Trait mindfulness refers to an individual's habitual awareness of present thoughts and emotions, encompassing observing experiences, labeling perceptions verbally, maintaining present-moment awareness, refraining from judging one's thoughts and feelings, and avoiding overreaction (6). According to the trait mindfulness coping model, when individuals encounter stressful events, trait mindfulness enhances cognitive flexibility, enabling them to respond through positive reappraisal (7). Therefore, when confronting stressful events, individuals with high trait mindfulness allocate more cognitive resources to maintain present-moment awareness, alter existing cognitive patterns (8), and reappraise past experiences positively (9), thereby shifting rumination from negative to positive (10). Since the 1970s, numerous studies have confirmed the efficacy of mindfulness training in alleviating social anxiety and depression. Mindfulness practice effectively treats various psychological disorders, offering significant benefits for rumination, anxiety disorders, and depression. Trait mindfulness helps college students reduce rumination primarily by using mindful meditation to detach attention from repetitive thoughts and redirect it toward present-moment experiences. Research indicates a negative correlation between trait mindfulness and rumination (11), enhances individuals' executive control functions (12), and positively impacts mental health by reducing rumination, increasing psychological flexibility, and boosting overall well-being through heightened mindfulness. Attention Control Theory posits that trait mindfulness enhances an individual's ability to manage attentional resources, while deficits in attention control are a key trigger for rumination. College students are prone to experiencing attentional dispersion or becoming “trapped in negative thoughts” due to external distractions (such as social media notifications or multiple academic tasks) or internal negative thoughts—precisely the foundation for rumination to occur. Through training in “anchoring attention (e.g., focusing on breathing), noticing distractions, and refocusing attention”, trait mindfulness enhances individuals' attentional stability and shifting abilities. This enables them to proactively redirect attention from negative ruminative content to present tasks or neutral information, thereby reducing the duration and intensity of rumination. Given this, this study proposes Hypothesis H1: Trait mindfulness has a negative predictive effect on rumination in college students.

Exercise behaviour refers to physical activities voluntarily chosen by individuals based on their needs, employing various sports methods combined with natural forces and hygiene measures (13). As a positive personality trait, the two core elements of trait mindfulness—“present-moment awareness” and “non-judgmental attitude”—can to some extent motivate college students to persist in exercise, thereby fostering consistent physical activity (14). Research indicates a significant positive correlation between trait mindfulness and exercise levels. Individuals with high trait mindfulness are more likely to maintain regular physical activity, which helps reduce rumination (15). Specifically, it positively correlates with sustaining physical activity, achieving exercise goals, and satisfaction with physical activity (16). Higher mindfulness levels among college students imply greater likelihood of long-term exercise persistence (17). In recent years, numerous scholars have increasingly focused on the impact of physical exercise on rumination. Research reveals a close relationship between physical exercise and rumination, with exercise exerting a positive influence on rumination. Brand et al. suggest that physical exercise of varying intensities can alleviate rumination among college students, with moderate-intensity exercise proving most effective in reducing rumination (18). Given this, this study proposes Hypothesis H2: exercise behaviour mediates the relationship between trait mindfulness and rumination.

Seligman's learned optimism theory posits that personality is divided into “optimistic explanatory styles” and “pessimistic explanatory styles”. Individuals with optimistic explanatory styles typically view failures and setbacks as temporary, caused by specific situational events and external factors, and confined to the immediate context. In contrast, individuals with a pessimistic explanatory style attribute failures and setbacks to long-term or permanent, universal, and personal internal causes, believing these will generalize to other matters. The concept of optimistic intelligence quotient (OIQ) extends and expands upon this explanatory style theory to some extent, emphasizing that individuals not only possess optimistic cognitive tendencies but also have the capacity to derive joy from both positive and negative events, thereby enhancing their levels of optimism (19). Research indicates that trait mindfulness significantly and positively predicts optimistic intelligence quotient (20), correlates positively with individual optimism (21), and facilitates the development of positive emotional regulation strategies, enabling individuals to remain more optimistic and confident when confronting negative events (22). Furthermore, optimistic intelligence quotient can reduce rumination when individuals face negative life events (23). Research indicates that optimistic intelligence quotient can tap into internal positive resources when confronting negative life events, actively coping with stress to adapt to the environment. Simultaneously, it enables individuals to effectively release negative emotions inwardly through reasonable means and outwardly seek help to build effective social support (24). Given this, this study proposes Hypothesis H3: Optimistic intelligence quotient mediates the relationship between trait mindfulness and rumination.

