Background Physical activity could benefit drug users' physiological and mental health. Previous research has suggested that physical activity levels change when drug users enter prison.
Methods Twenty-five class A drug users who were new to prison answered physical activity and drug use cross-sectional questionnaires, took a submaximal fitness test and wore a pedometer for 1 week.
Results Participants' mean aerobic capacity was estimated as 49 mls O2/kg/min (±12 SD). Their mean self-reported walking distance outside of prison was 4.67 miles on an average day (±4.14 SD). Pedometer data suggest they walked a mean of 1.8 miles/day in prison.
Conclusion Many class A drug users entering prison had high levels of fitness and physical activity before admission, often gained from walking. Walking activity reduced when they entered prison, posing a challenge to maintaining healthy activity levels.
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Physical activity has been shown to be beneficial to health, disease prevention and treatment in a wide range of populations.1 Drug users outside prison have been shown to participate in a range of sports and exercise activities.2,–,7 A range of exercise-related psychological8,–,14 and physiological10 benefits have been identified among this population, but rarely adequately measured.
Previous qualitative work has suggested that activity patterns change as class A drug users enter prison.15 Understanding this change could facilitate the development of physical-activity interventions for drug-addicted individuals. Hence, we investigated the physical activity and fitness levels of 25 class A drug users entering prison. Class A drugs are those that attract the highest legal penalty for illicit use, including heroin and cocaine.16
Recruitment and ethical approval
Between January and June 2011, participants were recruited through computer-randomised selection from a list of known class A drug users recently admitted to an all-male category B prison in England. Participation was voluntary; the study complied with the Declaration of Helsinki and had ethical approval from the Research Ethics Committee for Wales (reference 10/MRE09/01).
A researcher completed the Paffenbarger Physical Activity Questionnaire (PPAQ), the International Physical Activity Questionnaire (IPAQ), the Maudsley Addiction Profile (MAP) and a demographic questionnaire with each participant. Some modifications were made to these instruments for the prison setting. The PPAQ asks participants to report the number of steps walked up and the distance walked for an average day, and to list any regular sports, leisure or recreational activities for an average week.17 The IPAQ asks about the time spent carrying out vigorous-intensity physical activity, carrying out moderate-intensity activity, walking and sitting in a week.18 ,19 The MAP asks about the frequency, quantity and route of administration of drugs taken.20
Fitness test and other measures
The Chester step test (CST) was administered to those who were identified as ready to exercise with the Physical Activity Readiness Questionnaire or by their general practitioner.21,–,24 The CST is a submaximal stepping test that uses a graphical procedure to estimate aerobic capacity in mls O2/kg/min.24 Participants stepped up and down a 20 cm step to an incrementally faster metronome beat while wearing a Polar FS1 heart rate monitor. Participants' height and weight were recorded.
All results were recorded on paper and then double entered into SPSS version 19.0 for analysis.
The sample was 25 male participants who all self-identified as class A drug users either presently or in the past. In the 30 days before entering prison, all smoked tobacco, 17 drank alcohol, 19 used heroin, 15 consumed cannabis, 14 smoked crack cocaine, 13 took illicit benzodiazepines and 2 did not use any illicit drugs.
In the 30 days prior to entry into prison, 15 participants were prescribed methadone, 6 received benzodiazepines and 2 buprenorphine. On entry to prison, 21 were prescribed methadone, 12 benzodiazepines, 1 buprenorphine and 1 buprenorphine with naloxone.
They had a mean age of 33 (±6 SD) with a range of 23–47 years. They spent a mean of 10 days (min 2, max 15) in prison before testing. Nineteen spent time in police cells before entering this prison; the mean was 2 days with the longest being 3 days. Twenty participants self-identified their ethnicity as white British, three as Pakistani, one as black and one as mixed race (white and Asian).
