A woman sweating in the gym

There’s a scientific reason why exercise gets harder the less you do

Posted by for Workouts

A new study has highlighted the real reason we struggle with exercise after a break. 

Getting back into exercise after taking a break is tough – you can’t run as far or as fast, and the weights that you used to lift suddenly feel extra challenging. While you might think that’s as a result of laziness, a lack of motivation or a decline in muscle mass, a new study has found our struggle to exercise is down to entirely different reasons.

Researchers at the University of Leeds have found that doing less exercise can deactivate a blood flow sensor in the body, which reduces the density of capillaries carrying blood to the muscles. Restricted blood flow makes activity more difficult and means we are able to do less in our workouts.

The study, published in the Journal of Clinical Investigation, was performed on two groups of mice – one control group and one which had disrupted blood flow sensors. It was found that the second group had no less interest in exercise (they exercised for the same amount of time) but during that time they were running for fewer revolutions on the wheel and they ran slower.

Most interestingly, there was no change in respiration, energy metabolism, heart function or muscle mass – meaning the reduced performance wasn’t due to changes in other fitness markers.

The researchers referred to the change in blood flow sensors as “genetic detraining”. Essentially, the body had lost its fitness capability despite the fact that the mice still wanted to exercise and perform well. 

A woman struggling in the gym with a barbell
Exercise can get harder when you do less due to blood flow changes

Of course, studies in humans are needed to back up this theory. But there’s a concern that our desire to get back to fitness could potentially be blunted due to reduced performance. Haven’t you ever felt conscious or critical of your lack of ability in the gym after a break? Often, that frustration is enough to put us off trying again.

While researchers are now looking into ways to ensure active blood flow sensors in order to maintain exercise capability, you can take this research as a useful reminder that your fitness isn’t doomed. Your muscle mass and cardio function are still there, and the more you do, the easier it will get for those capillaries – so you may as well start now. 

Images: Getty

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Chloe Gray

Chloe Gray is the senior writer for stylist.co.uk's fitness brand Strong Women. When she's not writing or lifting weights, she's most likely found practicing handstands, sipping a gin and tonic or eating peanut butter straight out of the jar (not all at the same time).