"A highly trained aerobic athlete can get away with doing absolutely nothing for nine to 12 days before there will be an appreciable loss in fitness. However, it can take between eight and 12 weeks to regain fitness lost after taking four weeks off. That means if you don't exercise for the month of October, sometime in January you could be as fit as you were at the end of September. It is difficult to make significant strength and power gains from year to year if you spend three months losing and regaining fitness."
- Chris Carmichael, On the Road: Building the Foundation of Success.