How Long Does It Take To Lose Your Fitness And How Do You Get It Back?

After months of putting in the effort to build up your fitness – just how long does it take to lose it all?

So you had a vision, a goal, and a point to prove. You pushed your body through hundreds, maybe thousands of gruelling hours in the gym. You refused to relent while getting stronger, fitter, faster and leaner with consistent training and patient, increased goal setting.

And then, well, life got in the way. Maybe you came down with the flu, booked an all-inclusive month-long holiday, work commitments got serious … maybe you just downright lost your mojo. The first casualty when hiccups arise is usually your training time… But just how long can you get away with lounging around on the sofa eating cheesy chips before the gym dodging catches up with you?

What happens to your fitness when you stop training?

It takes three times as long to gain fitness as it does to lose it

“It takes three times as long to gain fitness as it does to lose fitness,” says Scott Alexander, founder of the Cardio Guru and ambassador for Bio-Synergy. So, unfortunately, you can expect a rapid loss of your cardio fitness levels, akin to running up a very steep hill, turning around and then rolling straight back down.

Why do we lose fitness so quickly?

Training makes the body feel under threat – it’s programmed to think you’re avoiding predators or need to work hard to successfully hunt for food. This sets off a metabolic trigger – known, in part, as the ‘fight or flight’ response – which results in the secretion of hormones called catecholamines, which are associated with dopamine and adrenaline.

“When we stop training [known as detraining] the body begins to rapidly feel safe and secure, and will preserve energy that is no longer required,” says Alexander. “All the biological factors that increase baseline cardio fitness in the first place are closely connected, and will fall like dominos when you completely stop your fitness regime.”

Expect to see a 20% drop in cardio fitness levels within only three weeks of detraining

So, when you stop training, your requirement for blood volume decreases almost immediately, and so does your stroke volume [the amount of blood pumped per heart beat] this increases your heart rate at both rest and during increased intensity demand which, in-turn leads to a loss of fitness.

“Expect to see a 20% drop in cardio fitness levels within only three weeks of detraining,” says Alexander.

Think that’s bad news? Unfortunately we have more:

“As the body’s ability to consume and process oxygen falls, watch as muscle mass, strength and flexibility all begin to enter atrophy [waste away]. This will cause your metabolism to change, meaning you will start to burn less fat and store lots more of it,” says Alexander. Bums.

But enough of the bad news – let’s have some good:

Can you regain that lost ground?

The simple answer is yes. But it’s going to take hard work and patience, with the initial stages feeling particularly difficult. That’s why complete detraining should be avoided where possible.

How to prevent losing your fitness in the first place

“If you know you’re not going to be able to exercise as often as usual, rather than stopping completely and undoing all the good work,  my advice would be to use a Heart Rate Monitor (HRM),” says Alexander.

“That way you can progressively increase your levels of training intensity to compensate for the decrease in training volume. Short powerful bouts of 8-15 min HIIT workouts will provide enough stimuli to keep your body’s adaptive pathways open and stop your current fitness levels falling dramatically.”

How to regain your fitness without getting disheartened

If you’ve really gone cold turkey on the fitness, don’t worry you can get it back, just don’t get disheartened if you don’t see immediate results.

“Motivation is always key to successful training, however time off means previous highs and PBs which ‘amped up’ your sessions won’t apply at the moment,” says Alexander. “The challenge has changed and you need to evolve your mindset to beat and defeat smaller goals – accept that it’s going to take you a while to get back to your best, but it’s certainly doable and it will happen!”

Looking to get your fitness back after losing it? Try these 3 HIIT workouts you can do at home – before you start hitting the gym.

For more information on HIIT and nutrition please visit and


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