Duke Treadmill Score: Keep Exercise Time, ECG Units and Symptoms Together

Quick Medical Calculator · Reading label 17 September 2026 · 4 min read

Retrospective study sequence, not publication date

An exercise-test report contains more than a duration and an ECG measurement. The protocol, the interpretability of the tracing and the reason exercise ended all affect whether a Duke treadmill score is meaningful. Entering three numbers into a calculator is the end of an input-checking process, not a substitute for it.

This is a prognostic exercise-test score. It is not an acute chest-pain exclusion tool, permission to start an exercise test or a stand-alone instruction to investigate or treat coronary disease. The AHA exercise-testing standards describe the need to consider contraindications, preparation, recording methods and protocol selection before interpreting a test. AHA issuing summary.

Check the Test Before the Time

The local Duke treadmill calculator asks specifically for standard Bruce-protocol minutes. Minutes from a modified protocol or a cycle test cannot simply be relabelled as standard Bruce minutes. A duration is not a protocol-independent measure of workload, and the software does not perform a validated conversion between protocols.

Confirm which portion of the test the reported time describes. A time including preparation or recovery is not the same as exercise duration. Where the report is ambiguous, clarify it with the reporting service rather than reverse-engineering a plausible answer from the final score.

The original Duke derivation combined exercise duration, ST deviation and exercise angina. Mark and colleagues, 1987, institutional record. The subsequent outpatient validation enrolled 613 people with suspected coronary disease; its outcome concerned prognosis in that study setting. Those facts do not establish that every modern referral population or uninterpretable ECG has the same calibration. Mark and colleagues, 1991.

Fictional Input Audit: A Clock Is Not a Decimal

An invented report records standard Bruce exercise duration as 8 minutes 45 seconds, the maximal ST-deviation input requested by the tool as 1.2 mm, and a clinician-confirmed symptom category corresponding to a model code of 1. These are assumed already established inputs for an arithmetic exercise, not an endorsement of the tool's precise ECG convention. This article is not an assessment form.

Convert the time before using it:

8 + 45/60 = 8.75 minutes

For these fictional established inputs, the score arithmetic is:

8.75 - (5 x 1.2) - (4 x 1) = -1.25

Entering 8.45 instead produces -1.55. The difference is caused by treating seconds as hundredths of a minute. It is not physiological change, and rounding the final answer cannot repair it. Retain enough precision in the duration and ECG measurement to avoid introducing a second error.

Keep the ECG Convention Visible

The implementation expects ST deviation in millimetres, not a voltage copied without its unit. The reporting clinician must establish the relevant maximal deviation during exercise or recovery and whether the tracing is interpretable for this purpose. The input label alone cannot resolve baseline abnormalities, pacing, recording quality or the meaning of an automated ECG measurement.

Do not turn an uncertain ST assessment into zero merely to obtain a result. Zero is an actual observation within the model, not a marker for "not measured". Similarly, a missing symptom description cannot safely become an absent-symptom code.

A test stopped for a non-cardiac reason illustrates a different problem. It may have a perfectly valid elapsed time, but the applicability and interpretation of the resulting score still need clinical judgement. The calculator cannot infer why the test ended from the duration entered.

Build a Three-Layer Report

An original checking resource separates three layers. Acquisition records the test protocol, interpretable tracing, exercise time and symptom assessment. Calculation records converted minutes, the stated ECG unit, the established symptom code and the unrounded arithmetic. Interpretation records the reporting clinician's conclusion and the limitations of this particular study.

For the fictional case, the arithmetic layer can be complete while the clinical layer remains unresolved. A score of -1.25 is not a diagnosis or a personal survival percentage. The local historical risk-band label should not be promoted into an automatic investigation pathway.

This layered report also makes corrections traceable. If the duration is corrected from 8.45 to 8.75, retain why the revision occurred. Do not describe the new score as an improvement in the patient's condition. The clinical question is whether the revised report changes interpretation, which belongs with the responsible cardiology team.

Finally, a low-risk exercise-test result cannot be repurposed to dismiss a new acute presentation. Different symptoms at a later time require their own assessment. Historical prognosis and today's diagnostic question should remain separate in both the notes and the conversation.

Retrospective educational reading plan: Day 13 of 50, labelled 2026-09-17. This is a study-sequence label, not a historical publication or clinical-review date. The publication date above records the actual release.