Evaluation of the Relationship between Heart Rate and Ventilation for Epidemiologic Studies

Abstract

Estimation of pulmonary exposure and dose in air pollution epidemiology has been impaired by the lack of methods for directly measuring ventilation in ambulatory subjects. Heart-rate monitoring offers an approach to estimate ventilation by using ventilation-on-heart-rate (VE-HR) regressions established during exercise testing to estimate ventilation in the field. Conventional methods and protocols for testing were used to evaluate the relationship between VE and HR during three tasks: (1) exercising on a cycle ergometer, (2) lifting, and (3) vacuuming. The relationship between VE and HR was curvilinear and was best fit with linear regression models, using a natural log transformation of VE. Considerable interindividual variability in slopes and intercepts was observed across all types of exercise tests. The variability about the fitted regression lines for individual subjects was minimal; for example, individual R2 values for the maximum exercise test on 15 men ranged from 0.90 to 0.99 (mean = 0.97). The regression slopes established during upper-body exercise were greater by approximately 30%, relative to those derived in lower-body exercise (paired t test, p < .001). However, VE-HR regression slopes derived from tests in which progressively increasing workloads were used were comparable to those obtained during variable and nonprogressive protocols. These findings indicate that predictive accuracy is maximized by deriving VE-HR regressions for individual subjects and for both lower- and upper-body activities.

Dynamic Ventilation and Power Output of Urban Bicyclists

“…2 ) in Table 3 are lower than past reported values from lab ergometer studies (1,8), which is attributable to greater measurement error in the indirect field measurements of 7 http://certification.acsm.org/metabolic-calcs ventilation rate (using the BioHarness chest strap with spirometer calibrations) than the direct laboratory measurements of ventilation rate (using facemasks and pneumotachometers).…”

“…Low-ranged values of the lṅ~̇ slope in these data could be attributed to a muted ventilatory response to dynamic power output. 8 Zoladz et al (26) found that ̇2 increases non-linearly at power output over 250W 9 the amount of energy derived from atmospheric oxygen that is translated to external work, previously defined as 10 A common model uses the oxygen uptake efficiency slope (OUES), which is defined as ̇2 = • 10̇+ .…”

“…That study used a facemask system to measure ventilation -a method also used in other onroad (6) and laboratory (1) study settings. Another approach has been to estimate dynamic onroad ventilation rate (̇) from measured heart rate ( ), based on laboratory-derived ̇~ relationships for individual subjects (7,8). Laboratory ̇ measurements typically use a bicycle ergometer (stationary bicycle) and a facemask.…”

Estimating the inhaled dose of pollutants during indoor physical activity

“…VĖ is difficult to measure in field studies due to some constraints such as discomfort for the user and the need for an elevated number of instruments to perform the evaluation of a representative number of individuals. However, VĖ can be estimated by measuring HR in fitness classes because HR is easily measured and is a good predictor of VĖ (Mermier et al, 1993;Zuurbier et al, 2009). Once HR is mainly influenced by oxygen consumption and the correlation between oxygen consumption and VĖ is high, HR and VĖ are expected to be strongly associated.…”

“…Although the author emphasized that, if the focus of the study is at the individual level, an overall equation of the whole group may result in substantial differences in estimated VĖ at the individual level. In the same way, Mermier et al (1993) indicated that it is necessary to calculate individual regression equations due to the individual variability among HR and VĖ.…”