OBJECTIVE To determine the importance of the duration and intensity of “warm up” exercise for reducing ischaemia during second exercise in patients with exertional angina.

DESIGN Randomised crossover comparison of three warm up exercise protocols.

PATIENTS 18 subjects with stable ischaemic heart disease and > 0.1 mV ST segment depression on treadmill exercise testing.

INTERVENTIONS The warm up protocols were 20 minutes of slow exercise at 2.7 km/h, symptom limited graded exercise for a mean of 7.4 (range 5.0 to 10.5) minutes, and three minutes of symptom limited fast exercise of similar maximum intensity.

MAIN OUTCOME MEASURES ST segment depression during graded treadmill exercise undertaken 10 minutes after each warm up protocol or no warm up exercise.

RESULTS Compared with exercise with no warm up, the duration of graded exercise after earlier slow warm up increased by 4.9% (95% confidence interval (CI), −3.3% to 13.7%), after graded warm up by 10.3% (95% CI, 5.6% to 15.2%), and after fast warm up by 16% (95% CI, 6.2% to 26.7%). ST segment depression at equivalent submaximal exercise decreased after slow warm up by 27% (95% CI, 5% to 44%), after graded warm up by 31% (95% CI, 17% to 44%), and after fast warm up by 47% (95% CI, 27% to 61%). Compared with slow warm up exercise, the more intense graded and fast warm up protocols significantly increased the duration of second exercise (p = 0.0072) and reduced both peak ST depression (p = 0.0026) and the rate of increase of ST depression (p = 0.0069).

CONCLUSIONS In patients with exertional angina the size of the warm up response is related to the maximum intensity rather than the duration of first exercise.