What can be the reason?

I started playing bollyball,daily for 1 hour in the morning , even after 7 days my leg muscles(thighs) feel light pain , while going upstairs or down stairs , why muscles are still not adjusted to load… even though initially i do running 3-4 times in a week for 10-20 minutes. i am type 1 diabetic for last 20 years and my bg controll was very poor for 15 years. now control is good