It's not surprising that the walkers benefitted from their exercise; what is peculiar is the distribution of their improvements. Both uphill and downhill walkers experienced a decrease in their LDL ("bad") cholesterol. Uphill walking also lowered triglyceride levels and increased the body's ability to handle fat. Downhill walking significantly increased the body's ability to handle sugar. Walking uphill did not help with sugar, nor downhill with fats.
The obvious solution is to walk both uphill and down whenever possible. What I want to know, however, is the reason for the differences. It's easy to make a case for walking uphill as the "best" exercise: it expends more energy, makes more demands on the heart and lungs, and seems to be a better workout for the muscles. Walking downhill is certainly easier, although I do find it harder on the knees. What is it about downhill walking that confers the unique positive effect on blood sugar? What is different about going downhill? It uses different muscles, and is a higher impact walk, jarring the body somewhat. No doubt the walkers also covered the same distance in a shorter time. Can any of these differences explain the benefit? If not, what? I hope someone is looking into this question, as well as trying to replicate Dr. Heinz Drexel's findings.
In the meantime, I'll keep walking, though it's mighty hard in Florida to find hills to walk either up or down.
