Nearly every sprinter has heard or been told that a key to faster acceleration sprinting is to “get low”. The idea here is that if we can project out at a lower angle relative to the ground, we can orient our force production in a more horizontal manner, leading to faster acceleration sprinting.
Coaches debate whether or not this is good advice, mainly because going lower than what your strength allows for can cause you to stumble, overstride, side-step, or get injured. While we certainly should avoid going so low that we fall on our face during sprinting, I believe it is important to perform sprinting workouts in a way that maximizes our ability to project out at relatively lower angles, maintain greater trunk flexion throughout acceleration, and to be able to endure greater angles of knee flexion during ground contact.
Before we go forward, understand that we do not want to stay low the entire sprint, and that this discussion mainly applies to acceleration. We still will rise each step, but the rate of rise should be spread out as long as possible, so long as it does not disrupt our ability to sprint.
Direction Of Force Application Is More Important Than Magnitude Of Force
Research suggests that the direction in which we apply force into the ground is more important than the magnitude of force produced. For example if you were to apply very large forces in either a forward direction, such as when we brake, or in a purely vertical direction, one would not sprint as fast as someone who applied that force in a more rearward or horizontal direction. When we see someone who is very skinny like Terrance Laird accelerating like a mad man, this is because his ability to apply force in the right direction is phenomenal. He may be producing as much or less total force than sprinters around him, but the force he does produce is applied in precisely the right direction.
In the study titled Relationships Between Ground Reaction Impulse and Sprint Start Acceleration Performance In Team Sport Athletes by Kawamori, Nosaka, and Newton, two quotes stuck out to me as being relevant to this discussion:
“...the faster subjects in this study applied ground reaction impulse in a more horizontal direction in achieving better sprint acceleration.” - RELATIONSHIPS BETWEEN GROUND REACTION IMPULSE AND SPRINT ACCELERATION PERFORMANCE IN TEAM SPORT ATHLETES
“This study showed that the magnitude of relative ground reaction impulse (resultant impulse) is not correlated with sprint acceleration performance and that the direction of impulse application is likely to be more important so that applying impulse in a more horizontal direction may lead to faster sprint acceleration.” - RELATIONSHIPS BETWEEN GROUND REACTION IMPULSE AND SPRINT ACCELERATION PERFORMANCE IN TEAM SPORT ATHLETES
Another study, called Technical Ability of Force Application As Determinant Factor Of Sprint Performance by Morin, Eduoard and Samozino, states the following:
“Force application technique is a determinant factor of field 100-m sprint performance, which is not the case for the amount of total force subjects are able to apply onto the ground. It seems that the orientation of the total force applied onto the supporting ground during sprint acceleration is more important to performance than its amount.” - TECHNICAL ABILITY OF FORCE APPLICATION AS DETERMINANT FACTOR OF SPRINT PERFORMANCE
To summarize, the direction that we apply force is more important than the total amount of force we can apply. You can stomp your way down the track and not run very fast if the force being applied is not directed in the proper direction. The earlier we are in the sprint, the more this force will be oriented horizontally relative to the ground. As our body rises through acceleration into upright sprinting, our ability to produce horizontal force decreases and force production becomes predominantly vertical relative to the ground. The fastest sprinters show the lowest decrease in horizontal force as they accelerate, such that they can continue to apply horizontal force deeper into the sprint.
Getting Low & Directing Force Horizontally
If we accept that the direction within which we apply force is an important factor for sprint performance, we then need to find tactics that can help us achieve a better direction of force application.
With regards to the sprint start and early acceleration, achieving greater trunk flexion and knee flexion angles will help us produce force in a more horizontal direction. The caveat is that we need to be strong enough and skilled enough to support our body in these more aggressive positions, and achieving trunk flexion at toe-off and knee flexion at touch-down is what we would generally call being low.
