Research from the world’s leading sport scientists proves that faster sprinters need strength for speed. They are able to apply more force to the ground than slower runners. Studies from institutions including Harvard University and SMU’s Locomotor Performance Laboratory have shown how these forces are the difference between faster and slower sprinters.
They’ve proven that if you want to maximize your speed, you need to apply big forces to the ground quickly. This is one aspect of strength that includes two different types of strength.
The Velocity Speed Formula has 4 main components and two of those are BIG FORCE and SMALL TIME. Now researchers have confirmed that these 2 components of the Speed Formula are a big difference between faster and slower sprinters.
Biomechanics of Sprinting
Sprinting has been studied for decades. However, most of this was done using video to analyze how sprinters moved. Using video gives you a picture of the kinematics. This is how we measure and describe motion through body position, joint angles and movement velocity.
This kinematic research has given us a lot of useful information. Still, there is another component to the biomechanics that hasn’t been looked at much, and that’s the kinetics.
These are the forces that are used to create that motion and body position. It’s a lot harder because you need a track full of force plates and moving cameras or a specialized research treadmill. Yet, it’s critical to understand the needs of strength for speed.
Kinetics of Speed – Force
To propel your body forward, and to keep you upright, your leg has to produce a lot of force into the ground on each step. That’s what builds your momentum during acceleration phases and keeps it going during your full speed sprinting.
You create that big force, by first getting your leg up into the right position on each stride. Picture a sprinter with their front thigh up high, about parallel with the ground. Then you use the explosive strength in your glutes, quadriceps and hamstrings to generate power and drive your foot down into the ground.
“The top sprinters have developed a wind-up and delivery mechanism to augment impact forces. Other runners do not do so.” Ken Clark, a researcher in the SMU Locomotor Performance Laboratoryhttps://blog.smu.edu/research/2017/01/30/new-study-connects-running-motion-to-ground-force-provides-patterns-for-any-runner/
Driving the leg down and back into the ground is going to create a big impact on each step. The peak force during that ground contact is gong to be 4-5 times bodyweight when sprinting. Now imagine a 200lbs athlete, that’s 800-1000 lbs. on a single leg, each step.
Kinetics of Speed – Time
Your linear speed dictates why the big force you generated has to be applied in a small time. The faster you sprint, the faster you need to apply that big force.
Think about it. As you sprint faster, your body is moving over the ground with greater velocity. You’re moving faster over that part of the ground under your foot. The faster you sprint; the less time your foot is in contact with the ground. That’s just simple physics.
When your foot hits the ground, it’s driving down with a lot of power. There’s only 90-130 milliseconds of time to get all that force into the ground.
To realize how fast that is take out your phone. Open the stopwatch. Try to hit “start”, then “stop” as fast as you can.
What did you get?
Most people will get between 00.12 and 00.15. Some may beat that. This should give you some perspective; it is a small time to apply that force of 4-5 times bodyweight.
Strength For Speed and Stiffness
Now let’s combine that big force with the small time. This is the hard part, and where some athletes fail. You need the explosive strength to get the leg attacking down at the ground as hard as possible.
And you need the reactive strength and kinetic chain “stiffness” to not collapse on contact. Only when you have the reactive strength to provide the stiffness can you fully benefits from those big forces of the leg swing. This is a key part of understanding strength for speed.
Your ankle, knee or hip all have to stay “stiff” enough to apply the force of 4-5 times bodyweight and not bend or absorb it. If they cushion it like a shock absorber, some of the force is wasted.
This doesn’t mean stiff as in lack of flexibility. It means that the muscles and tendons in your lower body can hit the ground and deliver all your power without stretching or relaxing.
The Bouncing Ball Analogy
An analogy to help visualize this is to picture 2 bouncing balls. One is a bouncy, superball made of a “stiff” rubber. The other is a beach ball, soft and compliant. Throw them down with as much force as possible. Which one bounces higher off the ground?
The stiffer superball bounces higher. Why? Because it stores elastic energy and applies the force back into the ground. The beach ball absorbs some of the force and doesn’t have the elastic energy to rebound.
That superball is like reactive strength. Your muscles and tendons don’t relax and absorb the force. They store elastic energy and use it to help you go faster.
“We found that the fastest athletes all do the same thing to apply the greater forces needed to attain faster speeds. They cock the knee high before driving the foot into the ground, while maintaining a stiff ankle. These actions elevate ground forces by stopping the lower leg abruptly upon impact.” Peter Weyand, director of the Locomotor Performance Labhttps://blog.smu.edu/research/2017/01/30/new-study-connects-running-motion-to-ground-force-provides-patterns-for-any-runner/
Sprinting Fast Requires Strength
The research on faster sprinters shows why you need strength for speed. And we are not just talking about weight on a barbell.
To generate a big force with your lower leg you will need explosive strength. To apply it you need reactive strength for stiffness. The good news is that research has also shown that getting stronger generally correlates with getting faster.
You can develop these specific strength qualities by working in the weightroom using traditional and Olympic lifts. You do it using plyometrics properly. Especially single leg plyometrics with an emphasis on reactive strength.
You create that stiffness building core and hip stability to transmit and control those forces. And most importantly, you develop it by sprinting with good mechanics.
We know you need strength for speed. The Velocity Speed Formula is built on science and proven in sport. The research is starting to catch up and show why it works and can help you get faster.
TO LEARN MORE: The Ultimate Guide To Speed Training
- Faster top running speeds are achieved with greater ground forces not more rapid leg movements Weyand, et. al , J Appl Physiol 89: 1991–1999, 2000.
- Are running speeds maximized with simple-spring stance mechanics?Kenneth P. Clark, Peter G. Weyand, Journal of Applied Physiology Published 31 July 2014
- Relationships Between Ground Reaction Impulse and Sprint Acceleration Performance in Team Sport Athletes, Kawamori, et. al, The Journal of Strength and Conditioning Research 27(3), April 2012
- Increases in lower-body strength transfer positively to sprint performance: a systematic review with meta-analysis, Seitz, et. al., Sports Med. 2014 Dec;44(12):1693-702
- New study connects running motion to ground force, provides patterns for any runner. SMU Research Blog, January 30, 2017. https://blog.smu.edu/research/2017/01/30/new-study-connects-running-motion-to-ground-force-provides-patterns-for-any-runner/