• Epidemiology
• clinical trials
• delivery of care
• public health
• cardiac rehabilitation

The Authors' reply Thank you for the opportunity to respond to two further letters.

Conraads and colleagues object that exercise training was insufficiently intense.1 Outpatient programmes provide organised and supervised training sessions (usually) once per week but also advise and encourage patients to self-exercise at home and, in later stages of rehabilitation, at leisure centres. We acknowledged that more intensive or longer programmes of exercise training …