Running Biomechanics is a complicated term to describe how you run, and gait analysis is the method of which you do this.  Although it is often simplified into putting one foot in front of the other, the reality when you look closely, is it is a complex movement that requires synchronisation of many systems to take place (Levine et al, 2012; Napier, 2020). Luckily, our bodies are, for the most part, able to carry out the action pretty easily without us really knowing everything that is going on.

Advances in Analysing Running Gait

Technology advances have allowed several different ways to analyse how you run these days (Shull et al,2014). An iphone can record and slow down your movements to see what is happening (in 2D),your Garmin can record your steps and cadence, and there are even 'wearables' to tell you how much your bouncing and about your stride.

Watches now have algorithms that can tell you if your run was productive or unproductive, even if you disagree with it.  

These things will most certainly give you some good information about your average day to day running.  However, the accuracy of the information, and lack of other significant factors might not be enough if you’re injured.

Before we get into the finer details of running gait analysis, more specifically what 3D gait analysis measures, lets first look at a ‘normal’ running pattern.

‘Average Running Pattern’

‘Normal’ as a term isn’t a very good term to use here as it blends sexes, age, physical fitness of individuals all into one standard. It also suggests that if someone doesn’t fit this ‘normal’ pattern it is undesirable or wrong, which is not true. Levine et al(2012), states that compensations are often shown as gait abnormalities and are often useful to the patient. However,to identify a problem or an abnormality, you need to have something to use as a comparison.

** This example refers to a heel-striker for simplicity **

Foot-strike to Midstance

1.     Your foot strikes the ground on the outside corner of your shoe. The ankle is in its strongest position here as it is ‘locked’ (pulled up) and needs to ‘unlock’ (point) to allow movement to follow through up the chain. Your foot therefore collapses as it pronates (* gasp!)…don’t worry,you need this to happen!

2.   The shin (tibia) in your lower leg then twists inwards on top of the foot to take up the force, followed closely by your knee hip and pelvis – whilst simultaneously slightly collapsing inwards

3.    Meanwhile your knee and hip are bending.

4.    The uptake of force at this stage is a winding up movement of rotation inwards towards the middle.

Mid-stance to Push-off

5.    Reaching the halfway point of your foot's time on the ground, to move you forward, your body now needs transfer the force and unwind everything outwards again.

6.     Your knee and hip extend, your foot points and pushes off the ground.

Simple isn't it? 

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This is a list of movements your body goes through whilst running, and are some of the measurements we take in a Run3D gait analysis assessment to help piece together the root cause to a problem.

Anterior Pelvic Tilt - how much forward and backward movement that your pelvis is making. If you put your hands on your 'hips' - the bony structure that you feel is your pelvis. If you think of the top of your pelvis like the rim of a bucket, it can help you visualise the movement. If you tip this bucket forwards, you have what is called and anterior tilted pelvis. If you tip it backwards, it is called a posteriorly tilted pelvis. The aim is to be in the middle of those two somewhere.

Pelvic Obliquity - this is when the pelvis moves side to side.If you have one side higher than the other from left to right, then your pelvis has a high obliquity on that side when that foot is on the ground. 

Hip Extension - is the amount that your thigh and leg extend behind you, just before your foot leaves the ground again. Generally, hip extension is good. It means you are pushing off the ground effectively. Reduced hip extension in runners is more common as a result of tight hip flexors (Dicharry, DATE)

Hip Adduction - this is looking from the angle of your thigh, and how much it collapses in towards the midline of your body. Too much hip adduction can result from weakness around the pelvis and hip musculature and can be problematic for causing injury.

Knee Flexion at Foot Strike - The amount of bend in your knee as your foot hits the ground can be a big injury indicator. The most common problem is not enough knee bend at foot-strike as this creates a lot of force into the joints (more specifically the knees).

Knee Abduction - the amount your knee collapses inwards towards the other knee. You’ve probably seen people running where their knees almost hit each other. The reason for this could be the result of a number of things, suchas too much movement at the hip, or lack of movement at the ankle.

Dorsiflexion at foot-strike - the amount your ankle bends upwards or downwards as your foot strikes the ground.

Tibial Internal Rotation - the twisting inwards of the tibia (the shinbone or lower leg) in relation to the foot. 

Maximum Eversion - the amount that the back of your ankle moves outwards as your foot hits the ground. This is one of the movements of pronation and is what we use to classify how much your foot collapses into wards the ground. Pronation is actually made up of 3 different movements, and is quite difficult to pin point by eye.

Why Injuries Happen

To move forward, your body needs to absorb forces taken up from your foot by simultaneously and synchronously moving your joints inwards, outwards,up and down, back and forth.

Injury happens when something along this process goes wrong. Whether that be; tight muscles, weakness, slow activation/timing, or something else –it can offset this dance ever so slightly to put things out of sync.  Our bodies are incredible at disguising and will make up for lost movement by changing their patterns ever so slightly to pickup the slack. You will still move forward and very likely  be none the wiser to any changes.

But something has to give, and this process will continue over and again,and compensations will keep being made until the problem is resolved or until it can’t hide it any longer and injury reveals itself. This is one of the main reasons why injuries appear to happen just out of nowhere – one minute you’re absolutely fine and the next you can’t bend your knee, but nothing happened? The real reason is because it has been happening for a while but your body has been fooling you to believe everything is fine.

This is where 3D gait analysis can break down these movements and pinpoint where the problem is, faster.

References:

Levine, D.,Richards, J., & Whittle, M. 2012, Whittle’s Gait Analysis, Churchill Livingstone,Elsevier.

Shull, P.,Jirattigalachote, W., Hunt, M., Cutkosky, M., & Delp, S., 2014, Quantified self and human movement: a review on the clinical impact of wearable sensing and feedback for gait analysis and intervention, Gait and Posture, Vol 40, No.1., pp. 11-19.

Dicharry, J.,2012, Anatomy for Runners, Skyhorse Publishing.

Napier, C.2020, Science of Running, Penguin Random House.

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