Perhaps my biggest regret of all of the articles I have written for SimpliFaster is my old split to velocity post years ago. I am pleased that the idea of how fast an athlete can run using distance intervals is popular, but the evaluation process of speed comparison is incomplete.
In this article I share a very simple method to make speed assessment more useful for the evaluation of athletes and make a case for why we need to focus more on this topic. Staying true to the soul of the first article, I share the calculations openly and make a plea for scholastic coaches testing large groups to consider addressing heterogeneous populations. Momentum is an important topic, and we need to make an evolutionary step forward.
Testing Speed in a Vacuum Is Pointless
I worked this past summer overseeing a testing combine for American football and discovered in horror that the leaderboard failed to rank the athletes in a fair manner. By looking only at total time and splits, larger athletes were put at an unfair disadvantage, especially the linemen. An offensive lineman at 285 pounds was compared to a skill position player of 175 during their sprints—this was a horrible idea because it misrepresented best relative performance and only reported the top absolute speeds. When factoring in the weight of the athletes, all the best talents at that combine, supported by scholarship offers and game video, were the linemen.It is deceptive to create a leaderboard or report without momentum, as it can artificially inflate the lighter athletes or unfairly push those who are heavy to the bottom of the list. Click To Tweet
It is deceptive to create a leaderboard or report without momentum, as it can artificially inflate the lighter athletes or unfairly push those who are heavy to the bottom of the list. The fastest athletes tend to have sprinter bodies, and time without mass isn’t a good start for popular sports such as rugby and American football. Even a soccer player who is a few pounds underweight can sometimes benefit from adding nominal mass without it interfering with speed—and it can theoretically help improve velocity.
Mass-specific force ideas from Barry Ross sounded great in theory, where an athlete just needed to deadlift more weight without gaining weight, but time proved that idea to be only good on paper. I give Ross credit for trying, it’s just that his training model failed to address eccentric or breaking forces and was limited to the concentric deadlift option too much. Still, at least he followed a model and tried to create a system to improve athletes. This article does not cover training techniques, but it does ensure you are grounded in calculating such an important measurement.
Appreciating Momentum in Nature
Humans are indeed part of the animal kingdom, but we have to understand we don’t have four legs, and we hunt differently than cheetahs and lions. Many coaches were excited to see this research study on cheetahs, where they tagged the cat with a solar-powered GPS collar. But the coaches were surprised that cheetahs also jog and stretch, which proves that the idea of sprint and rest being the only modalities needed is just fiction.
You can learn a lot from studying animal biomechanics, and nature in general, specifically the Froude number with animal locomotion. While momentum is the topic of discussion, we still must think about the size of the athlete being more than just mass or even leg length. Comparing apples to oranges, or in this case rhinos to humans, requires an understanding of how performance scales and trends.
We could get into other modeling concepts, such as bioenergetics (like metabolism) and even mitochondrial density of muscle. Remember, don’t model speed in a vacuum as it’s not about how fast someone can go in theory, it’s how to support the process getting there. Similar to conditioning for a game and conditioning an athlete for a season, we have to factor in all the requirements in preparing an athlete for the future.
In the book Power, Sex, Suicide, Nick Lane explains how animals scale based on size and metabolism. In the chapter titled “Power Laws,” Lane does a wonderful job explaining the challenge of powering larger animals and shares how nature scales with Kleiber’s law. Well-rounded coaches don’t need to search for pop science books such as MVP Machine and Will It Make the Boat Go Faster—cut the middleman out and just read the science directly. (On the other hand, both books were extremely well-written and can teach coaches how to explain what they do better to others outside the field.)
Calculating Peak Momentum
The math of transferring splits to momentum isn’t hard, but there are some difficulties capturing speed measurements properly as coaches rush to actuate it for social media instead of knowing the limitations of models. For example, how many coaches and scientists showcase their acceleration profiles or F-V charts online but don’t realize the testing procedure was less than ideal?
Even when adjusting for timing start procedures, the profiles of speed are still missing a massive number of confounding variables. For instance, why create any team testing report if you just list athletes in alphabetical order? All models are limited, just make sure you don’t let the obvious ruin a good testing session. Factoring in body mass is a good first step, and it is easy to do if you know the athlete’s estimate of peak velocity.
Nearly every coach has access to some sort of timing device, and calculating a flying sprint’s velocity starts with the known distance and known time interval. Keep in mind split conversions from intervals are mean velocities. When an athlete hits their peak velocity, they hit terminal velocity, so an average is acceptable but still not a true peak. In fact, the fastest step, specifically the propulsive phase of the stride, is the absolute peak of the run. Instantaneous velocity is when a laser or other device is used to continuously sample the change of speed over and over at a high frequency. What looks like a smooth curve or line is actually a staccato of data.
After you have the time segment converted into velocity, adding mass is easy, but don’t walk away thinking that kg x m/s is the finished score in a leaderboard. Other rate units such as the slug unit (often confused when ballistics are involved) are not a great fit for coaching environments. I prefer newton seconds, as there isn’t an imperial or metric connotation to the measure, and it doesn’t cause any emotional discord with the adoption groups. The formula is:
where p = momentum, m = mass, and v = velocity
Take the mass and the speed and simply multiply them and convert it into newton second units. For example, a linebacker running 10 m/s and weighing 100 kilos is 1,000 N⋅s. These are obviously convenient numbers for demonstration purposes, but using the metric system is great for leaderboard calculations as the end result is newton seconds, a unit of time that is universal.
I know coaches will ask about shorter acceleration splits for collision sports, where an athlete’s peak step velocity (the final one before impact) can’t be averaged without serious drawbacks. The contact sports also have to consider ramming velocity, as some athletes leverage their speed and time their blows better than others. In fact, many undersized talents are able to deliver impacts far beyond their speed and mass.
This is a complex and chaotic world of deep learning and AI that isn’t easily distilled in a short blog post. What is frightening is that many of the formulas from GPS companies are poorly designed, making me wonder if we can trust them for load management for concussion-prone athletes.
Let Momentum Carry You
Momentum is more than just a finishing touch to sprint calculations; it’s an important concept to better understand how a program works. When athletes break their rhythm technically, they are often losing their momentum, sometimes over and over if it’s a mechanical fault. Adding the consideration of momentum is an important step in evaluating performance and coaching.Momentum is more than just a finishing touch to sprint calculations; it’s an important concept to better understand how a program works, says @spikesonly. Click To Tweet
Down the road, I know this topic will grow in coaching discussions and be better used in the sports performance community. Before I can outline other more direct uses of momentum, calculating a simple estimate of peak momentum in sprinting is a good start. Let’s all start migrating away from oversimplified metrics and data taken out of context and start injecting logic and reason back into training.
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