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Are Runners Injured More Often than Football Players?

Competitive runners miss far more training from running injuries than athletes in virtually every other sport. Several years ago, Dan Lieberman of Harvard proposed that running shoes cause this incredibly high incidence of injuries by cushioning foot-strike force (Exercise and Sports Sciences Reviews, April, 2012).

LANDING ON HEELS: Modern running shoes have such heavy heel padding that they encourage runners to land on their heels. Landing on your heels during running increases the force of the foot striking the ground, which markedly increases running injuries. When you run at a six-minute mile pace, you land with a force equal to three times your body weight.

RESTRICTING FOOT MOTION: When you land on your heel during running, your foot hits the ground with tremendous force. To help protect yourself, you roll your foot inward. This is called pronation. Pronation helps to absorb the shock of the foot-strike force by distributing the force throughout your foot and lower leg. Then you roll your foot outward, before you toe off and step on your other foot. This is called supination.

So landing on your heel causes you to hit the ground with tremendous force and you try to protect yourself from an injury by rolling inward and outward. This constant rolling inward and outward of the lower leg twists the lower leg inward during the time of foot strike to increase injuries to the lower leg, knee, hip and lower back.

Read my report on RUNNER'S KNEE to understand how rolling inward after heel strike causes this most common running injury.

HOW PODIATRISTS TRY TO HELP: Podiatrists can prescribe orthotics, which are special custom inserts that go in the shoe underneath your foot. They help to prevent injuries by limiting pronation to reduce this inward twisting. This is good, but the main prevention of wear-and-tear running injuries is to reduce the force of your foot strike by landing on the front part of your foot.

LAND ON THE FRONT PART OF YOUR FOOT: Running barefoot helps prevent running injuries by encouraging a person to land on the front part of his foot:

• by minimizing the shock of the foot hitting the ground during running, and
• by allowing a runner to position his foot at the time of foot- strike to better absorb this force.

These advantages are gained by landing on the front part of your foot, not just by not wearing shoes (Exercise and Sport Sciences Reviews, January 2012).

HEEL-LANDERS ARE INJURED TWICE AS OFTEN AS FOREFOOT- LANDERS: Dr Lieberman and his coauthors measured the foot- strike characteristics of middle and long distance runners from a collegiate cross country team and characterized their injuries as they relate to where they land on their feet (Medicine and Science in Sports and Exercise, January 2012). Of the 52 runners studied, 36 (59 percent) primarily used a rear foot strike and 16 (31 percent) primarily used a forefoot strike. Seventy-four percent of the runners suffered injuries each year. Those who had a rear-foot strike had approximately twice the rate of repetitive stress injuries as individuals with a forefoot strike. Traumatic injury rates were not significantly different between the two groups.

WILL TAKING SHORTER STRIDES SLOW YOU DOWN? How fast you run is determined by how long your stride is times how many times you turn over your steps each minute. That's called cadence times stride length. Most elite runners take 170 to 180 steps per minute, regardless of how fast they run (Med and Sci in Spts and Ex, 1982;14:30-35). Less accomplished runners have a cadence of 150-160 steps per minute (British J of Sports Med, 1979;13:15-18). Cadence appears to be almost the same for all top runners. Taking shorter strides should allow you to move your feet faster, increase your cadence and help you to run faster.

HOW TO PREVENT RUNNING INJURIES: You do not need to run barefoot to prevent running injuries. You prevent running injuries by landing on the front part of your foot. This causes you to take shorter strides and land on the ground with less force. You can continue to use running shoes. However, try to:

• raise your knees higher,
• take shorter strides, and
• land on your forefoot.

Most of the major running shoe manufacturers have developed shoes that mimic the effect of running barefoot while providing the protection offered by a shoe sole. You may want to try some of these to see if they improve your running form to help prevent injuries.


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How Exercise Affects Blood Fat Levels


The Dangers of Sitting Too Much

The average adult spends more than 90 percent of his waking hours sitting down. A study followed 222,500 men and women for three years, and found that compared to those who sat for fewer than four hours a day:

• those who sat for at least eight hours a day were 15 percent more likely to die in that time, and
• those who sat for 11 or more hours a day were 40 percent more likely to die in that time
(Arch Intern Med, March 26, 2012; 172(6):494-500).

A review of the scientific literature shows that time spent sitting increases risk for chronic disease. Thirty minutes of physical activity is as protective as 10 hours of sitting is harmful (Exerc Sport Sci Rev, 2010;38(3):105-113). The more time you spend sitting, the less time you spend moving your muscles (Eur Heart J., 2011;32(5):590-597).

THIRTY MINUTES OF EXERCISE THREE TIMES A WEEK IS INADEQUATE FOR HEALTH: We now know that exercising for only 90 minutes a week leaves 166.5 hours a week for inactivity, which is harmful to your health. People who sit for long periods are sicker, fatter and are more likely to die of heart attacks.

A LITTLE EXERCISE DOES NOT PREVENT THE HARMFUL EFFECTS OF PROLONGED INACTIVITY: A study from Finland showed that exercise does not prevent the harmful effects of prolonged sitting (Scandinavian Journal of Medicine & Science in Sports, March 2012). Twenty-seven Finnish men and women exercised on one day and rested on the next. They wore special equipment which demonstrated that their muscles were inactive 70 per cent of the day whether they exercised or not. They spent the same amount of time sitting down on days they exercised for 30 to 150 minutes as they did when they did not exercise.

RESTING MUSCLES ARE INERT. Contacting muscles help to clear your bloodstream of sugar and fat, thus helping to prevent heart attacks, strokes, diabetes, cancers, and premature death. A high rise in blood sugar causes sugar to stick to the outer surface of cell membranes and destroy the cell. Resting muscles require insulin to prevent this high rise in blood sugar. Contracting muscles remove sugar and fat from your bloodstream without needing insulin. When you spend a lot of time sitting, your blood sugar and fat levels rise too high, which can damage your arteries and every other cell in your body.

THE BENEFITS OF CONTRACTING MUSCLES LAST ONLY UP TO 17 HOURS. A muscle's ability to extract sugar and fat from your bloodstream without needing insulin is maximal during exercise and only for up to an hour after you finish exercising. This benefit rapidly declines to disappear completely in fewer than 17 hours.

THE MESSAGE FOR YOU: Try to exercise every day and try to avoid sitting for prolonged periods of time.


Recipe of the Week:

A delicious new recipe from reader Patricia McCaffrey -- I'm not
sure whether to call this a thick soup or an appetizer. Enjoy it
either way!

Lebanese Hummus & Ful

You'll find lots of recipes and helpful tips in The Good Food Book
- it's FREE


April 1st, 2012
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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