To resume your swimming training programme, you can start with a warm-up of 400-600m low-frequency freestyle. Then you can perform some technique drills, for instance, swim with single arm drills freestyle for 25m while put the other hand aside your hip or put it at the front, and change hand for the single arm drills for another 25m.
For butterfly strokes, you can start with 5 strokes of the left hand and 5 with a right hand and thus, 5 full strokes. For backstroke, it is the same as the butterfly stroke. However, it is a little bit different for breaststroke. You can do the stroke with 3-2-1 breaststroke legs. Hold your breath for swimming 3 breaststroke legs and then a full stroke, then swim 2 breaststroke legs and a full stroke and one full stroke. For the swimming drills, you can decide the stroke you want to practice and make it to 400m.
After you have finished, you can do a 10-12 times 25m sprint. When you reach the 25m, swim slowly to cool down yourself to another side of the pool and start it again. It is better to set a time for yourself to do the swimming training programme step by step. For example, you can set 1 minute for each sprint including the cooldown to keep up the heart rate.
Advice by Sport