Ask most people to describe a healthy lifestyle and they will state similar actions: eat fruit and vegetables, drink plenty of water and exercise. Over the past few decades, the importance of exercise has been acknowledged by governments all over the world; with health campaigns actively encouraging individuals to walk 10,000 steps a day, get their heart rate up for 150 minutes a week and build muscle strength by weight training or carrying heavy shopping (1). Additionally, scientific and medical research on the health benefits of exercise all point towards the same conclusions – exercise increases longevity and reduces the occurrence of chronic illness. Maybe even more effective, many celebrities who influence masses of people on a daily basis are choosing the gym over gin. The ‘it’ girl of the noughties falling out of a club at 2am has been replaced with the ‘fit’ girl of 2019 up at 5am ready to workout. Thanks to social media, fit is the new fashion and many users find themselves skipping the late-night benders to gain themselves a gymshark-worthy physique. Exercise is on the up and the desire to become fit is stronger than ever before.
A combination of words you rarely hear paired together are ‘exercise’ and ‘unhealthy’. However, a mental health problem which is uncommonly acknowledged is exercise addiction. Exercise evokes feelings of pleasure and control; the ultimate combination for developing an all-consuming obsession. Like addictions to less healthy alternatives such as drugs and alcohol, your brain starts to crave the neurochemical stimulation associated with intense exercise and the physical results exercise produces. These behaviours convert a once beneficial habit into a harmful routine which can lead to a decline in physical and mental health. The pressures on young people to have an athletic, Instagram-esq image can normalise excessive exercise but the damage of over doing it extends much further than DOMs. So, how does your brain transform a ‘healthy’ lifestyle change into an unhealthy addiction?
I FEEL GOOD! The Chemicals of Exercise
After an exercise session, once you have drunk a litre of water and caught your breath, you normally feel really good. You have a sense of achievement for getting yourself through a tough workout and generally, feel happier and less stressed than you did before the sweat-a-thon. These sensations are generated by the up-regulation of specific chemicals in your brain; stimulating neurons in certain brain regions to evoke those positive feels. Some of these chemicals include:
1. Endorphins: a group of neuropeptides which stimulate opioid receptors. These are the same receptors that are stimulated by some recreational drugs that generate a ‘high’ sensation and prescribed pain-relief medications which promote analgesia. Exercise induces the release of endogenous (‘home-grown’) opioids in the brain which stimulate frontal cortex regions associated with reward and limbic areas responsible for emotional processing. A recent study has described that more intense exercise decreases the selectivity of opioid receptor binding (2), meaning the increased levels of opioids in the brain released due to exercise can stimulate more neurons in frontolimbic areas and boost pleasure sensations.
2. Dopamine: a monoaminergic neurotransmitter which is released before, during and after goal-directed behaviour. Dopamine stimulates neurons in ‘reward’ brain regions in the prefrontal cortex via its release from the ventral tegmental area. Therefore, this neurotransmitter reinforces goal-directed activities by making you ‘feel good’. Exercise increases dopamine levels (3) making you want to come back for more.
3. Serotonin: Another monoamine neurotransmitter which, in the brain, is responsible for regulating mood. Serotonin acts on 5-HT receptors in the forebrain and hippocampus to alleviate anxiety-like behaviours. Experimental studies in animals have demonstrated increased motor activity stimulates the firing of serotonergic neurons (5), triggering its release in the brain. Therefore, exercise lets you leave some of your worries behind
Together, these chemicals drive a happy, stress-free state of mind so post-workout feels are some of the best you can get.
I Just Can’t Get Enough: How Exercise Becomes Addictive
So, we now know how exercise makes us feel good and many people use exercise as a means of stress-relieve and mood-boosting. But too much exercise can create an addiction to these sensations. Addictions manifest due to over-stimulation of reward centres in the brain, resulting in behaviours such as cravings, loss of control and continuing commitment to the source of addiction, despite whether it is healthy or not. Recreational and therapeutic opioids have been extensively studied in animal models to reveal how the brain develops an addiction (6). In summary, taking such drugs makes you feel good as they directly bind to opioid receptors; generating feelings of analgesia while promoting dopamine release; leading to reward sensations and positive-reinforcement of their administration. Withdrawal from such drugs leaves reward regions with lower levels of dopamine and serotonin that the brain is used to, contributing to a negative emotional state and needing larger, more frequent hits to generate the same euphoric sensations.
