Relation between duration and intensity of first exercise and "warm up" inischaemic heart disease

Objective-To determine the importance of the duration and intensity of "war m up" exercise for reducing ischaemia during second exercise in patients wi th 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 se gment 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 ma ximum intensity. Main outcome measures-ST segment depression during graded treadmill exercis e 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 exer cise 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 depres sion 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 pea k 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 resp onse is related to the maximum intensity rather than the duration of first exercise.