AREA OF UNDER OXYGEN UPTAKE CURVE ON EXERCISE ONSET ESTIMATE ANAEROBIC THRESHOLD IN PEOPLE WITH IMPAIRED LEFT VENTRICULAR EJECTION FRACTION

¹Ukima Central Hospital, Rehabilitation, Tokyo, Japan

Background: It has been demonstrated that higher aerobic capacity leads to decreased mortality. However, little is known about cardiopulmonary responses to exercise onset under the influence of aerobic capacity.

Purpose: Purpose of this study was to expose the relationship between anaerobic threshold and cardiopulmonary responses to exercise onset through comparison with healthy people and people with impaired left ventricle ejection fraction.

Methods: 72 male subjects were participated in this study. 13 healthy (range 21-42 years) were volunteer, and people with impaired left ventricular ejection fraction had been admitted to hospital for cardiac rehabilitation due to their heart disease. We divided people with impaired left ventricle ejection fraction into two groups, 31 myocardial infarction (range 36-79 years) and 28 heart failure (range 36-82 years). In the study, participants underwent a sub-maximal cardiopulmonary exercise test to determine oxygen uptake at their anaerobic threshold (AT) level, using cycle ergometry. Data for analysis were time constant (TC), the area of under oxygen uptake curve (VO2AUC) from exercise onset to initial four minutes period on warming up phase, age, body mass index (BMI), left ventricular ejection fraction (LVEF), and oxygen uptake at AT revised by age (%AT). One way analysis of variation (ANOVA) had used for among the three groups comparison. Subsequently, Pearson’s product-moment correlation coefficient had used to represent the relationship between the variables and %AT on each groups. Statistical differences with a P-value 0.05 were considered significant. All analysis was done using SPSS (version 12).

Results: Mean (SD) age was 28.6 (6.4) years, mean BMI was 23.8 (2.9) kg/m2, mean TC was 10.4 (8.4) seconds, mean VO2AUC was 11.7 (4.4) ml/kg and %AT was 88.2 (4.9) % in healthy volunteers, mean age was 63.1 (10.0) years, mean BMI was 22.9 (2.5) kg/m2, mean LVEF was 59.8 (2.2) %, mean TC was 44.7 (29.3) seconds, VO2AUC was 12.6 (1.4) ml/kg and %AT was 63.5 (2.9) % in people with myocardial infarction, and mean age was 63.9 (11.3) years, mean BMI was 24.0 (4.0) kg/m2, mean LVEF was 48.8 (3.3) %, mean TC was 71.8 (40.2) seconds, VO2AUC was 9.1 (2.4) ml/kg and %AT was 56.0 (1.6) % in people with heart failure. There was a significant effect of amount of age, TC, %AT, and VO2AUC for the three groups (p 0.05). An independent-samples t test was concluded to evaluate whether myocardial infarction and heart failure (p 0.05). Pearson’s product-moment correlation coefficient between %AT and VO2AUC were 0.219 (p=0.472) in healthy volunteer, 0.556 (p 0.05) in people with myocardial infarction, and 0.538 (p 0.05) in people with heart failure.

Conclusion(s): These results suggested that an easily and safely obtained measurement of physical fitness is related to VO2AUC from exercise onset to initial four minutes period on warming up phase.

Implications: Therefore, VO2AUC from exercise onset to initial four minutes period on warming up phase could be powerful predictor to assess aerobic capacity in people with impaired left ventricular ejection fraction.

Funding acknowledgements: Auther thanks all subjects.

Topic: Cardiorespiratory

Ethics approval: All subjects were comprehensively agree to use the data for study, which was approved by ethics committee.

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