As we run, each foot comes into contact with the ground some 80-100 times per minute on average. This translates to a stride rate/cadence of 160-200 steps/minute, and I choose to keep the range broad here since cadence varies from person to person and to some degree with Asics Gel Lyte 3 Femme running speed. Every time you land, your foot impacts the ground with a certain amount of force, which is counteracted by an equal and opposite amount of force applied by the Nike Air Max 2017 Femme ground on your foot. This equal and opposite force is known as the ground reaction force or GRF for short. The ground reaction force comes in a number of components, typically broken into anterior-posterior (along the direction you are traveling), horizontal (side-to-side), and vertical (straight up and down). Of these, the vertical GRF is the greatest in magnitude, and is the one I will focus on here.
Below is a graph depicting the vertical ground reaction force curve for a heel-toe runner (modeled after Cavanagh and LaFortune, 1980On the vertical (Y) axis is the value of the vertical ground reaction force as a function of body weight. You can think of Nike Air Max 2017 Dam this as a proxy for how much force the foot is applying to the ground as you run. The horizontal (X) axis shows time in milliseconds – the amount of time each foot is in contact with Nike Air Max 90 Womens Pink the ground varies among people and at different running speeds, but 300 milliseconds (about 1/3 of a second) is a reasonable number for a typical runner. The curve depicted on the graph shows how vertical GRF changes from the point of initial contact of the foot with the ground (time 0) to the point where the foot leaves the ground on toe-off (about 300 ms). What you’ll notice in this graph is that there are two distinct force peaks. First, the impact peak is the initial force applied to the ground by the foot and lower leg at initial heel contact (remember, this graph is for a heel-toe runner). Full body weight is not being applied at this point, Nike Air Max 270 Femme so the impact peak is basically a function of the weight of the foot and lower leg hitting the ground. The active peak represents the force applied by the foot and supported body weight during roughly mid-stance. Notice that it is larger than the impact peak – this is the typical pattern.In the above graph, vertical loading rate is essentially the slope of the line from initial contact to to the impact peak (in practice, it is usually measured in the region from 20-80% between these points). The loading rate simply represents how quickly the impact force is applied – a steeper slope means a more rapid collision. A more gentle slope would indicate that force application during impact is being spread out over a longer period of time. A reasonable analogy would be punching the wall with your bare fist – your fist comes to a very www.aquarillon.fr rapid stop and the force is applied quickly. This is not a good thing for your fist. On the other hand, if we put on a boxing glove, we could still hit the wall really hard, but the cushion in the glove would slow down the impact and distribute the force over a longer period of time. Consequently, it would not hurt as much, and would likely not damage the bones in your hand. The same logic applies to crumple zones in a car – when you crash the crumple zone slows down force application to protect the driver and passengers from the sudden shock of an immediate impact.The upshot of the above information is that if you are going to run in a heel-toe style, putting Nike Air Max 270 Femme cushion under the heel will slow down impact and decrease the loading rate by spreading force impact over a longer period of time. This is a good thing for your heel bone Nike Air Max 90 Womens (the calcaneus), and why barefoot runners tend to move away from a heel strike, particularly on hard surfaces. Your heel fat pad does not provide enough protection to absorb impact during barefoot heel-toe running. If you are a heel-toe runner, particularly one who overstrides with an extended knee and a pronounced heel strike, you should by all means wear a shoe that has a cushioned heel.
