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November 14, 2012
Why Moving Slower Can Make You More Explosive
I just got back from Kansas University to install our software technology with the force plate. The coaching staff is focused and cohesive, but the hardest concept to grasp for myself and these colleagues continues to be how more TIME on the ground can make you a faster athlete. After all, don’t we all want to be quicker and more explosive? Of course, but it is not that simple, especially in sports where timing and sequencing are more critical. We have discussed this concept with Usain Bolt before, how he runs faster because he spends more TIME on the ground (see Sparta Point). Basically, his body type and technique leads to a longer stride length and less steps over a 100 meter race than his competitors. But, this post will go into more scientific explanations of his performance, specifically aligning the Force-Velocity curve with our Force-Time curves we use to analyze, train, and monitor athletes.

The Force-Velocity Curve Defined

Authors from the University of Essex in a 2010 study explained that Bolt’s slower muscle contractions allow him to optimize the force-velocity curve. This graph is shown to the right, with the y-axis representing muscle force and the x-axis representing muscle velocity. The muscle force depends on the total number of attachments, contractile elements known as cross-bridges that slide past adjacent muscles to cause contraction, or shortening. As these contractile elements slide past one another faster and faster, the muscle contracts and shortens with increasing velocity. As you see to the right,  increasing speed forces a decrease in muscle force production. This trade-off occurs because less cross-bridges can attach at higher speeds. On the other hand, as this sliding velocity and muscle contraction rate decreases, more cross-bridges have time to attach and to generate force, and thus force increases.

Bolt is Actually Slower

This force-velocity curve can explain why more TIME on the ground can improve your performance. Bolt was found to spend more TIME on the ground than his competitors and take less steps, a track & field characteristic known as stride rate (see Sparta Point). This lower stride rate basically means a lower muscular contraction velocity. Not only was Bolt able to generate 17% more force due to his SLOWER muscular velocity, but his efficiency was greater as well. So Bolt actually reduced stride rate and quickness, which allows him to increase his TIME on the ground, shown in this 2010 review by a larger impulse, which is the width of the force-time curves shown below (see Sparta Point).
Adding more TIME to this graph…
..increases the width of a Force-Time Curve
The relationship between the force-velocity curve and force-time curve are also more clear; longer ground contact TIME = higher on the force-velocity curve = higher impulse = gold medal You can also ignore TIME and focus on stride rate, the mile run is in the Olympics too. Beneke R, Taylor MJ. What gives Bolt the edge-A.V. Hill knew it already! J Biomech. 2010 Aug 10;43(11):2241-3. Epub 2010 May 5.
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November 14, 2012
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17 thoughts on “Why Moving Slower Can Make You More Explosive”

  1. This is an interesting article! Thanks for the input.

    I was approached by a “personal trainer” in the gym the other day who was critiquing my counter movement jump. He suggest that I was going to deep into my squat. He explained the force + time stuff which I am familiar with thanks to your site but in my mind I was getting deeper to create more force in my concentric explosion. Being in the GPP I felt that this would not be a hindrance because most of my other work is focusing on strength/acceleration benefits of sprinting. I would be more worried about ground contact during power/speed phases when i’m trying to train as specifically as possible..

  2. Hey Phil and Sparta,

    Great post. So to increase force into the ground, will the weighted sled marches be good? And how many sets/reps/frequency is necessary?

  3. Lester, Weighted sled marches help sprint technique and TIME because the added resistance cause longer ground contacts. Sets/reps/frequency is a complex response, but we keep it between 10-15 yards for movement quality

  4. Good stuff Phil. I talked with Dr. Andy Fry of KU on Tues and he mentioned he had the opportunity to “talk shop” with you last week when you were there installing the Sparta software. Keep up the great work! Why wouldn’t other university and pro teams do the same thing?

    John Weatherly

  5. Bolt, has longer contact time because he’s actually a 10+ second sprinter but is 6’4″+ and overcame drive phase deficiency of his earlier career. Bolt takes 40-41 strides in the 100M. Gay, Blake, Gatlin, etc. all take 44+. So If Bolt had to take 44 strides he would do it in roughly 10.2 seconds. Without using my Dartfish here’s a fairly solid estimate: Bolt’s stride length (general estimation) is 6′-8″ so 4 more strides would be 320″ or 26′-8″. Bolt covered his last 20M in his 9.58 in 1.61 seconds. See here: http://berlin.iaaf.org/mm/document/development/research/05/30/83/20090817081546_httppostedfile_wch09_m100_final_13529.pdf

    So that last 20M or 65′-7.25″ or 787″ were covered in 1.61 seconds. So 41% of that (322+”) is .661 so 4 more strides on 9.58 = 10.24.

    Now that the math is done, here are some general visuals. Bolt’s hip position when compared to the other sprinters is very similar – no collapsing. He’s – hips up – shoulders down (see that as shoulders relaxed). So he is not “dropping” his center of mass/hip-pelvic bowl to increase/extend ground contact.

    Another visual picture – get on a scooter. Push-push-push come to full speed, stay at top speed for 20M (so you are erect and “flicking” the ground) then attempt to increase your ground contact slightly. What happens? A slight halting movement that causes DECELERATION; we struggle as a coaching staff with football players who become sprinters. They want longer contact time after the acceleration phase and get smoked over 30-80M by my long time sprint guys.

    For strike efficiency see Carmelita Jeter in London last leg of the 4×1. The other variable is the state of the complete kinetic chain during the strike. Bolt runs: very relaxed has an excellent efficiency strike – see consistent dorsiflexion through his races, has M:S ratios that are top in the world and here’s the big one: TAKES 40 STRIDES.

    Something to think about

  6. Do you always want to widen the box, i.e., add more time? People used to always be impressed with Shawn Marion’s rebounding because he could pogo stick quickly in traffic. He seemed to have a really short ground contact time. Perhaps he would want to play to his strengths and continue to emphasize force? So, e.g., instead of trying to move a 30 inch vertical to a 35 inch, try to shorten the time it takes to reach his maximum 30 inch vertical?

  7. All great articles. Our 2 fastest athletes run with 2 different movement signatures, one with high FORCE, the other high TIME, explaining the conflicting articles you present. This blog post highlights the more overlooked aspect of how “slower” athletes can be fast.

  8. Michael, Certain movement signatures make athletes successful in specific sports and/or aspects like rebounding. Our goal is to not take away those strengths, just minimize imbalances and provide more “tools”.

  9. Do we know where (what part of the race) this extra time spent on the ground and extra steps were? Was it mostly during his acceleration phase, which would make sense as it has been shown to be beneficial to spend more time on the ground to produce more force and with him being so tall. Or is he still spending more time on the ground during the top-end phase than his competitors?

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