Exercise testing: contraindications, stop criteria, Bruce, cycle, walk and step tests

1Why test exercise capacity

• Diagnosis: exercise-induced ischaemia, arrhythmia, desaturation or bronchospasm.
• Prognosis and risk stratification: before cardiac rehab (see the IHD page), before surgery.
• Functional capacity: how much the patient can do (METs, distance).
• Exercise prescription: safe heart-rate range, walking speed, need for oxygen.
• Outcome measure: response to rehabilitation or treatment.

Types: laboratory tests (treadmill and cycle ergometer, with ECG; cardiopulmonary exercise test with gas analysis) and field tests (six-minute walk, shuttle walks, step tests).

2Absolute and relative contraindications (7 marks in W18, W20, S26; 3 marks in W19, S23)

3When to stop a test

4Treadmill and cycle tests

Bruce protocol (3 marks in S16)

A symptom-limited treadmill test in which speed and gradient both increase every 3 minutes, with ECG, BP and symptoms monitored. The result is the exercise time, the stage reached (METs), and any ischaemic changes, arrhythmia or BP problems.

Modified Bruce (for older, deconditioned or cardiac patients, early after MI): two gentler starting stages at 1.7 mph with 0% and then 5% gradient, before stage 1 of the standard protocol. It avoids the big jump in workload at the start.

Cycle ergometer testing (3 marks in S22)

5Field walking tests (3 marks in W22)

Six-minute walk test (6MWT)

• Walk back and forth along a flat, straight course of at least 30 m, as far as possible in 6 minutes, at the patient's own pace; rests are allowed; standard encouragement every minute.
• Record distance, SpO₂ and heart rate (before, during, after), Borg breathlessness and fatigue before and after, and any stops. Do a practice test where possible.
• Do not test (ATS 2002): unstable angina or MI in the previous month. Caution: resting heart rate above 120, BP above 180/100 mmHg.
• Stop for: chest pain, intolerable breathlessness, leg cramps, staggering, sweating, pale or ashen appearance.
• Meaning of a change: in chronic respiratory disease, a change of about 25–33 m (often quoted as 30 m) is the smallest that matters to patients.

Shuttle walk tests

• Incremental shuttle walk test (ISWT): walk around two cones on a 10 m course in time with audio beeps; speed increases every minute through 12 levels; the test ends when the patient cannot reach the cone in time or stops with symptoms. A maximal, symptom-limited test; distance relates closely to peak oxygen uptake.
• Endurance shuttle walk test (ESWT): constant speed set from the ISWT result (a high percentage of peak); measures endurance time; sensitive to change after rehab.

6Harvard step test

• Method (original): step up and down a 20-inch (about 50 cm) step at 30 steps a minute for 5 minutes or until exhausted (keeping time with a metronome). Lower steps are used in modified versions for women and patients.
• Recovery pulse: count the pulse for 30 seconds at 1–1.5, 2–2.5 and 3–3.5 minutes after stopping.
• Fitness index (long form) = (duration in seconds × 100) ÷ (2 × sum of the three pulse counts).
• Short form = (duration in seconds × 100) ÷ (5.5 × the 1–1.5 minute pulse count).
• Interpretation (long form): below 55 poor; 55–64 low average; 65–79 high average; 80–89 good; 90 or more excellent.
• Use: a quick fitness test for healthy people; not suitable for most cardiac or respiratory patients (high, uncontrolled intensity).

7Exam corner

Past questions (MUHS, 2016–2026)

• 7-mark questionsAbsolute and relative contraindications of the exercise tolerance test (W18). Various exercise tests, with advantages and disadvantages of each (S19). Absolute and relative contraindications for exercise testing (W20, S26).
• 3-mark questionsBruce protocol (S16). Three advantages and disadvantages of cycle ergometer stress testing (S22). Compare the six-minute walk test and shuttle walk test (W22). Absolute contraindications for exercise testing (W19). Three relative and absolute contraindications (S23).