The Power of Changing Cadence, How to Perform a Running Analysis, & When to Change Running Shoes
In PT school, your orthopedics classes teach you how to evaluate and treat all kinds of musculoskeletal injuries. What they don’t teach is how to apply each injury to a specific sport. Of course the general rehab principles are the same. The phases of tissue injury don’t change, but the rehab emphasis needs to change once the patient is progressed to the return to sport phase. A necessary job requirement of a sports physical therapist is to understand the demands of the sport. Running is perhaps one of the most overlooked sports because it seems so simple. You just go out and run, right? No. The repetitive nature of the sport makes runners very susceptible to injury. If you’re interested in running or treating runners then this post is for you. If you’re not interested in working with runners, too bad. In an outpatient orthopedic clinic, you’re going to be working with runners at one point or another.
The Power of Cadence
Cadence. Aside from overall running volume, this is probably the single most important variable you can address as a clinician. Many runners already know their cadence from monitoring it on a smart watch and all you have to do is ask them. If they don’t know it, be sure that you determine their cadence (steps per minute) when you perform the running analysis. Cadence is not necessarily running speed. It is simply the turnover rate of the feet.
Altering a runner’s step rate can have dramatic effects on overall joint loading. A lower cadence will increase the duration of stance phase and the amount of knee flexion. This can lead to higher loads of torque to the knee joint resulting in knee pain. There is plenty of evidence suggesting that increasing step rate can decrease loads to the patellofemoral joint and thus reduce knee pain during running. One popular study concluded that, “patellofemoral force magnitude, loading rate, and impulse are all diminished when increasing running step rate by 10%.”
Conversely, a higher cadence will cause increased load to the Achilles tendon. This may present as symptoms of calf pain, heel pain, or pain at the tendoachilles junction. This article from JOSPT describes the increased stresses to the Achilles tendon and calf from a forefoot strike pattern. Understanding the biomechanical loading effects associated with various running cadences can help you advise your patients in the right direction.
If you’re unsure of where to start when treating a runner, try altering their cadence first. As a general rule of thumb, try this…
- For patient’s with patellofemoral pain during running, try increasing their step rate by 10%
- For patient’s with Achilles tendon pain during running, try decreasing their step rate by 10%
- The target goal cadence should be 180 steps per minute. This cadence allows for an ideal balance of joint forces through the lower extremity.
How do you advise a patient to alter cadence? There are plenty of smart watches available that can monitor cadence. Another great way to control cadence is through music. There are entire websites dedicated to matching songs with different running cadences. Jog FM is a website that you can search your desired cadence (example: 180 beats per minute) and it will provide you with songs that match that cadence. This is only one of the many websites that you can use to find songs to match your cadence.
Analyze Running Pattern
If you evaluate a runner without looking at their running pattern, you’re setting yourself up for failure. I always do a gait assessment with my patients. With runners, I will use their iPhone on slow-motion and video them running on a treadmill in the clinic. Be sure to video from the side and the back. You won’t always find issues with their running pattern and that’s okay. However, if there’s something that really stands out, you need to make sure to address it. The following list is not all-inclusive but it outlines a few things I look for…
From the Posterior View
- Foot/Ankle
- Yes I do look at pronation. No I don’t necessarily thing overpronation is always an issue, but it can be. If the midfoot collapses enough to internally rotate the tibia enough to cause a dynamic knee valgus, then it could be an issue.
- Also look for medial heel whipping. This may indicate control issue at the trunk/pelvis/hip. I also want to look and see if the runner crosses midline with each step. If this is the case, there is likely excessive hip adduction from impaired control of the hip abductors.
- Knees
- This is pretty straightforward. You’re looking to see if the runner exhibits a dynamic knee valgus.
- You also need to look at the Knee Window. Look to see how close the medial femoral condyles are from a posterior view. If they are almost touching, the runner may be going into too excessive hip adduction. Now it’s you’re job to figure out why (hip or ankle).
- The popliteal crease should be pointing straight backward during the stance phase.
- Hip/Trunk
- You may pick up on increased frontal plane motion of the pelvis in this view (Trendelenburg sign).
- Arms
- For distance runners, an arm swing that deviates significantly out of the sagittal plane may lead to wasted injury.
- If arms are carried far from the body, there may be an underlying balance deficit that needs to be addressed. Running is a single leg activity after all.
From the Side View
- Foot/Ankle
- This is the best view to see striking pattern. If you’re a firm believer in one best striking pattern for running, I encourage you to be open to changing that mindset. There is a time and place for heel striking, midfoot striking, and forefoot striking. I will post another article on this topic in the future.
- Knees
- There usually isn’t much that you’ll pick up from a side view of the knee. If the patient has knee hyperextension you may see this but I don’t generally find any issues here.
- Hip/Trunk
- Looking at functional hip flexion and extension during running is important. If a patient is lacking hip extension due to soft tissue or capsular restrictions, you’re going to see increased lumbar extension during the end of stance phase. This can lead to SIJ dysfunction and low back pain during running. An ideal running posture of the trunk includes a slight forward trunk lean. A mentor of mine once said that walking and running are essentially “controlled falling.” The trunk should be slightly forward bent to allow for linear translation forward.
When to Change Running Shoes?
I get this question a lot and there is not always one answer. Some resources say 300-500 miles. I think this is a great guideline but it doesn’t consider the weight of the runner. Heavier runners are going to wear down the support of their shoes faster than lightweight runners. I advised my patients to use the following calculation.
- (75,0000/weight in pounds = miles before new shoes)
- For example, lets use a 160lb runner. 75,000/160 = 468.75 miles until changing out shoes.
Using several pairs of shoes decreases injury risk. The foam in most running shoes takes about 24 hours to expand to its original state. Having several pairs of shoes to train in can allow you to train on back-to-back days without risking injury. A study in the Scandanavian Journal of Medicine concluded that runners who use multiple pairs of shoes throughout the week actually had a 39% less chance of developing an injury from running. I always advise patients who train multiple days in a week to have at least two pairs of running shoes to switch between. As far as type of shoes, that will be covered in a future post. Stay tuned.
Running Progression
As far as a running progression for return to running after injury, there are many factors to consider. After the first phases of rehabilitation are complete and full range of motion and strength are restored, the runner must build up a baseline of cardiovascular fitness. When a runner is training for a race or event that requires them to increase mileage, I typically advise them to increase mileage no more than 10-15% a week. This number will vary depending on overall conditioning of the runner and their baseline but I find that this is a safe progression. I advise runners to complete two runs of equal distance with one day of rest in between. If they can successfully complete these runs without any pain or discomfort, they may increase mileage by another 10-15%. I also advise most runners to aim for a cadence of about 180 steps per minute.
Want To Learn More About Running?
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