The current research aims at designing a recommended training program for basic endurance (En-1(to identify the basic endurance level of junior swimmers, with reference to anaerobic threshold (AT( improvement percentages of basic endurance and digital levels of junior swimmers, effects of improving basic endurance on the digital levels of junior swimmers and correlations between basic endurance and the digital levels of junior swimmers. The researcher used the quasi-experimental approach (one-group-design) with pre and post- measurements. Research community included 20 junior swimmers (male/female) from Tanta Sports Club (12-13 years) who are registered in the Egyptian Federation of Swimming. Sample of 12 male junior swimmers was purposefully chosen and 2 other swimmers from the same research community and outside the research sample were chosen to the pilot study. The researcher concludes the following: Canonizing the (En-1(training load improves the digital levels of 400m, 200m and 100m freestyle. Canonizing the (En-1) training load,with reference to anaerobic threshold, improves total distance of T-30 test as a positive indicator for improving endurance. Canonizing the (En-1) training load, with reference to anaerobic threshold, improves 100m free style digital level on (En-2). There are significant correlations among all durations of 400m, 200m and 100m and total distance of T-30 test for junior swimmers. There are significant correlations among all duration variables of 400m, 200m and 100m.