Barefoot running has become more than just an oddity in the running community. It has become more than just a trendy phenomenon as more runners have embraced the natural form of running. The reason: the foot strike.
The Impact of Biometrics
When people run with shoes on, they strike the ground first with the heels. In a study conducted at Harvard University, heel strikes create more force. In fact, in the Harvard study, the researchers found:
“This kind of collision leads to a rapid, high impact transient about 1.5 to as much as 3 times your body weight (depending on your speed) within 50 milliseconds of striking the ground. This is equivalent to someone hitting you on the heel with a hammer using 1.5 to as much as 3 times your body weight. These impacts add up, since you strike the ground almost 1000 times per mile!”
The research also found that running shoes are designed to reduce that impact by spreading the force over the entire foot. But, the impact is still there and it can be damaging to the musculoskeletal system.
On the flip side, most natural runners find that forefoot running is better for the body. The same Harvard study that looked at the biometrics of heel strikes also looked at the biometrics of forefoot running. The results were surprising. With forefoot running, the impact on the body is much less than with heel strike running. According to the study, the heel strike generates 6.8% of total body mass, but the forefoot strike generates 1.7% of total body mass.
So how does this translate into back pain? It’s all about the impact.
What the Runners Say
When the heel strikes the ground, the impact due to the heel colliding with the ground sends a force up the body through the skeletal system. Imagine the force like a shock-wave. Then, do this repeatedly for several miles. It’s rather easy to imagine what can happen to the spine.
But, with the forefoot strike, there is very little impact, so there is little to no shock that travels up the spine.
However, other studies have not shown much difference in foot strike and lower back pain. When studying biometrics, numbers support forefoot strikes, but when studying people, the data isn’t clear. Both running styles have pros and cons.
Runners who use a heel strike put more load on their hips and knees, while forefoot runners put more load on their calves and ankles. Runners who use a heel strike put more pressure on their knees in the sagittal plane (vertical plane) and the frontal plane – this can put pressure on the rest of the leg. But, those who run with a forefoot strike put more load on their Achilles tendons. In fact, according to a study published in Annals of Biomedical Engineering, the load on the Achilles tendon is “an additional 47.7 body weights for each mile run.”
Stride Length vs Stride Type
Both types of strikes have different effects on the body. But, what seems to be the best stride for the body is a shorter stride. Numerous studies have found that shorter strides reduce running injuries. One study published in Medicine and Science in Sports and Exercise found decreased stride lengths decreased problems with hamstring loads and patellofemoral joint (knee) injuries.
So, recommending a particular stride might not be the best choice for anyone in the healthcare field. With studies unable to determine if forefoot strikes or heel strikes are better for runners, it appears the best recommendations for runners is to shorten their strides if they want to avoid injuries.
There have also been several studies that have found relationships between knee pain and back pain. One study published in the Journal of Pakistan Medical Association found a connection that knee pain can cause low back pain and vice versa. Knee pain can create back pain, but back pain can worsen with knee pain. So, if a runner with a heel strike develops knee pain, that runner could develop back pain. Then, the back pain could worsen the knee pain.
Should that heel strike runner then switch to a forefoot strike? It depends on the runner. Achilles tendon injuries have been on the rise, especially with middle-aged male runners. In a study published in Foot and Ankle Sports Medicine:
“Chronic tendinopathies are most commonly thought to be a result of repetitive overuse injuries, which explains a tenfold increase in Achilles tendon injuries in runners.”
Therefore, runners who have never used a forefoot strike and may have weak Achilles tendons could be susceptible to painful injuries, like Achilles tendon ruptures which is painful and often requires surgery to repair.
Conclusions Based on the Research
Forefoot running should be better for the back, but not for runners who are out of shape or who have issues with their knees. Achilles tendon injuries could put an end to running careers, for those who make drastic shifts from heel strikes to forefoot strikes. According to the research, it is better for runners to change the length of their strides, than to make a major heel strike change.
Another study to consider when looking for ways to reduce back pain while running was published in the Journal of Biometrics. It found that core muscle strength was key to preventing lower back pain. Weak core muscles, which include the erector spinae, longissimus thoracis, multifidus, quadratus lumborum, and psoas, increased the chance that runners would experience low back pain.
This study found that when runners have weak core muscles, runners have more pressure on their lower lumbar vertebrae. Through the repetition that happens with running, runners can do damage to their spines and the structures that support them. Therefore, along with shortening the stride, strengthening, deep core muscles is the best way to prevent low back pain if you are a runner. Clearly, there is more to running than just choosing what part of the foot to strike first.
About Dr. Wells
Serving Wasilla, Anchorage, and the surrounding communities, Dr. Brent Wells offers patient-centered, personalized and innovative chiropractic care. A California native, Dr. Wells earned a bachelor’s of science degree from the University of Nevada. He then attended Western States Chiropractic College in Portland, Oregon. In 1998, he and his wife Coni moved to Alaska and opened Better Health Chiropractic in Wasilla. He is a proud member of the American Chiropractic Association and the American Academy of Spine Physicians.
BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.