Investigating the reliability and validity of age-estimated heart rate in predicting VO2max from submaximal exercise testing.

Objectives: Age-estimated maximum heart rate (maximum heart rate=220-age) is commonly used for; assessing cardiorespiratory fitness in terms of VO2max, determining health status and designing exercise programs. Even though it is the method of choice in many submaximal tests, its validity has been questioned. This study investigates the test-retest reliability and criterion validity of age-estimated heart rate in predicting VO2max. Study Design: An experimental, test-retest reliability and criterion validity study. Setting: Queen Margaret University. Participants: Fourteen female members of a Queen Margaret University sports team aged 17-30. Methods: Maximum heart rate, heart rate at specific intervals and exercise level data was collected during maximal and submaximal exercise testing using the multistage fitness test and Chester step test respectively. Each participant completed both test twice. Interventions: Heart rate and exercise level achieved were used to calculate VO2max for each participant from all tests. Outcome measures: Heart rate and VO2max. Results: Itraclass correlation coefficients between age estimated VO2max calculated from Chester step test 1 and 2 showed moderately strong levels of reliability, ICC=0.649. Analysis of criterion validity using Bland and Altmans Limits of Agreement displayed an average error of 7mlO2/kg/min (17.1%). This was also extremely variable from a single underestimation of 1.3mlO2/kg/min to overestimation of 18mlO2/kg/min (-2.64% to 44.4%). Conclusions: Age estimated VO2max showed moderately strong test-retest reliability. However, when compared to a maximal criterion, age estimated VO2max displayed significant disagreement and variation. Therefore age estimated maximum heart rate is not valid in predicting VO2max. Keywords: VO2max, heart rate, submaximal, exercise testing