Physical exercise demonstrates positive effects across various domains, with positive emotions primarily derived from such activities. Exercise behaviour positively influences college students' levels of optimistic intelligence quotient (25), and related variables (frequency, duration, intensity) significantly predict their optimistic intelligence quotient (26). Research indicates that individuals with higher exercise behaviour exhibit greater optimistic intelligence quotient (27), and university students' optimistic intelligence quotient levels increase with longer exercise duration and higher frequency (28). Regular physical exercise effectively improves mood states, promotes the adoption of positive coping strategies, and mitigates stress-induced harm (29). Self-Determination Theory explains this relationship through the lens of motivation and psychological need fulfillment. Physical exercise satisfies three fundamental psychological needs: autonomy, competence, and relatedness. Fulfilling these needs enhances intrinsic motivation, making individuals more inclined to actively seek positive experiences and cope with setbacks. This tendency toward proactive mental regulation constitutes a core component of optimistic intelligence quotient. Thus, regular exercise provides an internal driving force for enhancing optimistic intelligence quotient by fulfilling psychological needs. After physical exercise, college students often more readily attain positive subjective experiences such as subjective well-being, euphoria from exercise, a sense of accomplishment, enjoyment of physical activity, positive interpersonal relationships, and social support. These positive subjective experiences are all manifestations of high optimistic intelligence quotient (30). Based on this, this study proposes Hypothesis H4: Exercise behaviour mediates the relationship between trait mindfulness and optimistic intelligence quotient in a chain-like manner.

In summary, to examine the influence of trait mindfulness on rumination among college students, this study proposes to construct a chain mediation model (as shown in Figure 1) and will test the following aspects: (1) Trait mindfulness significantly and negatively predicts rumination in college students; (2) Exercise behaviour and optimistic intelligence quotient exert separate mediating effects between trait mindfulness and rumination in college students; (3) Exercise behaviour and optimistic intelligence quotient mediate the relationship between trait mindfulness and rumination in college students through a chained mediation effect.

Using convenience sampling, an online questionnaire survey was conducted from September 1 to September 20, 2024, among 2,024 college students from 15 universities in Liaoning and Henan provinces, China. The survey employed the Trait Mindfulness Scale, Rumination Scale, Exercise Behaviour Level Scale, and Optimistic Intelligence Quotient Scale. Liaoning and Henan were selected due to established collaborative relationships and their large, diverse student populations. During questionnaire screening, 20 responses with inconsistent answers to reverse-scored items, 11 responses completed in excessively short time frames, and 10 responses showing systematic errors were excluded. Ultimately, 1,983 valid questionnaires were recovered, yielding a response rate of 97.9%. Among the respondents, 996 were male (49.8%) and 987 were female (50.2%), with an average age of 19.10 ± 1.07 years. All 1,983 participants actively engaged in exercise behaviour and demonstrated understanding of the concepts of trait mindfulness, rumination, and optimistic intelligence quotient.

To mitigate the impact of common method bias on research outcomes, necessary controls were implemented during data collection, such as requiring anonymous responses from participants and employing reverse scoring for certain items. The Harman single-factor test was applied to assess common method bias. Results indicated nine factors with eigenvalues exceeding 1. The first factor explained 27.1% of variance, significantly below the 40% critical threshold (36), confirming no common method bias in the data.

Independent samples t-tests were conducted to analyze gender differences in trait mindfulness, rumination, exercise behaviour, and optimistic intelligence quotient. Results revealed that male college students significantly outperformed female students in trait mindfulness, rumination, and exercise behaviour. Conversely, female students demonstrated significantly higher optimistic intelligence quotient than male students (see Table 1).

