It's early January - you're probably looking to work off some of your Christmas kilos and shed that festive spare tyre. For millions of people around the world, that means making a New Year's resolution, buying a new pair of runners and hitting the road for a jog. But a new musculoskeletal study has concluded that the average modern running shoe is significantly more damaging to your knees, hips and ankles than running barefoot - or even walking in high heels. With osteoarthritis of the knee representing the biggest cause of disability in the elderly, this is a serious finding that's worth taking into account if you want to protect your joints.
Time and again, nature's solutions for physical architecture prove the most effective in the long run - and the world of running is waking up to the fact that the traditional cushioned running shoe might actually be doing more harm than good.
When you run barefoot, you naturally run on the balls of your feet, which lets your foot and ankle act as a wide-angled shock absorber for your whole leg. It's a scaled-down version of the way four-legged animals use their rear legs. The arch of your foot flattens with each stride and provides extra spring to the next step.
But when you use the average cushioned running shoe, with its elevated heel and arch supports, the tendency is to hit the ground with your heel first. While the shoes are designed to soak up a fair bit of the shock, they transmit the rest back up through the ankle, knee and hip, cumulatively causing the joint and cartilege damage that leads to conditions like osteoarthritis.
Published in PM&R, from the American Academy of Physical Medicine and Rehabilitation, "The Effect of Running Shoes on Lower Extremity Joint Torques" took 68 healthy young adult runners of mixed sex and asked them to run at their normal comfortable pace on a treadmill after warming up.
Through onboard instrumentation, they collected data on the rotational torque that each runner's stride placed on the ankle, knee and hip - and had them run barefoot and in conventional running shoes chosen to exemplify the general traits of the genre.
From the study: "Increased joint torques at the hip, knee, and ankle were observed with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus torque were measured when running in running shoes compared with barefoot."
From the study: "The findings at the knee suggest relatively greater pressures at anatomical sites that are typically more prone to knee osteoarthritis, the medial and patellofemoral compartments. It is important to note the limitations of these findings and of current 3-dimensional gait analysis in general, that only resultant joint torques were assessed. It is unknown to what extent actual joint contact forces could be affected by compliance that a shoe might provide, a potentially valuable design characteristic that may offset the observed increases in joint torques."
The study supports the sentiment among a growing number of distance runners who are choosing to run barefoot and take advantage of what advocate Barefoot Ted describes as "the best pair of shoes you will ever own" - your feet.
But not everyone's got iron soles like Ted - so in the shorter term there's changes you can make if you wish to switch to a less harmful running style. For starters, you could switch to running in flat-soled shoes with minimal padding, and changing your stride to avoid passing shock up through your heel - for most people, this adjustment comes naturally when the cushioning effect of a running shoe is removed.
Or you could take the concept further - Vibram have built a running shoe that's basically designed to be nothing but a flexible, high-traction shield for the bottom of your foot, held on by the minimal possible fabric and with tiny pockets for each toe to give your feet the ability to move as naturally as possible.
The "Five Fingers" range (see above) have been building in popularity as a 'barefoot lite' option that opens up a wider range of surfaces and terrains for barefoot runners and protects the sole while encouraging a natural running motion.
If you've had any experience with barefoot or minimal-shoe running, let us know in the comments below.