By John A. Mercer, Ph.D.
Biomechanics Laboratory, University of Nevada, Las Vegas
Runners get injured … anyone reading this part of the newsletter either knows this first hand or knows someone who has had a running injury. There is a wealth of research documenting the risk of injury to runner and can be summed up by considering this: If a 100 runners are followed during a marathon training program, as many as 75 will probably have some type of injury with about 20 of them having to stop running to let the injury heal.
Why is there such a high risk of injury during running? Each time your foot strikes the ground, there is an impact force of about 2-3 times your body weight. In a 30-minute run, a typical runner will have about 5000 impacts … it is the accumulation of all those impacts that are likely the root of the injury problem.
Unfortunately, no shoe design, or lack of wearing shoes, is going to solve the problem. The solution to avoiding running injuries is to avoid Too Much Change Too Soon. The body is amazing at adapting muscles and bone strength to stress like running. However, the body needs time to adapt … an injury is almost certain if too much stress is applied with too little time to adapt.
Any change in running distance, speed, surface, or shoes (new or change in model), for example, can be thought of as ‘change’ … too much of this change too soon can lead to an injury. The injury may not be immediate … which is why avoiding running injuries is so hard. Sometimes we do not realize how much stress we are placing on our bodies with a normal run … let alone a change in run in some way. Be sure to plan in your rest days and keep track of injuries … looking back on your training log you can sometimes figure out how much change in stress your body can handle.
What should a runner do when he/she is injured? This is a difficult question to answer because there are so many different types of running injuries … some of them you can continue to run with, some of them you will be better off not running and letting the body heal. Let’s say your injury is in that category … runners are notorious for going crazy if they can’t run! Here are some options: Elliptical trainer, Body weight support treadmill, and deep water running.
The Elliptical Trainer was designed to mimic the running motion while eliminating the impact with the ground. Overall, this does accomplish that … but the stride length is limited and the upper body motion is often restricted.
If you have $25,000, you can run on a Body Weight Support Treadmill. This type of treadmill ‘lifts’ the runner up to support some of the body weight. By doing that, the impact with the ground is less severe and some runners may still be able to train this way. The downside of this is that these treadmills are hard to find and are very expensive.
Another way to continue to run while injured is to run in the water. There is a good body of research that has demonstrated that runners can maintain their on-land running fitness and performance after using water running programs. There are two main categories of water locomotion: Shallow and Deep Water Running. During shallow water running, the feet are still in contact with the ground … it is a good idea to wear an old pair of shoes (or you can buy shoes specific for the pool). The downside of shallow water locomotion is that runners with certain types of injuries may not be able to place any weight on the feet.
Deep water running is down in the deep end of the pool where the runner cannot touch the bottom. Many runners will use some type of flotation device to help keep them upright so they can focus on maintaining a running motion (vs. treading water). There are several ways to ‘run’ in the water … it is a good idea to search YouTube for Deep Water Running (also known as AquaJogging). The two main styles are often described as ‘high-knee’ and ‘cross-country’. During high-knee style, your legs are moving up and down sort of like stair stepping … buy you are still trying to mimic a running motion. During cross-country, you are trying to reach forward a bit more with the leg … sort of like taking long strides. When using this style, you need to be careful that sometimes you can place too much stress on the back side of the knee when you are pulling the leg back.
In reviewing the research on training studies of deep water running, it seems the programs that are most successful are the ones that incorporate high-intensity intervals. Sorry folks … it seems you need to actually try harder in the water than you would on land to make this work! By using interval training, you can work in some high-intensity efforts with some easier efforts in order to extend the time in the water. Your high intensity efforts may only be about 10-seconds long … try to work up to 30-seconds.
In an attempt to try to avoid running injuries, you might even want to add some deep water running to your training program to supplement your on-land training. Just remember: Too Much Change Too Soon can lead to injury. Give your body a chance to adapt and it will.
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