The word gait and the term gait analysis are terms that are becoming more recognisable in the everyday language of the average person in the street. However, it would appear that the understanding behind the terms still remains a mystery. A big part of the problem lies with the sports stores that offer a fitting service for running shoes, a pet hate of mine and more about that in a while.
An accepted definition of gait is:
Human gait refers to locomotion achieved through the movement of human limbs. Human gait is defined as bipedal, biphasic forward propulsion of center of gravity of the human body, in which there are alternate sinuous movements of different segments of the body with least expenditure of energy.
As you can see in the quote, locomotion is achieved by the movement of human limbs. From a lower body perspective, the key limbs would be thighs, calves and feet combined with the hip, knee and ankle joints and the pelvis. Unfortunately, this is not made clear by many companies that offer “gait analysis”.
What most people think is a Gait Analysis?
So, back to my pet hate. I cannot believe how many high street stores have gait analysis as part of their service and then proceed to describe how they can fit you with a nice pair of shoes. In almost all cases, they place you on a treadmill and take video footage of your feet. The resultant video will then be examined in more detail, sometimes with the use of lines overlaid on the image, to decide whether your foot strike pronates (collapses inwards on the arch), supinates ( a high arch) or is neutral (neither pronating nor supinating).
The end result of this process is that your shoes will be tailored to bring you to a neutral position, usually with the use of orhthotics (sole inserts) in the shoe.
This process might be referred to as video gait analysis but it is more a visual review of the feet.
This is incorrect on so many levels.
Firstly, you have to consider the accuracy of the process.
While a treadmill is very convenient to have in a room or a shop, it does not guarantee to accurately reflect the way that we naturally walk or run.
A breakdown of the walk would look like the following:
The walk is a gait which keeps at least one foot in contact with the ground at all times and is performed with the following steps:
1. Lift one leg off of the ground
2. Using the leg in contact with the ground, push your body forward.
3. Swing your lifted leg forward until it is in front of your body
4. Fall forward to allow your lifted leg to contact the ground.
5. Repeat steps 1–4 for the other leg.
6. Repeat steps 1–5 to continue walking.
When an individual uses a treadmill they prepare themselves for the movement of the treadmill. Some people may adapt or change their style of movement for the treadmill. An assessment of an individual on a treadmill is not guaranteed to be an analysis of the persons natural movement.
Secondly, you will not be looking at the natural stride duration of a person, you will be looking at the stride duration as defined by the speed of the treadmill. Everybody has their own favoured stride duration in any gait, be that walk, jog or run. It is why you will see elite runners running with their own stride duration during a race. If they were to fall into the stride duration of another competitor, that would not be efficient for the athlete, and could have negative impacts towards the end of the race when greater effort will be needed.
Thirdly, drawing lines onto images is not an exact science. Certainly from a repeatability perspective, it would not just differ between operators but also between subsequent analyses with the same operator.
Lastly, adjusting the angle of a persons’ feet without understanding the knock-on effect on the joints above (knee and hip) is not a particularly responsible approach. The individual may notice some short term improvements in comfort while running but, in many cases, there have been longer term issues in the knees and hips as a result.
This approach is not just confined to sports stores. There are many websites offering services from physiotherapy to podiatry or core strength and balance sites that all offer the same approach; an analysis of the feet that is referred to as gait analysis.
Force Plate or Pressure Plate Gait Analysis
Force platforms or force plates are measuring instruments that measure the ground reaction forces generated by a body standing on or moving across them. They attempt to quantify balance, gait and other parameters of biomechanics. They usually take the form of an individual platform that has to be walked on as part of the patients overall walk or in some cases they may be a longer measuring area, rather like a carpet in a passageway.
The smaller force plates are more tricky in their use as the patient is always aware that they need to tread on the force plate and to find the centre. This means that their walk will be false and the resultant measurements will be inaccurate. The longer walkways are much better as they allow the patient to walk normally along the length of the force mat.
The other issue is that you are only able to analyse one leg at a time. This means that to get both legs they will be from different strides and therefore you cannot actually see what one leg is doing when the other moves in a certain way.
While the force plates are able to accurately measure the forces applied by the feet during movement, there still have to be a number of assumptions about what is happening to the limbs above the feet. This could mean that conditions may be incorrectly diagnosed. In an attempt to rectify this, some companies will use cameras with their force plates to provide a visual review. There is some very useful information that can be gleaned from ground forces in a person but there are also limitations.
Video Gait Analysis
Video gait analysis is the use of a series of cameras to video the patient from different positions and then to use software to amalgamate that data and to make calculations and assumptions about the movement. These can range from small single camera systems, up to a full blown gait laboratory. At the last count we had approximately thirteen major gait laboratories located in hospitals around the UK and there are also some major gait laboratories in Universities.
Single camera systems have limitations in that they cannot give you forwards (sagittal) and sideways (coronal) movement for both legs at the same time. As you can deduce, you would need a minimum of four cameras to have a chance of getting both legs and of course you only have truly accurate data when the person is standing directly in front of the camera. Once again, this often means that the individual has to walk to ensure they are at a certain place at a certain time and also facing in a particular direction. This is very difficult to achieve with the person still moving naturally.
