Cardiopulmonary Function Assessment Scores (CPET)

Anaerobic Threshold (AT) Value Index Calculator

Clinical calculation support · Verify results before clinical use

Calculate VO₂ at Anaerobic Threshold

Enter oxygen uptake measured at AT and peak oxygen uptake from the same CPET report.

— % of VO₂peak

VO₂ at AT (mL/kg/min) Required Oxygen uptake at the anaerobic/ventilatory threshold, as reported by CPET.

VO₂peak / VO₂max (mL/kg/min) Required Use the peak or maximal oxygen uptake from the same test and in the same units.

Heart rate at AT (bpm) Optional Displayed for context only; it is not part of the percentage calculation.

About this calculation

The calculator expresses oxygen uptake at the anaerobic threshold (AT) as a percentage of peak oxygen uptake (VO₂peak), using values measured during cardiopulmonary exercise testing (CPET).

Formula VO₂ at AT (%) = VO₂ at AT ÷ VO₂peak × 100

How to use

Enter VO₂ at AT from the CPET report.
Enter VO₂peak or VO₂max from the same test, using the same units.
Optionally enter heart rate at AT for display alongside the result.

VO₂peak and VO₂max are related but not interchangeable in every clinical context. Use the term and value reported by the testing laboratory.

Clinical context and limitations

AT is usually identified from CPET gas-exchange patterns, such as the V-slope method and ventilatory equivalents, when these can be interpreted reliably. It is not calculated from heart rate alone.

There is no universal percentage cutoff that classifies AT as normal or abnormal across all populations and protocols.
Interpretation depends on the patient population, exercise protocol, measurement quality, and confidence in AT identification.
Do not use this percentage alone to diagnose disease, estimate prognosis, or determine treatment.

References

American Thoracic Society; American College of Chest Physicians.

ATS/ACCP Statement on cardiopulmonary exercise testing. Am J Respir Crit Care Med. 2003;167:211–277.

doi:10.1164/rccm.167.2.211

Radtke T, Crook S, Kaltsakas G, et al.

ERS statement on standardisation of cardiopulmonary exercise testing in chronic lung diseases. Eur Respir Rev. 2019;28:180101.

doi:10.1183/16000617.0101-2018

Poole DC, Rossiter HB, Brooks GA, Gladden LB.

The anaerobic threshold: 50+ years of controversy. J Physiol. 2021;599:737–767.

doi:10.1113/JP279963