Exercise—defined as any planned, structured, or repetitive physical activities, often with the goal of increased fitness [1
]—is increasingly understood as an important resource for people struggling with harmful substance use. Harmful substance use is indicated by damage to physical health, mental health, or social functioning due to drug or alcohol use, and the danger of repeated use (in addition to these harms) is the individual’s physiological adaptation to substances [2
]. A recent meta-analysis reported that participation in an exercise intervention significantly increased the abstinence rates of substance use disorder patients [3
]. Numerous reviews have proffered clinical and theoretical mechanisms for this efficacy, including less severe withdrawal symptoms during detoxification [3
], reduction in craving [4
], lessened co-morbid anxiety and depression [3
], improvement of positive affect and mood [5
], and reduction in stress reactivity [6
]—overall reducing the chance of relapse among people in treatment and afterwards. Exercise can also serve as an important alternative behavior, an activity that takes up the time and energy otherwise consumed by substance use [7
], and a majority of people with substance use disorders are interested in assistance beginning or maintaining an exercise regime [8
The Norwegian health authorities [9
] recommend exercise as an adjunct treatment for substance use disorders because, in addition to clinical benefits, it is cost-effective and accessible after the formal treatment system. Importantly, exercise reduces the risk of numerous preventable chronic diseases [10
], of which people with substance use disorders already experience earlier and with more fatal consequences [12
Despite this consensus, people with harmful substance use issues typically report far lower rates of exercise than the general population [8
]. This is true for out-of-treatment users, inpatients [16
], and outpatients [16
], with mixed evidence from inmates [18
]. Substance use disorders are the most common mental disorders among inmates, with pooled estimates of a 51% prevalence of drug use disorders worldwide, and a 24% prevalence of alcohol use disorder [20
]. The restricted prison environment and reduced access to illicit substances may spark a need to develop new coping mechanisms and stress management techniques [21
Prison can provide an ideal setting for exercise and other health behavior interventions, as the inmates’ exposure to interventions can be controlled [24
]. Many of the barriers to exercise identified by substance users, such as a lack of time, transportation, or finances [8
] can be easily removed in incarceration settings. Exercise interventions among inmates have increased fitness and functional cardiorespiratory capacity [27
], improved psychological well-being [21
], and reduced aggression [33
]. Only two of these studies reported on inmates with some sort of harmful substance use: 105 inmates with “substance abuse problems” pre-incarceration, no diagnosis reported, self-reported improved physical fitness and alleviated anxiety, stress, and depression [28
], and 19 inmates in methadone maintenance treatment improved strength and cardiorespiratory capacity [30
]. Few studies have examined inmates’ capacities to adopt exercise without interventions. Substance users in the UK reported reductions in physical activity during the first week of incarceration [19
], while cross-sectional studies from Italy and Nigeria found both positive and negative relationships, respectively, between exercise frequency and length of incarceration [34
In other naturalistic studies of incarceration settings, prisons are not realizing their health-promotion potential, as weight gain [36
] and unhealthy diets are commonly reported [18
]. Furthermore, smoking is more prevalent among inmates than the general populations in 35 of 36 countries [38
], which one study suggests may be because smoking is perceived as one of the few freedoms allotted to inmates [39
]. A limitation of these studies is that they do not tell us how diets and smoking behaviors changed during incarceration.
Data from the 1499 inmates participating in the Norwegian Offender Mental Health and Addiction (NorMA) study showed that 47% reported daily substance use in the six months prior to incarceration, an important indicator of potentially problematic substance use [40
]. Prisons may have different health effects for substance-using and non-using inmates. In one study, inmates who used drugs before incarceration were twice as likely to self-report better health after incarceration than inmates without pre-incarceration drug use. For alcohol users, the pattern was reversed: the majority reported worsened self-rated health after incarceration [18
Little research has been conducted that explores substance-using inmates’ changes in multiple health behaviors during incarceration, without interventions. It is vital to understand how the prison environment can support or hinder inmates’ health behaviors, and whether or not positive changes can be induced without the implementation of potentially costly interventions. This analysis therefore aims to answer the following questions:
What is the prevalence of exercise and nicotine use among inmates with and without harmful substance use?
