There are many physical and psychological benefits of exercise, so it might seem paradoxical that there is also a risk that, at really high levels, excessive exercise may produce negative effects, including an unhealthy addiction to it.
What is Exercise Dependence?
A psychologist called William Glaser was the first to differentiate between a negative addiction and what he called a “positive addiction” to exercise.
Positive addiction is characterised by an individual’s love of an activity which has a positive impact on their physical and psychological wellbeing. The “positively addicted” individual is able to control their exercise participation and schedule it around other important aspects of their life.
In contrast, Glaser described a negative addiction as a compulsive need to exercise that takes priority over an individual’s health, relationships and other interests. If they miss a workout, a negatively addicted exerciser will experience unpleasant emotions, such as depression and guilt, as well as physical symptoms like insomnia.
Since Glaser’s first insights into exercise addiction were published in 1976, several terms have been used to describe the phenomenon, including exercise dependence or obligatory exercise.
Broadly speaking, exercise dependence occurs when an individual performs any type of physical activity at such high frequencies or durations that it becomes difficult for them to stop or reduce the amount of time they spend exercising, even if they are injured or have other commitments. When so much time is devoted to exercise at the expense of other areas of life like work or relationships, the behaviour becomes abnormal or dysfunctional .
Primary and Secondary Exercise Dependence
In primary exercise dependence, an individual is addicted to exercise for reasons associated with simply doing the activity. For instance the compulsive runner for whom running has become an end in itself rather than a means to an end (such as training for a marathon or to get fit) 
In secondary exercise dependence, the key motivation is to control and manipulate body composition. The problem is typically associated with individuals who have a fear of becoming overweight and who do excessive amounts of cardiovascular activities to burn calories. But exercisers who want to increase the size of their physique or have a fear of losing muscle might also be at risk for developing a dependence on their workouts . In secondary dependence, an eating disorder or steroid abuse is likely to be present too.
Am I Addicted to Exercise?
Just because you work out a lot and are strongly committed to keeping in shape, doesn’t necessarily mean that you are, or are at risk of becoming, exercise dependent. In fact, the prevalence of true exercise dependence is relatively low within the general population.
A psychologist called Veale  has proposed a set of clinical standards for diagnosing the disorder, which are based on similar criteria for substance dependence. Drawing upon Veale’s criteria, there are some key differences between those who are strongly committed to exercise, and those who are dependent on it .
Ask yourself: Do I get irritable, moody or angry when I miss my workout?
Ask yourself: Do I exercise against medical advice or when I am injured? Have I already suspected that I exercise more than is good for me, but not been able to stop?
Ask yourself: Am I doing more exercise this year than I did last year just to feel ok?
Ask yourself: Have I ever considered that I am risking my job, relationship or health because of my exercise routine? Is exercise dominating my life so much that when I am not doing it, I am thinking about it? Am I having more arguments about the time or money I spend on exercising?
How much exercise should I be doing?
Healthy levels of exercise have an anabolic (tissue-building) effect on the body, but excessive exercise, whether it is a conscious decision or a habit you are finding hard to stop, can have a catabolic (tissue-destroying) effect on the system. The amount of exercise and fitness training you can healthily sustain will depend upon your goals, fitness levels and the time you can devote to training. Speaking with a qualified personal trainer will help you plan a programme that will not only challenge you but also includes adequate recovery intervals.
Recovery time is an important aspect of physical training and without it you are likely to eventually experience physical symptoms, such as muscle or joint damage, prolonged fatigue, and be more prone to infections. Don’t ignore physical symptoms just because you want to keep exercising: consult a physiotherapist, sport injury specialist or your GP.
If you are keen to continue exercising when you are rehabilitating from an injury, a qualified strength and conditioning coach can help you structure a routine that will allow you to repair the current damage whilst continuing with appropriate levels of physical activity.
What to do if you are concerned that you or someone you know is exercise dependent
The research does demonstrate that it is possible, although relatively rare, for some people to become dependent on exercise in ways that have a negative impact on their wellbeing. The problem is starting to receive more attention, helping psychologists understand more about how exercise dependence might develop, how to identify it, and prevention or treatment options.
If you are concerned that your exercise routine is having a negative impact on your life and preventing you from meeting other commitments, if you are experiencing feelings such as anxiety or depression when you are unable to exercise, or if other people have expressed concern that you are losing too much weight through exercise, your should seek the advice of a qualified psychologist.
Speaking with a psychologist can help you understand the extent to which exercise might be controlling your life rather than being a source of wellbeing, and explore the underlying reasons why you are exercising at such high levels. You can find a qualified psychologist at www.bps.org.uk.
About the Author
Helen O’Connor is a sport and exercise psychologist, in training with the British Psychological Society. She established her psychology consultancy in 2009 and works individually and in groups with adults and teenagers who are looking for support to make healthy lifestyle changes, such as increased physical activity.