What If We Quit Exercising?

Getting to our ideal body takes a great deal of discipline and dedication. For some, it becomes a chore and a burden and the desire to let go becomes more attractive. What will happen to all those efforts? To understand how the body becomes “unfit”, we first need to understand how we become fit. The key to becoming fitter – whether that’s improving cardiovascular fitness or muscular strength – is to take the body out of homeostasis. The stress that this has on our body makes us adapt and become more tolerant, leading to higher fitness levels.

The time it takes to get fit depends on a number of factors, including fitness levels, age, and even environment. Studies indicate that even in the beginning, a new exercise habit leads to increases in maximal oxygen uptake and improves how efficiently our body is able to fuel itself using the energy stored in our cells. For strength training, some gains in muscle force can be shown in as little as two weeks, but changes in muscle size will take a couple of months.

Cardiovascular fitness

When we stop training, how quickly we lose fitness also depends on many factors – including the type of fitness we’re talking about (such as strength or cardiovascular fitness).

As an example, let’s look at a runner. This person spends five to six days a week training. They’ve also spent the last 15 years developing this level of fitness. After they stop running, their plasma volume may decrease by around 5 percent. The effect of decreased blood and plasma volume leads to less blood being pumped around the body with each heartbeat. 

These levels only drop to where we started, meaning we won’t get worse. Of course, most of us aren’t marathon runners, but we’re also not immune to these effects. As soon as we stop exercising the body will start to lose these key cardiovascular adaptations at a very similar rate as highly trained athletes.

Strength training

When it comes to strength, evidence shows that it takes the average person around 12 weeks for a significant decrease in the amount of weight they can lift.  Research shows we are able to maintain some of our strength. What is intriguing is that despite the significant decrease in strength, there’s only a minimal decrease in the size of the muscle fibers. 

The reason we lose muscle strength largely has to do with the fact that we’re no longer putting our muscles under stress. For the average person who lifts weights they would experience a drop in the size of their muscles.  This will make it harder to lift heavy loads as they have less muscle fibers being recruited.

Staying active is key

So even after all that effort to get fit, we start losing cardiovascular fitness and strength within 48 hours of stopping. But we don’t start to feel these effects for at least two to three weeks for cardiovascular fitness and around 6-10 weeks for strength. Rates of “de-training” are similar for men and women, and even for older athletes. But the fitter you are, the slower you’ll lose your gains. The key is to keep being active; simply change the routine if you’ve become bored with it. A personal trainer is always here to help spice up workouts and help keep our bodies challenged. 


Written by Emily Morris – personal trainer and yoga instructor