The V˙E/V˙co2 Slope During Maximal Treadmill Cardiopulmonary Exercise Testing: REFERENCE STANDARDS FROM FRIEND (FITNESS REGISTRY AND THE IMPORTANCE OF EXERCISE: A NATIONAL DATABASE).

PURPOSE: Cardiopulmonary exercise testing (CPX) is the gold standard approach for the assessment of cardiorespiratory fitness (CRF). The primary aim of the current study was to determine reference standards for the minute ventilation/carbon dioxide production (V˙E/V˙co2) slope in a cohort from the "Fitness Registry and the Importance of Exercise: A National Database" (FRIEND) Registry. METHODS: The current analysis included 2512 tests from 10 CPX laboratories in the United States. Inclusion criteria included CPX data on apparently healthy men and women: (1) age ≥20 yr; and (2) with a symptom-limited exercise test performed on a treadmill. Ventilation and V˙co2 data, from the initiation of exercise to peak, were used to calculate the V˙E/V˙co2 slope via least-squares linear regression. Reference values were determined for men and women by decade of life. RESULTS: On average, V˙E/V˙co2 slope values were lower in men and increased with age independent of sex. Fiftieth percentile values increased from 27.1 in the second decade to 33.9 in the eighth decade in men and from 28.5 in the second decade to 33.7 in the eighth decade in women. In the overall group, correlations with baseline characteristics and the V˙E/V˙co2 slope were statistically significant (P < .05) although generally weak, particularly for age and body mass index. CONCLUSION: The results of the current study establish reference values for the V˙E/V˙co2 slope when treadmill testing is performed, and all exercise data are used for the slope calculation. These results may prove useful in enhancing the interpretation of CPX results when assessing CRF.

Peak oxygen pulse responses during maximal cardiopulmonary exercise testing: Reference standards from FRIEND (Fitness Registry and the Importance of Exercise: an International Database).

INTRODUCTION: Cardiopulmonary exercise testing (CPX) is the gold-standard approach to assessing cardiorespiratory fitness (CRF). The current study puts forth reference standards for peak oxygen (O2) pulse from the "Fitness Registry and the Importance of Exercise: A National Data Base" (FRIEND) Registry. METHODS: The current analysis included 13,318 tests from CPX laboratories in the United States, Canada and Europe. Inclusion criteria included CPX data on apparently healthy men and women: 1) aged ≥20 years; 2) with exercise tests performed on a treadmill; and 3) achieving a peak respiratory exchange ratio ≥ 1.00. RESULTS: Peak O2 pulse 50th percentile values decreased from 20.8 ml/beat in the 2nd decade to 11.2 ml/beat in the 8th decade in men and from 13.6 ml/beat in the 2nd decade to 7.9 ml/beat in the 8th decade in women. Linear regression analysis results produced the following statistically significant (p < 0.001) equation: peak O2 pulse (ml/beat) = 23.2-0.09(age) - 6.6(sex); female = 1 and male = 0. DISCUSSION: The assessment of CRF through CPX is an important health metric. Reference standards, such as those put forth in the current study, allow for the comparison of key measures of CRF to expected normal responses across the adult lifespan.