The Biomechanics of Running

An Overview of Running Biomechanics

Links to Injury Prevention

Overview of Running Biomechanics

An understanding of running biomechanics can be very beneficial to athletes and coaches alike. Knowledge of the movement and forces present in our bodies during running can hold the key in identifying the source of injury and increasing performance. As technology evolves this information is becoming more and more accessible to athletes of all classifications. In the following article we will look at the main biomechanical measurements which aid in identifying such injury risks, as well as the methods of deriving such information.

Impact forces have long been identified as possible causes of a number of injuries during running. The impact force refers to the force at which the body hits the ground during foot strike. These forces occur at varied intensity dependant on a number of factors such as position and angle of the foot at first point of contact. There are a number of different styles of running, the main variation being the point of contact with the ground, i.e. heel, midfoot and forefoot running. Ongoing research aimed at concluding on “the best” running style is both varied and conflicting. Each style has advantages and disadvantages but none can be judged as optimal as every athlete is different. Arguably the best advice seems to be to run the way which feels natural to you and ensure your body is adequately conditioned to deal with the forces and movements involved. 

When assessing running biomechanics another key area is the understanding of the movement of the foot when it is in contact with the ground. This typically involves the foot naturally rolling from a lateral to a neutral position and pushing off centrally at the forefoot. This “rolling” action or pronation, is a much hyped phenomena by running shoe companies whom make shoes with denser midsoles to help to slow down the rate of pronation with the aim of reducing risk of injury. It is important to note that pronation is a natural shock absorbing mechanism of the foot. However, problems may occur when this rolling motion occurs too quickly and excessively for the associated leg and foot muscles to deal with. This excessive foot motion would cause increased Q-angle (hip to knee cap angle) which would in turn create ITB tightness. This issue is more prevalent in women than men owing to wider hip-knee angle in women. Excessive pronation alone is unlikely to directly cause an injury and it is more likely a combination of the factors which we have discussed in this paragraph along with poor postural alignment and excessive training loads.

Variations of Running Styles

As mentioned above there are a number of different styles of running, the most common being rearfoot (heelstrike), midfoot and forefoot. Much has been written of these different types of running styles but understanding of the variations is often vague. The following is a brief overview of each type and the advantages and disadvantages of each respectively.

A rearfoot strike or heelstrike is the most prevalent style of running which approximately 85% of people utilise. Initial centre of pressure (COP) occurs in the first third of the foot. The foot naturally rolls from the outside to the inside and pushes off the ball of the foot. An initial impact is present as the heel strikes the ground which is evident in figure 1. The graph shows a typical force (kg/f) vs time curve present during a heel strike. As the foot is in front of the body at initial contact there is increased tibial acceleration and ankle joint stiffness. Typically common running injuries associated with rearfoot striking are anterior tibial syndrome (shin splints), patellofemoral pain syndrome (runner’s knee) and stress fractures of the tibia, fibula and metatarsal bones.

A forefoot strike is classified as having the initial COP in the front third of the foot. The hips and knees are aligned with the foot on landing with increased joint flexion. This will result in increased cadence and decreased stride frequency. As shown in the figure to the right there will be a decrease in initial impact forces and loading rate. The shock will be attenuated more so by muscles and less through bones and joints. While this means less stress on the bones there will be an increase in muscular strain of the triceps surae (calf muscles). 

A midfoot strike is present when the initial COP occurs in the middle third of the foot with the heel and ball of the foot landing simultaneously. There is normally an impact peak, albeit to a lesser extent to a heel strike. Increasing numbers of running shoes are available to accommodate such running style. Look for a lower ramp angle shoe with an 8mm heel to toe differential.

Running Shoe Technology

Running shoe companies in conjunction with scientists and engineers are constantly researching running biomechanics and developing their technologies accordingly. At present there are substantial differences of opinion on the best type of running shoes, an issue creating vociferous debates within the running community. “Barefoot” and minimal footwear has reinvigorated in recent years and is now a significant part of the market. As there are such variations in running shoes at present, it is important to have a clear understanding of what a running shoe offers before deciding to utilise it. Luckily there are is multitude of running specialist retailers available to offer you such advice in selecting the best shoe for your foot. Whether you run with a heel or forefoot strike, are in need of lightweight or support, there is certain to be a shoe to suit your needs with the vast amount of variety available today. These such specialist retailers now utilise advanced technology which enables high definition video analysis of treadmill running, pressure scanning of your feet as well as lower limb and foot physical assessments. This equipment enables the assessor to investigate your lower limb biomechanics such as mentioned earlier in this article and help you choose the best fit for your needs. 

Important variations to consider within running shoes include the amount of support, stability, heel-to-toe ramp angle, flexibility and weight. These factors can influence your running style and it is important to understand the function of the shoe prior to purchase. It is important not to get drawn into marketing hype by major companies on particular shoes, rather seek advice from impartial experts who will help you select the correct shoe regardless of price or brand. Many shoes now offer lower ramp angle (flatter) shoes which promote more of a midfoot/forefoot landing. This type of shoe can greatly benefit some people but as mentioned earlier it can also cause increased strain on the triceps surae (calf muscles) and higher pressure under the forefoot. Pressure scanning of the foot can greatly aid in determining if this is the best type of shoe for you. 

Barefoot running has been advocated as a means of strengthening of the foot muscles and encouraging a better style of running. However, it has also been associated with increased incidence of stress fractures and abrasions of the foot. It has been hypothesized that when implemented carefully within a running program, this type of training can offer benefits which would not be seen within running in cushioned shoes alone. Think of it as a conditioning session for your foot. Of course this is not a new principle and has been used by runners for generations, just without the current marketing hype! Research is ongoing and it would be unfair to jump to conclusions on the barefoot matter without conclusive evidence. Remember every individual is different and what works for one may not work for you.

The aim of this article was to explain the fundamental elements of running biomechanics with the hope that it may aid you in your training and in your future shoe choices. This has been an unbiased account of running styles and running shoes and hopefully it well help you to draw your own conclusion on what best suits your needs.

Thomas Twomey

Sports Biomechanist at Footpro

BSc. Sport and Exercise Science

MSc. Sport and Exercise Biomechanics