The sudden outbreak of the coronavirus disease (COVID-19) pandemic in 2019 triggered a global mental health crisis. Internationally, the incidence of COVID-19 was related to increased depression, anxiety, excessive stress, drug abuse, and increased suicidal ideation among the general population (Czeisler et al., 2020). Moreover, the COVID-19 outbreak exerted a serious impact on life, work, and studies, which led to several negative psychological reactions (Shi et al., 2020). Specifically, the high contagiousness of COVID-19 caused widespread negative emotions, such as anxiety, helplessness, and panic (Bo et al., 2020; El-Hage et al., 2020). One of the typically negative psychological outcomes of the epidemic was post-traumatic stress disorder (PTSD) (Fekih-Romdhane et al., 2020; Liu et al., 2020). For example, the author in (Xiong et al., 2020) analyzed the literature on PTSD in the context of the new crown epidemic and found that the incidence of PTSD ranged from 7 to 53.8% (Xiong et al., 2020). Therefore, exploring the effect of mind–body exercises on the relief of PTSD symptoms despite the continued global spread of COVID-19 can not only provide effective exercise prescriptions for patients with PTSD but also alleviate anxiety and panic as a result of the epidemic. Moreover, it can even prevent the occurrence of PTSD during the COVID-19 epidemic.

Events that lead to PTSD symptoms can also occur indirectly, such as when a person hears about the details or scenes of the death or serious injury of a loved one or a friend (Forbes et al., 2007). PTSD is typically caused by extensive traumatic experiences and is, therefore, common among survivors of war or major natural disasters, people recovering from major epidemics, victims of violence, and veterans. Surveys demonstrated that the prevalence of PTSD in the general population ranges from ~5 to 10% (Forbes et al., 2007). A census in the United States illustrated that more than half of the population (60.7% of men and 51.2% of women) reported experiencing traumatic events (i.e., flood, fire, natural disaster, life-threatening accidents, rape or sexual assault, witnessing a death, or severe injury). Among these people, 7.8% suffer from PTSD throughout their lives, whereas women are twice as likely to suffer from PTSD symptoms than men (Kessler et al., 2005).

Studies have demonstrated that the effects of PTSD are multifaceted. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a diagnosis of PTSD is composed of four major symptom clusters, namely, negative cognition and emotion; reminders to avoid events; excessive arousal; and intense revisiting of traumatic events through destructive memories and nightmares (Hegberg et al., 2019). In addition to the characteristic symptoms of PTSD, changes in brain structure that lead to functional changes (Hayes et al., 2012a; Miller et al., 2017) and cognitive impairment (Hayes et al., 2012b; Woon et al., 2017) are also well-documented. People with PTSD may suffer from severe issues with social survival and interpersonal communication due to the characteristics of the diseases, such as long-term invasiveness, avoidance, and excessive arousal, which results in impaired quality of life (Schnurr et al., 2006). In addition, patients with PTSD tend to exhibit activities in the higher sympathetic nerve and lower parasympathetic nerve (Fonkoue et al., 2018). Compared with healthy people, patients with PTSP display symptoms of low heart rate variability (Streeter et al., 2012). Although psychological interventions and traditional medication were proven effective in treating symptoms associated with PTSD (Cukor et al., 2009; Lancaster et al., 2016), many problems emerged regarding the side effects and therapeutic effects of drugs. Moreover, patients with PTSD typically report several obstacles, such as treatment cost, motivation, stigma, and access to care (Sayer et al., 2009; Dickstein et al., 2010). Although exercises present hindrances and drawbacks, such as limited motivation, self-efficacy, or exercise time, they are widely available, low-cost, and low-risk forms of intervention that can effectively prevent the side effects associated with traditional pharmacological and psychological intervention methods.

