The experiments were carried out at free speed and the participants were given the instruction to walk at their normal pace. This will represent the onset stage in our training protocol. On the other hand, offset stages can be represented as walking aside on the same step the exercisers reach when the onset period finishes; this continuous walking on the same step is the perfect match of the offset stage in the treadmill interval training exercise.

All participants were instructed to use their left legs for the first step, to only place one foot on each step foot-over-foot ascent and to continue walking in straight line. Based on the simulation results in the previous section, the exerciser needs 12 iterations to reach his desired setpoints.

Practically, the experiments results for a new male subject Subject No. In the first iteration, 60 seconds is set to be the onset and offset times. Accordingly, the controller adjusts the time of onset and offset periods for the next training session.

Table 7 shows the controller parameters and their corresponding experimental results for Subject No. HR response after the first iteration a , HR response after the second iteration b and HR response after the third iteration c.

Referring to the results from Table 7 and Figure 10 , we can conclude that the exerciser has almost reached his desired setpoints after only 3 iterations, when the simulation results showed that it can be done after 12 iterations. This shows how our controller has accomplished its duty with minimum number of iterations.

It is worth mentioning that for a proposed training regime based on an averaged model; we expect each subject to respond differently to a particular exercise or training protocol, of interest was Subject 10 who reached his desired set points after only three iterations.

We may reach the desired set points or a steady state for another subject after 10, 11 or even 12 iterations, it depends totally on the intra- and inter- model uncertainties.

During the study, it was considered that after a certain number of training sessions, the training capacity of the subject will improve and this may affect the result of his HR response.

In the next step of the study, we will recruit more subjects in order to verify our results and to even improve the performance of our controller. A designed square-wave exercise protocol was applied to investigate the dynamic characteristics of HR and VO 2 responses for both the onset and offset exercises.

The K 4 b 2 portable device was used to measure breath-by-breath VO 2 and beat-by-beat HR. According to the experimental results, it was concluded that the time constants and steady state gains of the onset exercise for both HR and VO 2 are distinctively different with those of the offset exercise.

Based on the identified dynamic characteristics for both HR and VO 2 , we proposed an interval training protocol to improve cardiovascular fitness.

A switching RC circuit model was presented to simulate HR and VO 2 responses for the proposed interval training protocol. In order to adapt to individual users, a multi-loop integral control scheme has been proposed to regulate the HR response for interval running exercise under free living conditions.

In the next step of the study, we will recruit more subjects for the validation of the proposed models, interval training protocol and the feedback control based adaption scheme. Acharya R, Kumar A, Bhat IP, et al.

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IEEE Control Syst Mag , 29 2 — Article MathSciNet Google Scholar. Download references. The authors are thankful for the supports from the Centre for Health Technologies, the University of Technology, Sydney UTS , Australia, and the school of human movement studies, the Charles Sturt University CSU , Australia.

Special thanks go to Dr. Cheyne Donges the school of human movement studies, CSU , Dr. Rob Duffield, and Professor Aaron Coutts the Centre for Health Technologies, UTS for their help and guidance.

Faculty of Engineering and IT, University of Technology, Sydney UTS , Sydney, Australia. You can also search for this author in PubMed Google Scholar. Correspondence to Steven Su. AH carried out the experiments and drafted the paper; YZ carried out the simulation part.

SS supervised the overall project and the revision of the paper. BC supervised the project. HN supervised the project and revised the paper.

All authors read and approved the final manuscript. Open Access This article is published under license to BioMed Central Ltd. Reprints and permissions. Haddad, A. et al. Modelling and regulating of cardio-respiratory response for the enhancement of interval training.

BioMed Eng OnLine 13 , 9 Download citation. Received : 04 November Accepted : 22 January Published : 06 February Anyone you share the following link with will be able to read this content:.

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Download PDF. Purpose To develop an effective training protocol to improve cardiovascular fitness based on modelling and analysis of Heart Rate HR and Oxygen Uptake VO 2 dynamics. Methods In order to model the cardiorespiratory response to the onset and offset exercises, the K 4 b 2 , Cosmed gas analyzer was used to monitor and record the heart rate and oxygen uptake for ten healthy male subjects.

