Is there a correlation between ankle and lower back pain? We think so!
Your feet have an important stability function. If the foundation that you stand on is unstable, stresses will be transmitted to other parts of your body with discomfort and pain being felt in your ankles, knees and lower back.
An easy way to understand the process is to remember the last time that you hurt your foot, kicked your toe, twisted your ankle or the horrible feeling of standing on glass or a nail. From that moment, you instinctively try to relieve the pain in that location by putting more weight on the other foot, leaning and limping. For temporary relief this natural reaction is good. The pressure is no-longer on the affected area and you are feeling some form of comfort. But if this process is continued for longer periods of time, the outcome is not as pleasant.
Your feet and ankles act as your natural shock absorbent. When functioning properly, the arch of your foot will soften the impact of walking and running. Over strenuous activities or accidents can lead to ankle, knee and lower back pain making it unbearable to walk or run. If you suffer from flat feet or high arches, the result is either too much or too little shock absorption. If you are over compensating for an injury, you apply more pressure than expected in an area that can then become injured and cause more damage.The right foot support can help you get back in shape faster.
Centre of Gravity
To measure the impact of stress on your joints, you need to look at your centre of gravity. Your centre of gravity affects your stability. As you grow and put on weight your centre of gravity will change, this has a significant impact on your core structure. When you put on weight your centre of gravity may move forward and your body will naturally try to correct the problem and put more strain on your ankles, knees and lower back. This also changes the force being applied to your joints and muscle when you move.
The amount of force being applied to the body can be calculated using a reference datum, arm and moment to calculate your centre of gravity.
The reference datum is a reference plane that allows accurate, and uniform, measurements to any point from which all horizontal distances are measured for weight and balance purposes. If you stand with your feet together the nominated central datum point is taken from the centre most point where the arch of your feet touch.
The horizontal reference datum is an imaginary vertical plane or point, arbitrarily fixed somewhere along the longitudinal axis from which all horizontal distances are measured for weight and balance purposes.
The arm is the fore-and-aft distance from the datum to any point.
The moment is a measure of force that results from an object’s weight acting through an arc that is centred on the zero point of the reference datum distance. Moment is also referred to as the tendency of an object to rotate or pivot about a point (the zero point of the datum, in this case). The further an object is from this point, the greater the force it exerts. Moment is calculated by multiplying the weight of an object by its arm.
What this means is that the more weight you have and the taller you are the more force is exerted on the ankle and lower back pain and core structure that this force is being applied.
Knowing this information is important because you can use this to your advantage. The law of leverage comes into play and a small change in the foundations can have an enormous impact the further you extend past the datum point.
One way of correcting the problem is to go back to the origin of the problem and make subtle changes that can then correct the imbalance to relieve long term damage. This can be done using a “Weight Bearing Orthotic”
## Calculating the forces exerted on the foot and ankle while walking involves bio-mechanics, which is a complex field that takes into account many variables. However, we can make a simplified estimation using the concept of ground reaction force (GRF), which is the force exerted by the ground on a body in contact with it.
The GRF during walking can be approximated to be about 1.2 times the body weight during the stance phase of the gait cycle. This is because when you walk, you’re not just supporting your weight, but also propelling yourself forward, which requires additional force.
Let’s calculate this for a person weighing 100 kg.
Please note that this is a simplified estimation and the actual forces can vary based on many factors such as walking speed, gait pattern, footwear, and individual bio-mechanics.
Let’s proceed with the calculation.
The ground reaction force exerted on the foot and ankle while walking for a person weighing 100 kg is approximately 120 kgf (kilogram-force) or 1200 N (Newtons), considering Earth’s gravity.
Please note that this is a simplified estimation and the actual forces can vary based on many factors such as walking speed, gait pattern, footwear, and individual biomechanics.
## Formula and measurements calculated using Walfram|Alpha
Weight Bearing Orthotic
We need to focus on the foundation and the alignment of your core.
If you try to correct your misaligned centre of gravity without support, you turn your feet out to over compensate. The action of turning your feet out is known as supination. The supination action is created by making the muscles fire earlier and for longer. A weight bearing orthotic can apply force below the datum point to correct this imbalance. The orthotic will provide a stable plain that alters the position of the foot and creates a natural resistance. Without effort your feet will now turn back into the corrected alignment.
Long term use of a weight bearing orthotic can retrain the core components of the feet to relieve pain and discomfort.