In recent years, adjuvant treatments for patients with PTSD and other trauma-related diseases have increasingly received scholarly attention. In exploring methods for promoting physical and mental health, many studies have shifted their focus on mind–body exercises. They have mainly utilize physical, mental, psychological, and behavioral exercises, such as breathing adjustment, physical exercise, meditation (Wynn, 2015; Zhang et al., 2019b; Zou et al., 2019a). This form has emphasized the holy trinity of exercise, i.e., combining the body, mind, and breathing. At the same time, it has the advantage of improving physical and mental health (Chan et al., 2013; Cushing and Braun, 2018; Zou et al., 2018a,b; Zhang et al., 2019a). Recently, various modalities of integrative mind–body intervention, which are increasingly employed in the treatment of PTSD, have emerged. Moreover, an increasing body of evidence has illustrated that mind–body interventions have exerted a positive impact on the psychological status, physical health, stress reduction, and quality of life of individuals with PTSD (Gordon et al., 2004, 2008; Grodin et al., 2008; Descilo et al., 2010; Bormann et al., 2011; Staples et al., 2011; Kearney et al., 2012; Hegberg et al., 2019). In 2010, 39% of people with PTSD reported using complementary and alternative medicine interventions, which includes various mind–body exercises that combine breathing and stretching exercises, such as tai chi, yoga, qigong, and meditation (Sapolsky et al., 2000). In fact, previous studies have demonstrated that mind–body exercises may positively influence PTSD-related symptoms through psychological and neurophysiological mechanisms, such as exposure and desensitization to internal arousal cues, improved cognitive function, normalization of the hypothalamic–pituitary–adrenal (HPA) axis function, motor-induced neuroplasticity, and reduction of inflammatory markers (McEwen, 2002; Yehuda and Golier, 2009; Streeter et al., 2012). In addition, emerging evidence supports the notion that mind–body exercises can effectively improve the symptoms of stress-related diseases through neurological and biological mechanisms (Bernardi et al., 2001; Vaiva et al., 2004; Brown and Gerbarg, 2009). Therefore, mind–body exercises may improve symptoms associated with PTSD, such as depression and anxiety, and may have the potential for use as an adjunctive treatment for patients with PTSD.

This study aims to review the effects of mind–body exercises (i.e., yoga, tai chi, qigong, and meditation) on PTSD symptoms. These four intervention methods require more active participation but less environment and related facilities. Moreover, they exhibit a high degree of portability and a huge dissemination potential for easy promotion and implementation (Zhou et al., 2019). Recently, numerous studies evaluated the specific effects of mind–body exercises on the presence of mood disorders related to PTSD symptoms, depression, and anxiety in patients with PTSD. However, these studies reported varying impacts on PTSD symptoms due to variability in sample selection (i.e., content, age, and gender) and the implementation of specific interventions (i.e., timing, frequency, method, and duration). Therefore, the current meta-analysis intends to explore the intrinsic regulatory mechanisms of mind–body exercises in patients with PTSD and to assess their effects on the symptoms and mood disorders associated with patients with PTSD to provide appropriate exercise prescriptions. Meanwhile, the exercise intervention program proposed by this study is expected to alleviate the mental health burden associated with COVID-19 at the global level.

This systematic review and meta-analysis aimed to analyze the effects of mind–body exercises on PTSD symptoms, depression, and anxiety in patients with PTSD and to lay the foundation for the development of rational exercise prescriptions. The results suggested that mind–body exercises can improve PTSD symptoms, depression, and anxiety in patients with PTSD. When a patient's physical condition permits, medical staff can use mind–body exercises as an adjunct to conventional treatments to further optimize the treatment plans for patients with PTSD.

The findings of this systematic review are consistent with those of published articles that concluded that mind–body exercises can improve PTSD symptoms, depression, and anxiety in patients with PTSD. Specifically, the effect size of PTSD, depression, and anxiety ranged from −0.64 to −0.19 (p < 0.001), from −0.5 to −0.15 (p < 0.001), and from −0.74 to −0.12 (p < 0.001), respectively. In addition, a high level of heterogeneity may exist in the study of Kim et al. (2013), who recruited only 22 participants and exhibited an attrition rate as high as 14.3%. Thus, the lower sample content of the final experiment may be the major reason for the heterogeneity.

