Improve Your Acceleration Biomechanics | Sprinting Technique
Most of us understand that high performing sprinters do certain things differently than slower sprinters, but determining what it is that constitutes these differences can at times appear elusive. Once you identify the proper way to sprint, you must then go about implementing this proper technique into your sprint training program.
Previously we’ve discussed how the best sprinters exhibit a hammer-like, whip from the hip action of the leg in their sprinting technique, which is especially visible from mid-acceleration and into upright sprinting. The idea is that by throwing the leg to the front side in a certain way, we can load the hamstrings as they lengthen, eventually reversing the leg toward the ground leading to an aggressive ground strike. If you haven’t seen this video, I’d suggest checking it out.
While this is all well and good in upright sprinting, we still need to look at what comes before upright sprinting, namely the acceleration phase of the sprint. Here we will discuss what combination of factors is important for your success in acceleration and the transition to maximal velocity upright sprinting, and how you can use this sprinting technique to run a fast 40 yard dash, 100 meter dash, or any other sprint distance.
Form & Function
In biology, anatomy, and most of reality itself, form and function are intimately tied together. The shape of a molecule dictates which receptors it can bind with, and those with which it binds determine the functional effect of the molecule. Essentially, the form dictates the function.
On the larger level of human anatomy, the form of a musculotendinous unit will dictate its function, based on where the muscle originates and inserts, the pennation angle, the length of the muscle fibers themselves, and the fiber type distribution therein.
When we zoom out even further to the level of the organism as a whole, the sprinter’s body positioning can dictate how certain muscles function, how limbs are coordinated, and can make or break the athlete and their performance.
When we think about how we can improve the sprinting performance of a given athlete, it is imperative that have some basic understanding that the result of our efforts (i.e. sprint times) are directly and inextricably linked to how we position the body throughout the sprint.
Archetypes Of Poor Acceleration Sprinting Technique
When we see less skilled sprinters accelerating, we usually see one of the following archetypes:
- The Stabber: Pushing & stabbing too far into the sprint.
- The Leaner: Leaning forward from the ground & exhibiting backside mechanics.
- The Reacher: Reaching forward & grabbing the ground in front of themselves.
As we will learn later, despite the failures of these archetypes, there is something to be learned from each of them that can help us become better sprinters.
The push and stab, which is often seen in athletes who try to be too quick, is a common problem seen when athletes try to accelerate while not understanding real sprinting technique. These athletes, at little to no fault of their own, think that acceleration is all about stabbing the ground behind them.
The stabber may accelerate well over the first steps of the sprint, but tends to fall off the wagon after 10 or 20 meters as they end up rotated forward and in a position that does not allow for optimal upright sprinting. This forward rotation will manifest as someone whose whole body angle is tilted forward from the ground up, their movements quick, but their stride will lack fluidity and they may experience a lot of injuries due to the poor timing of their movements.
The stabber uses a strategy that works well for steps one, but they try to apply it toward the entire sprint as a whole.
Similar to the stabber, the leaner is someone who sprints by leaning forward and over-rotating at the pelvis, but who exhibits a cyclical leg action that is heavily biased toward the back side.
At toe-off, these athletes tend to pull their foot straight up instead of compressing the leg up and forward, such that at its highest point the foot hangs out behind the athlete instead of under them. Because of the delay in getting the leg to move forward to the front side, these athletes do not have the time needed to cycle the leg properly and they end up slamming it down under them at the last moment, exhibiting large braking forces and a bad ratio of effort to sprinting speed.
These athletes are trying to take the spring mass model that applies to jogging and running, and inappropriately apply it to sprinting.
The reacher is the athlete we have all seen struggling at the end of a race, who attempts to propel themselves forward in a manner similar to how people walk. The reacher is the stereotypical over-strider, who got seared into the collective coaching mind to the extent that everyone started coaching stabbers out of fear of coaching reachers. Unfortunately, both approaches are equally flawed.
At first glance, people confuse pulling on the ground with pulling through the air, as it was discussed in my video on using your legs like hammers. When we sprint effectively, we let the leg float to the front side, opening up as tension loads in the muscles of the leg, only to reverse the leg back down to strike underneath the athlete. The reacher definitely lets the leg get out in front of them, but they fail to get it back under themselves, instead landing too far out in front of their center of mass.
While subtle to the casual observer, the implications of landing in front of you versus whipping the leg under you are significant. Reaching and grabbing the ground in front of you is a recipe for a hamstring strain, whereas whipping the leg forward and then back under you is a recipe for success.
Elites Do It Differently
When we watch elite sprinters, we do not see one of the aforementioned archetypes - instead we see a blending of all three.
