i live in michigan and from dec to march riding a road bike is almost out of the question.however after putting in 100 to 150 mile a week this year, more than i have in a while, after the season was over i have noticed stiffness/soreness in my lower back area. it feels good after a ride on the trainer,but will return if i skip a day or two. any good exercises/stretches to reduce the discomfort thanks