The analysis of existing information on physical activity and fitness as elements of health and well-being reveals that they are achieved particularly effectively in contact with nature. Physical education lessons outdoors, as a form of healthy training, have been performed in numerous countries for years, providing a response to the traditional indoor model of this kind of education. The purpose of this paper is to clarify the relationship between the participation of students in outdoor and indoor lesson activities and the change in their physical fitness. 220 students participated in an experimental study. The experimental group, which did exercise usually in open spaces, included 49 boys and 54 girls. The control group, which exercised inside school, consisted of 63 boys and 54 girls. The study period lasted two years and involved the fifth and sixth form of primary school. Experimental group subjects were 11.26 years old (±0.32) during the initial test, and the control group individuals were 11.28 years (±0.32). During the final test, the average ages of experimental group subjects was 12.96 years (±0.32), and 12.98 years (±0.32) in the control group. The International Physical Activity Test was applied in the study. The differences between the levels of particular components of physical fitness were not statistically significant during the initial measurement (p-values ranged from p = 0.340 to p = 0.884). After two years of outdoor physical education lessons, there was revealed a considerable increase in the speed, jumping ability, and aerobic endurance of the students. Statistically significant differences were observed in these three tests, including running speed (p = 0.001), legs power (p = 0.001), and endurance (p = 0.000). The findings encourage one to continue pedagogical experiments regarding physical activity in outdoor natural environments.
Keywords: natural environment; outdoor and indoor physical education (PE) lessons; physical activity (PA) physical fitness.