Introduction

Depression and anxiety are common mental disorders characterized by high prevalence, high rates of recurrence, increased risk of suicide, and significant disability. These conditions pose a major public health challenge worldwide[1]. According to the latest data from the Global Burden of Disease (https://vizhub.healthdata.org/gbd-results/), approximately 280 million people worldwide suffer from depression, while 301 million are affected by anxiety. Central to these mental health issues is repetitive negative thinking (RNT), a cognitive pattern involving repetitive, ineffective, and uncontrollable contemplation of negative events[2–3]. RNT includes two primary forms: rumination and worry[4]. Rumination involves persistent reflection and overanalysis of past negative experiences[5], which is closely associated with depression[6]. Conversely, worry is characterized by excessive concern about potential future negative events[7] and is strongly linked to anxiety disorders[8]. Given that RNT predicts the onset and maintenance of depression and anxiety[9], interventions targeting RNT may offer significant benefits for mental health outcomes.

The etiology of RNT is multifaceted, with both biological and environmental factors playing influential roles[10]. For instance, biological factors like genetic predispositions and hormonal imbalances have been implicated in RNT development, while environmental factors such as chronic stress and adverse childhood experiences contribute significantly to its persistence. These diverse influences highlight the need for holistic approaches to intervention[10]. Current treatments for RNT include pharmacological and psychological interventions. Pharmacological approaches, such as the use of selective serotonin reuptake inhibitors (SSRIs) and mood stabilizers, have demonstrated effectiveness in reducing RNT by addressing physiological mechanisms[11]. However, long-term use of pharmacological treatments can result in adverse effects such as weight gain, sedation, and cognitive impairment[12–13]. On the other hand, psychological interventions like Metacognitive Therapy and Mindfulness-Based Therapy emphasize cognitive and emotional regulation, with promising results[14]. Nevertheless, these interventions often lack a direct physiological impact, highlighting the need for more comprehensive, side-effect-free approaches.

Emerging evidence supports the potential of physical activity-based interventions to reduce RNT. Physical activity, unlike pharmacological and psychological treatments, offers a unique triadic effect on physiological, psychological, and social dimensions. Studies suggest that physical activity enhances cognitive control, reduces emotional reactivity, and mitigates the impact of rumination and worry[15–16]. Moreover, physical activity-based interventions have been shown to reduce sensitivity to anxiety[17–18], thereby impacting RNT pathways. These mechanisms include enhanced neuroplasticity, endorphin release, and improved cognitive control, which facilitate the regulation of negative thought patterns[19–20].

Research indicates that physical activity-based interventions positively affect a range of psychological disorders, including worry, rumination, and memory bias. However, their influence on other critical psychological conditions like anxiety, PTSD, and persecutory delusions remains underexplored. Given that these conditions share RNT as a transdiagnostic feature, the potential for physical activity to target this common mechanism across multiple disorders warrants further investigation. Furthermore, while the positive impact of physical activity on various psychological outcomes is well-documented, the mechanisms through which these effects occur remain unclear. It is uncertain whether the observed reductions in worry, rumination, and other RNT-related symptoms can be solely attributed to reductions in RNT or if additional mechanisms are at play.

Despite the existing literature, gaps remain in the understanding of how physical activity influences RNT. The rationale for linking diverse psychological disorders with distinct symptom profiles and risk factors to a singular variable—RNT—requires further clarification. While cognitive control deficits are a known precursor to RNT[15], it is essential to understand how physical activity uniquely impacts these deficits compared to other interventions. Moreover, the current body of research has not sufficiently justified the study’s novelty or the significance of investigating the direct effects of physical activity on RNT.

Physical activity interventions offer multiple benefits, including low cost, ease of implementation, and minimal side effects. Nonetheless, inconsistencies in findings highlight the need for further research. Some studies, for example, report no significant change in worry levels following physical activity interventions[21], while others show significant reductions in worry and rumination[20,22]. These mixed outcomes could be due to variations in participant characteristics, intervention design, and measurement tools. To address these gaps, this study aims to conduct a systematic review of the impact of physical activity-based interventions on RNT. By synthesizing current research, the study seeks to identify unresolved issues, clarify the conditions under which physical activity is most effective, and provide guidance for future research and practical applications. The novelty of this study lies in its systematic evaluation of heterogeneous findings, with a focus on elucidating the specific conditions that yield optimal intervention outcomes.

