Leaks while running are common but not normal. I had a client who could not run any more than 4 km because she always had a leak at that point.
I educated her about balanced breathing patterns and how the paradoxical breathing can kick in with her running. She observed her breathing while she was running at the 4 km mark and realized she was breathing in a reverse way (her words). I asked her to explain more about it and she said that she feels she bears down (pushes down) during exhale at 4 km of running and rather than being able to gather and push the breath out without it.
And guess what, when you can observe any wrong pattern in your body, the first thing your body wants to do is change it. She could change it while in the middle of the run and ran 7 km without any leaks. It's amazing to use something so subtle and still get the results we want.
Observation is the key, if you catch it early, you can change it before it causes any damage.