Results By observing the original data for each subject, we can clearly identify that all subjects have similar HR and VO 2 profiles. Introduction Heart rate HR and oxygen uptake VO 2 are key indicators of functional health status; their measurements can aid early detection of cardiac diseases [ 1 , 2 ].

Experimental equipment and exercise protocol Subjects Eight healthy non-smoking males were invited to join the experiments. Table 1 Physical characteristics Full size table.

Results and discussion Experimental results It is known that many internal and environmental factors may have drastic effects on the readings during the experiment [ 2 ], even when all of the laboratory conditions have been standardized and set to be the same for all participants. Figure 1. Full size image.

Figure 2. Table 2 Estimated time constants and normalized steady state gains of HR response Full size table. Table 3 Estimated time constants and normalized steady state gains of VO 2 response Full size table.

Table 4 Averaged values of time constants and steady state gains Full size table. Table 5 Relationship between HR max and VO 2max Full size table. Table 6 Exercise intensity levels that coincide with HR max and VO 2max Full size table.

Figure 3. Figure 4. Figure 5. Individualized adaptation for the proposed interval training protocol The proposed interval training protocol is based on the established average model for eight healthy young male subjects. Figure 6. Figure 7. Figure 8.

Figure 9. Control system verification This section provides a practical method to examine and verify the functionality as well as performance of the proposed controller. Table 7 Control system parameters and their corresponding experimental results for subject no.

Figure Conclusion A designed square-wave exercise protocol was applied to investigate the dynamic characteristics of HR and VO 2 responses for both the onset and offset exercises.

References Acharya R, Kumar A, Bhat IP, et al. Google Scholar Duffield R, Edge J, Bishop D: Effects of high-intensity interval training on the VO 2 response during severe exercise. Article Google Scholar Gibala MJ, et al.

Article Google Scholar Rakobowchuk M, et al. Google Scholar Suh M-k, Rofouei M, Nahapetian A, Kaiser WJ, Sarrafzadeh M: Optimizing interval training protocols using data mining decision trees.

Article Google Scholar Haskell WL, Montoye HJ, Orenstein D: Physical activity and exercise to achieve health-related physical fitness components. Google Scholar Koga S, Shiojiri T, Shibasaki M, Fukuba Y, Fukuoka Y, Kondo N: Kinetics of oxygen uptake and cardiac output at onset of arm exercise. Google Scholar Duffield R, Dawson B, Pinnington HC, Wong P: Accuracy and reliability of a cosmed K4b 2 portable gas analysis system.

Article Google Scholar Su SW, Huang S, Wang L, Celler BG, Savkin AV, Guo Y, Cheng T: Nonparametric Hammerstein model based model predictive control for heart rate regulation. Google Scholar Stanula A, Gabrys T, Szmatlan-Gabrys U, Roczniok R, Maszczyk A, Pietraszewski P: Calculating lactate anaerobic thresholds in sports involving different endurance preparation.

Google Scholar Inbar O, Oten A, Scheinowitz M, Rotstein A, Dlin R, Casaburi R: Normal cardiopulmonary responses during incremental exercise in 20—yr-old men. Google Scholar Goebel R, Sanfelice R, Teel A: Hybrid dynamical systems. Article MathSciNet Google Scholar Download references.

Acknowledgements The authors are thankful for the supports from the Centre for Health Technologies, the University of Technology, Sydney UTS , Australia, and the school of human movement studies, the Charles Sturt University CSU , Australia.

View author publications. Additional information Competing interests The authors declare that they have no competing interests.

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A Quiz for Teens Are You a Workaholic? How Well Do You Sleep? Health Conditions Discover Plan Connect. What Is Cardiorespiratory Endurance and How Can You Improve It? Medically reviewed by Elaine K. Luo, M. Tests Exercises Takeaway Overview.

Cardiorespiratory endurance tests. Exercises to improve your cardiorespiratory endurance. Share on Pinterest. How we reviewed this article: Sources. Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations.

We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy. Sep 29, Written By Emily Cronkleton.