Materials & methods

This systematic review adhered to the PRISMA 2020 statement: an updated guideline for reporting systematic reviews (https://www.prisma-statement.org/). The protocol for this systematic review was registered on INPLASY (202440095) and is accessible in its entirety on inplasy.com (https://doi.org/10.37766/inplasy2024.4.0095).

Search strategy

A comprehensive search was conducted across PubMed, Web of Science, Cochrane Library, and APA PsycNET databases. The search covered studies published from database inception to December 31, 2024. The inclusion criteria for selecting studies were as follows: (1) studies that utilized physical activity as the primary intervention; (2) studies that measured RNT-related outcomes such as rumination, worry, or perseverative thinking; (3) peer-reviewed, full-text articles published in English; and (4) studies with clear pre-test and post-test measures. Exclusion criteria included review articles, conference abstracts, case reports, and studies without accessible full texts or usable data.

To ensure transparency, the search strategy included the following key terms: “physical activity,” “exercise,” “aerobic exercise,” “resistance training,” “acute exercise,” “exercise training,” “repetitive negative thinking,” “rumination,” “worry,” and “perseverative thinking.” This strategy was applied across all databases to maximize coverage. It is worth noting that “resistance training” was included as a search term, addressing a prior discrepancy where it was listed in Table 1 but not the search strategy.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Table 1. Characteristics of selected studies.

https://doi.org/10.1371/journal.pone.0319806.t001

Results

Selection process and results

The study selection process is illustrated in Fig 1. A total of 4,248 studies were identified from electronic databases. After removing 238 duplicate records, 4,010 studies remained for title and abstract screening. During this phase, 3,938 records were excluded due to irrelevance, leaving 80 studies for full-text retrieval. Among these, 48 reports were excluded for not meeting the research objectives, resulting in 32 studies being assessed for eligibility. After further evaluation, 13 studies were excluded for various reasons, including incomplete or unusable data (n =  7), unclear grouping (n =  2), duplicate publications (n =  2), and other reasons (n =  2). Ultimately, 19 studies met the inclusion criteria and were included in the systematic review. The selection criteria required studies to have a randomized controlled trial (RCT), quasi-experimental, or pre-post design, etc. with physical activity as the intervention and pre-post outcome measurements related to RNT.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Fig 1. PRISMA(2020) flowchart of record identification, screening, and inclusion.

https://doi.org/10.1371/journal.pone.0319806.g001

Risk of bias assessment

The methodological quality of the 19 included studies was evaluated using the Physiotherapy Evidence Database (PEDro) scale. The overall quality was categorized as moderate to high. Specifically, 14 studies were classified as moderate quality (Aalsm et al., 2022[40]; Alderman et al., 2016[39]; Basso et al., 2022[23]; Craft, 2005[35]; de Bruin, 2016[24]; Gordon et al., 2020[25]; Gordon et al., 2021[26]; Herring et al., 2011[27]; Herring et al., 2017[28]; Herring et al., 2019[29]; McDowell et al., 2016[38]; Shors et al., 2018[36]; Shrimal et al., 2024[37]; van Aalst et al., 2021[21]), and 5 studies were classified as high quality (Jacoby et al., 2024[30]; La Rocque et al., 2021[31]; Plag et al., 2020[32]; Schuyer et al., 2016[33]; Vollbehr et al., 2021[34]). The lowest scoring items on the PEDro scale were blinding of subjects, blinding of therapists, and blinding of assessors. The absence of blinding for these roles could introduce performance and detection bias, which may influence the observed intervention effects on RNT. The overall quality assessment results are presented in Fig 2, while Fig 3 presents the quality assessment results for each included study. Fig 2 illustrates the distribution of PEDro scores for each included study, highlighting the proportion of high- and moderate-quality studies. Fig 3 provides a visual heatmap of the quality assessment for each included study, detailing the compliance of each study with 11 PEDro criteria.

