New research reveals the real reason exercise is harder after a break

Preparing for training. (Credits: Getty Images/iStockphoto)

Returning to an exercise routine after taking a break is always tough, with all those months of hard work feeling like they’ve been undone in no time at all.

There’s no doubt that it seems to take longer to build fitness levels up, than it does to lose them. And, as it turns out, this is more than just a feeling.

New research from the University of Leeds has found the answer to why those weights might feel heavier, or your runs more challenging, when you’ve had a period of no activity.

The study found that a period of not exercising could deactivate a vital protein in the body – the Piezo1 protein – which acts a blood flow sensor.

This deactivation then reduces the density of capillaries carrying blood to the muscles, leading to restricted blood flow and making exercise more difficult.

Published in the Journal of Clinical Investigation, the team of researchers say the results help to explain the biology of why exercise becomes harder the less you do.

While these tests were carried out on mice, this same vital protein is found in humans – meaning that the same results could be applicable.

The experiment, funded by the British Heart Foundation, saw scientists comparing two groups of mice – a control group, and a group whose level of the blood flow sensor protein had been disrupted for 10 weeks.

Lab mouse

The experiment was carried out on two groups of mice (Picture: Getty Images)

It monitored their activity walking, climbing and running on a wheel. The group with the restricted blood flow showed ‘a striking reduction in activity levels’.

Although the two groups exercised for the same amount of time and showed the same amount of interest in the activities, the group with reduced levels of blood flow sensors performed less wheel revolutions per session, as well as running at a slower pace.

This suggests that they had the same interest and desire to exercise, but were physically less able.

Additionally, the study found no differences in levels of respiration, energy metabolism, heart function or muscle mass – meaning their reduced performance wasn’t due to changes in other fitness markers.

Basically, despite the fact that the mice were exercising to the best of their ability, and had an equal desire to do so, the deactivation of the protein had led to restricted blood flow and a reduced capability to do so.

Lead author Fiona Bartoli, a Postdoctoral Researcher in the University of Leeds’ School of Medicine, said: ‘Our study highlights the crucial link between physical activity and physical performance made at this level by Piezo1.

‘Keeping our Piezo1s active by exercising may be crucial in our physical performance and health.’

The study ideally would need to be replicated in humans but certainly suggests that, in essence, maintaining levels of activity will keep our blood flow sensors active, and therefore increase our stamina.

So, next time you find it difficult to return to the gym after a break, don’t be disheartened. Your fitness is still there, you just need to build back up your capillaries and blood flow sensors.

You’ve got this.

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