Biking has *immensely* help my back. As in no longer having pain at all, and stronger and more resilient. Before I started riding, my back would go out a couple times a year, generally doing something as mundane as lifting a laundry basket! Now--knock wood--it doesn't at all.

My body also complains for the first 10 miles or so. Sometimes only 5, and you can see this in my heart rate, which for that first 5 (or 10) is 130+ or so for moderate efforts. Then it drops, to 110-120 for those same efforts, like my body is saying "okay, you win, I'll play nice."

I have some chronic illnesses going on, and biking has been magic for helping my health!