Empirical studies have shown that social capital [3,4], social support [5,6], self-esteem (sEstee) and self-efficacy (sEffic) [7,8] reduce the indicators (or effects) of general stress on university students. Studies on AS conducted in Latin America focused on their correlation with psychological variables—social support, anxiety, depression, suicidal ideation, coping styles, sEffic and sEstee—as well as sociodemographic—sex, socioeconomic level and type of family—[9,10]. However, there are no specific studies on the relationship between social capital and AS. Outside of Latin America, Changmin Yoo [11,12] found that bonding social capital (BSC) decreases indicators of AS in university and secondary school students.

This paper aims to generate a model that explains the effect of social capital on AS. To this end, initially, the involved constructs are precisely defined, then, an explanatory model is proposed.

1.1. Literature ReviewFrom the cognitive model, AS is a systemic process by which demands—internal and/or external—of the university environment are evaluated by the students as a threat to their integrity—biological and psychological—and to the quality of their meaningful social relationships when they perceive that they do not possess the necessary resources—external and/or internal—to meet the demands; in other words, stress only occurs when demands exceed their coping capability. External demands correspond to expectations, requests or requirements of significant people, as well as to social demands or limitations; internal demands are personal expectations based on one’s own values, goals, and beliefs. On the other hand, external resources are provided by the social environment and are both tangible, i.e., material, and intangible, i.e., socioemotional; finally, internal resources correspond to personal characteristics, i.e., emotional self-regulation, knowledge, problem-solving ability, sEffic and sEstee) [15,16,17].The perception of threat produces a systemic imbalance between the student and his environment due to the possible loss of resources that allow survival, either directly or indirectly [18,19]. Imbalance manifests itself in symptoms of AS: physical, psychological and behavioral. Physical symptoms include sleep disturbances, chronic fatigue, headaches, muscle aches and digestive problems. Psychological symptoms (PsyS) include cognitive symptoms, such as problems with concentration, attention, memory and reasoning, as well as emotional symptoms, such as impatience, impulsiveness, the inability to relax, irritability and sadness. Behavioral symptoms include changes in food intake, increased frequency of personal conflicts and isolation [15,20,21].Symptoms are the most objective indicators for assessing stress levels. In addition, they are the best predictors of the consequences of stress on mental and physical health, both in the medium- and long-term [22,23,24]. As far as AS is concerned, PsyS (cognitive as well as emotional) are the most common and have a greater relationship with stressors [25,26].In the presence of symptoms, students develop coping strategies to regain balance; coping is defined as “a dynamic process, cognitive and behavioral, aimed at activating the necessary resources to meet the demands” [15] (p. 20). These resources, both internal and external, are related to social networks, social capital and social support.From a structural relational approach, the social network is a structure made up of a defined set—i.e., with clear limits—of individuals or groups connected to each other by multiple ties or relationships; it is a product of continuous transactional interactions of tangible and intangible resources [27,28,29]. Social networks are the basis of social capital [30,31].Social capital is the sum of resources, potential and real, tangible—e.g., money, titles, real state—and intangible—e.g., education, social status, political power—accumulated by a person through their access to a network of stable, reliable and reciprocal social connections. In other words, social capital includes: (a) the embedded available resources, derived from the exchange process that takes place in the social network. (b) The social network itself, which is considered to be an additional resource. These resources are used to meet objectives, meet needs or to cope better with unfavorable situations [32,33].From the configuration, characteristics and functions of the connections of social networks and social capital can be divided into dimensions. The most widely used in research are: (a) BSC and (b) Bridging social capital [30,34,35]. BSC has a bigger effect on AS [11] and on general stress [36] in university students, reducing stress symptoms.Several studies demonstrate that psychological symptoms of stress are associated with a low level of social capital. Thus, a higher prevalence of these symptoms was found in Chinese university students with reduced social capital (i.e., low level of economic and social resources) [37]. In addition, a higher level of the same symptoms (i.e., depression, anxiety) was found in Chinese medical students with low level of social capital (i.e., living alone, with economic difficulties, low access to social support and with a dysfunctional family network) [38]. Finally, these symptoms (i.e., depression, anxiety) are higher in low-income high school students in Norway [39].The process by which accumulated resources (i.e., social capital) are employed to meet needs is called social support. More precisely, social support is “the process (e.g., perception or reception) by which the resources of the social structure are used to meet functional (e.g., instrumental and expressive) needs in routine and crisis situations” [40] (p. 383). This process can be tangible (i.e., actual receipt of resources) or only perceived (i.e., to assume that such resources are available or may be received thereafter) [41]. BSC is the main source of social support [41,42,43,44], as it is based on strong social ties or relationships, where contact is frequent, trust and reciprocity are high, and more intense emotional attachments are held [31,45,46].Depending on the needs covered by social support, it can be divided into: (a) Socio-emotional support (SES), which is affective as well as expressive-informative and includes the reception and/or perception of being able to receive affirmations and demonstrations of love, value and acceptance, as well as listening, advice, guidance and feedback. (b) Instrumental support, which is the reception and/or perception of receiving material resources or services [41,42,43,44].SES is shown to have more effects on AS [12] and general stress [36,47] in university students, reducing symptoms or indicators of stress. This happens because social resources—i.e., social capital—are channeled through SES to meet expressive and emotional needs, generating two internal—i.e., psychological—resources, basic for stress coping: sEffic and sEstee [48,49,50,51].Perceived sEffic is shaped by a person’s beliefs regarding the ability to regulate his/her own performance and be able to control events affecting their lives [52,53]. Furthermore, “efficacy beliefs influence how people think, feel, motivate and act” [54] (p. 2). On the other hand, sEstee is the “positive or negative attitude toward the self as a totality” [55] (p. 141). It includes two components: (a) Cognitive, that is, beliefs about oneself, and (b) Affective, the feelings that these beliefs generate. In addition, the affective component determines the intensity and its positive or negative character. In addition, sEstee is the result of a self-assessment primarily linked to sEffic and social acceptance; that is, sEstee depends on the degree to which a person is considered accepted on their social networks for possessing attributes that are valued on the same network [44,55,56]. For this reason, sEffic increases the levels of sEstee [57,58]. In university students, sEffic reduces levels of AS [59] and general stress [60,61] while sEstee only reduces the latter [47,61,62].