The Science of Strength Training for Vertical Jump and Change of Direction

Athletes who can jump higher and change direction rapidly have advantages over other athletes in many sports. Two recent studies point to strength as being an important causal factor and predictor of these skills.

Speed is often measured by how quickly an athlete can run in a straight line. But for many sports, athletes rarely run in a straight line as they often have to make some type of directional change. Take a look at John Wall in the video below:

From a biomechanical and bioenergetics perspective, changes in direction are very complicated. Muscles have to absorb force and then energize to move the person in the opposite direction that his or her body is going. It takes a great deal of strength to handle those stresses. It also takes a rapid neurologic response to activate the opposing muscle fibers quickly. What does the research say about skills needed for developing change in direction?

Deadlift Improves Vertical Jump and Rapid Torque Development

Keiner and colleagues found that many strength-training activities improved change in direction speed (see Doug Dupont’s synopsis here). You might expect that exercises such as squats might help with agility as they incorporate a change in direction (although not rapid) as the person switches from an eccentric to a concentric movement. Deadlifts usually only focus on the concentric portion of the movement as little to no effort is placed on lowering the bar back to the ground in a slow controlled fashion.

Thompson and colleagues investigated whether a deadlift program (twice per week) would affect vertical jump and rate of torque development in untrained athletes. This was an interesting study as the untrained athletes were all supervised for their twice weekly sessions and they did not participate in other activities. After ten weeks, the researchers found an increase in deadlift (expected), but also in vertical jump and rapid torque.

On the surface, these results seem a bit unexpected as training only the deadlift would not seem to help in explosive agility activities. One potential reason for the results might be the group being studied. The participants were untrained athletes and maybe any exercise would help these athletes. A study with more advanced athletes would be helpful.

Strength Is Strongest Predictor of Change in Direction Speed

Spiteri and colleagues examined semi-professional female basketball players with at least five years of competitive experience. The authors included different tests for change in direction, but the T agility Test highlights the results of all the tests (and it is something that many of you may have done yourselves).

In these experienced athletes, all measures of strength correlated with ability to run through the agility tests quickly, as indicated in the chart below. (A correlation indicates the strength of a relationship; scores closer to 1 or – 1 are the strongest; anything above .7 is very strongly correlated.) Surprisingly, power (as measured by a vertical jump) was the least correlated (although a -.46 is still a very significant relationship between power and agility.)

 

The big advantage with using trained athletes in a study is that you can see how much each type of strength plays a role in agility. It allows us to generalize and plan for training trained athletes. However, we cannot know strength or agility came first or whether one caused the other. Whereas, the first study allowed us to take a little better look at the causal mechanism of gaining strength followed by agility as athletes only completed deadlift training. In both studies, strength seemed to be one of the most important factors for agility.

The Take-Home

Barry Sanders was said to have close to a 600lb squat. He is also known as one of the most elusive American football running backs and for his ability to change of direction. The above research as well as many individual cases seem to point to strength as one of the most important factors in building change in direction speed.