Fitness first and then swimming, basically focusing on fitness, because swimming is already very sour, and you can't concentrate on it. Swimming is to do active aerobic activities to relax and discharge metabolites such as lactic acid produced by fitness.

If you swim first and then exercise, the lactic acid accumulated after exercise needs time to relax. Moreover, after swimming, there is already physical exertion, which is not suitable for a large number of fitness activities.

Personally, I mainly swim. So after swimming, I will practice the external circumflex muscle of the back and the external oblique muscle of the abdomen slightly to improve the swimming shoulder and enhance the core stability respectively. The time is not long, and the weight is not very big, about twenty minutes. I have been strengthening freestyle kicking recently, so I added the exercise of triceps femoris.

As for the specific purpose of losing weight, I don't have much experience, just stretching the corresponding parts.

Under normal circumstances, you should be prepared to go into the water after the activity to prevent cramps in the water. Of course, some people prepare for outdoor activities, mainly depending on their own situation. Before entering the water, you should rub the water from the swimming pool on yourself to feel the water temperature, and then you should do some preparatory activities in the water (swim slowly first) before you can start swimming or even participate in swimming competitions.