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Fig 2. Histogram of Risk of Bias Assessment results of the included studies.

https://doi.org/10.1371/journal.pone.0319806.g002

Download:

• PPT
  PowerPoint slide
• PNG
  larger image
• TIFF
  original image

Fig 3. Heatmap of Risk of Bias Assessment results for included studies.

https://doi.org/10.1371/journal.pone.0319806.g003

Discussion

The present study aims to comprehensively analyze whether physical activity-based interventions can reduce RNT. Therefore, searches were conducted in databases such as PubMed, Web of Science, etc., from inception to December 2024. Through screening, a total of 19 studies relevant to the research topic were included for systematic review. Based on the findings of included the studies, the following discussion is presented:

Firstly, physical activity-based interventions consistently demonstrate a positive trend and conclusion in reducing RNT, which aligns with previous research findings[39]. However, studies involving single-session physical activity interventions showed no significant reduction in worry and rumination. This is consistent with findings indicating that short-term interventions may not induce sufficient physiological and psychological changes to significantly affect RNT. One possible reason is that single-session activities do not provide sufficient stimulation for long-term neuroplasticity, which requires repetitive training to induce stable changes in brain structure[41]. Additionally, single-session interventions may trigger cognitive biases, such as negative memory biases, especially in individuals with high levels of rumination[42]. As a result, short-term interventions may exacerbate certain negative thinking patterns rather than reduce them. Therefore, sustained and repeated interventions are recommended to achieve lasting effects on RNT. Instead, single-session interventions may exacerbate certain cognitive biases, such as negative memory biases, particularly in individuals with high levels of rumination[42]. RNT is the result of multiple factors, mechanisms, and targets interacting with each other, making its underlying mechanisms quite complex[4]. Although identifying the mechanisms is beyond the scope of this study, several potential physiological, psychological, and social mechanisms can explain why there are positive outcomes in RNT following participation in physical activity-based interventions. Firstly, there are physiological mechanisms at play. Physical activity is believed to influence the brain’s physiological processes, including neurotransmitter release, neurogenesis, and enhancement of brain function[43–44]. For instance, physical activity promotes the release of endorphins, which are endogenous chemicals associated with pleasure and relaxation, thus alleviating anxiety and depressive symptoms and reducing the tendency for RNT [45–46]. Endorphins bind to opioid receptors in the brain, which are linked to feelings of pleasure and relaxation[47]. This process helps reduce cognitive processes such as worry and rumination by alleviating negative emotional arousal, which has been associated with a decrease in RNT. The release of endorphins triggers activation of the opioid receptors in the brain, which are linked to feelings of pleasure and relaxation[47]. This mechanism may contribute to a reduction in cognitive processes such as worry and rumination, as the reduction of negative emotional arousal has been associated with lower RNT. Therefore, the role of endorphin release serves as a crucial physiological mechanism in the relationship between physical activity and RNT. These improvements at the physiological level are closely linked to mental health. Additionally, research suggests that individuals who engage in regular physical activity may be less susceptible to the impact of rumination on the hypothalamic-pituitary-adrenal axis reactivity, thereby mitigating the effects of rumination on the cortisol output pathway[48]. Therefore, attaining these physiological effects may help reduce negative emotions in individuals, thereby inhibiting the onset of RNT.

