Nick Lawson: What sort of exercise regime do you recommend for a 39 year old indoor rower who is not overweight and for a variety of reasons can only usually exercise once a week? My main aim is to avoid physical atrophy and a heart attack in my 40s. Having rowed competitively at university, I am quite happy working hard on my Concept 2 but am aware that pushing it too much might be damaging. I have a heart rate monitor and try to keep my heart rate down but seem to be able to row quite long pieces (30 minutes) at a relatively high heart rate (170+) which is probably pushing me into my anaerobic zone.Terry O'Neill: Your preoccupation with heart problems worries me; do you have a heart condition or is there a family history of heart disease? If you have a sound heart you cannot have a heart attack because of exercise but you may have a heart attack during exercise as a result of a dicky ticker. With a dicky ticker you would stand the same chance of a heart attack doing exercise as having a shag, and I know which way I would rather go. There are too many other things going on in the body that would shut down long before a healthy heart gave out. The heart responds to demands placed upon it for blood and oxygen to supply working muscles. In an unfit person the inefficiency of the body would mean that it is unlikely to be able to stress the heart. There is a difference between being unfit and being unhealthy. Being unfit means the inability to overcome a given task and this is not a medical condition. Being unhealthy is a medical condition and this may make you unable to carry out certain activities.Now as for the idea of a one day a week training programme, very difficult. One of the laws that applies to training is reversibility. What this means is that any improvement that you acquire as a result of training leaves you when you stop training. Therefore day one you train, day two you recover, day three you are ready to train again having adapted to the training load but, if you don't train, you start to lose it on days four, five and six. You need to come up with some time on two more days, even if it is only a total of 1 hour.