Speed & Agility Training Zone!

How To Use the Tec Model to Train for Acceleration

By: Nick Winkelman

Part of the EXOS Speed, Agility & Acceleration Series

Acceleration is one of the most important movement skills. Athletes need the ability to change gears. From a physics perspective, acceleration refers to any change in velocity. Within sport, acceleration occurs from a static position, such as a wide receiver sprinting off the line from a two-point stance, and from a dynamic position, such as a soccer defender crossing over and accelerating after getting beaten on an inside move.

In both cases the athlete must optimize the magnitude and direction of force to close in on or separate from an opponent. Think about making efficient gear changes in a car. You know you'll jerk down the road if you try moving from first to fifth gear. The body reacts the same way if you put it in an inefficient position to generate speed, ultimately exhausting its mechanics.

From a training perspective, we'll have the athlete accelerate from a two-point stance, three-point stance, or a position common to their sport, such as accelerating from a crossover or open step for base stealing. Sprint distances will range from five-yard to 20-yard efforts, with 10 yards being the most common distance to develop acceleration.

Technical

We'll assume the athlete is sprinting from a two-point stance over 10 yards. As the athlete accelerates, they'll initially push back off both legs before continuing to drive off the front leg in an effort to optimize hip, knee, and ankle extension. Within the same timeframe, the back leg will drive forward in an effort to optimize hip flexion (90 degrees), knee flexion (less than 90), and ankle flexion or dorsiflexion.

This piston-like action maximizes the magnitude and direction of force needed to produce the horizontal forces associated with acceleration. Throughout the initial push, the athlete should achieve a 45-degree lean (note that weaker athletes will be at a larger angle), maintaining a straight line from head to heel as they "toe-off" the ground.

Once the athlete leaves the ground, he'll "exchange" the legs through what's known as the flight phase. The front leg should now drive back into triple extension (back side leg action), while the back leg drives forward into triple flexion (front side leg action). Throughout this exchange the athlete's posture from head to hip should stay neutral, as this provides the foundation with which the arms and legs will pull. While the athlete will continue to drive back, the angle of the body will progressively rise to a vertical position that represents the absolute speed phase of the sprint. (This will be covered in the next segment.)

Upper-body mechanics also play a role in acceleration, as you want to transfer energy from the upper body to the lower body through the trunk. The arms move similarly to the legs, with the arm moving forward flexing at the elbow (less than 90 degrees) and the arm moving back extending at the elbow (more than 100 degrees). The arms and legs synchronize around a neutral trunk, allowing the athlete to maximize the first eight to 12 steps of the acceleration phase of sprinting.

Errors

While there are many errors that can emerge during acceleration, we'll highlight and prioritize the dominant five.

1. Posture
With posture/pillar, athletes stay low for too long, producing too much trunk flexion and/or rotation. Sometimes they're flexed because they lack strength or they're leaning because they think the falling forward position is the optimal movement. Whatever the cause, errors within the pillar need to be addressed first, as they influence the next four errors.

2. Front side leg action
With front side leg action, the athlete is unable to achieve adequate hip flexion (80-90 degrees). As a result, the athlete uses a cyclical running motion rather than the preferred piston-like action. As the foot comes off the ground, the heel should move up and forward (piston) rather than moving toward the sky (cyclical). If the heel goes up and the hip is not flexed – only the knee – an inefficient cyclical action is created. Without hip flexion, the athlete will step down early as a protective measure – likely popping up rather than maximizing drive. Not only is this inefficient, but such repetitive movement could lead to injury.

3. Back side leg action
With back side leg action, we see an inability to reach the extended position of the hip, knee, and ankle. If we see this error because the athlete is taking short, choppy steps due to poor front side mechanic, then what appears to be an extension issue likely is a timing issue with front side mechanics. If the front side mechanics are acceptable and you still see an issue with hip extension, then that should be the emphasis of your coaching.

4. Ground contact
The error here comes from the foot striking the ground too far in front of the body. The athlete should focus on driving back as opposed to down, as down will cause the athlete to pop up prematurely. In addition to striking back, we're also looking for responsiveness at the foot and ankle. If the heel slaps the ground and stays there through the push, only peeling off the ground at the last moment, we know there is a lack of lower-limb responsiveness. If you observe the athlete consistently "sitting" or "sinking" as they strike the ground, this is a telltale sign that they may lack the strength needed to translate the force from the hips – via the foot and ankle – to the ground.

5. Arm action
We don't want to see arms coming across the body, which causes rotation and changes the direction of the force. We also don't want to see athletes leave their elbows fixed at 90 degrees. Instead, we want to see a whipping, hammering action in the arms, much like the legs. Note that mobility issues in the shoulder and thoracic spine often will limit the athlete's ability to express proper arm action.

Correction

Here we look at corrective coaching cues for each of the prioritized errors. While we emphasize coaching cues, it helps to consider the physical qualities (mobility, stability, and strength) that potentially could correct the error. You can also use teaching drills (e.g., marching, skipping, sled running, etc.) that can help the athlete understand the concept and correct the errors.

1. Posture (pillar)
With posture, we want the athlete to focus on staying long. Use the following cues to reinforce this concept:

a. "From head to heel strong as steel"
b. "Drive out like the top of your head is a battering ram"
c. "Drive out like you are sprinting up a hill"
d. "Drive out like a jet taking off" or "be a jet not a helicopter"

2. Front side leg action
With front side leg action, we want to see the leg swing stay low and piston-like in an attempt to optimize hip flexion. We'll use the following cues to reinforce this concept:

a. "Keep your laces/shoe low to the ground"
b. "Drive your knees forward as is you're trying to break through a pane of glass"
c. "Imagine you have water balloons in your pockets…attempt to burst them when you sprint"
d. "Drive toward the fence" (insert any object in front of them)

3. Back side leg action
Here we want to see the athlete direct as much force back as possible, which, if done correctly, will result in triple extension at the hip, knee, and ankle. We'll use the following cues to reinforce this concept:

a. "Drive off the ground"
b. "Push the ground back rapidly"
c. "Accelerate like the ground is pushing you forward with each step"
d. "Attack back like an ax to a tree"

4. Ground contact
Here we want to see a responsive foot and ankle that doesn't collapse into the ground, and, as with back side action, we want to see the athlete contact back as opposed to down. We'll use the following cues to reinforce this concept:

a. "Drive out like a cheetah is two steps behind you"
b. "Stay rigid through the push" or "run like your Achilles are stiff springs"
c. "Focus on striking the ground before the ground strikes you"
d. "Strike the ground fast like you're running on hot pavement in your bare feet"

5. Arm action
With arm action, emphasize an aggressive exchange that synchronizes with the legs. The key is to see a linear action with the elbow closing as the arm moves forward and opening as the arm moves back. We'll use the following cues to reinforce this concept:

a. "Drive your arms back like you're hammering nails"
b. "Whip your arms back as if you're throwing something at a wall"
c. "Throw your hands back like you're flicking gum off your pinkie"
d. "Drive your arms aggressively like you're sprinting up a sandy hill"

Now that you've learned the TEC model for acceleration, you'll be able to analyze your athletes' movements, identify and prioritize errors, and deliver targeted cues that will upgrade skills without causing overthinking. We'll use this same approach to examine absolute speed in our next article.

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(January 2016)