Improving health symptoms and conditions

I have been on Prednisone for 3 months for PMR (polymyalgia rheumatica)and so far the pros have far outweighed the cons. PMR is an extremely painful condition that affects the shoulders and hips especially at night and early morning, I spent all of December and January sitting upright in a chair trying to sleep, untill I was diagnosed and prescribed Prednisone and oxycodone. I started at 25 mg and I'm now down to 15mg. The side effects that I do have are weight gain (about 10 pounds), mild mood swings and insomnia.I am an avid bicycle rider (25-35 training miles per day on week days a lot more over the weekend),I am 60 years old and now back on the bike. The strange thing is after about one month back in training I am much stronger this year than last even with the added weight. Last year, a solo, 30 mile hard ride I would average about 17 mph this week I went out on my same training ride at 19.4 mph, over 2 mph faster. Everything I read about Prednisone says that it wastes muscles,but I have become stronger. Is it possible that it's the Prednisone?