The current UK guidelines suggest that adults should accumulate 150 minutes of moderate intensity physical activity across the week (National Institute for Health and Care Excellence [NICE}, 2012). Despite evidence of the positive health benefits, a paradox exists where exercise may produce negative effects such as depression and anxiety (Szabo, 1998). A dependence on exercise is often cited as a symptom of an underlying eating disorder, such as anorexia nervosa (Yates, Leehey & Shisslak, 1983) conditions all of which are recognised by the DSM-V. This has raised a debate about whether the dependence on exercise can occur without another underlying psychological disorder being present.
Positive and Negative Dependence
Research examining the negative consequences of physical activity has mainly focused on exercise dependence (Hausenblas & Symons Downs, 2002a). The term was first used to describe over-commitment to exercise in middle-aged men who continued to exercise despite suffering injuries from involvement (Little, 1969). Baekeland (1970) suggested that exercise dependence can have either a positive or negative nature. It was first described as a ‘positive’ addiction because it was thought to produce both psychological and physiological benefits such as feelings of euphoria, increased mental strength and could lead to self-transcendence (Glasser, 1976). By contrast, a negative addiction reflects the withdrawal symptoms of agitation, anxiety and depression (Szabo, 1998) experienced by exercisers when they are denied access to exercise opportunities (Allegre, Souville, Therme & Griffiths, 2006).
Negative dependence on exercise was researched by Morgan (1979). Dependence was present if the individual required daily exercise in order to exist or cope and if deprived of exercise, the individual would manifest withdrawal symptoms (such as depression, anxiety or irritability) Morgan argued that these withdrawal symptoms were no different to the chemical-dependence process seen for other drug and substance abuses. Symptoms of negative dependence include: an increased in dose dependence with exercise, an increase in withdrawal symptoms (including depression, anxiety, irritability, muscle tension and decreased appetite) and putting exercise as a high priority (Morgan, 1979). In 1985, Dishman coined the term obligatory exercise which described people who have an unhealthy need to exercise. This included the three symptoms of negative dependence described by Morgan.
Classification in the ICD and DSM
Goodman (1998) argues that addictions are distinguished from impulsive and compulsive behaviour by their dual capacity to reduce negative affect and create a positive mood. The ICD-10 doesn’t classify exercise dependence as an individual disorder, but rather as: symptoms of compulsion (a desire/compulsion to take the substance); impaired control (difficulty in controlling behaviour regarding the substance); withdrawal (occurring once the substance has been withdrawn); relief use (substance is used to avoid or relieve symptoms of withdrawal); tolerance (increased amount of substance required to achieve the desired effect) and salience (increase in the amount of time taking, obtaining and recovering from the effects of the substance).
By contrast, within the DSM-V, exercise dependence is not classified as a standalone disorder but rather as a symptom of another such as anorexia nervosa (APA, 2013). Despite this, Hausenblas and Symons Down (2002b) used the DSM-IV criteria for substance abuse to demonstrate the plausibility of individuals fulfilling the criteria of this disorder. These include: tolerance (need for an increase in exercise); withdrawal (anxiety or fatigue); intention effect (more exercise is undertaken then was intended); lack of control (a desire or unsuccessful effort to cut down or control exercise); time (spent on activities needed to obtain exercise); reduction of other activities (such as social or occupational) and continuance (exercise is continued despite the knowledge of an injury or psychological problem).
Currently, within the sport and exercise psychology literature, the Hausenblas and Symons Down (2002a) definition is utilised. However, the debate still continues as to whether it can ever be viewed as a primary or secondary phenomena. Indeed, revisions of the DSM made to version 5 saw the introduction of gambling disorder which reflects the evidence that some behaviour activated the brain reward system with effects similar to those of drug abuse (APA, 2013). This lack of recognition of exercise as a form of substance abuse further illustrates the divergent opinions on the origins of dependence on exercise.
Primary and Secondary Dependence
As described above, exercise dependence can be split into two elements namely: primary dependence and secondary dependence. Primacy dependence is defined as meeting the criteria for exercise dependence and continually exercising solely for the psychological gratification resulting from the exercise behaviour its self (Bamber, Cockerill & Carroll, 2003). Secondary exercise dependence is defined as meeting the criteria for exercise dependence but using excessive exercise to accomplish some other end (e.g. weight loss) that is related to another disorder, such as an eating disorder (Bamber et al., 2003). Secondary exercise dependence is secondary to a more severe psychopathy and presents more severe consequences such as earlier eating disorder onset, lower BMI, more eating disorder symptoms and higher anxiety (Dalle, Grave, Calugi, & Marchesini, 2008).
