Introduction: During weekdays, primary school children spend the majority of their waking hours at school, where they sit 50 to 70 percent of the time (Abbott 2013, Aminian 2015, Clemes 2016). This has led to multiple stakeholders encouraging schools to integrate more physically active learning methods into their teaching and learning program in order to break up and reduce sedentary behavior. Due to the ever-increasing pressure of academic performance and reaching educational targets as formulated by the government, schools mostly focus on academic core subjects such as reading, language, and mathematics (McMurrer & Kober, 2007). Consequently, teachers face a conundrum of how to balance physical activity with academic instruction (Christian et al., 2015; Parks, Solmon, & Lee, 2007). This conundrum can be overcome by using an approach that effectively combines physical activity and academic learning in the normal classroom instruction time (termed “physically active lessons” (PAL)). PAL intend to teach academic content through the use of physically active teaching methods (e.g. mathematics bingo, relay race, task trail) and as such they are distinct from short physical activity breaks, which are not linked directly to educational outcomes. Two recent reviews show encouraging evidence of improved physical activity and educational outcomes following physically active lessons, and both students and teachers enjoyed and reacted positively to these teaching methods. However, too few studies exist to draw firm conclusions and there is a knowledge gap regarding factors decisive for a successful implementation (Martin & Murtagh, 2017; Norris, Shelton, Dunsmuir, Duke-Williams, & Stamatakis, 2015; Turner & Chaloupka, 2017). To this end, we investigated factors influencing the implementation of physically active lessons in elementary schools.

Background: The Active Smarter Kids (ASK) study was a seven-month cluster-randomized controlled trial investigating the effect of school-based physical activity on children’s academic performance (Resaland et al., 2015). 1129 fifth-grade children from 57 elementary schools in Sogn og Fjordane County, Norway, were randomized by school to either intervention or control in the 2014/2015 school year. Control schools were offered the same support and teacher training the following year. The ASK intervention is designed to increase physical activity (165 min/week in addition to normal activity curriculum) and was comprised of three components: 1) PAL in the core subjects, i.e. Norwegian, mathematics and English, carried out mostly in the school playground; 2) physical activity breaks during classroom lessons; 3) physical activity homework prepared by the teachers. The study observed a significant effect on numeracy for children in the lowest tertile of numeracy performance (Resaland et al., 2016).

Objectives: The aim of this qualitative study was to explore teachers and principals’ perceptions of factors that influence the teachers and principals with regard to implementation of PAL in elementary schools.

Methods: Eleven face-to-face semi-structured interviews were conducted 12 months after the cessation of the ASK intervention with seven teachers, of whom four females and three men's, and four principals', of whom three females and one man, from four elementary schools in Norway. The interviews were conducted during the school day at the principal's office and in private meeting rooms with the teachers and lasted in average 30 minutes. Data were analysed using content analysis.

Results: Three themes emerged as central to teacher's implementation of PAL in the schools' teaching and learning program, including 1) time/workload, 2) school environment and 3) support. Time (e.g. scheduled time for planning, development of materials, execution compared to competing tasks) was perceived as the biggest barrier to implementing PAL. Both teachers and principals are experiencing an ever-increasing academic pressure, which challenges the facilitation of allocating more time to PAL and it ultimately becomes a matter of prioritization. However, allocating timetable sessions for PAL, and commitment and unity among the colleagues in advance of implementation were emphasized by teachers as important factors to overcome time constraints. Further, teachers experienced that the presence of a need for a change of current practice is an important factor for teachers in order to successfully implement PAL. Unwillingness to share knowledge and experience or an absence of such culture among teacher colleagues were experienced as barriers. Teachers experienced the participation of the school management as vital for implementation. Principals need to support PAL, motivate the teachers and carry out democratic processes where the teachers are able to get the opportunity to influence the implementation. If PAL was adapted to the school's philosophy and stated goals, teachers stated a greater likelihood of thorough implementation. Credible and motivating support, in addition to detailed information about PAL, from stakeholders, researchers or academia were experienced from both teachers and principals as a crucial factor for implementation.

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