They Know When To Stab
Elite sprinters will often exhibit a stabbing motion of the leg during early acceleration, in particular for the first one to three steps of the sprint. At low horizontal velocities, the stab can be an effective way to overcome inertia and project out, but loses it’s utility as velocities increase. As the sprinter’s horizontal velocity increases, the leg motion needs to become more cyclical and akin to the hammer-like action spoken about in previous posts of mine.
They Know How To Lean
Elite sprinters certainly know how to lean, or in other words how to stay “low”. While the novice sprinter might try to get low by having their leg motion behind them, trying to look like they just left the blocks for every step of the sprint, elite sprinters have the strength and mobility to bend at the hips and keep their torso forward while their leg motion transitions from the block start into a true sprinting motion.
They Reach In The Air, Not On The Ground
Elite sprinters know how to let their shin & foot float forward while in the air before returning it aggressively toward the ground, which is essentially the idea behind the “whip from the hip” cue. Novice sprinters throw their leg forward but leave it there, over-striding and exposing themselves to significant braking forces and risk of injury. Elite sprinters throw the leg forward and reverse it backward without delay, allowing them to load tension in the leg in preparation for a force downward strike with the leg under their center of mass.
A Magic Combination
It can be easy to look at certain things in isolation, when in reality we need to look at systems and integrated mechanisms with respect to how individual parts work together to form the whole. In the case of acceleration sprinting mechanics, we need to see a combination of factors in order for the sprinter to realize their maximum potential.
Once clearing the blocks and somewhere around steps two through four, athletes need to exhibit the proper combination of forward torso positioning (forward lean from the hips) paired with front side, whip from the hip style leg mechanics.
As stated previously, most athletes can achieve the forward lean of the torso while maintaining backside mechanics, while other athletes can achieve the front side leg action but can only do so with their torso more upright. We do not achieve forward lean by tilting our pelvis (and body as a whole) forward from the ground up, but rather we keep the pelvis neutral and let the torso be angled forward.
What one must realize is that these two qualities of forward lean and front side leg action are intertwined in their form and function, meaning that when used together, they can significantly enhance one’s sprinting potential.
Effects On Tension
We know that getting the leg to the front side allows for a significant buildup of tension in the muscles and tendons of the leg, and this tension aids in producing force during the subsequent ground strike.
When combined with a forward torso positioning (forward lean from above the hips), hamstring and glute tension is increased dramatically, leading to an even greater potential for increased tension and force production during this phase of the sprint.
If properly trained using a blend of strength training, strength-mobility, and technical drills, athletes can dramatically improve the efficiency of their movement by developing this acceleration sprinting technique.
Effects On Leverage
Beyond the effects that a combination of forward lean and front side leg mechanics can have on generating tension (and therefore force) in the leg muscles, this combination of positioning and leg action also aids in improving the leverage an athlete has when they eventually strike the ground.
If an athlete is getting their leg to the front side but not pressing their torso forward, it is much easier for them to strike in front of the body and end up pulling themselves over the ground from a disadvantageous position.
If an athlete is leaning forward from the ground up, and their leg motion gets stuck behind them in a perpetual stabbing motion and bias towards backside mechanics, the athlete will reach a point where they cannot produce force quickly enough to continue to propel themselves forward. If the entire body is tilted forward from the ground up, gravity will rotate the body forward and eventually the athlete will feel like they’re going to fall on their face. This is commonly seen toward the end of a race, where athletes must over-stride to decelerate and not go head first into the track.
What We Want To See
To sum up what we want to see in acceleration sprinting technique, there should be a combination of front side leg mechanics and a forward torso position that does not include excessive anterior pelvic tilt. When done properly, you will feel as if you are right on top of yourself and balanced during the ground contact phase. If you achieve the lean via anterior pelvic tilt like “the leaner” we discussed earlier, you will not feel balance and instead feel like you’re going to crash into the ground.
At peak hip flexion, we want to see a sideways V shape, or a greater than symbol, form from the front leg thigh and the torso of the athlete. The rear leg will not likely achieve full extension, which is fine as long as the athlete does not artificially reduce their range of motion (just as they shouldn’t try to achieve full extension artificially either).
The early steps of the sprint can exhibit the typical stabbing movement we often see, but this needs to transition incrementally as the sprint progresses. During the swing phase in mid acceleration, we will see the shin opening up to vertical or just beyond vertical, returning back to the ground to strike nearly vertically. We do not want the athlete to throw their foot forward as if to kick the finish line, but rather the foot should be moving forward by virtue of having relaxed hamstrings and aggressive hip flexion, opening up as the thigh reverses toward the ground and you intentionally drive the leg downward. Focusing on forward and backward cues are often futile for athletes, so an up & down sensation of leg movement paired with relaxation that allows the foot to float forward is really the way to go.
Let the leg progress toward a movement more akin to maximal velocity sprinting mechanics before you let the torso rise fully upright, and let this rise to upright happen incrementally. We do not want to see the athlete dramatically change their posture at any given point, as this can disrupt their rhythm and in extreme cases expose them to injury.
