Some recent research has shown that modern running shoes may actually inhibit the foot's natural ability to absorb impact and that running barefoot has lots of benefits. Not to miss a marketing opportunity Nike has introduced a line of shoes designed to mimic barefoot running while still providing some cushioning. The shoes are called Nike "Free".

I used to be a distance runner but I'm not into that as much anymore. I still run though. If you put in a lot of hard miles on a bike you should mix it up with some weight bearing exercise like running, higher impact aerobics, or strength training. High mileage cyclists are at risk for losses in bone density and need weight bearing exercise to compensate.