Posts tagged running injuries
How Does My Running Cadence Impact Forces In My Legs?

Cadence, or the amount of steps taken each minute, is a common and effective running assessment. This assessment can be done in both healthy and injured runners, but its’ modification is most impactful in the latter group. In our Boulder Physical Therapy practice, we routinely utilize running gait retraining to reduce abnormal forces in the lower quarter. While most runners self select between 160-180 steps per minute (up to 200 in elite runners) this rate can be altered to change force distribution across injured and healthy tissues. For example, a faster cadence (shorter stride) may be utilized to reduce knee pain from arthritis and a slower cadence (longer stride) can take pressure off a healing achilles tendon. Recent evidence has shown self selected cadence to be unrelated to load rate in a healthy runner, but cadence remains a valuable assessment in the injured runner.

A recent research article examined the relationship between cadence, loading rates, and a runner’s leg length (Tenforde et al. JOSPT. 2019). Authors performed a cross sectional study of both healthy (N=40) and injured (N=42) runners who utilized a rear foot strike pattern. All runners underwent a structural assessment and biomechanical analysis while running. As expected authors reported an inverse relationship between a runner’s leg length and their cadence rate, but leg length only explained a small relationship indicating others factors are at play. Injury status did not influence the association between leg length and cadence. Surprisingly, no relationship was found between cadence and vertical loading rates when normalized to a runner’s leg length.

This research adds to our understanding on cadence rate, loading rates, and injury status. Based off the current research, cadence remains one variable which may be altered to reduce ground forces among injured runners.

Real Time Feedback Reduces Forces In Runners

Up to 80% of recreational runners will experience an injury limiting training time or competition in a given year. Running injuries are multifactorial in nature with contributions from muscle imbalances, training errors, and running biomechanics. High magnitude and rates of lower limb loading have previously been associated with running injuries. In our Physical Therapy practice, we utilize gait retraining in runners with real time feedback to correct these biomechanical errors in turn reduce the abnormal forces across the lower body. Often runner’s will feel an immediate change in their symptoms will simple gait corrections. A recent study supports the utilization of gait retraining for runners with high rates of peak braking forces.

Napier and colleagues studied the impact of real time running gait biofeedback in 12 female recreational runners with high peak braking forces (JOSPT. 2019). All runners were given 8 lab based sessions of gait retraining at weeks 1, 2, 4, 6, 8, 10, 12, and 14 of their 1/2 marathon training. Real time feedback was provided to help reduce the peak braking forces occurring at foot strike. Authors found the runners reduced their peak forces by 15% during the training by reducing their step length and increasing their step frequency. The researchers also found the changes in each runner’s gait became part of their natural running gait cycle at the end of the trial.

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Does Running Gait Retraining Translate To Running Outside The Lab?

Researchers and clinicians continue to explore interventions to reduce the significant numbers of running related injuries. These injuries, mainly overuse in nature, often cause a loss in training time and are found among both novice and experienced runners. In addition to strength training, gait retraining has shown promise in reducing the forces placed across the lower body during running. Simple strategies such as reducing step length (heel to mid foot strike) and landing softer (reducing vertical forces) can quickly reduce forces during gait. In addition, providing runners with real time feed back through simple video analysis and verbal cuing accelerates utilization of these new running strategies. Few research articles have examined the retention rate and transfer of learning between laboratory running gait retraining and a runner’s outdoor training, but a new study shows old running habits may die harder than originally thought.

Zhang and colleagues examined runners’ gait mechanics under various conditions including overground running, treadmill running, as well as, running inclines and declines (Gait Posture. 2019). Each runner’s lower body forces were measured in a biomechanics laboratory during their preferred running gait. Based off this analysis, runners were then provided with 8 sessions of gait retraining with real time feedback (soften your foot strike) to reduce forces across the lower body. Runners were then reassessed to determine if the gait retraining transferred to an outside environment. Consistent with prior research, the majority of runners were able to reduce lower body forces during gait retraining in the laboratory. Outside of the gait retraining, they were able to reduce their overall forces during overground and treadmill running, but peak forces were not reduced during overground running. Not surprisingly, this study highlights the difficulty of changing a movement pattern like running. Consistent, deliberate practice with the principles learned during gait retraining is required to create an automatic process with athletes.