Subgroup analysis indicated that mindfulness exercises for 60–150 min per session over a span of 8–16 weeks resulted in further significant improvements in PTSD symptoms in patients aged <45 years. In the subgroup analysis for frequency, exercises conducted 1–3 times per week were found significant. In addition, mind–body exercises may be more effective in improving PTSD symptoms among males. For depression, once per week, 4–8 times per week, 60–90 min, or 150–180 min of yoga displayed larger effects on patients with PTSD who were aged more than 45 years. Unfortunately, RCTs on the effect of mind–body exercises on anxiety symptoms in patients with PTSD are limited. Therefore, we were unable to determine the most effective frequency, duration, experimental period, and type of intervention. However, the exercise prescription should follow the recommendations provided by the International Organization of Physical Therapists in Mental Health for the generally healthy population. These recommendations include 150 min of moderate-intensity exercises or 75 min of vigorous exercises per week (Vancampfort et al., 2012). Notably, in the subgroup analysis of PTSD and depression, yoga exhibited differences in heterogeneity for the PTSD (I² = 54.5%) and depression (I² = 0.0%) subgroups. The mechanisms by which PTSD symptoms and depression occur in patients with PTSD may be the main source of the outcome bias.

PTSD symptoms can inflict a serious impact on a patient's normal social and daily life. However, low-to-moderate-intensity mind–body exercise intervention exerts a positive impact on PTSD symptoms (Telles et al., 2007).

Unhealthy lifestyles and personal traumatic experiences are expected to exert adverse effects on the body, which leads to an imbalance in the HPA axis (McEwen, 2002). Dysfunction in the HPA axis, which is characterized by abnormally high levels of corticotropin-releasing hormone (CRH) and low cortisol levels, is one of the unique neuroendocrine characteristics that distinguish PTSD from other mental diseases (Yehuda, 2002; Yehuda and Golier, 2009). Many studies have demonstrated that cortisol plays a crucial role in the pathophysiology of PTSD. However, among healthy individuals exposed to an acute stressor, the HPA axis can respond to the stressor by secreting relevant hormones, such as the CRH from the hypothalamus, adrenocorticotropic hormone (ACTH) from the anterior pituitary, and glucocorticoids from the adrenal cortex (Sapolsky et al., 2000). Increased basal levels of cortisol can improve declarative memory and performance and are associated with the normalization of glucose metabolism in the limbic system (Twamley et al., 2004). Patients with PTSD symptoms exhibit low basic levels of cortisol (Boscarino, 1996). Compared with individuals without PTSD, the sensitivity of the negative feedback inhibition of cortisol in the HPA axis is higher (Yehuda, 2002). In patients with PTSD, elevated basal cortisol levels are associated with improvement in symptoms (Aerni et al., 2004). Several related studies indicated that exercise is related to the transient increase in plasma cortisol (Brandenberger and Follenius, 1975) and improvement in cognitive function (Twamley et al., 2004). Conversely, CRH secretion is abnormally high in patients with PTSD (Bremner et al., 1997), but the level of ACTH is low, which is the hormone that causes the adrenal cortex to secrete glucocorticoids (Smith et al., 1989). The slow response of ACTH to CRH may lead to a decrease in ACTH secretion in the pituitary, which leads to a decrease in the production of cortisol in the adrenal cortex (Smith et al., 1989). Dehydroepiandrosterone sulfate (DHEAS) is an anabolic steroid molecule that enhances an individual's resistance to stress by preventing cell death and behavioral deficits through neuroprotective effects. Relevant studies have illustrated that reasonable exercise can effectively increase DHEAS levels (Johnson, 1997; Rasmusson et al., 2004). Therefore, mind–body exercises can effectively improve PTSD symptoms in patients with PTSD.