A one-way ANOVA was conducted to compare differences in trait mindfulness, rumination, exercise behaviour, and optimistic intelligence quotient across different grade levels. The results revealed significant differences in trait mindfulness, rumination, exercise behaviour, and optimistic intelligence quotient among college students of various grades. Overall, upperclassmen exhibited higher trait mindfulness than underclassmen; freshmen exhibited the lowest rumination levels, while sophomores demonstrated the highest; freshmen showed the strongest exercise behaviours, whereas juniors displayed the weakest; sophomores had the weakest exercise behaviours, while juniors exhibited the strongest (see Table 2).

Pearson correlation analysis was conducted on all variables to validate the potential relationships among trait mindfulness, rumination, exercise behaviour, and optimistic intelligence quotient. As shown in Table 3, significant negative correlations were found between trait mindfulness, exercise behaviour, and optimistic intelligence quotient (p < 0.01). This indicates that higher levels of trait mindfulness are associated with stronger exercise behaviour and optimistic intelligence quotient, while lower levels of rumination are observed, thereby supporting Hypothesis H1. The strong statistical significance of these correlations indicates suitability for subsequent mediation analysis and supports further hypothesis testing.

Due to significant correlations among all variables, multicollinearity may exist, potentially leading to unstable results. (Multicollinearity refers to the strong linear relationship between two or more independent variables in a multiple linear regression model, resulting in inaccurate parameter estimates and reduced explanatory power.) Therefore, this study conducted collinearity diagnostics and standardized (Z-scored) all predictor variables in each subsequent equation. Results indicate that all variance inflation factors (VIF) for predictor variables (ranging from 1.439 to 4.100) are below 5. Thus, the data exhibit no multicollinearity issues, meeting the conditions for further chained mediation effect testing.

Since trait mindfulness, rumination, exercise behaviour, and optimistic intelligence quotient all showed statistically significant correlations (P < 0.01), they met the criteria for mediation effect testing. Using trait mindfulness as the independent variable, rumination as the dependent variable, and introducing exercise behaviour and optimistic intelligence quotient as mediating variables, we examined whether trait mindfulness exerted a significant mediating effect and chain mediating effect on exercise behaviour. This study employed the PROCESS macro program for SPSS provided by Hayes (37), utilizing Model 6 (mediation model) with grade and gender as control variables to test the chain mediation model effects. Bootstrap samples were set to 5,000 with a default 95% confidence interval; results were considered significant when the confidence interval did not include zero.

Results indicate that before including mediators, trait mindfulness significantly predicted rumination (β = −0.185, t = −2.750, p < 0.001). After including the mediating variable, the predictive effect of trait mindfulness→rumination remained significant (β = −0.062, t = −1.693, p < 0.001). Specifically, the path coefficient (β) for trait mindfulness→exercise behaviour was 0.120, exercise behaviour→ rumination was 0.267, trait mindfulness→optimistic intelligence quotient was 0.031, optimistic intelligence quotient→rumination was 0.412, and exercise behaviour→ optimistic intelligence quotient was 0.015 (Table 4).

Using bootstrap sampling with bias correction, the total mediation effect was examined. As shown in Table 5, the total mediation effect value was −0.040, with the 95% bootstrap confidence interval not containing zero. This indicates that the total mediation effect of trait mindfulness on rumination among college students is significant. The total mediating effect comprises three pathways: Ind1: “trait mindfulness → exercise behaviour → rumination” with an effect value of −0.005; Ind2: “trait mindfulness → optimistic intelligence quotient → rumination” with an effect value of −0.003; Ind3: The effect value of “trait mindfulness → exercise behaviour → optimistic intelligence quotient → rumination” is −0.093. Among these, the Bootstrap 95% confidence interval does not include 0, indicating that the chained mediating effect is significant. The results of the three paths respectively validate Hypothesis 2, Hypothesis 3, and Hypothesis 4.

