Can You Lose Most of Your Fitness Gains in Only Two Weeks?


Can You Lose Most of Your Fitness Gains in Only Two Weeks?

No matter how dedicated you are to working out, you might occasionally feel like taking a week or two off to do other things or to simply chill out and relax. Or maybe you’re taking a vacation for a few weeks and want to leave your exercise shoes at home. What harm could there possibly be in taking a few weeks off from training?

And then there’s the issue of injury. Suppose you sustain an injury that forces you to stop exercising for a few weeks or longer? It’s not something you want to think about but it does happen. If you’re forced to take a few weeks break, how likely are you to lose most of your fitness gains?

Based on a new study, it doesn’t take long for the health and fitness benefits of exercise you worked so hard to gain through training to reverse, even after a relatively short break. Not only might it be harder to get back into the swing of things when you return, but you may also find your fitness level has declined, even if you only stopped working out for 2 or 3 weeks.

What the Study Showed

In this study, researchers from the Institute of Aging and Chronic Disease at the University of Liverpool asked a group of healthy volunteers of normal body weight to limit their physical activity for 14 days. Previously, the participants had been walking an average of 10,000 steps daily, as measured by an activity tracker they wore on their arm.

During the 2-week study, the participants did no structured workouts and were asked to avoid all unnecessary exercise. In response, the number of steps they took daily dropped to around 1,500. In essence, they became couch potatoes and spent most of their day sitting. At the end of 2 weeks, the researchers measured various markers of health in the individuals as well as their exercise performance.

The results? After only 2 weeks of inactivity, the participants showed a significant drop in their endurance and fitness level – and there were other repercussions. The participants shed, on average, a pound of muscle and gained body fat as well. It’s not surprising that they experienced these changes, but what IS remarkable is how rapidly the changes happened.

Keep in mind that the results would likely have been different had they not restricted their activity to the degree that they did, essentially curtailing all unnecessary activity. If you stopped exercising for 2 weeks while on vacation, you would most likely still stay fairly active doing all the things people love to do on vacation.

The Detraining Effect

The process of getting out of shape or losing your fitness gains is called detraining. When you stop exercising, you eventually lose the gains you worked so hard to achieve. In terms of aerobic capacity, other studies show that aerobic capacity drops by about 7% within the first 2 to 3 weeks after aerobic training stops. However, it takes around 2 months to completely lose V02 (aerobic capacity) gains you developed during training. This is a less pronounced drop-off than what the study above showed.

In response to the lack of training, the volume of fluid in your blood vessels drops and it becomes harder to deliver oxygen to working muscles. Plus, the number of energy-producing mitochondria decline in number, so you don’t produce the same amount of ATP to fuel muscle contractions. Along with these changes, the volume of blood that your heart pumps with each beat declines. Your heart essentially becomes a less efficient pump.

It’s not surprising that this happens. You know the saying, “use it or lose it.” Your body simply adapts to accommodate a more sedentary lifestyle. You don’t need the extra plasma volume or mitochondria to make ATP when you aren’t training. Your body is actually very good at adapting to your level of physical activity – in both directions.

What about the loss of strength and power gains? Studies show we hang on to those gains a bit longer. A study showed that men who regularly did high-intensity weight training lost 12% of their muscle strength after only 2 weeks of living a sedentary lifestyle. They also lost more than 6% of their fast-twitch muscle fibers. Fortunately, muscles have “memory,” meaning those movement patterns are embedded in your brain. Plus, the extra muscle fiber nuclei you gained from strength training are retained for 3 months or longer, meaning your muscles are primed to return to their former state, even if you take a few months off.

How quickly you lose fitness gains may also depend on how long you’ve been training. Studies show that athletes who have trained for a long time may still retain half their gains after 3 months of no training, whereas a person who exercises for a few months, makes gains, and then stops, may lose all of their gains in as little as 2 months.

What’s reassuring is that you can retain most of your gains by simply cutting back on training rather than stopping entirely. If you shorten the time that you work out and maintain the intensity, you may be able to hold on to all of your gains. Intensity is more important than duration for preserving fitness gains.

Fitness Gains: Getting Back on Track

Keep in mind that taking a few days off from training won’t cause you to give back your fitness gains. In fact, a few days off here and there can be therapeutic. It’s longer breaks – two weeks or more where you may start to feel the effects of detraining. The good news is this. You can rapidly regain any fitness you lost after taking a long break.

Although you can re-coop fitness gains fairly quickly, it’s better not to completely lose them in the first place. As mentioned, reducing the frequency and duration, but not the intensity, while continuing to work out is a better approach. You don’t have to exercise an hour a day every day to maintain your fitness level. Just as importantly, keep your overall activity level high. Unstructured exercise too is important for good health. So, keep your body moving and you’ll continue to enjoy the many benefits that exercise offers.



Health Day. “Just 2 Weeks on the Couch Can Trigger Body’s Decline”
Running.Competitor.com. “How Long Does It Take To Get Out Of Shape?”
Berkeley Wellness. “The Exercise Detraining Effect”
Exercise Physiology. Eighth ed. McArdle, Katch, and Katch. 2015.


Related Articles By Cathe:

Training Consistency: How It Can Make or Break You

The Detraining Effect: How Long Does It Take to Get Out of Shape?


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