I'm starting to see a pattern in my health which seems to indicate that I have a max amount of exercise I can do in a period of 7 days of about 5000 calories – irrespective of if this is 6 seperate sessions or just 2 during this period. If I go over this level I become ill more than likely due to a battered immune system.

Does this ring any bells with anyone else?

Does anyone have any tips on how I can extend this ceiling so I can ride more or is this something which I will just have to live with?

It perhaps doesn't help I have two young children who take great joy in bringing all manner of bugs home from nursery and school.

What sort of exercise are you taking to get to your 5,000kcal level?

Do you always exercise hard when you do, or do you do some hard sessions mixed with some steady sessions?

Mainly just cycling (MTB or BMX) and have some steady sessions and hard – wouldn't say I really push it all the time.

I know what you mean, although have never equated it to a calorie burn value… stopped wearing a HRM about 4 yrs ago when the batteries died.

Mountain Mayhem does it for me most years – combination of ragging it all weekend, invariably getting wet and lack of sleep. Guaranteed flu / cold / run down knackeredness a week later.