Secondly, there are psychological mechanisms at play. Physical activity can promote the release of endogenous chemicals such as endorphins, leading to feelings of pleasure and relaxation, alleviating anxiety and depressive symptoms, and reducing the tendency for RNT[45–46]. Moreover, research evidence suggests a close association between cognitive control deficits and RNT[15]. Physical activity, on the other hand, contributes to enhancing cognitive control abilities, improving cognitive reappraisal[49], and regulating self-monitoring and thought regulation abilities. This helps individuals avoid getting trapped in meaningless thought loops, thereby reducing RNT[10]. Furthermore, physical activity can promote a sense of agency and self-efficacy, which are critical for mitigating repetitive and negative thought patterns. These psychological benefits may vary depending on participants’ adherence to physical activity protocols. Research indicates that voluntary engagement in physical activity may yield greater psychological benefits compared to participation as research subjects, as it reflects intrinsic motivation and long-term commitment[50]. Voluntary engagement fosters a sense of autonomy, competence, and relatedness, which are key components of intrinsic motivation[51]. This suggests that interventions encouraging voluntary participation may result in stronger and more sustainable reductions in RNT. Intrinsic motivation, driven by the satisfaction of one’s psychological needs for autonomy, competence, and relatedness, is a key determinant of sustained engagement in physical activity[51]. By fostering a sense of voluntary engagement, physical activity programs may promote higher levels of adherence, thereby enhancing the effectiveness of interventions targeting RNT.

Thirdly, there are social effects mechanisms at play. Physical activity is often a social behavior, such as participating in team sports, fitness classes, and outdoor activities, which can promote communication and interaction with others, fostering positive social relationships[52]. Positive interactions and social engagement in the social environment can increase individuals’ self-esteem, self-confidence, and sense of belonging, thereby reducing the occurrence of RNT[53]. Additionally, the social support system also plays a crucial role in the impact of physical activity on mental health. Research evidence suggests that individuals with strong social support networks are more likely to actively engage in physical activity and have better coping abilities when facing stress and difficulties[54]. This form of social support can originate from various sources such as family, friends, colleagues, and the community. It provides individuals with emotional and informational support as well as tangible assistance, which can mitigate the risk of mental health issues, including the propensity for RNT. Furthermore, when examining the social factors influencing the relationship between physical activity and RNT, the integrated role emphasized in the Biopsychosocial Model must not be overlooked. This model posits that physiological, psychological, and social factors interact to collectively shape an individual’s overall health status[55]. Therefore, considering the combined influence of physiological, psychological, and social factors can provide a more comprehensive understanding of the impact of physical activity on RNT and offer a stronger basis for developing targeted interventions. Furthermore, compared to single physical activity interventions, combined interventions that include meditation, mindfulness, and other psychological interventions have shown significant positive effects in reducing RNT. These research findings support previous studies[56]. The study suggests that the positive effects of combined interventions can be discussed from multiple perspectives. Firstly, combined interventions simultaneously regulate both the emotional and cognitive aspects of individuals. Physical activity reduces depressive and anxious emotions [57], while psychological training helps individuals establish healthier psychological mechanisms [3,58]. Therefore, combined interventions can effectively intervene in RNT by addressing both emotional and cognitive regulation simultaneously. Secondly, combined interventions provide additional support and resources, enriching the avenues through which individuals benefit and enhancing the effectiveness of interventions. Research evidence indicates that following combined meditation and aerobic exercise interventions, there was a significant reduction in rumination in the experimental group, while the control group, which engaged solely in physical activity, showed no significant change[36]. This suggests that combined interventions, which target both emotional regulation and cognitive processes, are more effective than single interventions in reducing RNT[36]. Such results may be attributed to the fact that in combined interventions involving physical activity and psychological training, individuals not only benefit from the exercise but also gain additional psychological support, emotional guidance, and cognitive-behavioral skill practice through the psychological training component. These factors contribute to individuals’ better understanding and management of their emotions and thoughts, thereby enhancing control over the allocation of limited brain resources[59]. This enables them to address the negative issues associated with RNT more effectively. Thirdly, combined intervention strategies can enhance overall physical and mental health by improving physical health levels[60]. By integrating physical activity with psychological training, individuals may achieve a better balance at both physiological and psychological levels. Such a holistic mind-body intervention approach can assist individuals in developing healthy lifestyle habits and establishing robust psychological mechanisms, thereby better equipping them to counter the effects of RNT. Finally, it should be noted that this combined intervention approach falls under the category of mind-body exercises, which integrate physical activity with psychological training. Therefore, it is recommended to consider mind-body exercise programs such as tai chi, health qigong, yoga, etc., when addressing RNT. These mind-body exercise programs not only enhance physical health but also improve cognitive control and emotional regulation abilities[61,62], thereby improving mental well-being and providing effective strategies for addressing RNT issues.

