hiya mate. i do thai boxing and we use skipping a lot to keep fit. it is really good for warming up and good for CV fittness. but at the end of the day the best way to train is to practice the things you will be tested on eg Running, press, push and pull ups. it could be a good idea to use skipping when doing circuits. i wouldnt say skipping helps running directly but in the long run it will help your general fittness.