Experts from Firstbeat, leaders in advanced performance analytics, explain why skipping a session sometimes isn’t such a bad thing after all.

When not to work out Men's Fitness UK

Sometimes a workout does more harm than good

Hitting the gym or training hard is a great way to relieve stress, release endorphins and make you feel better.

However, there are times when smashing your session could actually be causing your body negative damage. Heavy training can increase your stress levels and affect your ability to both recover and deal with life’s stresses.

“Heavy exercise taxes the body, with very intense exercise causing cortisol (the stress hormone) levels to rise significantly,” says Tiina Hoffman, exercise physiologist and Master Trainer for Firstbeat.

“The heart will also be beating fast, blood pressure will be elevated and rapid breathing will all tax the cardiovascular system. Under normal conditions – with sufficient food, sleep, hydration and rest – these are all perfectly fine for most individuals. However, there are times when it could cause problems.”

  1. If you’ve had a very stressful day

Heavy exercise further stresses the body, elevating the heart rate significantly and even releasing more cortisol, the stress hormone.

Long-term elevated cortisol can lead to lower immune function and bone density, increased weight gain, blood pressure, cholesterol, and heart disease.

Heavy exercise late into the evening can also affect your body’s ability to slow down into ‘restore mode’, meaning you won’t be able to recover as much overnight.

Easy exercise, such as a light evening walk or stretching, is usually a much better alternative after a stressful day – it also helps prepare you for a good night’s sleep.

  1. Hungover or before a drinking session

After a heavy night out, your sleep quality will be seriously compromised.

“Just having as little as one unit of alcohol in your system at bedtime can delay the onset of restorative sleep by around one hour,” says Nigel Stockill, performance director at Firstbeat.

“While having just two large glasses of wine (approximately six units) late in the evening and sleeping for six hours means you may not get any restorative sleep at all, and therefore won’t recover overnight.”

The general stress level of the body and the heart will also be high as it is dealing with removing the toxic alcohol.

When not to workout Men's Fitness UK

If you’ve slept poorly, don’t put your body under even more stress with a heavy gym session

  1. After a terrible night’s sleep

If you’ve slept poorly, you will not be recovered. In most cases it is best to skip the heavy session, focus on your pre-bed routine and get a solid night’s sleep and workout the next day.

Some people may still wish to train, but it is important to consider lowering the intensity and focus on getting a good sleep the following night.

  1. If you’ve done heavy gym sessions that week

Heavy training sessions really take their toll on the central nervous system (CNS). If you have taxed the CNS severely the previous few days, it may be best to rest if you are tired, sore and not feeling 100 per cent.

Even if it’s in your diary to train legs, it is important to listen to your body and adjust the training plan if needed.


Firstbeat experts ensure hundreds of thousands of athletes worldwide keep performing at their best. The Lifestyle Assessment, offered direct and through partners and providers, offers a snapshot of your lifestyle and how your body reacts to stressors, and how it recovers.