Generally, to get aerobic conditioning from swimming, you need to

The answer is "you need to keep up a pace that makes you feel pleasantly tired, but not exhausted".

A strong aerobic base implies that you have the continuance to swim in the pool or the sea for quite a while at direct force. Swimming at a strong aerobic pace enhances your body's capacity to convey oxygen to your muscles. The best approach to enhance your wellness base is via preparing at the strong aerobic level for expanded periods.

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