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Errors in predicting maximal oxygen consumption in pregnant women
F K Lotgering1, P C Struijk, M B van Doorn
1Department of Obstetrics and Gynecology, Erasmus University School of Medicine and Health Sciences, Rotterdam, The Netherlands.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 1, 1992
Summary
Estimating maximal heart rate (HRmax) and oxygen consumption (VO2max) during pregnancy is inaccurate. Standard estimation methods do not reliably replace direct measurement of HRmax and VO2max in pregnant individuals.
Area of Science:
- Exercise Physiology
- Reproductive Health
- Cardiovascular Health
Background:
- Accurate assessment of maximal heart rate (HRmax) and maximal oxygen consumption (VO2max) is crucial for exercise prescription and health monitoring.
- Pregnancy significantly alters physiological parameters, potentially affecting the validity of standard exercise testing estimations.
- Existing formulas for estimating HRmax and VO2max may not be accurate during gestation.
Purpose of the Study:
- To determine the accuracy of estimated maximal heart rate (HRmax) and maximal oxygen consumption (VO2max) during pregnancy.
- To evaluate the impact of advancing gestation on the relationship between heart rate and %VO2max.
- To compare different estimation methods for VO2max against measured values during pregnancy.
Main Methods:
- Measurements of heart rate (HR) and VO2max were taken at rest and during graded cycle ergometry (CE) and treadmill tests (TE) in pregnant individuals and postpartum.
- Standard formulas (220 - age) were used to estimate HRmax.
- Astrand's nomogram (VO2max, est1) and linear extrapolation of submaximal data (VO2max, est2) were employed to estimate VO2max.
Main Results:
- The standard HRmax estimation formula (220 - age) overestimated measured HRmax by 8% (CE) and 5% (TE).
- Pregnancy altered the HR-%VO2max relationship, with an increased intercept and decreased slope as gestation advanced.
- Estimation methods for VO2max exhibited large individual errors (SD 17-28%); VO2max, est1 overestimated VO2max by 20% during CE, while VO2max, est2 appeared accurate due to compensating errors.
Conclusions:
- Standard formulas for estimating HRmax and VO2max are inaccurate during pregnancy.
- The relationship between heart rate and oxygen consumption changes during gestation, invalidating standard extrapolation methods.
- Direct measurement of VO2max is necessary for accurate assessment in pregnant individuals, as estimation methods are unreliable.