Sprinters are Inefficient:
If you want to know what an inefficient runner looks like, watch a sprinter run at 5-minute mile pace. If you are used to watching the smoothness of a runner like Nick Willis, the sprinter’s mechanics don’t look pretty.
There’s a stiffness about them as they run slow. Their arms are awkwardly open, going through a complete arm-stroke with their hands open as if they were running much faster. There’s little rotation in the upper body and excessive bounce as they undulate down the track. In short, it often looks like a slower version of sprinting.
You don’t have to take my word for it. It’s been studied. During a paced trial, collegiate sprinters and distance runners showed marked biomechanical differences, and the authors stated that “when slowed down, sprinters would still run with sprint technique, and distance runners when attempting to sprint, would still run with distance form.”
How could athletes who have honed and adapted a skill to such a degree be labeled inefficient?
The answer is obvious but underappreciated.
Sprinters are maximizing their mechanics for force application. Distance runners are maximizing theirs for efficiency of movement.
When we work on running mechanics, we often conflate the two, mixing and matching what we consider ideal and making statements to the effect of “You take thousands of steps during the 5k, imagine if you were 1% more efficient or had a 1% longer stride from increasing your stride length.” We all know the claims. We see them in running form guru’s media promotions, and perhaps make them ourselves.
Yet, underlying that assumption is that the system of mechanics we are teaching will accomplish outcomes, efficiency, and power.
The Inefficiency of Sprinters
In a study comparing competitive sprinters, 400m, middle-distance, and distance runners while running at a variety of speeds below anaerobic threshold, the authors saw a clear trend in metabolic efficiency.
For example, while jogging at the same speed (~8:00min mile pace), the oxygen cost for each group is listed in the chart below:
(The lower the metabolic cost, the more efficient)
|Type of Runner||Metabolic cost (l/km)|
|Long Distance runner||188|
The results shouldn’t be that surprising, distance runners are more efficient running slow. It should be noted that this occurs even with distance runners who violate every known mechanical prophecy known to man (i.e. horrible heel strike, etc.).
Yes, the gangly looking distance runner slamming his heel into the ground is more efficient running slow than Usain Bolt.
Why? Because metabolic efficiency isn’t the same thing as mechanical efficiency. They are intertwined and connected, but not the same. As famed sprint coach Tom Tellez once told me “If you want to become really efficient, go run a lot of miles. The body will figure it out and you’ll get really efficient at what you do.” His point wasn’t that we should all go run lots and lots of miles, but that in order to turn mechanical efficiency into metabolic efficiency, we need repetition, lots of it. And it largely involves letting the body figure it out.
But, according to Tellez, if we could achieve a level of mechanical efficiency before we added on loads of repetition to convert it to metabolic efficiency, then we had the best of both worlds.
As we’ve come to appreciate, mechanical efficiency isn’t the same as sprint mechanics or a concern for force application. Instead of power and rigidity, we want the nebulous smoothness and relaxation. Our arm swing is more compact, rhythmical, our legs churn in synchrony with our upper body, and the landing of our foot takes on a dual role of not only force application, but also energy absorption. Our body balances the need for force with the need to protect our muscles, tendons, and bones from the repetitive stress of hundreds of thousands of impacts.
The Balance of Power and Efficiency
It helps to conceptualize efficiency and force application as sitting on opposite ends of a seesaw. If we overwhelm one side, the other will compensate accordingly.
Our 100-meter sprinters don’t care about metabolic efficiency. Their races and training seldom depend on efficient oxygen delivery, so why in the world would the body adapt in favor of it.
Instead, it’s all about force into the ground. What propels us forward. Even at slow speeds, sprinters tend to have shorter ground contact times, according to research. Why? According to researchers, “It is understandable to estimate that with all of the high-speed training they complete, sprinters are ingrained to recover their steps as quickly as possible – even when the pace is slowed.” In other words, the same skill they need for force application, likely makes them inefficient at slower speeds.
Car analogies are apt in this comparison. Would we design the engine of a Prius and a McLaren F1 in the same way? One is built to maximize power, the other gas mileage. Our runners are the same.
There are tradeoffs when changing mechanics. Place the emphasis on mechanical changes that improve force production and we’ve increased the metabolic cost of running at that speed.
A look at undulation or vertical movement is a good example. For runners, there is an optimal amount of vertical displacement, or bounce, for each runner. If we were only concerned with efficiency, we’d teach our runners to be almost completely flat. Lifting the body costs us mechanically and metabolically. However, if we look at force production, we need some vertical oscillation. It allows us to generate more potential energy, as we attack the ground from a greater height, increasing our ability to throw force into the ground. It’s also the reason why sprinters knees or thighs tend to come up higher than distance runners.
Therefore, for each speed and runner, there is a balance. What’s the benefit of generating more force versus the metabolic cost of lifting the body or thigh higher into the air?
Are you changing for force application or efficiency?
As a distance coach who appreciates biomechanics, I am confronted with the debate over changing runner’s mechanics often. I hear it often at track meets, sprint coaches lamenting about a distance runners mechanics, insisting that they’d be so much faster if they only fixed them. And by fix, they mean to look more like a sprinter.
There is some truth in the statement, but the underlying assumption is incorrect. What that runner needs at race pace might not look entirely “correct” from a mechanical point of view. They are balancing a mix of efficiency and power that is different than looking at form from a purely mechanical point of view.
The answer isn’t for distance runners to forget about mechanics, or for us to load them up on lots of miles for the sake of efficiency. Along the same lines, there
So what do we do?
As a distance coach, I’m reminded of what Tom Tellez relayed to me and what the great coach Mihali Igloi professed. Running is a skill. And running at different speeds is a skill. We need to understand the subtleties of speed, possessing the ability to work our way through speeds from jogging to sprinting.
What that means is that mechanically, distance runners should focus on efficiency of movement to a large degree, while honing the ability to change gears and adopt some sprint-esque mechanics. Igloi called this “long and short swing.” He wanted his runners to have the capacity to adopt slightly different mechanical paradigms, depending on what they needed in the race. As the fatigue set in and a runner needed to muster up a kick in the final 200 meters of the race, Igloi would have his runners switch to a “long swing” type of running, for example.
In the end, it’s about knowing where, for your event, you fall on the force application versus efficiency continuum. And what that means for the runner in front of you. To what degree are you training for force application and what degree are you training for efficiency.
Understanding what differences those entail from a teaching standpoint, and then determining where you need to fall on the balance between the two for the athlete you are working with is crucial.