Foot Mechanics & Their Relationship to Running Shoes: How to choose? Advice from sports Physiotherapists.
Selecting Running Shoes:
Looking from left to right: Far left is a cushion shoe with curved last (Asics), ideal for supinators. In the middle is a curved shoe with a semicurved last (Brooks) more suited to a neutral foot and on the right is a motion control shoe with straight last (Brooks), ideal for pronators
The goal of the running shoe is to control the timing, rate, and excursion of sub-taler join ( STJ) motion. Pronation and supination occur at the STJ. The purpose of this is to allow the joints and muscles in the lower extremity to function in a range that is closer to that required for optimal shock absorption and force transmission. As physiotherapists working with runners, we will usually do some sore of gait analysis along with a foot biomechanics assessment in both weight bearing and non-weight bearing.
Once we have an idea of this persons mechanics there are a number of shoe options which help to improve foot mechanics and reduce overall load/shock to the body. It is important to clarify that abnormal function, alignment and posture are not the primary problem, rather it is the forces behind the function that relate to injury. Although an Individual who has alignment, posture or functional abnormalities will generally break down at a quicker rate when forces are increased. It is interesting to note that running puts 3-4 times body weight through each leg. Some individuals may have what is considered normal foot mechanics, but the forces may still be abnormally high depending on the type of sport, training intensity and volume leading to injury. This necessitates an appropriate shoe with adequate function for individual foot mechanics and forces.
Foot types that under pronate – (supinators) tend to have a C-shaped foot with a high arch, a wide forefoot, and, often, a clawing of the toes. These feet need a high and wide toe box. These foot types lack shock attenuation and accommodation to terrain and thus tend to need shoes with a curved external last, which encourages flexibility, pronation and more cushioning in the midsole. Typical injuries associated with supinators are: chronic ankle sprains, heal and foot pain (plantar fasciatis/opathy, metatarsalagia), stress fractures, ITband irritation, SIJ and low back strain.
Foot types, which excessively pronate tend to require a shoe with a straight external last, and broader mid-foot shape, which encourages more stability/motion control and less pronation. These shoes often provide a compromise between motion control and cushioning by using materials that assist in shock attenuation but also incorporate motion control features such as a firm heel counter, dual density mid sole and more rigid material imbedded into the mid foot region of the midsole to facilitate greater torsional rigidity. It is also essential to observe the shoe from behind to confirm the heel is vertical and that symmetry is present from side to side. Typical injuries with overpronators are nerve compression (mortons neuroma), achilles tendonitis/opathy, shin splints, anterior knee pain (patella femoral syndrome), SIJ and low back pain.
WHAT TO LOOK FOR IF YOU PRONATE: The shoe should resist torsional forces along the long axis (i.e. hard to twist along its length). It should bend easily at the metatarsal heads (toe mounds) but not at the mid foot.
CUSTOM ORTHOTICS: Sports physiotherapists are also trained in custom orthotic fitting and for those with biomechanics problems (hip, knee or foot) often a custom orthotic is the way to go to ensure the mechanics of the foot are as optimal as possible to avoid problems.
In cases where an orthotic is being used, generally a neutral shoe with no excessive stiffness in the mid foot or dual density mid sole is preferred.
WHEN DO I GET NEW SHOES?
Timely replacement of running shoes should be stressed to maintain appropriate cushioning and control. The general recommendation has been to replace shoes approximately every 300 miles or 6 months, but it is also dependant on weight, weather conditions, terrain and other factors.
For more information check in with our Physiotherapists at Back In Action Physio. They can help you select the appropriate foot-wear,’ as well as assessing and treating running related injuries and prescribing and customizing othotics if appropriate. Lets ‘Keep you Playing.’
This blog was written by Bianca Matheson: BSc. PT , Dip Sports PT. Back in Action Sports Physiotherapy is Whistler’s highly qualified Sports Physiotherapy clinic and is proud to serve the sea to sky and Whistler community by providing as much interesting and up to date research to help with injury prevention and keeping our community active.