An individual with depression may experience symptoms such as the mood issues, loss of interest or pleasure, a lack of energy, feelings of guilt or low self-esteem, disturbed sleep or appetite, and difficulty concentrating [1]. There is a higher risk of disease associated with depression, which adversely affects human health and well-being [1]. It has been well-documented that depressive symptoms have a detrimental impact on psychological and physical health from infancy through to old age [2,3]. For example, depression in childhood has a long lasting negative effect on mental health later in life [4], and can lead to neurological abnormalities in the aging population [3]. Specifically, the detrimental health outcomes of high levels of depression include diabetes [5], cardiovascular disease [6], cancer [7], and other health problems [8]. Furthermore, depression is an important predictor of cardiac mortality and morbidity, such as cardiac functioning and coronary heart disease [9]. Depression also affects biological factors and, consequently, contributes to physical disability [10] (see Fig. 6).

The high prevalence of depression has been established in the existing evidence. According to the World Health Organisation, the prevalence of depression is increasing globally, and 4.4% of the world's population was predicted to suffer from depression in 2015 [11]. A systematic review synthesised 14,866 non-duplicate articles, and an estimated 19.1% pooled prevalence of depression was observed in children, adolescents, and young adults [12]. Further, the weighted mean prevalence of depression was 30.6% in university students [13], while the prevalence ranged from 0.9% to 49% in the aging population [14]. Notably, evidence from a scoping review has shown that 20% of the participants suffered from depression during the COVID-19 pandemic [15]. The potential factors leading to the increasing prevalence of depression are mainly due to the environmental changes, including high prevalence of obesity, unhealthy diet, insufficient physical activity, and inappropriate light and lack of sleep [16]. To reverse the situation on the large number of patients suffering from depression or a group of people at the risk of developing depression, clinical practice or evidence-based recommendations strongly suggest that doing more physical activity (PA) can provide a feasible and effective approach against depression [[17], [18], [19], [20], [21]]. There has been a great amount of literature examining the relationship between PA and depression [17,18,22,23], especially review studies [[24], [25], [26]]. This is because review studies can not only summarise in-depth research knowledge, but also allow for the determination of future research directions. This type of study design has, thus, become increasingly popular, and more researchers have studied PA and depression using reviews [[27], [28], [29], [30], [31]]. Additionally, considering some unknown research issues in the context of PA and depression, more research in this field is required. The use of the bibliometric analyses serves as a useful analytical approach to comprehensively summarise the current state of review studies on PA and depression is [32].

Bibliometric analysis is centred on the citations of publications [32]; referring to the number of research articles that cite a given published article [33,34]. The total number of citations not only establishes the academic impact of a specific article in the field, but also serves as a basis for determining a journal's impact factor, which can then be used as an indicator for assessing its quality [33,35,36]. Across the vast majority of research fields, a research article with more than 100 citations can be considered a high-quality paper [37,38]. On the basis of citation analysis, many studies have attempted to conduct bibliometric analysis to better understand recent scientific progress and research trends in a particular subject area [32,39,40].

Given that the publications concerning PA and depression in the literature are evolving rapidly, the relevant research scope and characteristics are worth studying. Therefore, the main objective of this study was to identify the 50 most-cited review articles focusing on PA and depression, using a citation analysis. The second aim of this study was to visualise the most active countries/nations, author groups, and most frequent keywords using the VOSviewer software. This kind of analysis can help to deepen our understanding of the current state of research on PA and depression and is expected to offer novel insights into future research.