The main psychiatric abnormalities in patients with PTSD are typically symptoms of depression and anxiety (Javidi and Yadollahie, 2012). An increasing number of studies demonstrate that proper exercise is beneficial for depression and anxiety symptoms, including those in patients with PTSD (Rebar et al., 2015; Schuch et al., 2016). Evidence exists that impaired adult hippocampal neurogenesis (AHN) is related to various neurological diseases, including PTSD, depression, and Alzheimer's disease (Gao et al., 2017; Barnett et al., 2019). Thus, enhancing AHN can effectively reduce the mood symptoms of the depression model, improve memory resolution, and avoid the recovery of panic experience (Sahay et al., 2011; Hill et al., 2015). In the pathogenesis of PTSD, a dysfunction in the AHN leads to the onset of cognitive impairment and related psychiatric symptoms (Malberg, 2004; Catlow et al., 2013; Besnard and Sahay, 2016). Therefore, improving AHN can effectively alleviate cognitive dysfunction and emotional problems related to patients with PTSD.

The tight regulation of AHN is derived from the interaction between environmental factors and endogenous ecotropic regulators (Toda and Gage, 2018). For example, the PI3K/Akt pathway plays an important role in linking pro-neurogenic gene transcription factors with various neurotrophic and growth factors, such as brain-derived neurotrophic factor and epithelial growth factor signaling (Yin H. et al., 2019; Yin L. et al., 2019). Alternatively, several studies provide evidence that highlight the importance of Akt signaling in regulating AHN. In addition, Akt1 is highly expressed in the adult hippocampus and may influence the synaptic plasticity of the CA1 sub-region (Levenga et al., 2017). Scaffold protein disrupted-in-schizophrenia 1 can regulate AHN via the Akt pathway (Wu et al., 2013). Moreover, exercise-mediated Akt signaling may also play a role in cognitive and emotional regulation and promote synaptic plasticity and synapse formation at the same time (Qian et al., 2015; Levenga et al., 2017). Hippocampal neurogenesis is an important neuroplasticity that provides adaptability under stress and regulates cognitive function and antidepressant behavior (Gao et al., 2017, 2018). Thus, a certain density of immature neurons also contributes to the clearance of fear memory, which, in turn, improves memory resolution (Pereira et al., 2014; Johnston et al., 2016).

Previous studies have demonstrated that as a mature non-drug treatment method, psychosomatic movement is reliant on the activation of Akt by AHN to play a role in improving cognition/anti-depression, in promoting AHN, and in improving neurobehavior. In the medical field, scholars are increasingly interested in studying the physical and psychological effects of mind–body interventions, such as mindfulness and yoga. Mind–body exercises can enhance the ability of patients with PTSD to endure unpleasant emotions, which reduces mental stress (Brown and Gerbarg, 2005; Rocha et al., 2012; West et al., 2014). Yoga focuses on a combination of physical exercise and breathing, where the main exercises include body movement, muscle relaxation, and meditation (Granath et al., 2006). Slow and rhythmic breathing in conjunction with yoga body movements can help to activate the parasympathetic nervous system and stimulate vagus nerve activity (Papp et al., 2013), which can effectively alleviate the symptoms of overexcitement. In this manner, this process is beneficial to patients with PTSD. Other studies depicted that yoga can help restore balance to the HPA axis by lowering the levels of the stress hormone cortisol (Gothe et al., 2016). Streeter et al. (2012) proposed that yoga can reduce a stress-induced unsteady state load using three stress response systems, namely, the HPA axis, the autonomic nervous system, and the GABA-ergic system. Therefore, yoga also may be effective in improving the symptoms of patients with PTSD, including depression and anxiety (Kjellgren et al., 2017). Through mindfulness practice, yoga provides practitioners with a strategy for concentration and for enhancing mind and body awareness (Iverson et al., 2011). Specifically, enhancing mindfulness can increase one's acceptance of one's emotions, improve regulation, and reduce avoidance (Mitchell et al., 2014).

