The interplay of exercise, immunity, and suboptimal health in college students: an integrative narrative review with public health implications

Background The immune system, vital for pathogen defense and tissue repair, is strongly influenced by lifestyle. With declining physical activity and rising chronic disease burdens, the role of exercise in modulating immunity has drawn growing attention. College students, undergoing critical life transitions, are susceptible to lifestyle-related risks such as sedentary behavior, insufficient sleep, and high psychological stress, which often lead to suboptimal health status. Population risks in college students Immune and inflammatory risks are a concern among college students: prolonged sedentary behavior, chronic sleep deprivation, and elevated psychological stress frequently co-occur. Each of these behaviors is associated with low-grade inflammation and altered immune regulation in adults, and their clustering in students is therefore a reasonable basis for concern, although the strength of the association with immune outcomes has seldom been measured directly in this group. The term suboptimal health status is used in this review as a self-reported functional syndrome, defined in Section 3.4, rather than as an established clinical entity. Effects and mechanisms of different exercise behaviors We examine the effects of different physical activities on immune function, chronic low-grade inflammation, and suboptimal health status in college students, outlining the basic framework of exercise immunology and distinguishing acute from chronic exercise responses. Evidence is categorized by exercise type, including moderate-intensity aerobic exercise, high-intensity training, resistance training, and mind–body practices, and their mechanisms, such as myokine-mediated anti-inflammatory signaling, immune cell mobilization, fat loss, and the mediation of sleep and emotion, are summarized. Methodological challenges We critically discuss the methodological challenges in this field, separating two sources of disagreement that are often conflated: study design, which determines the causal question a study can answer, and measurement method, which determines how accurately exposure and outcome are captured. We analyze the limitations of each, including the inability of cross-sectional studies to establish causality, measurement bias in self-reported data, and ecological validity and compliance issues in trials, and we note how the same distinction applies to outcome assessment, from self-reported symptoms to immune-cell, cytokine, and clinical infection measures. Research gaps Notable gaps are identified, including the “population mismatch” whereby findings from other populations are extrapolated to college students, limitations in sample selection and measurement standardization, and the lack of individualized and comprehensive intervention studies. Research significance and public health implications This narrative review underscores the importance of understanding the relationship between exercise and immunity in college students, provides an overview of current knowledge, identifies critical limitations, and proposes future directions. Evidence was assembled through a structured narrative search, and findings obtained directly in college students are distinguished throughout from those extrapolated from athletic or clinical populations. It also offers public health implications for Chinese university settings, emphasizing targeted health education, campus-wide exercise interventions, sedentary behavior reduction, and integrated sleep and stress management to promote student wellbeing.