Since the 2012 Lancet Series on physical activity, progress regarding this topic has been negligible at global level. Thus, improving physical activity levels in specific populations through new methodologies is positioned as a priority. The aim of this study was to determine the effects of a physical activity intervention on body fatness composition, and measured and self-reported physical fitness components based on the use of a smartphone app. The investigation included 100 Spanish university students, cluster-randomized into the smartphone app intervention group or a control group (n = 35 and n = 31 respectively, after applying exclusion criteria). The physical activity intervention comprised a 9-week programme designed to promote a healthy physical activity pattern using a smartphone app. Specifically, an mHealth approach was taken containing five BCTs. The results showed that the intervention group improved their physical fitness (F = 8.1, p = .006) and reported better general scores in self-reported physical fitness (F = 7.4, p = .008) over time, in comparison to the control group. However, the intervention group did not show any changes to their fatness. Further research is needed to disentangle which BCTs are more effective to achieve physical health improvements when using physical activity apps.
Keywords: body composition; exercise; lifestyle; mobile applications; physical fitness; smartphone applications; undergraduate students.