The biomechanics of running



Written by Ian Griffiths BSc(Hons) PGCert MChS
Musculoskeletal Podiatrist

Foot function is of key importance to runners of every level in the unfortunate occurrence of an injury. Running is an excellent form of exercise but subjects the body to significant stress. Each time a foot hits the ground it strikes with a force equivalent to roughly three times the runners' body weight. This can result in micro-damage to the soft tissues at a level that is undetected until failure of the tissue or injury occurs. This is the classic 'over-use' injury seen in runners (and indeed sportsmen and women generally) in which symptoms present insidiously (all of a sudden with no apparent cause).

The pain arises when the repetitive dosage of training/sport has exceeding the healing process, leading to a breakdown in the tissues involved - a biomechanical overload. The pain coupled with lack of function usually results in an inability to continue activity. This process is exacerbated by a sudden increase in training, and most importantly poor skeletal alignment - which may arise with (or as a direct result of) foot motions and compensations.

The most common injuries to runners that are associated with poor foot function and poor alignment are:
  • Lower back injury (e.g. Sacro-iliac joint pain)
  • Hip/Buttock injuries (e.g. Ilio-tibial band irritation/Piriformis syndrome)
  • Knee injuries (e.g. Patellofemoral pain)
  • Leg injuries (e.g. Medial shin pain)
  • Foot injuries (e.g. Achilles tendinopathy/Plantar fascial pathology)

Foot types and testing for injuries

People have individual characteristics in their foot type, and some running shoes take this into account, which is why evaluation of them forms part of a good podiatric consultation. Reputable running stores can also identify foot types and recommend appropriate shoes using video analysis techniques.

A pronated foot type tends to be one which has a flattened arch appearance, and bulging around the medial (inside) aspect of the foot and ankle. This foot type can give rise to rotations in the leg that can make a sports person unstable when on one leg (which is most of the time when running). Try standing on one leg in front of a mirror and look at what happens to the foot. Try bending the knee down into a one legged squat position, and see if the knee cap stays in nice straight alignment over the foot as you bend - often with a pronating foot you will become unstable.

The myths of pronation

  • Pronation is a normal part of the gait cycle
  • We all pronate, and some research suggests it is one of the ways we absorb shock
  • Pronation related problems can occur if you pronate at the wrong time, the wrong amount or the wrong speed/velocity (i.e for too long, too much or too fast)
  • Running shoes/orthotics do not 'stop' you pronating, but try to control how you pronate
High arched (supinated) foot types tend to be more stable, but can be associated with stress type injuries.

The standing single knee bend is one of the tests that podiatrists and physiotherapists use to check if an individual is predisposed to running injuries. If an individual fails this test then they may want to consider having a video analysis of their running technique, including a foot examination.

The importance of core/proximal stability

Just as important as foot mechanics and appropriate footwear is the consideration of core stability - being able to maintain good postural alignment of the pelvis and lower back when running. A podiatric assessment/video gait analysis should not consist of foot examination and function alone, as the foot does not work in isolation. Knowledge of stability at the pelvis is just as important - it should be considered that the pelvis controls everything beneath it, and just as foot movements and compensations can cause leg rotations and problems higher up, pelvic instability of poor glutei recruitment or timing can do the same from the top down.

For this reason most successful injury management is with a multi-disciplinary approach, with concurrent podiatry and physiotherapy.

The success of the multidisciplinary approach

  • Prevention of injury through sound assessment and application of multi-disciplinary treatment.
  • A Podiatric assessment is considered an essential part of an overall assessment to understand injury and identify the factors contributing to injury in the lower limb and in chronic low back pain.
  • Core Stability training is used as a foundation for movement control and postural stability.
  • The use of orthotic devices is recommended only when necessary to complete the rehabilitation process, and enable prevention of an injury in the future.
  • All treatment is based on the application of research based approaches in musculoskeletal healthcare.
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