Can some exercises be bad for you?

Jay Brewer Jay Brewer Former Professional Head of Clinical Wellbeing at Nuffield Health
Exercise can be good for your health and your happiness, but can some exercise actually be bad for you? Our Head of Physiology, Jay Brewer investigates.

Recent research has thrown everything we knew about how we respond to exercise in the air. The Heritage Family Study indicates that genetically some of us are ‘responders’ and some are ‘non-responders’, meaning that some us will improve our health with a certain amount of exercise while others will need much more exercise to see the same benefit.

And the research goes further. It highlights that roughly 10 percent of people have an adverse reaction to exercise with either their blood pressure or cholesterol levels.

While this research points to genetic differentiators, could there also be so exercise that is bad for everyone?

Aerobic exercise

Aerobic exercise done correctly can be really beneficial for the body, boosting your mood, reducing risk of diabetes and improving your cholesterol levels to name a few benefits. But some further research has shown that long, strenuous sessions of aerobic exercise completed on a regular basis actually increase the amount of damaging oxidative molecules in the body. One study found that the rate of damage after a 42km run continued for an entire week, while a Canadian study highlighted that the number of years spent training, number of competitive marathons and ultra-endurance (>50 miles) marathons completed related to the rate of heart valve thickening (myocardial fibrosis).

So while aerobic exercise is an important staple in your fitness regime, these studies indicate that more is not better in regard to exercise and extensive aerobic training in particular should not be performed for long periods over time. If you’re an enthusiast, ensure you have regular ‘season breaks’.

High intensity exercise

High Intensity Interval Training (HIIT), with its short sessions, can have a positive impact on your health. But other high intensity training over long durations, such as running in particular, can be damaging. The effort required to propel the body in running takes huge cardiovascular effort that commonly pushes individuals close to their maximal heart rate. Running regularly at such intensity results in chronic build-up of the stress hormone cortisol, which encourages weight gain around the abdomen and suppresses the immune system. Runners should only perform close to race pace running once or twice per week, using the other sessions for technique or slower aerobic base training.

Core work

Lower back pain is the leading type of back pain in the UK followed by neck pain. Most target what is known as a weak ‘core’ and typically focus on strengthening deeper stabilising muscles, specifically the transverse abdominus (which is activated in exercises such as the famous ‘plank’).

Researchers noted that when the transverse abdominus is activated so is the back stabiliser called the multifidus. However, further studies have shown that even fully functioning core muscles work only a small amount, 1-3% most the time. In fact simply moving more is as beneficial as performing concentrated core work and comes with added benefits such as increased calorie burning, increased fat utilising enzymes and improved joint stability.

Further, most people progress core ‘stability’ to core ‘strength’ too quickly or blend the two concepts together resulting in impaired pelvic floor activation as the upper abdominals become overly dominant.

Getting fit, improving your physique and staying healthy are all sensible goals, but what the research is showing is that moderation and consistency is essential in achieving these over a long term, and reducing any potential damage as a result of over-straining. But ultimately, there is no one-size-fits-all approach, and getting qualified advice on how to achieve your goals will be of the greatest benefit.

Last updated Wednesday 16 September 2020

First published on Monday 22 June 2015