Biomechanical Differences Between Different Foot Strikes
Why do Different Foot Strikes Matter?
Here we focus on the difference between heel striking and forefoot striking (see bottom of page for more on midfoot striking which is often intermediate). In heel striking, the collision of the heel with the ground generates a significant impact transient, a nearly instantaneous, large force. This force sends a shock wave up through the body via the skeletal system. In forefoot striking, the collision of the forefoot with the ground generates a very minimal impact force with no impact transient.
Therefore, quite simply, a runner can avoid experiencing the large impact force by forefoot striking properly.
Check out this link for more info and VID CLIPS
http://www.barefootrunning.fas.harvard.edu/4BiomechanicsofFootStrike.htmlhttp://www.blogger.com/img/blank.gif
Foot Strike while Running
There is a controversy among runners about foot-strike. Should a runner hit the ground with the heel, the midfoot, or the toe? Some runners are very passionate about this question. In an effort to give information about this aspect of running technique, I am presenting information from web sites and books that discuss the question. If you know of other web sites that discuss foot-strike, please email me the links.
Summary
This section summarizes the pros and cons of the different types of foot-strike that are being used. Once a runner knows his/her strike, the runner can do exercises to counteract the weaknesses of that strike.
Foot-Strike -- Pro /Con
Heel - Stretches the calf muscles. Less stress on calf muscles and Achilles tendon. Contributes to over-striding, slower running, and poorer form.
Midfoot - Better shock absorption due to a bent-leg. Contributes to better form, and faster running. Less stress on calf muscles, Achilles tendon, IT band than toe-strike. More stress on the calf muscles and Achilles tendon.
Toe - Less stress on knees and ankles. Reduced stride. Contributes to better form, and faster running Keeps calf muscle contracted, contributing to shin splints, Achilles tendinitis, and muscle pulls.
For an excellent in-depth look at foot-strike, go to this article.
Details
About.com Sports Medicine
A normal foot strike lands flat or on the outer-back portion of the heel and then rolls onto the sole and ends with the push-off from the ball of the foot.
A heavy heel-strike can lead to excessive traumatic forces and actually slow you down.
Landing hard on the midfoot or ball of the foot places more stress on the achilles tendon (which will contract to counterbalance the force of the strike). This is seen often in sprinters. For these runners, stretching the calves and Achilles regularly is recommended to reduce injuries.
A System for the Measurement of Impact Force in Footwear
Measurements of the energy absorption by the soles of running shoes have shown that running shoes vary considerably in the amount of energy absorbed. The conclusion I draw is that we should choose shoes based on our foot-strike pattern.The results demonstrated considerable variability between shoes for different speeds and for both toe and heel strike. Discussion here is based on the shoes which score well for both heel and toe strike energy measures and how these results relate to retail cost. Shoe F for example is the highest performing shoe for heel strike at both speeds but rates low for toe strike. The shoe is moderately priced but rates high for energy and would be more appropriate for low intensity joggers or walking where heel strike is predominant. Shoe D is also well priced and performs well for fast heel and toe strike and is therefore more appropriate for a higher performance runner. Shoes A and B are effective for toe strike at both speeds but performance is relatively low on heel strike. These shoes are more appropriate for the more competitive runners who perform at higher velocities and require more effective fore foot energy absorption. Shoes D and E both perform well on heel strike over toe strike but vary with speed.
Dr. Stephen M. Pribut's Sports Pages
Some say to run on the ball of your foot, others say contact the ground with the heel. We take a middle of the road approach. Studies have shown that good long distance runners usually contact with the midfoot. Slower runners contact between the midfoot and the heel, faster runners a bit further forward. We feel that only sprinters or short to middle distance runners should contact the ground with their forefoot or the ball of the foot. While there may be exceptions to the rule, this [midfoot] is a good way for most beginning and intermediate runners to start out. It allows for better shock absorption, less stress on the calf muscle and Achilles tendon, and better rolling forward onto the next stride. Your muscles then end up being used in a similar manner to how you walk, and this is the pattern of muscle firing and contact pattern they are accustomed to.
Dr. Pribut serves on the Board of Directors of the American Academy of Podiatric Sports Medicine (AAPSM), is the current President of the AAPSM and also serves as Chair of the AAPSM Shoe Committee.
The Pose Running Method
Conclusions: Pose running was associated with shorter stride lengths, smaller vertical oscillations of the sacrum and left heel markers, a neutral ankle joint at initial contact, and lower eccentric work and power absorption at the knee than occurred in either midfoot or heel-toe running. The possibility that such gait differences could be associated with different types and frequencies of running injuries should be evaluated in controlled clinical trails.
"Reduced Eccentric Loading of the Knee with the Pose Running Method", Medicine & Science in Sports & Exercise: Volume 36(2) February 2004 pp 272-277