Running I find is alot better exercise than swimming, it is easy to become lazy when swimming if you are not diciplined, and you will just stop and rest, or tread water. Running when the treadmill is going or you have a circuit to finish just pushes you that bit further. Running does not hurt your joints if done correctly, using the standard running techniques.
Yous should run first and then go swimming, the swimming can be your cool down exercise (after you've pushed yourself at it for a while)
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