کنترل ضربان قلب برای چرخه ارگومتر و تمرین تردمیل
Abstract
1- Introduction
2- Methods
3- Results
4- Discussion
References
Abstract
Objective: To develop a unified heart rate (HR) control approach for cycle ergometer (CE) and treadmill (TM) exercise, and to empirically compare the common controller’s performance between the CE and TM. Methods: The control method used frequency-domain shaping ofthe input-sensitivity function to address rejection of disturbances arising from broad-spectrum heart rate variability (HRV). A single controller was calculated using an approximate, nominal linear plant model and an input-sensitivity bandwidth specification. FiftyHRcontroltests were executedusing the single controller:25healthymaleparticipants each did one test on the CE and one on the TM. Results: There was no significant difference in mean root-mean-square HR tracking error: 3.10 bpm ± 0.68 bpm and 2.85 bpm ± 0.75 bpm (mean ± standard deviation, bpm = beats/min); CE vs. TM; p = 0.13. But mean normalised average control signal power was significantly different: 1.59 bpm2 ± 0.27 bpm2 vs. 1.36 bpm2 ± 0.28 bpm2; CE vs. TM; p = 3.5 × 10−4. Conclusion and significance: The lower values for RMS tracking error and control signal power for the TM point to decreasing HRV intensity with increasing HR, because, in order to match perceived exertion for the two modalities, mean HR for the TM was set 20 bpm higher than for the CE. These HR-intensitydependent differences in HRV are consistent with previous observations in the literature. The unified HR control approach for CE and TM exercise gave accurate, stable and robust performance in all tests, thus lending support to the concept that HRV disturbance rejection is the main issue in HR control design.
Introduction
Feedback systems for automatic control of heart rate (HR) have been developed separately for cycle ergometers [1–3] and treadmills [4–6]. Heart rate controllers are important because they allow accurate implementation of arbitrary HR profiles, such as are employed as part of cardiovascular training programmes [7,8]; recommended strategies include high-intensity interval training (HIIT), where intensity is varied by flexibly combining exercise periods of different durations and at different levels of heart rate [9,10]. In the present work, we set out to develop and test a novel, unified heart rate control approach that can be applied to both cycle ergometers (CE) and treadmills (TM). This undertaking was motivated by the recent observation thatthe time constant of heart-rate dynamics at moderate-to-vigorous (“somewhat hard”) exercise intensities is not significantly different for the cycle ergometer and the treadmill [11].