How do exercise and nicotine use change over time?
Which variables, including individual and system-related, are associated with increased exercise frequency during incarceration?
Inmates with harmful substance use entered prison with higher rates of negative health behaviors than inmates without problematic use, including 81.3% who smoked cigarettes, 61.3% who were physically inactive, and 26.0% who used smokeless tobacco. However, inmates with harmful use also exhibited more behavioral changes during incarceration: they adopted exercise, ceased smoking, and adopted smokeless tobacco at higher rates during incarceration than the non-harmful group. The non-harmful group also adopted exercise and smokeless tobacco, but exhibited no changes in cigarette use during incarceration.
The significant positive change in exercise behavior among inmates with harmful substance use, both in the amount of inmates beginning to exercise and in frequency, suggests that exercise may be an important replacement behavior for substance use under incarceration. This replacement mechanism could be a de facto replacement, as inmates have reduced access to substances: 22.7% of this group reported substance use at least four times during incarceration, which is a clear decline from the 55.5% daily use reported pre-incarceration. Exercise likely also induces neurological adaptations in reward-, inhibition-, and stress-related systems that directly counter and compete with the effects of substances in these same systems [57
Pre-incarceration exercise was found to predict current exercise and this was expected, as exercise is a behavior in which within-person variation is decisive in predicting change. The low correlation of current mental distress to current exercise frequency is promising, as it suggests that mental health concerns need not be assumed prohibitive to inmate exercise. Muller and Clausen [59
] were similarly able to engage residential substance use disorder patients with the highest mental distress in a pilot group exercise program. Age negatively predicted exercise frequency for harmful substance users, but was unrelated to non-harmful users’ exercise. Manocci et al. [35
] also found exercise frequency in Italian prisons to be negatively related to age, and positively related to physical health-related quality of life and non-Italian nationality, with no relationship between exercise and amount of cigarettes or education level. Furthermore, sentence duration was not an important predictor of exercise frequency in our analysis, in line with Manocci et al.’s findings but not those of Olaitan et al. [34
] in Nigeria.
Previous longitudinal, population-based studies have found exercise uptake to result in improved self-rated health [60
], and exercise reductions in worsened self-rated health [61
]. Similarly, we found strong correlations of current exercise and current self-rated health among both inmate groups. As with non-exercisers, inmates with poor health could be targeted as having potentially more to gain. Exercise cannot change incarceration itself or elements such as overcrowding or a lack of healthcare, but it could change the experience of incarceration, such as by providing a sense of autonomy, a challenge to boredom, and a relief against stress, elements which have been identified as reasons for the poor health of inmates [62
]. Helping inmates exercise can also be seen as a way to equip them with an anti-depressive and stress-reducing tool that they can continue to use post-release [63
]. One-third of inmates in a previous American study experienced an increase in depression and stress after release, probably reflecting the environmental stressors of community living and the difficulties of post-release reintegration [65
]. Exercise could thus be a tool used not only during, but also after, incarceration.
It is important to emphasize that exercise should not be uncritically assumed a positive behavior. Exercise will necessarily increase the risk for exercise-related physical injuries, for example, and health screening may be necessary to identify prisoners with circulatory or heart problems who would benefit more from low-intensity or otherwise modified exercise [66
]. Meek and Lewis also speculate that some prisoners with low self-esteem, eating disorders, or body disorders may be more predisposed to anabolic steroid use if they begin exercising. Steroid use is associated with a range of adverse health consequences, including cardiovascular effects and mental health problems [67
], and lifetime anabolic steroid use is already found to be many times higher among prisoners [71
] than the general population [73
]. These individuals could greatly benefit from learning that the positive effects of exercise can be reached without steroids.
