Regular physical activity (PA) and the reduction of sitting time or a predominantly sedentary lifestyle are associated with improvements in physical, psychological, cognitive, and functional health [1–3]. The World Health Organization (WHO) recommends a weekly moderate exercise time of 150 min per week for older adults to obtain health benefits [4]. Percentages of older adults aged 60 years and above meeting the recommended PA levels ranged from 2 - 83 %, depending on the study. In 45 of the 53 studies included in the systematic review by Sun and colleagues that reported PA levels for adult populations, 20 - 60 % of older adults met the recommendations [5].

Determinants of PA initiation and maintenance can be categorized into personal, psychological, social, and environmental factors. Personal determinants playing a role in the uptake and maintenance of PA include age (i.e., older adults become less active with increasing age), gender (i.e., men tend to be more active than women), and overall health status (i.e., good overall physical health is predictive of higher levels of PA) [6, 7]. Psychological and social determinants of PA include self-efficacy, perceived benefits, enjoyment, intention, and readiness to change behavior. Specifically, persons who report high levels of self-efficacy and have developed an intention (or readiness) to engage in the behavior, who perceive PA to be beneficial to their health, and who report enjoying PA tend to engage more frequently in the behavior. Determinants concerning the social or physical environment include the availability of a social network (i.e., having a good social network and/or a sports partner is associated with PA initiation and maintenance) and social support (e.g., receiving social support from significant others is associated with an initiation of PA), perceived safety of the environment, and perceived access to sports/exercise facilities [6]. Thus far, a multitude of studies addressing the above mentioned determinants of PA to varying degrees have demonstrated the effectiveness of PA interventions.

Furthermore, interventions providing information on PA as print versions or face-to-face have a long tradition [8–10]. However, the increased use of the internet and mobile technologies in recent years may open new opportunities to promote PA in adult populations, including older adults [11]. eHealth is defined as “the transfer of health resources and health care by electronic means” [12]. This includes, among other things, the delivery of health information through the internet and mobile technologies. In the elderly population, a growing number of individuals use electronic devices, such as computers, smartphones, or tablets [13]. Results of previous systematic reviews and meta-analyses indicate that eHealth interventions are an effective intervention vehicle to promote PA among adults of various ages [14–18]. However, in the majority of the studies included in these reviews, PA interventions were combined with other intervention components, such as recommendations for lifestyle changes, either for weight loss or the management of type 2 diabetes. Furthermore, the evidence for the effectiveness of these interventions in regard to PA promotion among older adults is mixed. While some studies suggest that eHealth approaches effectively promote PA [19–21], other studies report no beneficial effect of eHealth PA interventions compared to non-eHealth interventions [22, 23]. The aim of this systematic review and meta-analysis is to compare the effectiveness of eHealth interventions solely promoting PA in older adults aged ≥55 years with either a no intervention or a non-eHealth intervention. This systematic review protocol will adhere to the reporting guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement [24]. The completed PRISMA-P checklist can be found in the Additional file 1.