This study found a significant negative correlation between trait mindfulness and rumination among college students. After controlling for variables and incorporating mediating variables, trait mindfulness significantly predicted rumination negatively, indicating that higher levels of trait mindfulness correlate with lower rumination levels. Hypothesis H1 was thus validated. The trait mindfulness coping model posits that mindfulness reduces rumination by altering individuals' responses to negative emotions and thoughts (8), thereby improving mental health (7). It also helps individuals recognize and interrupt rumination patterns, enhancing acceptance and regulation of negative emotions to effectively lower anxiety levels (10). This model provides theoretical support for understanding mindfulness's role in rumination. Research indicates that trait mindfulness, as a psychological process focused on nonjudgmental awareness of the present moment, can help curb rumination (11). In summary, these findings align with previous research (10, 11), confirming that trait mindfulness effectively reduces rumination levels among college students.

Mediating variables are crucial for explaining how trait mindfulness influences college students' rumination. This study constructed a mediation model of trait mindfulness influencing rumination in college students, with exercise behaviour and optimistic intelligence quotient as mediating variables. The finding that exercise behaviour mediates the relationship between trait mindfulness and rumination indicates that mindfulness negatively predicts rumination in college students (17) while also indirectly influencing rumination levels through exercise behaviour. Related research on the relationship between mindfulness and health behaviours reveals that mindfulness positively promotes health behaviours (15). Studies indicate that trait mindfulness can effectively enhance exercise behaviour through state mindfulness and intentional self-regulation, with higher trait mindfulness levels correlating with stronger exercise motivation (13). For instance, mindfulness-based recovery therapies can top-down improve unhealthy lifestyles like alcohol abuse and promote exercise behaviour through cognitive control. Trait mindfulness enables exercisers to reach higher exercise stages (16). Furthermore, engaging in moderate physical exercise can effectively reduce an individual's rumination.

Optimistic intelligence quotient is not merely an attitude but a capability—a power to influence or alter an individual's future. It is a factor more decisive of personal destiny than IQ or EQ (35). As a positive intervention method that enhances optimistic intelligence quotient, mindfulness training helps develop effective emotional regulation strategies (24), enabling individuals to face negative events with greater optimism and confidence (22). Extensive research has promoted mindfulness training as a positive intervention to enhance physical and mental health and well-being across schools, families, and communities. Implementing mindfulness training in education can elevate college students' optimistic intelligence quotient levels and foster a positive, optimistic learning environment (23). Furthermore, college students with high optimistic intelligence quotient are adept at deriving positive emotions from negative events (20) and recover more quickly from setbacks (21).

The Bootstrap method validated the chain mediation effect of exercise behaviour and optimistic intelligence quotient in trait mindfulness's negative influence on college students' rumination. The constructed chain mediation model offers new perspectives for further advancing and understanding the relationship between trait mindfulness and rumination among college students. Research indicates that exercise behaviour positively influences college students' optimistic intelligence quotient, contributing to its enhancement (28). As exercise duration and frequency increase, students’ optimistic intelligence quotient levels steadily rise. Exercise behaviour serves as both the mediating variable and the core value through which optimistic intelligence quotient promotes directional mental health development (25), exhibiting a significant positive predictive effect on college students' optimistic intelligence quotient (26). This stems from the fact that engaging in exercise behaviour allows college students to experience overcoming physical fatigue and challenging themselves, thereby enhancing their stress resilience. This fosters positive thinking and emotions, leading to heightened positive affective experiences (30). Evidently, exercise behaviour plays a significant role in cultivating college students' optimistic intelligence quotient.

This study examines the relationship between trait mindfulness and rumination among college students. The constructed chain mediation model reveals the underlying mechanism through which trait mindfulness influences rumination in university settings, offering new perspectives and insights. This holds significant theoretical and practical implications for reducing rumination among college students. However, the study also has several limitations: (1)

First, the study sample consisted of college students from selected universities in Liaoning and Henan provinces, excluding students from other regions and other groups. The representativeness and generalizability of the findings require further expansion. Future research should broaden the scope by recruiting a more diverse sample to examine the applicability of these conclusions. Additionally, the use of convenience sampling may introduce bias risks. Liaoning and Henan provinces represent regions with moderate economic development. Student traits such as trait mindfulness, exercise behaviour, optimistic intelligence quotient, and rumination levels may differ in regions with higher or lower economic development. This could potentially affect the universality of the findings.