How quickly do you lose fitness and muscle if you stop exercising?

I’ve recently been on holiday, a relative of mine who usually exercises has been ill, a friend has needed to go and care for a parent.  These are all scenarios that many of us will be familiar with, but what happens to our fitness levels and our muscle tone when we stop exercising?  Here’s what I found out.

The short answer is it depends on your starting point.   How quickly you lose muscle tone and fitness generally seems to it depend on how fit you are now, how long you have been exercising and how long you’ve had to stop for.

Here are some basic statistics:

  • Aerobic power can decline about 5-10% in three weeks.

  • It takes about 2 months of inactivity to completely lose the gains you've made.

  • Extremely fit exercisers will experience a rapid drop in fitness during the first three weeks of inactivity before it tapers off.

  • Muscles retain a memory of exercises for weeks or even months.

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How fit you are now is an issue

The research indicates that very fit people don’t lose their fitness as quickly as people who are new to exercise.  A study on people new to exercise followed them through an eight-week training programme.  These people showed dramatic increases in their cardiovascular fitness by the end of the programme.  However, once they stopped all exercise, after three months they had lost all of the original fitness they had gained!

The two types of fitness

There are two types of fitness: firstly your aerobic fitness that is  your endurance, and the second type, your orthopaedic or structural fitness, the ability of your muscles, bones, tendons and ligaments to withstand impact sports such as running.  Both are important but you lose this fitness at different rates.

Endurance or aerobic fitness starts to decline after around 7-14 days but if you're a lifelong runner, you'll retain much of your aerobic fitness for several months. Structural fitness hasn’t been studied that much but injury can lead to rapid declines in this area.  The consensus is that endurance is lost more slowly than your structural strength.

The effect on your blood pressure

Blood pressure is also a measure of fitness.  In the short term when you exercise, your blood pressure goes up because there is an increase in blood flow to the heart.  This prompts your arteries to widen to enable greater circulation. The arteries remain like this for up to 24 hours before returning to normal if you don’t exercise. But these effects are only temporary and it’s only after 12 weeks that your arteries can begin to narrow and harden if you remain inactive.

The good news is that studies have shown women who walked briskly for at least three hours a week had the same protection against heart disease as women who ran for 90 minutes a week.

What about strength training?

 Studies show that muscle loss doesn’t begin until after two or three weeks of no training at all i.e. no weightlifting or formal exercise of any kind. So the idea that you start to lose muscle after a matter of days is incorrect.

If you have to stop your strength training the good news is that when you start lifting weights again, you can expect to gain size and strength faster than you did the first time around.  This is the science behind muscle memory.

What can you do to retain your level of fitness?

During any period of inactivity, a small amount of strength work can help you maintain your body's ability to withstand aerobic exercise like running or a dance class.

Studies have shown that you can prevent declines in cardiovascular fitness for up to three weeks simply by doing higher intensity exercise (70-75 percent of maximum heart rate) for as little as two days per week.

If your main goal is to maintain your fitness level during a few weeks of reduced training, then some moderate exercise for 30 minutes every other day is probably all you need. 

In conclusion…

Generally the better shape you are in when you stop exercising the slower you lose it and the faster you regain it.   

If you are getting back to exercise after a break, it is important to re-introduce exercise in a gradual way, give your body time to get used to working out again and remember to take rest days.  These tips will help you avoid injury.

Before you go

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