It's not always possible to train in a pool and it is important to workout when you are not swimming, this training can be called dryland training. Stretching and strengthening the muscles you use during swimming is very important. CoachUp Nation shares some of their certified exercises that work your core, arms and legs when you are on dry land:
- squats
- flutter kicks
- planks
- jumprope
- medicine ball
- huddle up
See Dryland Workouts For Swimmers for detailed instructions.