Despite the well-known impact of PA on mental health and wellbeing [19, 20], little is currently known about PA among asylum seekers, a population which is known to display high prevalence of trauma-exposure and mental ill health including PTSD [3, 4, 8]. The results of this study revealed several noteworthy findings. First, almost 50% of the study population did not meet the international recommendations for a sufficient level of health-promoting PA, and were classified as either inactive or insufficiently engaged in PA. Second, both inactive and insufficient PA were found to be significantly associated with more PTSD symptom severity compared to those who met the recommendations for a sufficient level of PA. Finally, this association persisted and additionally accounted for a marked proportion of the variance in PTSD symptom severity even when analyses were controlled for sex, age, and exposure to torture.
A proportion corresponding to almost half of the cohort of this study not meeting the recommendations of sufficient PA appears as noticeably high compared to both international and national estimates of insufficient PA (also including those being completely inactive). According to the WHO Global Health Observatory data of 2016 [39], the worldwide estimates of insufficient PA were in average 27.5%, whereas the same estimate for the general population in Sweden was 23.1%. In general, the estimates of insufficient PA is higher in high-income countries than in low-income countries, with in average 36.8% of the populations in high-income countries being insufficiently active compared to 16.2% in low-income countries [40]. Most asylum seekers originate from low- or middle-income countries [1], indicating that the high prevalence of insufficient PA in our study may possibly be viewed as attributed to overall conditions associated with the process of forced migration, trauma exposure, and being an asylum seeker. More specifically, previous research has established that people with severe mental ill health are less likely to engage in PA and are more sedentary in comparison to the general population [41, 42]. Given the high rates of trauma-related ill health [3, 4], disrupted daily life and work routines from home country [4, 6], as well as other barriers to engage in PA that are likely to be faced by forced migrant populations, such as economic strain, access to facilities, and lack of motivation when living under extreme stress and uncertainty about the future [25, 43, 44], it may be concluded that asylum seekers are more readily susceptible to insufficient PA. An increased focus on assessment and promotion of PA is thereby justified. Moreover, recent research [45] has demonstrated important health benefits even at much lower doses than advocated by generic PA guidelines, especially when moving from completely inactive to some activity [46], suggesting that the promotion of any level of PA may be advisable among those currently inactive or at the lower end of the insufficient PA spectrum.
Our findings of a dose-response pattern of differences in PTSD symptom severity relating to level of PA, support that there is an association between mental ill health and insufficient PA. Previous research has found substantial reductions in PA and active leisure time habits after the onset of PTSD [18], which may indicate a direction of mental illness as a contributing factor or an antecedent to insufficient PA. However, research has also shown that low levels of PA can act as a major risk factor for the development and maintenance of mental ill health, including PTSD and comorbidity [26, 42, 47, 48]. For example, LeardMann et al [26] found that higher levels of pre-trauma PA, among U.S service members, was associated with decreased odds of developing PTSD symptoms. It is thus possible that a similar pattern is reflected in the findings of the present study. In that case, low levels of PA may adversely influence mental health and PTSD symptom severity among asylum seekers who have been exposed to severe traumatic experiences. Taken together, the associations indicated by the differences in regard to insufficient PA and PTSD symptom severity may as well be bi-directional in the same line as delineated by the Mutual Maintenance Model [49]. This model proposes that PTSD symptoms and chronic pain are mutually maintaining conditions, and that there may be several pathways by which both conditions can lead to an escalation of symptoms and distress following trauma. Concerning PA, this would imply that PTSD symptom severity may partially influence level of PA while also simultaneously be adversely influenced by insufficient PA. Promotion of PA may, in this case, be seen as both a preventive measure and an attempt to alleviate current symptom severity. Further, our findings of differences in PTSD symptom severity also between those being completely inactive compared to those with insufficient PA, might indicate that even a low dose of PA can yield important health benefits [45, 46].
The possibility that levels of PA may, to some extent, influence PTSD symptom severity, was furthermore supported by the results of the analyses in which exposure to torture, as a main predictor of PTSD [9, 10], was controlled for.
While exposure to torture displayed an expected high explanatory function for PTSD symptom severity, insufficient PA provided additional high explanation for the variation in PTSD symptom severity beyond exposure to torture.
Although those not exposed to torture may still have experienced other severe trauma, the overall pattern indicates that insufficient PA may be a risk factor, mediator, or aggravator of PTSD symptom severity for those inflicted by severe trauma. However, these results need to be replicated by means of longitudinal studies in order to clarify causality and to assess each factor’s contribution to symptom severity. In addition, there may be other symptoms or conditions, such as chronic pain [50], poor social support [51], and low self-efficacy [52], that may influence both PTSD symptoms and level of PA, which are warranted further investigation in future studies.
Our results regarding different clusters of PTSD symptoms, i.e., arousal/intrusion and avoidance/numbing, showed similar patterns of differences and associations with insufficient PA as that of the overall PTSD symptom severity. These results deviate to some extent from the inferences of a systematic review by Vancampfort et al [25], suggesting that the only correlate consistently associated with low PA in people with PTSD is symptoms of hyperarousal. Our findings, however, could also be viewed in light of other studies that have suggested that physical and social inactivity may also comprise a part of avoidance symptoms and negative cognitions and mood, e.g., avoidance of trauma-related stimuli, feeling isolated, and decreased interest in activities [18, 28, 47, 53]. Moreover, these symptom clusters may as well be closely interrelated in regard to their influence on PA, such as avoiding activities or exercise due to lack of energy or motivation, fear of bodily arousal (e.g., muscle tension, increased heart rate, shortness of breath), or fear of intrusive memories that may be triggered by physical strain. In addition, the role of social, cultural, environmental, and policy factors on PA participation among people with PTSD in general [25], and for forced migrant populations in particular [44, 54], is unknown and need to be addressed by future research.
Strengths and limitations
To our knowledge, this is the first assessment of prevalence of PA and its association to PTSD in a cohort of asylum seekers in a high-income country setting. The use of a cross-culturally validated measure for PTSD and well-established measures of PA, availability of information on the sample population, and an adequate sample size that provided necessary statistical power for assessment of associations and the possibility to establish the actual response rates compared to the total eligible study population, are the strengths of the study. It is, however, a limitation to the study that the proportion of those choosing to participate was just slightly more than one fourth of the total population. Still, such response rate is common in surveys conducted among hard-to-reach populations in general, and in forced migrant populations in particular. Thus, obtaining data on PA and severity of PTSD symptoms among 26.8% of all eligible individuals could be considered acceptable in this context. However, the generalizability of the estimates of prevalence of PA to other settings and other forced migrant groups may be limited.
Further, it has been reported that mental health problems may be more common among non-respondents [55, 56], which may also bias the results concerning the PA prevalence estimates. However, since the estimates of associations, compared to that of population characteristics, are less prone to bias caused by non-response [56, 57], the results concerning associations of PA with PTSD symptom severity may be viewed as less influenced by this condition.
Moreover, given the cross-sectional design and the observational data in the study, causal directions in links between PTSD symptomology and PA cannot be established by means of the obtained empirical data. Bearing this in mind, our ambition has not been to assess the casualty of these associations and we have opted to discuss the possible directions of these associations against the background of the existing literature. Nevertheless, the results provide some evidence for the potential importance of PA in regard to PTSD symptomatology and mental health of asylum seekers. Our results also encourage more in-depth examination of PA and mental health among forced migrants and provide an interesting starting point for future studies using prospective and longitudinal designs.