Running – What Actually Happens?

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By Physiotherapist, Alex Contyrunning biomechanics

We all know the various benefits of running, it improves cardiovascular function, reduces risk of stroke and heart disease, reduces blood pressure, improves bone density, its good for weight management, and mental alertness.  It also helps to alleviate symptoms of depression, to name only a few!

To prevent running injuries and/or simply improve on our running technique and speed we need to look into what is happening to our body on a biomechanical level when we run.  Many gait abnormalities seen during running are due to past or present injuries, faulty postural alignment, or muscular imbalances, all resulting in poor technique or/and compensatory movements and potentially more injuries.

The best way to find and address any running imbalances or imperfections is to have a running assessment, where we can assess your running gait and advise on how to correct any imbalances, avoid injury and improve efficiency.*

But for this feature, we are going to breakdown the actual running gait to look at the biomechanics of the activity we all instinctively do from infancy. This is very much an overview, but if it is of interest to you, please keep an eye out on Facebook/website for details of an evening talk next month where we will be going into more detail.

The running gait cycle is split into two phases (the gait cycle is completed as the foot in contact with the ground moves through a full stride to make contact with the ground again):

• Stance phase – during which the foot or part of it touches the ground
• Swing phase – during which that same foot doesn’t touch the ground

This can then be broken down further to:

Stance Phase:
1. Initial contact
2. Midstance
3. Propulsion / take offrunning phases

Swing Phase:
1. Initial swing
2. Mid swing
3. Terminal swing

We take a look at each of these in turn:

Initial contact (strike to midstance)
Initial contact is when your foot lands on the ground.  It is the cushioning phase of the gait cycle.  The knee flexes just before the foot hits the ground on its outside edge to then progressively pronates or rolls in.  This causes the foot and leg to act together as shock absorbers.

Midstance (foot flat to heel off)
During midstance the foot and leg provide a stable platform for the body weight to pass over.  By now the foot should have stopped pronating.  If the foot is still pronating at this time it can leads to too much movement and/or instability, resulting in excessive inward rotation of the lower limb – corrective exercises and either footbeds or corrective trainers should be considered.
Midstance occurs when the other foot is in swing phase, so all the body weight is borne by a single leg.  This also means that the lower limb is particularly susceptible to injury, but with correct running form this can be avoided.

Propulsion (heel off to toe off)
Propulsion is the final stage of the stance phase.  It begins immediately as the foot lifts off the ground.  As the big toe turns upwards (dorsiflexes) the windlass mechanism comes into play, tightening the plantar fascia and helping to raise the arch of the foot, controlling excessive pronation and stabilising the leg.  This mechanism is very important since it allows the foot to act as an efficient lever.  It is your big toe that leaves the ground last and is used as a source of propulsion to move you forward.  It could be argued that the large joint in your big toe is one of the most important joint in your body for proper and efficient running form.  It is very important to have the proper running shoe to support these motions – good footwear can really help with injury prevention.

Swing phase
The swing phase begins with ‘toe off’ and ends just before the foot makes contact with the ground again and a new gait cycle starts.
This phase is important to set the foot and leg up in preparation for foot contact and the next stance phase.

Initial swing – Mid swing
During initial swing to mid swing phase, internal rotation of the lower limb occurs:  Assuming that your foot has experienced proper toe-off, your foot will leave the ground with your leg in the position of internal rotation.  That is, your toes are pointing towards the midline of your body.
While your leg is moving forward through the air, your hip, knee, and ankle, must all rotate outwards to allow your foot to land again on its outside edge.

Mid swing – Terminal swing
During mid swing to terminal swing phase, external rotation of the same lower limb occurs:  As your leg moves forward and crosses the plane of your other leg, it should be in a position of external rotation, meaning that your toes are pointing slightly away from the midline of the body.  This allows your foot to strike the ground on the outer edge and the whole cycle of gait begins again. And again. And again…..

Upper Body
During a gait cycle, your upper body is also very important.  Your right arm is connected to your left leg and your left arm is connected to your right leg.  As you can imagine, it is very important to utilise your arms for proper running form.  Swinging your arms front to back will help to propel you forward and make you more of an efficient runner.  It is not uncommon to see people swinging their arms from side to side instead of font to back whilst trying to go forward with their legs – this is wasting energy and propulsion.

A strong core stability is also important to minimise twisting for injury prevention and energy efficiency.

Foot Strike Patterns
Foot strike patterns should also be noted, as they too influence the biomechanics and running efficiency.  There are three identifiable strikes – the heel, midfoot and forefoot strike.

foot strike patterns

Many runners are heel strikers and over the years trainers have evolved to support this quite aggressive strike, generally on the outer edge of the heel.  But there is growing evidence to suggest that running injuries such as plantar fasciitis and tibial stress fracture or shin splints are linked to heel foot strikers and this is due to the repeated impact and the resulting loading and ground forces affecting the lower limb. Forefoot strikers / toe runners over use their calf muscles (especially if they are used to wearing heels in the day which already result in slight shortening of the calves muscles) and potentially end up with tight calves and other related injuries. plantar fasciitis

The most effective and efficient strike is midfoot, having the least negative effect on the body – both the ankle joint and calf muscles absorb impact and roll though the inward rotation more effectively than landing on heel or toes.  Runners needs to be sure they are not landing flat footed with a slap, but rolling through the base of the mid foot.  In principle the greater the noise when you land the greater the impact on the body is!

Improving Your Gait:
It is almost impossible for a runner to simply “fix” the way they run based on awareness of a problem.  Instead, they need to train the various regions of the body how to “feel” what a proper movement is like and then condition the involved muscles to be able to carry out proper movement repetitively.

There are scores of running drills out there and they can be deemed as essential when trying to improve speed and efficiency – simply pounding the pavement or treadmill will not improve your speed without some focused training.  Next month we look at some of these ‘essential’ drills.  But specific drills to improve on an imbalance or poor running posture will need to be prescribed personally after assessment.

If you have any concerns about your running gait or injury, want to improve your performance or simply correct a bad habit/running form, book in to see one of us to have a biomechanical running assessment and we will equip you with some corrective drills to help you reach your goal.

Please keep an eye out on Facebook/website for details of an evening talk coming soon on Running Biomechanics, where we will be going into more detail on the above and answering individual questions.

*(we have three professionals at the clinic who can carry out such assessments; myself and fellow physiotherapist, Claire as well as Personal Trainer, Katie).

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