensities at both onset and offset of exercise.MethodsTwenty-one untrained healthy subjects performed treadmill trials following both single switching exercise (e.g., single-cycle square wave protocol) and repetitive switching exercise (e.g., interval training protocol). During exercise, heart rate (HR) and oxygen uptake (VO 2) were monitored and recorded by a portable gas analyzer (K4b 2, Cosmed). An equivalent single-supply switching resistance-capacitor (RC) circuit model was proposed to accommodate the observed variations of the onset and offset dynamics. The single-cycle square wave protocol was utilized to investigate the respective dynamics at onset and offset of exercise with the aerobic zone of approximate 70% - 77% of HR max, and verify the adaption feature for the accommodation of different exercise strengths. The design of the interval training protocol was to verify the transient properties during onset-offset switching. A verification method including Root-mean-square-error (RMSE) and correlation coefficient, was introduced for comparisons between the measured data and model outputs.ResultsThe experimental results from single-cycle square wave exercises clearly confirm that the onset and offset characteristics for both HR and VO 2 are distinctly different. Based on the experimental data for both single and repetitive square wave exercise protocols, the proposed model was then presented to simulate the onset and offset exercise responses, which were well correlated indicating good agreement with observations.ConclusionsCompared with existing works, this model can accommodate the different exercise strengths at both onset and offset of exercise, while also depicting human onset and offset exercise responses, and guarantee the continuity of outputs during onset-offset switching. A unique adaption feature by allowing the time constant(Continued on next page) (Continued from previous page)and steady state gain to re-shift back to their original states, more closely mimics the different exercise strengths during normal daily exercise activities.

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Section: Introductionsupporting

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Section: The Proposed Modeling and Verification Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An equivalent circuit model for onset and offset exercise response

Zhang

Haddad

et al. 2014

BioMedical Engineering OnLine

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“…The subjects were required to take a light meal prior to the experiment activity and not to participate in any intense exercises one day before the experiment [14][15][16]. The environmental temperature during the experiments was set at 25 C, and the humidity was at about 50% [17]. The HR monitor (HM131) was fitted to the middle of the chest of every subject by using electrode pads.…”

Section: Subjectsmentioning

confidence: 99%

Multi-Loop Integral Control-Based Heart Rate Regulation for Fast Tracking and Faulty-Tolerant Control Performance in Treadmill Exercises

Zhang¹,

Guo²,

Yang³

et al. 2018

Adaptive Robust Control Systems

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In order to offer a reliable, fast, and offset-free tracking performance for the regulation of heart rate (HR) during treadmill exercise, a two-input single-output (2ISO) control system by simultaneously manipulating both treadmill speed and gradient is proposed. The decentralized integral controllability (DIC) analysis is extended to nonlinear and non-square processes especially for a 2ISO process, namely multi-loop integral controllability (MIC). The proposed multi-loop integral control-based HR regulation by manipulating treadmill speed and gradient is then validated through a comparative treadmill experiment that compares the system performance of the proposed 2ISO MIC control loop with that of single-input single-output (SISO) loops, speed/gradient-to-HR. The experimental validation presents that by simultaneously using two control inputs, the automated system can achieve the fastest HR tracking performance and stay close to the reference HR during steady state, while comparing with two SISO structures, and offer the fault-tolerant ability if the gains of the two multi-loop integral controllers are well tuned. It has a vital implication for the applications of exercise rehabilitation and fitness in relation to the automated control system.

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