In general, patients with PTSD undergo a lengthy disease duration and a high relapse rate; thus, long-term treatment can place a serious financial burden on individuals and families. Estimates suggest that trauma-related disorders cost over $45 billion USD per year in medical and related costs (Tanielian et al., 2016; von der Warth et al., 2020). Thus, mind–body exercises as a complementary alternative therapy can effectively reduce medical expenditures and reduce the burden on society and families. PTSD symptoms may include, but are not limited to, rapid heartbeat, difficulty in breathing, muscle tightness, hyper-arousal, inability to relax, chronic pain, mood issues, racing thoughts, and substance abuse (Briere and Spinazzola, 2005). Low levels of self-esteem, lack of coping skills, and lack of interpersonal skills constitute a range of symptoms that can impact a patient's quality of life and relationships (Van der Kolk, 2006). In this regard, mind–body exercises can effectively relieve muscle tension and improve breathing problems and other related symptoms through physical activities with breathing exercises, which can improve the quality of life of patients to a certain extent.

In the present review, all articles indicated the significant effect of mind–body exercises on PTSD symptoms among patients with PTSD. Specifically, Reinhardt et al. (2017) presented a sample attrition rate of as high as 52.6% and a sample type of veterans. Therefore, many studies face the challenge of retaining veterans for treatment. Moreover, Carter et al. (2013) and Mitchell et al. (2014) suggested that yoga is feasible as a complementary treatment for veterans with PTSD despite the fact that the results of the intervention for PTSD symptoms among veterans failed to consistently indicate significant changes. In summary, additional RCTs are required to demonstrate the effects of mind–body exercises on PTSD symptoms, depression, and anxiety in patients with PTSD. Therefore, mind–body exercises can be used as an alternative treatment for patients with mild forms of PTSD, as well as an adjunct to recovery and home care for patients with moderate or even severe PTSD.

Although the current literature review tentatively established the benefits of mind–body exercises for patients with PTSD, the limitations of the existing studies should be noted. The reliability of the results may have been influenced by age; gender; duration of the disease; frequency, duration, and intensity of the experimental intervention; and type of exercise. Several qualitative differences were observed for the studies included in the review. (1) Several studies employed small sample sizes with very limited age range and/or race and region (many participants were predominantly white). (2) Only three studies indicated that the sample allocation used hidden allocation, which could be a cause of systematic bias in the treatment effect. (3) Only three studies used assessor blinding in measuring the outcomes. (4) The absence of the descriptions of disease duration and degree of illness in the majority of the literature relatively influences the specific analysis of the effectiveness of mind–body exercises on symptom improvement in patients with PTSD. (5) For anxiety, we were unable to determine the optimal frequency, timing, duration, and type of exercise for mind–body exercises for improving anxiety symptoms in patients with PTSD due to the limited number of eligible RCTs. (6) Lastly, methodological differences in the timing, frequency, duration, and outcome measures of the interventions contributed to the differences in outcomes and led to the difficulties in interpretation. Although these issues limit the generalizability of the studies to different populations, the positive correlation between mind–body exercises and PTSD-related symptoms in these studies provides evidence for the generalizability of the findings.

Research has proven that mind–body exercises can effectively improve PTSD symptoms, depression, and anxiety in patients with PTSD and can be used as an alternative or adjunctive treatment according to the unique situation of each patient. In cases where patients with PTSD can exercise without adverse effects, then medical staff may use mind–body exercises as a supplemental regimen to conventional treatment. In addition, the conclusion of this research requires further confirmation using additional high-quality RCTs with large samples. Meanwhile, the current review can also provide an exercise prescription for relieving stress and traumatic stress disorders for people experiencing PTSD symptoms due to COVID-19.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s.

LL and LW presented the conceptualization and design of the study protocol. LZ, LW, and LL applied the search strategy and screened the literature based on the selection criteria. LZ and X-zL assessed the risk of bias for the screened literature. All researchers were involved in the collation and analysis of the data and interpreted the results of the data analysis. LZ wrote this manuscript, which was further revised and edited by LW, LL, and X-zL. All authors have read the final revised manuscript and agree to its publication.

This work was supported by the Ministry of education of Humanities and Social Science project (17YJA890025); the Fundamental Research Funds for the Central Universities (WUT: 2020VI001).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.