While many inmates were able to adopt exercise without structured interventions, nicotine use increased for the cohort as a whole. Inmates with harmful substance use reduced their rates of smoking during incarceration, yet smoking rates remained quite high, as has been reported internationally [38
]. Three-quarters of the harmful use group continued smoking when interviewed, as did half of the non-harmful substance use group, and both of the groups increased rates of smokeless tobacco use. This suggests that various types of nicotine use among inmates will not be reduced in the absence of cessation programs (or among harmful substance users, in the absence of the ability to exercise). It is also likely that some inmates are substituting smokeless tobacco for cigarettes, or using smokeless tobacco to reduce their cigarette use. A recent meta-analysis of 85 articles concluded that complete smoking bans can successfully reduce smoking rates during incarceration, but only smoking cessation programs have effects that last post-incarceration [38
]. Makris et al. [74
] reported that simply the establishment of a cessation program may provide motivation to quit. At the same time, inmates are able to understand the health risks of smoking and still choose to smoke: van den Berg et al. [39
] found that in a prison with a complete smoking ban, prisoners who perceived smoking as an expression of freedom were more likely to plan to resume smoking upon release compared to those who without such an association. Yet after release, all prisoners reduced their average amount of cigarettes by half—again supporting the establishment of cessation programs, rather than bans, and highlighting the need to understand why inmates engage in various health behaviors.
4.1. Limitations and Strengths
Some of the limitations of this analysis arise from the data collected in the questionnaire, most obviously that causation cannot be concluded from cross-sectional data. The cigarette and smokeless tobacco variables were dichotomous, therefore we were not able to differentiate between casual smokers or smokeless tobacco users from daily users. Similarly, lacking a standard definition of exercise, participants’ reports may not represent recommended amounts of exercise. Somatic health problems were outside the scope of the NorMA study, and while the self-rated health question was likely a strong proxy for health limitations, it was not possible to identify whether certain problems—for example, cardiovascular disease or obesity—particularly inhibited the adoption of exercise.
The intention of this study was to collect participant-reported information. It is difficult to predict whether a population will over- or under-report current exercise, according to a meta-analysis [75
], but self-reports of historical exercise, from 24 h to 10 years earlier, have been reported to be valid in numerous countries, although currently overweight individuals may over-report historical exercise [76
]. If certain groups over-reported pre-incarceration exercise, then exercise may have been adopted during incarceration to an even greater extent than reported here. In general, participants in the NorMA study were representative of the national prison population in terms of gender, citizenship, and country of birth [48
4.2. Clinical Implications
An array of earlier literature has revealed the large health burden of substance users, such as early onset cardiovascular disease and hypertension [79
]. The negative health behaviors documented in this paper can, if modified, reduce many future health risks. Our findings strengthen the argument for prisons to enable exercise as a public health intervention, with demonstrated benefits including improved physical and mental health [21
], and reduced aggression [33
], and inmate-identified benefits in one review including improved self-esteem, confidence, and the construction of a new identity [81
]. Incarceration should be seen as an opportunity for positive behavior change, and it is encouraging that inmates with pre-incarceration harmful substance use seem particularly able to adopt such changes. Given that inmates’ need for substance treatment far outpaces access to treatment, actively facilitating exercise among inmates even without instituting formal interventions—e.g., by increasing the amount of time available for exercise, preventing inmate exclusion from facilities by other inmates, or resisting the revocation of exercise privileges as a punishment measure—could be a cost-effective method to provide substance-using inmates with a healthy alternative to substances. It may be particularly important to facilitate exercise among non-exercisers entering prison, as this group may not have the health knowledge or self-efficacy to begin independently, or may have health needs that require tailored or facilitative programs [66
]. Prison staff should be aware of lifetime steroid use and current steroid risk, such as harmful substance use and being underweight [82
], and future qualitative research among inmates should aim to understand the meanings of steroid use, exercise, and other health behaviors explored in this article.