To understand why increased cadence could prevent running injury, let’s review running biomechanics. Running subjects the body to high-impact forces. With each foot-strike, forces 2 ½ times body weight travel from the feet and ankles through the body. These forces, combined with training errors, cause injury to the bones and soft tissues. Cadence is the number of steps taken per unit of time or distance. Whether we are short or tall, long- or short-legged, we tend to take 120-140 steps per minute when we run. The fewer steps we take, the longer the stride will need to be to run fast. The longer the stride, the more likely the heel will contact the ground first. If the stride is long and the heel contacts the ground far in front of the body, several negative things happen.
First, a spilt-second braking force occurs as the heel hits the ground. The forward momentum of the body moving over the contact leg is temporarily slowed. Next, a second impact force is generated as the rest of the foot contacts the ground. These forces are implicated in development of running injuries. Gait researchers have found when runners are retrained to land mid-foot instead on the heel, braking force is lessened and foot contact time is shortened. Force loading rates and impact peaks reduce up to 30%! But, when runners take a shorter stride landing mid-foot, they cover less distance and speed slows. To increase speed, cadence must increase.
Besides decreased force generation, increased cadence was found to be beneficial in unexpected ways. Decreased foot contact time improves running efficiency. This means less oxygen is required to power the body over the same distance. Mid-foot strike promotes better pelvic core muscle recruitment, meaning that the gluteals and other muscles supporting the hips and knees, contract stronger. In my clinic, many runners with knee pain have reported instant improvement just by increasing cadence during my treadmill gait evaluation.
So, increasing cadence seems to help reduce injury and improve performance, but, changing the way we run is difficult as it’s a fundamental motor skill. As I discussed in past articles, it takes time to adapt to new movement patterns. To avoid injury, cadence manipulation, like any other new technique, should be incorporated SLOWLY into a training program.
Cadence between 170-180 foot strikes per minute is the recommended target rate. Start by practicing increased cadence using an interval program in the middle of your regular run. An easy, safe way is to use cuing from a simple metronome app downloaded on a smart phone carried while you run. Run at your natural cadence for several minutes to warm up. Set the metronome for a rate between 170-180 and increase the steps you take using the beat as a cue. You will need to slow down a lot initially and it may seem like you are shuffling. Run at this increased cadence for 1 minute, then, go back to your natural cadence for 1 minute. Repeat this interval 5 times (a total of 10 minutes). Finish with several minutes running at natural cadence and a short walk to cool down. During the next run, do 6 intervals (12 minutes), the next run, 7 intervals (14 minutes) and so on for 1-2 weeks. Then, as it begins to feel more natural, run longer intervals at increased cadence and decreasing intervals at your natural cadence. In about 3-4 weeks, most runners can feel when they are running at increased cadence without the cue of the metronome and can complete training using increased cadence.
Marie-Christine Leisz, DO is board-certified in Physical Medicine and Rehabilitation and Sports Medicine, with advanced training in the diagnosis and management of running and endurance sports injuries. She is medical director of the Running and Endurance Sports Injury Clinic at Courage Kenny Rehab Institute and collaborates with the Courage Kenny RunSmart PT Program. Learn more at http://www.allina.com/ahs/ski.nsf/page/running_endurance and http://www.allina.com/ahs/ski.nsf/page/Run_smart