Motivate me to exercise with you: The effects of social media fitness influencers on users' intentions to engage in physical activity and the role of user gender

Objective Social media fitness influencers are evolving into a new digital form of health communicators whom consumers might turn to for assistance with more physical activity and exercise at home, especially in the current COVID-19 crisis. Drawing from source credibility theory, social cognitive theory, protection motivation theory and literature on physical activity, physical fitness and gender, we analyse how male and female users' evaluations of social media fitness influencers and user health-related variables impact intentions to exercise with the social media fitness influencer. Methods Two consecutive studies using male and female YouTube fitness influencers were carried out. Structural equation modelling was conducted to test the proposed models and estimate the path coefficients. Results Study 1 (N = 507) shows that the respective influencer's perceived trustworthiness, expertise and attractiveness are important for the influencer's evaluation, and that it is the perceived motivating power rather than the attitude toward the influencer that increases intentions to exercise for male and female users. Study 2 (N = 445) extends Study 1 and shows that physical fitness, training involvement with YouTube fitness videos and lower health increase behavioural intentions. A more negative body image also raises intentions to exercise, but only among female users. Conclusion Social media fitness influencers who are perceived as trustworthy, as experts and as attractive, can be effective for increasing men's and women's physical activity. Perceived motivating power of the influencer emerged as a key variable that predicts intentions to exercise. User health-related variables have different effects on intentions to exercise for men and women.