“After you recover from the knee replacement, I don’t want you to do any more running.  A few foolish people do run but it is not a good idea.  It may loosen everything and wear it out prematurely.”  “What about speed walking and race walking,” I asked. “You can do all the speed or power walking you want.  But race walking might not be good.  Too much twisting of the hips and locking the knee all the way back.”


With that, my forty years of running and racing came to an unwelcomed, sad and sudden end. I was now officially a walker.  It is not the worst thing in the world, but certainly not the same in my mind as being a competitive runner.  To cheer myself up, I did more research to see how walking compares to running.  As I wrote in a previous article, the health benefits are similar, with one exception being that running is better at controlling weight.   In a new study involving 33,060 runners and 15,045 walkers, it was again found that both were equally effective in reducing the risk of heart disease, hypertension, high cholesterol and diabetes.  Another study showed that longevity was extended the same for runners and speed walkers, when compared to inactive people:  3.8 years for males and 4.7 for females.


Of course, it takes more time walking than running to achieve the same calorie expenditure.  Different studies have come up with various ways to compare the two.  One showed that if a runner covered 3 miles in 38 minutes (12:40 per mile) it would take a walker 75 minutes (17:26) and 4.3 miles to burn the same number of calories.  Another study had both traveling at the same pace: 4 mph (15 min per mile).  This is very slow for running and quite fast for walking.  The walkers required an hour and a half to equal the calorie burn the runners got in one hour.


When it comes to injuries, there is no contest.  Approximately half of all runners sustain some sort of injury, while only one percent of walkers do the same.  This, of course, is due to the difference in ground reaction force.  Running averages 2.5 times body weight with each step, while brisk walking is only 1.2.  Downhill running makes those forces even greater.  The impact force is the reason running is contraindicated after knee replacement and is so tough on the body.


Because walking is done at a lower intensity than running, it always stays aerobic.  This means the body is using a mixture of fat and carbohydrates (glycogen) as fuel.  Running is often close to the anaerobic threshold, where the primary fuel is carbohydrate.  Hitting the wall at 20 miles in a marathon occurs when glycogen levels fall to critical levels.  Walkers don’t hit the wall in the same way and can go on all day long if they want.  And, walkers can easily refuel with food without worry about a stomach too blood deprived to accept nourishment.  Runners often make the mistake of doing too much of a good thing.  Most medical experts advise 2-3 days per week at a moderate pace to derive all the health benefits.  Competitive running requires more than that, but it raises the risk of injury.  There is no restriction on the amount of walking that can be done safely.


So, the bottom line for me is that even though I can’t, run and I definitely miss running, I can still apply myself to becoming a speedy walker and reap many of the same physical and mental benefits.



Sam Graceffo, MD