Physical activity before entering prison
The two measures of self-reported physical activity PPAQ and IPAQ showed moderately correlated results (p=0.006, R2 linear=0.294).28 The PPAQ showed a mean 5007 kcal/week (±3942 SD, n=24) and the IPAQ a mean of 6488 MET-min/week (±6606 SD), which suggests a mean of 926 MET-min/day. According to the IPAQ's categorical scoring routine, 15 participants had high levels of physical activity before entering prison, 6 had moderate levels and 4 had low levels.29
Only eight participants reported taking part in any regular sports or leisure activity in the PPAQ. Similarly, in the IPAQ, 9 participants reported any vigorous-intensity activity in the last week before entering prison, while 12 reported moderate activity, including 7 who reported both.
The PPAQ showed a mean walking distance of 4.67 miles on an average day (±4.14 SD, min 0, max 15, n=24) and the IPAQ showed a mean walking time of 1339 min/week (approximately 22 h/week, ±1699 SD, min 0, max 6300), which suggests a mean of just over 3 h of walking per day.
Fitness when entering prison
From the CST, a mean aerobic capacity of 49 mls O2/kg/min (±12 SD, min 33, max 80, n=19) was predicted. After controlling for age, gender and step height, eight participants' aerobic capacity was classed as excellent compared to the general population, seven classed as good, three as average, one below average and none as poor.22 Six did not take part in the CST due to concerns about their health.
The mean weight of participants was 70.04 kg (±8.40 SD, min 57.15 kg, max 88.90 kg, n=24), mean height was 1.75 m (±0.07 SD, min 1.6 m, max 1.88 m, n=25), which equates to a mean body mass index of 23 (±2.6 SD, min 18.6, max 29.0, n=23).
Activity within prison
Pedometer readings showed a mean of 25 468 steps over 7 days walked in prison (±13 888 SD, min 1249, max 61 561, n=22). This equates to mean of 3638 steps per day, and assuming that 2000 steps equate to 1 mile,30 participants' mean walking in prison was 1.8 miles/day.
Class A drug users engage in activities that suggest low regard for physical well-being, and induction into drug use has been linked to risk-taking attitudes.31 Counterintuitively, our sample proved to be relatively fit, with 15 participants being classified as having good or excellent aerobic capacity following performance in the CST.
Self-reports of activity prior to entering prison suggest that fitness levels were primarily influenced by participants' walking, rather than by sports. Only eight participants reported taking part in any regular sports or leisure activity in the community in the PPAQ. However, fitness can be achieved by brisk walking,32 and participants spent a mean of just over 3 h per day walking (IPAQ) a mean of 4.67 miles (PPAQ). This exceeded minimum activity levels generally recommended for a week on every average day.1
Once participants entered prison, pedometer-reported walking reduced to a mean of approximately 1.8 miles/day. While this measure was taken early on during the prison stay and offenders with long sentences might change habits, this result reflects a general trend towards less walking – and possibly physical activity – within prison than in the community. Outside prison, walking as a form of affordable transport is an important physical activity in the daily life of class A drug users, who often have limited economic resources.15
We acknowledge that the small sample size limits generalisability and that low fitness can bias against participation in tests. Furthermore, recall data for drug use and physical activity are limited in validity, as participants often struggle to remember accurately.33 There are inherent limits to the reliability of measurements and predictions.23 ,24 However, we used the most reliable and appropriate measures possible in this unique environment.
Despite its limitations, this study has shown that levels of fitness in class A drug users were surprisingly high, and one challenge to maintaining fitness is the reduction in walking as they enter prison. This is likely to be occasioned by prison restrictions on mobility. Structured aerobic exercise interventions might benefit this population's health in compensating for reduced walking activity.
The authors would like to thank Laura Sheard for assisting with their MREC application, their funder, prison staff and participants.
Funding Oxford Brookes University Research Fund (and Helen Dawes is funded by the Elizabeth Casson Trust).
Competing interests None.
Ethics approval Ethics Committee for Wales (reference 10/MRE09/01).
Provenance and peer review Not commissioned; externally peer reviewed.
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