Finally, interventions characterized by moderate duration, moderate frequency, moderate intensity, and longer duration demonstrate a predominance of positive effects on RNT in the studies included. The study suggests that the continuity and frequency of interventions, timing, as well as the adaptability of both physical and psychological aspects are important factors in explaining these research results. Firstly, continuity and frequency play crucial roles. The sustained and moderate frequency of exercise interventions significantly influences their effectiveness. Moderate-frequency exercise interventions ensure sufficient continuity, allowing participants to continuously benefit over a period of time. Additionally, intervals between sessions help the body adapt to the exercise load, preventing fatigue and overtraining. Additionally, studies have found that individuals with high levels of rumination may experience more negative memory biases during acute exercise, exacerbating rumination[42]. These findings support the notion that the short-term impact of exercise on rumination may be relatively limited, indicating that short-term exercise interventions may not be sufficient to trigger lasting physiological and psychological changes. Instead, they may have a noticeable adverse effect on RNT. Secondly, the time window is crucial. Research indicates that both psychological and physiological changes require time to stabilize and consolidate[63]. Long-term exercise interventions allow individuals to gradually adapt to exercise and derive benefits from it. Moreover, prolonged exercise interventions may require more time to induce changes in neuroplasticity[41], thereby influencing cognitive and emotional patterns. Thirdly, physical and psychological adaptability. Sustained moderate-intensity exercise may provide the body with sufficient opportunities to adapt to the exercise load, promoting cardiovascular health, enhancing muscle endurance, and more. This physical adaptation may have a positive impact on emotional and cognitive states, reducing the tendency to engage in RNT. Thirdly, physical and psychological adaptability. Sustained moderate to moderate-intensity exercise provides ample opportunities for the body to adapt to the exercise load. This adaptation optimizes the effects of exercise and consequently exerts positive influences on emotional and cognitive states, reducing the tendency for RNT. Hillman et al[64] proposed that at least 30 minutes of moderate-intensity physical activity is necessary to induce cellular changes in the brain, which subsequently affect cognition. This process has been linked to changes in neuroplasticity, particularly in the prefrontal cortex, which is responsible for cognitive control and executive function. The findings in this study align with this notion, as interventions lasting 30-60 minutes demonstrated improvements in cognitive reappraisal and reductions in RNT. The intervention effects of programs lasting 25 to 60 minutes, as observed in the included studies, support this proposition, that physical activity over a certain duration can disperse attention, reduce the focus on negative thinking, and thereby alleviate the occurrence of RNT. The most significant point is that this finding aligns with the American College of Sports Medicine’s (ACSM) Exercise Testing and Prescription Guidelines, which recommend engaging in moderate-intensity exercise for at least 30 minutes, 3-5 times per week, to promote and maintain health. This alignment highlights the relevance and practical significance of the current findings for public health initiatives and mental health intervention strategies[65]. This indicates the relevance and applicability of the results to existing guidelines.

Conclusions

Based on a systematic review and analysis of 14 studies, the following conclusions have been drawn: Physical activity-based interventions have the potential to reduce RNT, with combined interventions that integrate physical activity and psychological training showing even greater effectiveness. This suggests that a holistic approach that simultaneously targets emotional and cognitive components may yield better outcomes. Moreover, intervention protocols characterized by longer durations, moderate frequency, moderate intensity, and extended intervention cycles demonstrate superior improvements in RNT. These findings contribute to a more comprehensive understanding of the mechanisms through which physical activity influences RNT and provide crucial theoretical references for the development of evidence-based intervention strategies.

Supporting information

Acknowledgments

We would like to thank Xichen Duan for her invaluable assistance in creating the figures for this paper.