Who is susceptible?
There has been research carried out to try and identify who (if anyone) is susceptible to developing exercise dependence. Research suggests that the number of people suffering from exercise dependence ranges from 2-3% (Symos Down, Hausenblas & Nigg, 2004; Griffiths, Szabo & Terry, 2005) to 20-30% (Zmijewski & Howard, 2003; Anderson, Basson & Geils, 1997). Research also suggests that between 15-20% of people with exercise dependence are also addicted to nicotine, alcohol or drugs (Aidman & Wollard, 2003) and it is also common within individuals who are addicted to sex and have buying addiction (Lejoyeux, Avril, Richoux, Embouazza & Nivoli, 2008; Carnes, Murray & Charpentier, 2005). Endurance sports such as running, swimming and triathlons are believed to attract or develop people with an addiction to exercise (Chapman & DeCastro, 1990; Kerr, 1997; Pierce, McGowan & Lynn, 1993; Veale, 1985).
Exercise Dependence and Eating Disorders
It has been suggested that 39-48% of people who suffer from an eating disorder also suffer from exercise dependence (Hausenblas & Downs, 2002a; Klein, Bennett, Schebendach, Foltin, Devlin & Walsh, 2004; Bamber, Cockerill, Rogers & Carroll, 2000). As discussed earlier, this idea of exercise dependence in line with an underlying psychological disorder is referred to as secondary dependence. There is strong empirical evidence that links eating disorders to secondary exercise dependence (Blaydon & Lindner, 2002). With this in mind, Bamber, Cockerill and Carroll (2000) argue that in the absence of an eating disorder, those who identify as exercise dependent do not exhibit the level of psychological distress that warrant primary exercise dependence as a widespread pathology. Eating disorders serve as an ineffective coping strategy to cope with emotional regulation, with exercise also serving as a similar regulatory function (Lawson, Baron-Cohen, & Wheelwright, 2004).
The characteristics of exercise dependence are common among eating disorder patients (Touyz, Beumont, Hook, 1987). 28% of eating disorder patients described themselves as compulsive exercisers (Brewerton, Stellefson, Hibbs, & Hodges, & Cochrane 1995) while another study found that 93% of eating disorder patients felt their need to be active was out of control (Davis, Kennedy, Ralevski, & Dionne 1994). Bamber et al, (2000) state that if exercise dependence is pathological, sufferers should display clear evidence of psychological issues, at a similar level for other behavioural pathologies. In a study for pathological gamblers, 60% had a lifetime mood disorder, 40% a lifetime anxiety disorder and 87% a personality disorder (Black & Moyer, 1998). Similarly, 60% of heroin addicts have been found to have an anxiety disorder and 41% have a depressive illness (Darke & Ross, 1997). There is little information on psychological disturbances and distress as general characteristics of exercise dependence (Bamber et al., 2000) suggesting that exercise dependence is a secondary disorder to another disorder, such as an eating disorder.
Within the exercise dependence and eating disorder literature, the primary focus is with exercise dependence and anorexia nervosa (Veale, 1987). There is a strong similarity between obligatory runners and anorexic patients (Yates et al., 1983). Yates et al, (1983) argued that male obligatory runners resembled anorexia nervosa patients on personality traits such as introversion, inhibition of anger, high expectations, depression and excessive use of denial and as such they could be viewed as ‘sister activities.’ Exercise behaviour is also reinforcing to individuals who suffer with anorexia nervosa (Klein et al., 2004).
There is also evidence to suggest that exercise dependence is linked to muscle dysmorphic disorder in experienced bodybuilders and strength athletes (Hurst, Hale, Smith & Collins, 2000). Muscle dysmorphia is a condition that can be characterised by individuals having a distorted body image including gaining muscle size and definition and a fear of being perceived as weak or thin (Hurst et al., 2000). An exploratory study predicted that some individuals start bodybuilding because they suffer from poor self-esteem and become dependent on the training to feel good about their body (Smith, Hale & Collins, 1998). Although, as this was only an exploration, more research would need to be conducted before this relationship can really be determined.
It is clear that exercise dependence does in some form exist. However, in order for those suffering to get access to the treatment they need, than it should be included as a primary disorder and not just treated alongside a secondary eating disorder. Although more research is being done into the area, better methods of testing should also be developed before this area is fully understood.