Taking quicker steps is one of the few proven ways to reduce running stress and save your knees.
A running stride is as unique as a fingerprint. Many factors—running history, speed, leg length, leg alignment, and injury history—influence how you run. Consequently, the search for one unifying set of stride mechanics—one “ideal” running pattern to improve performance and reduce injury—is unrealistic.
That’s why blanket advice about foot strike, barefoot running, arch shape or shoe characteristics has limited effectiveness in reducing running injuries. There just isn’t a one size fits all fix. While you shouldn’t be told how you should run, there may be some value in being told how you shouldn’t.
Some runners actively try to lengthen their stride or over-stride in the belief that covering extra distance with each step will improve speed. That gait characteristic, the running equivalent of driving a car with one foot on the gas and the other on the brake, is increasingly being associated with excessive forces during running and injury.
When running, landing the foot in front of the body increases the peak braking force, a horizontal force that occurs opposite the direction of travel. According to one recent study, conducted by researchers from the University of British Columbia-Vancouver, runners with the highest values of peak braking force were eight times more likely to sustain a running-related injury.
But thankfully there appears to be a solution. The same group of UBC researchers, led by 2:33 marathoner and physical therapist Dr. Chris Napier, found that the braking force can be modified by increasing running cadence, or step rate.
In the experiment, a group of 12 female recreational runners with high peak braking forces (greater than 0.27 body weight) was selected for the intervention. Using a gait-training program with real-time biofeedback, the runners completed an 8-session gait retraining program while training for a half-marathon. The program focused on training the runners to shorten stride length and increase step frequency, while maintaining speed. Because speed is a product of stride length and stride frequency, increasing the number of strides per minute decreases stride length.
At the end of the study, by increasing step rate, the gait retraining program had reduced the peak braking force by an average of 15 percent. This matches findings from other research, specifically that increasing stride rate decreases the forces on the body when running. One in particular found that increasing step rate reduced the peak force on the kneecap by 14 percent. An important finding given that the most common site of injury is the knee, and kneecap pain the most frequent complaint.
Additionally, an increased cadence has also been shown to increase the firing of the gluteus medius, which may further reduce braking forces and the stress on the kneecap and lower leg.
One common fear of making changes in running mechanics is the fear that the changes will be hard to incorporate and will reduce efficiency and speed. Any change in mechanics, including step rate, can reduce running efficiency as it forces the brain and body to work a little harder.
Not in this case, says Napier. “Typically, when making any changes in how you run there is a period of decreased efficiency, but by the end of the study, the runners reported a lower perceived exertion when running at the same speed, indicating that the changes had become more natural and efficient.”
Jay Dicharry, a physical therapist and expert in running biomechanics, says changing step rate influences two aspects of running—injury and performance. “This stuff isn’t rocket science,” says Dicharry, “The vast majority of runners over-stride, and when you ask them to increase their cadence, you essentially ask them to take more shorter steps and decreasing the over-stride—both of which are tremendously helpful in decreasing the stress per stride.”
From a performance perspective, since it can significantly change stride length, Dicharry believes that taking a bunch of tiny strides isn’t the best strategy. “For the majority of runners what you want to do is shorten the over-stride and increase the push out the back side to preserve stride length.” Meaning that the goal of increasing stride rate is to train the runner to move the foot closer to the body, not to create a stride with an ungainly high turn-over rate or land on a particular part of the foot (forefoot/midfoot/rear foot).
Napier was able to identify which runners might benefit most from an intervention by determining peak braking force, a value difficult for the average runner to calculate. Without access to a running lab, he suggests using the sound of your running. If you’re audibly punishing the ground or treadmill and have a stride rate under 170 steps/minute, you are likely over-striding, perhaps necessitating a change in stride rate.
While over-striders have potentially the most to gain from a change in cadence, there is little downside. “Changing cadence is a pretty safe intervention, one that’s unlikely to cause a problem,” says Napier.
Don’t rely on any universal number, however. “Having any absolute value for stride rate is short-sighted—e.g. 180 steps/minute, a commonly quoted target rate—especially when it isn’t based on any empirical evidence,” says Napier.
When making a change in stride rate, he recommends that runners change no more than 5-10-percent (8-18 steps/minute).
In sum, taking a few more steps per minute can make your running healthier, and help re-program your stride so you brake less, become more efficient, and eventually run easier and faster.
From: Podium Runner