There are some companies that are offering video gait analysis and are looking at all the lower limbs and not just the feet. This is a much better approach but it still means that the individual is performing in a contrived environment. There are many factors that can adjust your natural movement. One of these is the fact that you will be in a purpose designed room that will obviously have walls. The human brain does some interesting things when faced with boundaries. It tries to adjust your movement to fit with the boundaries and therefore will have an impact on stride length and stride duration.
Also, if the gait analysis includes pressure plates, this can bring it’s own issues. The individual needs to walk exactly on the pressure plate which will have an impact on the movement. I have spoken to orthopaedic consultants who have said that the gait labs they use have covered pressure plates so that the patient is not aware of their location. However, if the patient does not walk correctly on the pressure plate then they have to re-direct their walk which gives the game away and can induce un-natural movement again!
Another issue with video labs is that the patient needs to have sticky dots placed on them at various positions by the operator which impacts on repeatability. The sticky dots also give another problem. The cameras can not always see the sticky dots and when this happens, the data collection is lost. This means that the software has to “guess” where the dot was and make an educated calculation.
It is widely accepted by orthopaedic consultants that gait labs provide beneficial data and would like to utilise the services on a regular basis to support their work in clinic. However, the time required to complete an assessment combined with the costs mean that hospital gait labs are predominantly used for cerebral palsy patients. Also, most orthopaedic consultants that I have spoken to freely admit that they struggle to understand the information provided to them from a gait lab. the data needs to be accurate and relevant to the needs of the consultant.
The opportunity for information from the gait labs to be used to support physiotherapy in patient rehabilitation is non-existent.
Sensor-based Gait Analysis and the GaitSmart system
There is a newer, alternative approach to gait analysis, which is to use sensors. The sensors are usually small devices that are placed on the patient. Some systems only use a single sensor, placed on the back which looks at body movement to make assumptions about the lower limbs. There are some systems that use two sensors, either one on the back and one on the shin or sometimes two sensors, one on each shin.
Once again there is a lot of assumed information with this approach. Also, you need to be aware of the components within the sensor which I will expand upon later.
Now sensors, you would think, would give you the freedom to get natural movement which must be an improvement. However, many of the systems either have their sensors wired to a unit of some description to collect the data or use wireless technology to collect the data.
The wired sensors are slightly clumsy in their approach and can cause movement irregularities. the wireless sensors have a limitation on range (we all know how consistent our wifi connection is in our home) and struggle to handle the amount of data that needs to be collected.
Another problem with sensors is that not all sensors are equal. The majority of sensor-based gait analysis systems around only use accelerometers. These are ok when measuring acceleration or force, but lack the finesse required to collect detailed gait data and have problems when there is no movement. A tri-axis gyroscope combined with an accelerometer are essential components in a sensor for gait analysis.
There are other issues for sensor-based systems. They are not easily able to measure rotation. Many companies will assure you that they can measure rotation but a magnetometer is required to accurately measure rotation as it provides a direct reference to where the north is. However, as you will be aware, magnets do not work well indoors as they are affected by metal which is usually everywhere in a building.
The other problem that those of you who have used sensor-based systems or (and especially) video-based systems, you will know that it is not easy to understand or interpret the results. They tend to be labour-intensive and time-consuming.
Why we think you should choose GaitSmart
Here at GaitSmart we are the only company that places sensors on all the lower limbs and have had excellent success with walking and sprinting as well as with functional movement assessment.
At GaitSmart our sensors are not wireless, per se, but they do not have wires. The data is collected locally at each sensor. This means that a person being assessed can walk wherever you would like them to, and if working with sports people, we can have them running on grass or running tracks; literally anywhere we feel would be beneficial.
GaitSmart sensors have three orthoganol accelerometers and three orthogonal gyroscopes. The GaitSmart sensor data has been validated against the “Gold Standard” optical gait lab (as part of an independent published paper on Gait and Healthy Ageing) and was within one degree of the optical system, and as such, either system could have been correct.
At GaitSmart we have refused to provide data that we are not able to guarantee is accurate. We have reviewed rotation data from many sensor-based systems and they have all proved to be inaccurate. We have a new version of our sensor in development and we expect to be able to provide accurate information on rotation in the not-too-distant future.
A big focus for us at GaitSmart was the operator and healthcare specialist interface. Whether you are an orthopaedic consultant, a physiotherapist or a strength and conditioning coach, you do not have the time to spend trying to interpret the gait or functional analysis results. We have an immediate display of all relevant motion data, with a traffic light style colour code that is very easy to understand and to act upon. We also ensure that the results are available in a .pdf format report within a minute or so of the analysis being completed. GaitSmart is currently being used in hospitals and clinics to analyse real patients as well as in professional sports clubs.
GaitSmart is the only analysis system, validated against the optical systems, that provides detailed, accurate data quickly and easily.
When all is said and done, the term gait analysis is widely mis-used. Also, the systems used by companies that attempt to provide a more comprehensive gait analysis, do have their limitations. We believe that sensor-based gait analysis allows the most natural movement and GaitSmart is the only validated, published gait and functional movement analysis system that can be used in all working environments.
I hope that the two conclusions that everybody can draw from this are that
1. Gait analysis and shoe fitting are not the same thing!
2. GaitSmart is the only choice for an accurate, practical solution for gait and functional movement analysis