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Why do you feel more tired on rest days than training days?

Posted by for Strength

Ever find you feel more knackered when resting than you do after a tough work out? Here’s the reason why… 

Logic would dictate that you should feel more tired on the days you get up early and bash out an exhausting workout. Yet, so many of us know that exercise can make us feel like we’ve actually topped up our energy tanks, rather than just depleted them.

That can come as a shock on a rest day when you feel more tired after doing nothing than you do when you train hard. “It’s not unusual to feel less tired on the days you’re exercising,” says Dr Folusha Oluwajana. In fact, there are three main reasons why your body might need an extra boost on the days you don’t hit the gym. 

You don’t have hormonal spikes

While working out is tiring, it can actually make you feel more alert. That’s thanks to the hormonal changes that occur when we workout, says Dr Oluwajana: “Exercise releases those feel-good endorphins, as well as serotonin, dopamine and oxytocin, that can energise the brain and body. The short-term effect of that can leave you feeling more pumped and energised.”

Interestingly, it’s also the spike in stress hormones that can increase alertness. A 2008 study found that high-intensity exercise increases circulating cortisol levels, the hormone associated with fight or flight. Too much cortisol is never a good thing, which is why daily HIIT isn’t recommended, but these spikes of the hormone can make us feel more energised on our training days. 

Your body is working hard to rebuild

Believe it or not, your rest days might mean not hitting the gym, but that doesn’t mean your body stops working. In fact, it’s when your body is actually working the hardest to rebuild the muscles that you tore in your workout. So much for a ‘rest’ day, huh?

A 2019 paper from Frontiers in Nutrition reported that muscle-building protein synthesis – the process of rebuilding muscles – is elevated for around 24–48 hours after resistance exercise, and has a “high metabolic cost” that needs to be accounted for. Essentially, this means your body is burning a lot of fuel after training to repair the tissue.

Meal prepped Tupperware with falafel and veg
You might feel more tired on rest days if you don't focus on nutrition

With your body working that hard behind the scenes, it’s no surprise you may feel a little knackered. But that’s particularly true if you are eating less on rest days, as is pretty common for gym-goers. “It’s actually normal to feel more hungry on rest days. Exercise can lower your appetite so you may not be that hungry on training days, but your body will want the extra calories to recover from your training when it starts to rebuild,” adds Dr Oluwajana.  

You oversleep

If you’re swapping your 6am alarm for an extra hour in bed now that you don’t have to hit the gym, you should be feeling bright eyed and well rested, right? Well, changing up your sleeping pattern can actually mess with your body clock and leave you feeling groggy.

“Despite getting a bit more sleep, we often wake up with feelings of inertia which make you feel rubbish,” Stephanie Romiszewski, sleep physiologist from the Sleepyhead Clinic, previously told Stylist.

Dr Oluwajana agrees: “Waking up at a regular time is so important with setting your circadian rhythm. Messing up your body clock means you’ll feel more tired, and then will struggle to sleep that night, which will have a knock-on impact on the rest of your week.” 

How to feel better on rest days

The key is to not use rest days as an excuse to do nothing. While a rest day is a day to not exert yourself, sticking to a similar routine is the best way to feel good. “Rest days are often associated with a ‘day off’ – meaning people stop thinking about eating nutritious foods, hydrating enough and moving away from screens,” says Dr Oluwajana. “These things all result in a natural lull in energy anyway, plus they can result in extreme swings in behaviour from training days and rest days which can make you feel worse.”

Of course, we’ll all have days when sitting on the sofa is the only option. “Sometimes doing nothing is absolutely fine,” says Dr Oluwajana “But you shouldn’t be feeling completely sleepy, down or hungry on days off.” If you do, it could be a sign of overtraining and too much reliance on the cortisol and adrenaline to keep you going, she says.

So while rest days are absolutely for resting, active recovery practices can be useful to shake off the sluggish feeling and “prevent the sudden drop in energy levels that can happen if you just do nothing,” says Dr Oluwajana.

Plus, a walk or a gentle yoga class can help release endorphins and get you out of the house – an often overlooked part of feeling energised. Getting outside within the first hour of waking up is also an easy way to spike your cortisol and wake you up without fatiguing the muscles that need a well-earned rest. Eating enough and eating well are also crucial, and stick with your usual bedtime and morning routines if you can. 

Images: Pexels

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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).