Just these past few days when I play Badminton, I found that for the first 2 hours, after consequently playing games which include smashing and hard hit, my inner lower bicep hurts. The pain I felt doesn't feel that it comes from the elbow. It is exactly right above it which I conclude it's a lower bicep. When it hurts, my hand feel numb and trembles when I hold my racquet. However, as I continue to play for the next 2 hours, the pain gradually decreases - at some point, completely.