By Nathan Koch, PT, ATC
Let’s start with the research: A meta-analysis of research assessing the biomechanical differences between barefoot and shod distance running in Sports Medicine, December 2013, found: “Pooled results [of 12 studies] indicate moderate evidence that barefoot running is associated with reduced peak ground reaction force (GRF), increased foot and ankle plantarflexion and increased knee flexion at ground contact compared with running in a neutral shoe. Limited evidence indicates barefoot running is associated with reduced impact GRF, reduced peak knee flexion and varus joint moments, and a higher stride frequency compared to a neutral shoe. Very limited to limited evidence also indicates power absorption at the knee is decreased while being increased at the ankle whilst barefoot running. Additionally, the effects of barefoot running on loading rate appear dependent on strike pattern adopted, with a forefoot strike pattern found to reduce loading rate, whilst a rearfoot strike pattern increases loading rate when running barefoot compared to shod.”
In October 2012, an article in the International Journal of Sports Physical Therapy concluded that running with a forefoot strike pattern and running barefoot both “resulted in significantly greater ankle plantarflexion and significantly less negative knee power (absorption)” compared to running with a shod rearfoot strike. Barefoot and forefoot strike runners “demonstrated decreased total lower extremity power absorption compared to the shod [rearfoot strike] condition but did not differ from one another.” In other words, they determined that forefoot style running in shoes is similar to barefoot and significantly different than running in shoes with a rearfoot strike pattern (commonly known as heel striking).
Interpretation of the research suggests it’s most often technique, not footwear, that’s the culprit of running injuries. One of the problems with specific shoe research and comparison is that the models change frequently and they are difficult to control in a long-term study. Anecdotally, there are plenty of “case studies” that runners, running store employees and sports medicine providers rely on when recommending a shoe for a runner. Biomechanical and anatomical knowledge is also helpful in picking the correct shoe, although there is no strong evidence in the literature to support a cookie-cutter approach to shoe selection.
SHOES. Motivation behind shoe selection can be based on color, comfort, performance or just wanting to follow the latest trend. Shoe brand or design is not one-size-fits-all, and choosing the correct shoe has more to do with art than science. All running shoes should come with a disclaimer stating: “Any shoe can be an adjunct cause of injury.” While there appears to be symbiotic relationship between runners’ feet and their shoes, running shoes alone do not cause injury. Shoe selection combined with foot type, running technique and training volume can combine to produce either running bliss or complete breakdown. And running barefoot doesn’t ensure you will be injury-free either.
Shoe types and common injuries related to them:
#1 The “pillow”: These are the shoes that feel like running on pillows. The dampening effect of the shoe can create greater movement at the hip and knee. A runner with genu varum (bow legs) could experience greater knee bending and bowing alignment resulting in knee pain or IT band syndrome. Sitting higher off the ground creates some inherent instability that can also result in a sprained ankle. If the shoes have a low heel to forefoot drop, they may create a risk of common minimalist injuries such as Achilles tendinitis/tendinosis.
#2 The minimalist or zero drop (and barefooters): These are shoes with little or no drop from the heel to the forefoot. Lightweight and lean, these are designed for midfoot/forefoot running and racing. With forefoot strikers they create increased stress and strain on the Achilles and on the bones in the forefoot, which can result in Achilles tendon injuries, metatarsal stress fractures and neuromas. With rearfoot strikers they increase the chance of stress fractures in the heel and lower leg.
#3 The “controller”: These are designed to control overpronation during the initial contact and loading phases of running, although there is debate in the literature about whether this is actually necessary or even possible. These tend to be heavier shoes with a higher heel to forefoot drop. They can result in greater injury to the heel (plantar fasciitis), knee and hip.
#4 The “I will make you forefoot strike if it kills you”: These are minimalist shoes on steroids that try to force runners onto the forefoot via a negative drop. The designs vary from a gentle guide to a heavy-handed thrust. These shoes can create even more stress at the forefoot via pressure and on the Achilles because of the negative drop. These may result in forefoot stress fracture, metatarsalgia, neuroma and Achilles tendon injury.
The important thing to remember is that there is no shoe that will prevent injury in every runner who wears it. I think a Mark Twain quote is appropriate here: “We should be careful to get out of an experience only the wisdom that is in it and stop there lest we be like the cat that sits down on a hot stove
lid. She will never sit down on a hot stove lid again and that is well but also she will never sit down on a cold one anymore.”
RUNNING TECHNIQUE OR STRIKE PATTERN AND LOADING. Runners try to emulate silky smooth professional runners because they are fast and their strides look so pretty. But being successful at a skill does not mean looking pretty, it means doing a few required movements consistently. With running, the basic movements needed to be successful or efficient are stride length and strike pattern. A running shoe may influence this skill, but it does not ensure a change in technique.
Physiological (heart rate and ventilatory capacity) and biomechanical factors will have a heavy influence on running technique. As the load on the heart and lungs increases, fatigue can set in and affect the function of the lower extremities, resulting in abnormal or less than optimal foot strike and stride length (see Iron-man athletes after mile 20 of the marathon). Morphological biomechanical factors like bone structure cannot be changed, but other biomechanical factors like stride length can be improved. In some runners an optimal stride length may not be possible because of musculoskeletal limitations such as tight or weak calves, but this type of limitation within the runner’s body can often be improved.
Additional factors that will influence strike pattern and loading: running speed, ankle mobility, training level, running distance and running frequency. Rearfoot strike patterns (heel striking) are more common at slower speeds and as the distance increases. Forefoot strike patterns are more common at faster speeds and shorter distances. It is possible that a forefoot strike pattern in some athletes is unsustainable over longer distances because of calf muscle fatigue and weakness.
Studies show that an increase in cadence substantially lowers loading through the hip and knee joints, creating less strain and stress on those joints. However, it increases loading in the foot and ankle, which increases stress on the bones and soft tissue around the foot and ankle.
Running techniques and common injuries related to them :
#1 Forefoot strikers and midfoot strikers: stress fracture, metatarsalgia, neuroma, and Achilles tendinitis/tendinosis.
#2 Heel strikers: plantar fasciitis, shin splints, chronic compartment syndrome, IT band syndrome, bursitis, patellar tendinitis/tendinosis, pes anserine bursitis/ tendinitis and low back pain.
#3 Low cadence (less than 90 steps/minute): longer contact and loading time results in shin splints, knee pain, patellofemoral pain, hip and low back pain.
#4 High cadence (more than 90 steps/ minute): shorter contact time and decreased vertical forces result in less injury. Increased muscular demand on the calf can cause Achilles and calf injuries.
#5 Long striders: hamstring strains and
#6 tendinosis, low back/SI joint pain. Short striders: foot pain and foot injuries.
It is important to understand that with a significant change in footwear or running technique, economy can actually get worse in the beginning stages resulting in a higher injury risk. Learning the “skill” of running, selecting the correct shoe and following proper training guidelines give you the best chance of a life of pain-free running.