Knee injuries are a common problem for bodybuilders. If you’re getting over some knee issues, you may
 want to go backward when you do cardio on a treadmill or elliptical. Researchers from South Africa had 39 subjects with various knee injuries follow a rehabilitation program that involved either forward or backward pedaling on treadmills and ellipticals. The group going backward increased their aerobic capacity by 10% more than the forward group. The backward group also increased their quad and hamstring strength more. So if knee problems are holding you back, take the backward approach to not only better strengthen your knee but to keep up your cardiovascular fitness, which means better fat burning.