The association of context-specific sitting time and physical activity intensity to working memory capacity and academic achievement in young adults

Background: To examine combined associations between self-reported context-specific sitting time (ST) and physical activity (PA) with working memory capacity (WMC) and academic achievement in a sample of Spanish adults. Design: Undergraduate students (n=371; 21 years +/- 3 years, 44% female) were recruited from University of Vic-Central University of Catalonia. Methods: Participants completed a 54-item survey that assessed socio-demographic variables (e.g. age, gender, academic year), min/week of light (LPA), moderate (MPA) and vigorous (VPA) intensity PA (International Physical Activity Questionnaire), min/day of domain-specific ST (Last 7 days sedentary behavior questionnaire) and academic performance (grade point average). WMC was assessed through a multiple complex span task that included: Operation Span, Symmetry Span and Rotation Span. These tasks interleave a processing task with a short list of to-be-remembered items. General linear models-adjusted by PA, ST and gender-assessed combined associations between ST and PA with WMC and academic achievement. Results: Performing more than 3h/week of MPA was related to increases inWMC (P < 0.001). However, PA was not associated with academic performance. More than 3h seated on a weekend day while performing non-screen leisure activities were related to reduced WMC after adjusting for PA (P = 0.012). Similarly, >3 h/weekday spent seated in these sedentary activities or in leisure-forms of screen time were inversely associated with academic performance regardless of PA (P = 0.033; P = 0.048). Conclusions: MPA may benefit working memory; however, specific domains of leisure-time sedentary behavior may have an unfavorable influence on working memory and academic performance regardless of time spent in PA.