I too suffer from a blocked/muffled ear (left) when doing heavy cardio exercises. It's a never strange sensation & all you can hear it you breathing & (sometimes) heart beat.
My GP doesnít have any ideas why this is happening & thinks it must be an inner ear problem.
I'm a fit 27 year old male & I had this problem for years!
Also, I don't know if this is linked, but I have a problem breathing through my left nostril (would require an operation to fix).
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