In order to stay fit, you need to continuously keep exercising. Once you stop, you can’t expect to stay in good shape for a long time, but how quickly do you actually start to lose fitness once you don’t work out anymore? This depends on several factors.
Age
This study found that “changes in functional capacity after short and long term detraining are affected by age in elderly adults.” This means that younger people can stay fit longer while not being active than older individuals.
Fitness Level
The more fit you are, the longer you will be able to enjoy the benefits after you stop working out. Fit athletes, compared to beginners, can make it a few weeks without noticing detraining. With beginners, this time frame is much shorter and if they go a few weeks without training they will feel like they’ve never even been active.
How Long You Don’t Train
Connected to the argument above, the length of break you intend to make will determine how unfit you will become. You can probably get away with a shorter break, like a week-long vacation, but anything longer than that can have consequences.
