Competitor answers the question: How much rest between training cycles is enough?
Generally, the greater your training load is within a training cycle, the longer you should rest afterward. Also, the longer your peak race is, the longer you should rest. A runner who peaks at 45 miles per week for a 10K might need only 10 days of rest to “reset” his body and be ready for the next ramp-up. A runner who peaks at 120 miles per week for a marathon is more likely to need at least three weeks of rest.
Rest is relative, and does not refer strictly to complete cessation of running. A transition period between training cycles should begin with at least a day or two of running avoidance. When and how you resume running depends on how much recovery your body needs coming off the last peak and how soon you’d like to peak again. If you really pushed your body hard in the last training cycle, you should not rush your return to running and should start very gently when you do resume running.
On the other hand, you don’t want to wait too long, lest you sacrifice too much running fitness and give up all of those hard-earned tissue adaptations to repetitive impact that keep you from getting injured.