Identification of anaerobic threshold using heart rate response during dynamic exercise

Abstract

The objective of the present study was to characterize the heart rate (HR) patterns of healthy males using the autoregressive integrated moving average (ARIMA) model over a power range assumed to correspond to the anaerobic threshold (AT) during discontinuous dynamic exercise tests (DDET). Nine young (22.3 ± 1.57 years) and 9 middle-aged (MA) volunteers (43.2 ± 3.53 years) performed three DDET on a cycle ergometer. Protocol I: DDET in steps with progressive power increases of 10 W; protocol II: DDET using the same power values as protocol 1, but applied randomly; protocol III: continuous dynamic exercise protocol with ventilatory and metabolic measurements (10 W/min ramp power), for the measurement of ventilatory AT. HR was recorded and stored beatto-beat during DDET, and analyzed using the ARIMA (protocols I and II). The DDET experiments showed that the median physical exercise workloads at which AT occurred were similar for protocols I and II, i.e., AT occurred between 75 W (116 bpm) and 85 W (116 bpm) for the young group and between 60 W (96 bpm) and 75 W (107 bpm) for group MA in protocols I and II, respectively; in two MA volunteers the ventilatory AT occurred at 90 W (108 bpm) and 95 W (111 bpm). This corresponded to the same power values of the positive trend in HR responses. The change in HR response using ARIMA models at submaximal dynamic exercise powers proved to be a promising approach for detecting AT in normal volunteers.

Comparison of anaerobic threshold determined by visual and mathematical methods in healthy women

“…Thus, our findings showed that the mathematical model was adequate for AT determination in sedentary healthy women. Other studies from our laboratory found that the ventilatory AT (gold standard method) was very close to the AT determined by the autoregressive integrated moving average model applied to middle-aged healthy men (10).…”

“…Some studies (8,9) have used the graphic visual method for the estimate of the disproportionate increase in ventilatory and metabolic variables, during the incremental dynamic exercise, as a gold standard for the quantification of AT. Additionally, other investigators have identified AT by analysis of heart rate (HR) (3,(10)(11)(12)(13) and of its variability (14), as well as by surface electromyography analysis (15)(16)(17).…”

“…Some investigators have proposed the use of mathematical and statistical models as a means to characterize responses of biological systems of the organism during physical exercise (8)(9)(10)18,19).…”

Influência da idade no comportamento da frequência cardíaca na transição repouso-exercício: uma análise por deltas e regressão linear

“…The subsequent increments corresponded to 10% of maximal power reached in the clinical exercise test. The TAv was visually identified when the rate of CO 2 release presented non-linear increment concerning the oxygen consumption (VO 2 ) 1,12 . The oxygen consumption (O 2 ) was picked breath-after-breath through a gas analyzer and metabolic measures (MMC Horizontal System, Sensormedics, Yorba Linda, CA, USA) and their values were expressed in means at every 15s.…”

“…Nevertheless, one cannot exclude the possibility of sympathetic contribution in this period. After the 60º second of moderate or intense exercise, slow HR increment is observed as consequence of the sympathetic contribution on the sinusal nodule 6,12 . Such behavior, represented by the variables of the 60-240º second interval (β, I and ∆), has its magnitude temporarily correlated with alterations in the blood lactate concentration 7,[26][27][28] .…”