I currently have a 36 mile round trip commute that I do 3 days a week and I hope to increase to 5 eventually.

When I started I was pretty out of shape and was struggling with lower back pain. I shower at a gym after my commute and have been doing an ab/core routine when I arrive and that has turned the lower back pain to lower back discomfort. One of the great benefits of my commute is that when I jog on my off-bike days my knee does not give me the issues it once did I suspect because the muscles around the knee are much stronger.

Given the tangible cross-training benefits I have experienced with the biking supporting my jogging I was curious to know if anyone out there has come across a lower and upper body exercise regimen or specific exercises that help with biking.