Reversibility

Just as too great of a training stimulus can be detrimental to one’s progression, so can be too little of a training stimulus. This follows directly from the overload principle and represents the flip side of overtraining. If you trained for and ran a marathon a few years ago and have not run since, you should not expect any carryover from that training for a marathon you decide to run on a whim next weekend. Plainly stated, the principle of reversibility states that inactivity leads to performance decline. Performance gains are reversed when the athlete ceases to train at a given level.

Obviously, reversibility does not mean that you can never take a break from training. The substantial losses of fitness associated with the principle of reversibility do not occur overnight. Substantial reversals in fitness gains take one to three weeks of inactivity to accumulate. But there is no need to be completely inactive for that period of time as long as you are healthy and have time to train.

Even during times when you are simply unable to train at your normal levels because other areas of your life prevent you from getting in the training you planned (work deadlines, holiday travels, unexpected illnesses, etc.), fitness can be maintained by following a reduced training schedule. The key is to not stop exercising completely.

One general rule when entering into maintenance mode is to counterbalance decreased training volume with increased intensity. Aim for a short, intense workout instead of the longer workout you had planned. Also, remember that training volume is the sum of both frequency and duration. If you don’t have a big block of time for that long run you originally planned, try to schedule shorter runs on back to back days or split the target duration over morning and evening runs that day. Strategies like these will allow you to maintain fitness for up to several weeks on a reduced training schedule. Just remember, something is better than nothing. The key to navigating those times of reduced training is to remain active and avoid complete inactivity.