Exercise Testing, Exercise Prescription, and Physical Activity
Exercise testing
Know indications, contraindications, and termination criteria. Common tests include treadmill or cycle protocols, the 6-minute walk test, shuttle walk, and cardiopulmonary exercise testing. The 6-minute walk test is submaximal and reflects functional capacity; do not interpret it as a maximal VO2 measurement. CPET measures ventilatory threshold, peak oxygen uptake, and breathing reserve, which helps distinguish cardiac, pulmonary, and deconditioning limits.
Before testing, obtain informed consent, review medications, and establish baseline heart rate, blood pressure, ECG, and SpO2. During testing, watch symptoms, rhythm, blood pressure response, and gas exchange. Stop for chest pain, significant ST changes, dangerous dysrhythmia, exertional hypotension, severe dyspnea, dizziness, or desaturation.
Exercise prescription
Use the FITT framework: frequency, intensity, time, and type. Calculate target heart rate with the Karvonen method when appropriate: target = resting HR + intensity fraction × (peak HR − resting HR). Use a range, not a single number. Account for beta-blockade, chronotropic incompetence, and pacemakers; perceived exertion and symptom thresholds may be more useful. Progress frequency and duration before steep intensity increases.
Worked example. Resting HR 70, peak HR 150. At 60–70% heart rate reserve: 70 + 0.60(80) = 118; 70 + 0.70(80) = 126. Prescribe 118–126 beats per minute, then verify against symptoms and Borg scale. Rule of thumb: prescribe a range and monitor the response; the equation is a starting point, not a guarantee.