It's a great question Hannah...

"Does wanting to run more miles in a shorter amount of time always cause you to tighten and does this always come from ego?"

The way you describe it suggest potentially that it does come from the ego - but not necessarily. That depends on your experience whilst you're doing it and what you want to get.

So, why are you wanting to run more miles in a shorter amount of time? Is it because it boosts your self esteem or you need to prove something? (which would be ego). Or does pushing yourself in this way feel like an ever greater expression of you? Does it feel better and better (is there an increasing sense of 'rightness' to it that just feels good for its own sake?

I can recall Chris's rowing experience - I can actually regress into the feelings. There was great joy in the constant feeling of improvement. However this was also masked by needing to prove something against other people - with its root cause in lack of expressed love from the father figure.

My advice would be to explore running as a feeling. Constantly asking yourself "how can I advance my technique so that it continually feels better?". If you work on stamina or muscle strength, always be present in the feelings - penetrate into them and become as-One with them. You may well find that significantly changes the dynamic in a positive way and simultaneously advances your consciousness.

A fascinating exploration indeed!

Open :-)

PS - I felt to add something on competing. It's another fascinating issue. Only the ego competes to beat another. However, competition also provides a feedback loop to the soul on how it is performing and how it might improve. So just because one competes, doesn't necessarily mean that's ego. Only the person themselves would truly know for what reason they are doing it.