Training For Acceleration Technique
Intertwined within any discussion related to technique is the idea that technique is limited by strength and force production capabilities. Someone with a strength level of zero who cannot get out of bed most certainly cannot sprint with proper technique. In a less extreme case, an athlete who is weak relative to their body mass cannot propel themselves through the air or move their limbs effectively enough to precipitate proper sprinting technique.
Types Of Strength Required For Acceleration Sprinting
Athletes should be strong enough re if they plan to accelerate effectively.
If you cannot perform single leg squat or step up onto a high box without some kind of momentum leading into the movement, you likely lack the general strength needed to accelerate effectively. Performing body weight exercises such as a step up, single leg squat, single leg glute bridge, lunges, push-ups, and pull-ups are a good way to build the first layer of strength needed for acceleration.
Next, athletes should be able to perform exercises such as step-ups, split squats, rear leg elevated squats, and sled pulls using moderate loads. As time goes on, loads should be increased incrementally such that you can easily perform exercises such as a rear leg elevated squat with more than your body weight loaded on the bar. Sleds can be utilized with large loads can be used to begin transferring some of this strength into an exercise that is somewhat akin to the movements we see in acceleration sprinting.
Because of the demands placed on the hamstrings, hip flexors, and calves, special exercises can be used to target regions of the body, specific movement patterns, or combinations thereof.
Rear leg elevated squats might progress to a rear leg elevated squat jump with a leg cycle, adding demands for power production, velocity, and coordination. Manipulating the rear leg position, front leg position, torso position, and hip flexion range of motion can assist in improving one’s ability to reach a given position, such as in an athlete who cannot simultaneously exhibit front side mechanics while also getting their torso forward.
Variations of hinges and leg curls can be used to develop hamstring strength at long muscle lengths, while curl and hip flexion exercises loaded at the ankle can help develop the leg recovery mechanism to improve stride frequency. Strength at long lengths will keep you healthy by preventing injury, and make you run faster by allowing you to achieve the positions you need and generate force when appropriate.
Isometric and explosive exercises that target the ankle are useful for developing overall structural rigidity in the body, while also aiding in forward propulsion. After step 1 or 2 of the sprint, forward propulsion is generated primarily from the hip and ankle joints. The knee joint contributes most significantly to the first stance phase of the sprint, contributing less and less as the sprint progresses.
For athletes who struggle with stretch shortening cycle movements, something like a staggered stance RDL can be progressed to a staggered stance hang clean, allowing the athlete to feel what it is like to lengthen and shorten the hamstrings with a bias toward one leg or the other.
As you can see, a wide variety of general and specific strength qualities are necessary for proper acceleration, and as such you need to develop yourself holistically with a high quality sprint training program.
Drills, Resisted Sprints, Submaximal Sprinting
Obviously, acceleration sprinting at maximal effort will help you develop this technique. Regardless, some athletes need other types of work in order to really grasp this technical model and integrate it into their full speed sprinting.
To develop the technical qualities needed to sprint in this manner, athletes can benefit from using drills, resisted sprints, and submaximal sprints. By working on one aspect of the movement, slowing things down, or adding an environmental constraint, it is sometimes easier for athletes to grasp the concept required to move in this way.
One drill I came up with is pretty simple, and I call it the transition drill. Essentially you start with your torso tiled forward, and to then kick each leg forward to achieve that sideways V shape discussed earlier. This can be done akin to a dribble, A-Run, or whatever other common drill you like. The point is that you have to combine the forward torso tilt with the front side leg action in order for it to be of use.
Resisted sprints can be useful as well if an athlete can’t quite get the feel for the movement, as the resistance allows you to manipulate how far they go or how long they’re in the air, and this can allow them to find the movement pattern that is appropriate. Also, this can add a force production stimulus for athletes who look good technically but they do not project themselves very far each step.
Submaximal sprinting is another way to work on this technique, and I do this a lot in my warmups. You can start with something like the transition drill mentioned earlier, blending this into a transition drill run and eventually full warm up sprints where you practice the positioning, posture, and progression of posture that we will want to see when you sprint at full intensity. As with the sleds or drills, slowing down the movement can help you grasp the feel, at which time you can then experiment with faster movements and ingrain these movement qualities at faster speeds as well.
Acceleration Sprinting Technique - Conclusion
In conclusion, to properly accelerate, athletes need to be able to achieve certain positions, actions of the leg, and be strong enough to handle these movements at high speeds.
Outside of typical sprint training, athletes can use a variety of drills, modified sprints, and strength training exercises in order to develop the qualities needed to effectively accelerate during sprinting.
By combining a forward oriented torso, and neutral pelvic tilt, and a front side leg action, sprints can improve their acceleration, their sprint times, and ultimately reach their full potential.