I was running on the treadmill Tuesday morning and hit my hand at the middle knuckle on the cross bar. It didn t feel particularly hard, so I continued to run. After 15 minutes I looked at my knuckle and it was swollen to the size of a grape. I iced it. Later that day the swelling was less but the entire top of my hand is now discolored. The discoloration covers from the middle knuckles of my three center fingers and the entire top of my hand.