Although exercise is good for your physical and mental health, the mechanisms of actions within the brain are not completely dissimilar from taking drugs. Each hour-long cardio class, run or weight training session stimulates the release of endorphins due to the ‘stress’ and pain your body has been under. Endorphins bind to opioid receptors, leading to dopamine release to reinforce goal-directed behaviour. This occurs alongside serotonin release which boosts mood, overall leaving you happy and motivated. Once a class is finished and you feel good, you know you can feel the same if you take another class tomorrow. Soon this could turn into two classes per day. Next, back to back classes. Why not throw in a run home? Getting to the gym before class to do 30 minutes on the bike to get even more of a high? All of a sudden, you realise you can’t sleep unless you have run at least 10K that day. This is when exercising gets out of control and can cause huge problems for your health.
In the brain, the chemicals released by exercise as mentioned can above promote addiction through pleasure, motivation and learning. However, not all exercisers develop addictions. It is thought the addictive element to an exercise routine is mainly driven by secondary motives such as trying to attain a certain physique, hit a personal best or to fill a void. If your motivation to exercise revolves around secondary factors, each workout is viewed as goal-directed behaviour. The large hits of dopamine you get post-workout enhances the desire you feel towards these goals due to increased activation of reward-learning regions. Dopamine also plays a role in memory formation so can transform ‘good’ feelings of exercise-associated goal achievements to a learnt behaviour; leading you not just to like exercise but want exercise. This ‘want’ can also be triggered in individuals who have suffered from previous addictions in the past, filling the space of a frowned-upon habit with one many wouldn’t bat an eye at. A study showed around 15% of exercise addicts had addictions to smoking or alcohol (7), and individuals with eating disorders are primed to substitute their calorie-deficit through eating with increased calorie burning through exercise (8). Therefore, it is thought exercise addiction can manifest in certain personality types over others.
Fighting Talk: How to Recognise and Combat Exercise Addiction
Differentiating a healthy and unhealthy relationship with exercise can be difficult for the person in the routine. However, if you are sacrificing social relationships for exercise, working out when injured or feeling completely lousy when you miss a class, your brain may have transitioned your well-intentioned actions into something more sinister. Questions to ask yourself about your exercise routine to check it is still a healthy habit include:
Am I still in control of this routine or is the routine controlling me?
If you are continuing to exercise through injury or other inappropriate times in your life, your routine may have more of a hold over you than you appreciate.
Am I going too hard and do I need to exercise more intensely to feel good?
If you set out to work out for an hour but end up going for two or three regularly can be a sign you are having trouble with exercise. If you feel like you need these extra-long sessions to feel ‘good’, this could be revealing your tolerance to exercise; a common effect of addiction.
Do I constantly think about working out and feel anxious if I am not exercising?
Take a minute to reflect on your thoughts. How often do you think about exercise? Do you spend a lot of time planning and thinking about workouts? And do you feel irritable and anxious when you are out of the gym for an extended period of time? This combination of emotions could be reflecting the craving and withdrawal aspects of addictive behaviour.
If you recognise these symptoms, it is important to consult with a medical professional and voice your concerns. There is an ‘exercise dependence scale’ exam which can indicate if your emotional and psychological relationship with exercise is healthy. No pharmacological interventions exist for exercise addiction but speaking about your underlying motivations for exercising may reveal other phycological symptoms which may be able to be treated. In general, counselling and therapy can be the most useful tool for gaining back control over your exercise routine.
Exercise addiction is still very challenging to pinpoint as we are all actively encouraged to get active. But reflecting on your own routine is important for both your physical and mental health. If you feel like exercise is controlling you, step back and speak to others. No six-pack is worth sacrificing yourself for.
Materials used for this post
1. Health matters: getting every adult active every day
2. Opioid Release after High-Intensity Interval Training in Healthy Human Subjects
3. Regulation of brain function by exercise
4. How to increase serotonin in the human brain without drugs
5. Activity of Serotonergic Neurons in Behaving Animals
6. The Neurobiology of Addiction: Where We Have Been and Where We Are Going
7. Prevalence of the Addictions: A Problem of the Majority or the Minority?
8. Compulsive exercise and eating disorders
9. Exercise Addiction: Literature Review of Behavioural changes
10. Exercise Addiction: Signs and Treatments