Should you increase vertical force to run faster?

In recent years there has been considerably more interest in the production of vertical forces to improve speed in running. What has not been talked about is how the vertical forces supposedly improve running speed and how vertical forces can be increased or decreased.

If you have been running for many years, most likely you have seen quite a few runners who appear to bounce as they run down the road or track. The up and down movements of the body are very noticeable, especially in comparison to high level runners. In order to create these up-and-down movements the body must generate strong vertical forces.

It does this by generating force into the ground so that you can be propelled upward. But what appears to be misunderstood is that these up and down movements do not help you run faster. To move forward as fast as possible you must move horizontally with little up and down vertical motion.

However, some runners, especially those who do not have sufficient background knowledge to understand and critique running research, believe that up and down movement is good. They believe it is needed to return the energy built up in each touchdown to propel the body upward and forward in the push off.

Some of the studies dealing with these up-and-down motions have explained this return of energy as being like a “bouncing ball” or having springs under the feet. On touchdown the ball (spring) compresses and when it releases, it bounces (springs) back up. However, this is an accurate description of what happens in jumping, it is only partially true in running.

Because you are moving horizontally in running, every time the foot makes contact with the ground you have horizontal and vertical forces generated. To absorb some of this force but to retain most of the force generated, the leg joints undergo slight flexion in which the muscles and tendons undergo lengthening and increasing amounts of tension. The greater the tension, the stronger the eccentric muscular contractions and the less you sink down on each touchdown. When the tension becomes sufficiently great, it stops the downward movement of the body.

As a result, you withstand more of the energy created on touchdown and then store it mainly in the calf muscle tendons. This energy is given back on the takeoff making this a very efficient way of running. It does not require additional muscle contractions to generate the force needed to push you forward.  You simply utilize most of the energy or force generated on touchdown in the takeoff, which is mostly horizontal but with a small vertical component.

The key to maximizing your running efficiency is to create greater force in a horizontal direction. This is done through an action known as pawback in which you drive the leg down and back to make contact with the ground. The vertical component at this time should be minimal. When you have a strong horizontal component the touchdown force is exerted (pushed) to the rear so that the reactive force will push you forward on takeoff.

In effective running when you drive the leg down and back, the foot should land as close as possible to the vertical projection of your center of gravity (underneath the body). In this way, you eliminate negative touchdown forces and generate energy that can be used to direct you forward horizontally.  If you land with the foot more in front of the body, when take-off occurs, the body will be more or less directly over the push off leg. As a result you will have a vertical push off resulting in more height rather than horizontal distance.

The more vertical (bouncing) push-off is usually seen with heel hitters who land on the heel of the foot, rock over and push off when the body is more or less directly over the take-off foot. When you land mid-foot, more under the body, your body will have time to move out in front of the foot so that when you push off, you will have a stronger horizontal component.  Thus, top speed is determined by how much horizontally imposed force you generate, not vertical force.

Some vertical force is needed to get off the ground but the less you have the more effective becomes your run. Don’t be swayed by the research saying that running is like a bouncing ball or spring. It is not. Running should be as low to the ground as possible with as little vertical oscillation of your center of gravity as possible.  When you can achieve these objectives in your run you will see that your run is not only much faster but it will seem even more effortless. An added benefit is that it will also help prevent injury.

For more information on this topic read Explosive Running and Build a Better Athlete.