The study titled Effect of Velocity Based Loading On Acceleration Kinetics And Kinematics During Sled Towing by Bentley, Sinclair, Atkins, Metcalfe, and Edmundson stated the following:
“Along with increased peak knee flexion, the authors believe that the increased trunk flexion at toe-off enables the athlete to increase their horizontal force application.” - EFFECT OF VELOCITY-BASED LOADING ON ACCELERATION KINETICS AND KINEMATICS DURING SLED TOWING
With this in mind, we can frame the concept of getting low in sprinting as achieving higher levels of knee flexion at foot-strike and trunk flexion at toe-off. This makes sense considering a flexed knee during ground contact allows for a more horizontally oriented shin, and a flexed trunk allows for the body to be more horizontally oriented overall, while also shifting the center of mass forward which makes it easier to push the body forward during acceleration.
How To Train To Get Low In Sprinting
In my opinion, there are a few aspects of training to consider as it relates to achieving lower angles during acceleration sprinting. Here we will discuss both physical aspects of development, as well as skill and technique development.
Sleds & Strength Development
From a physical training perspective, resisted sprinting with sprint sled towing and getting stronger in the gym are foundational if you want to make significant changes in your ability to get low.
Looking back at some of the research we’ve already discussed, sled towing is a good way to manipulate trunk and knee flexion angles during sprinting, allowing us to generate force in a more horizontal orientation:
Using sled sprints in your training will help you achieve greater trunk and knee flexion angles if performed with the intent to do so, meaning that you need to both use the sled and also intend to sprint with more aggressive angles while pulling the sled. You can use either a waist or sled harness, but a waist harness might be preferred.
The study titled Impact of Harness Attachment Point on Kinetics and Kinematics During Sled Towing by Bentley, Atkins, Edmundson, Metcalfe and Sinclair stated:
“Previous researchers have highlighted net horizontal impulses and propulsive force as being key to achieving high acceleration, as such it would be seen that the waist harness is more suitable when training for the acceleration phase of sprinting. It seems apparent that the kinematic alterations caused by the waist harness made the line of action more horizontal, resulting in greater net horizontal impulse.” - IMPACT OF HARNESS ATTACHMENT POINT ON KINETICS AND KINEMATICS DURING SLED TOWING
By using a sled with a load that causes around a 20% velocity decrement and a waist harness, we can create an environmental constraint that encourages us to generate our force production in a more horizontal manner, while also allowing for us to feel what it is like to sprint with greater hip and knee flexion.
Over time, we might be able to achieve both physical and skill oriented adaptations that can help us sprint faster without resistance. From a physical standpoint, we know that sled towing can improve power output and countermovement jump, and I personally believe that sleds can cause tissue adaptations in the muscles and tendons of the legs.
In the gym, getting stronger in large ranges of motion will help lay a foundation of strength that can support your body as you sprint in these more aggressive positions. Considering knee flexion angle at touch-down is related to one’s ability to direct force horizontally into the ground, building strength in positions with an acute knee angle makes logical sense as a general stimulus that should be included. This could be done with a deep squat, a high box push step up or rack step up, as well as performing lunges with maximal knee flexion. While these general exercises might not cause any direct improvement in your ability to sprint, they will help lay a foundation of strength and range of motion access which can then set you up to perform sled sprints more effectively.
Technique & Skill Development
From a skill or technique standpoint, training with a sled can allow us to achieve lower projection and joint angles which could affect our vestibular system and give us some kinesthetic context for what it feels like to sprint in a more horizontally directed manner. Over time, if we can learn what this feels like while pulling a sled, we may be able to bring some of this technique over into our unresisted sprints.
If all we ever do is sprint without a sled, it is challenging to get into positions with deeper trunk and knee flexion. Without any kind of environmental constraint, the body will typically default to whatever it is used to. Also, being more aggressive with projection angles without a sled can at first be a bit scary, as it feels like you might fall down, stumble, or risk getting hurt. Because of this, using a sled on its own or paired with unresisted sprints can help train the brain to be comfortable sprinting with greater trunk and knee flexion, and over time we can then try to mimic these technical qualities when we sprint without resistance.
If you start with heavier loads, you can get into very aggressive positions at lower velocities, which will give you more time exposure to what these positions feel like. As time goes on, the sled load can be reduced to increase the velocity of the sprints, while still aiming to achieve the same projection angles you felt in the heavier sleds. Over time, this can acquaint your brain with the feeling of firing out low and producing a good balance of horizontal and vertical force, and hopefully allow you to get as low as is optimal for your current strength and sprint capabilities.
How Low Is Too Low?
To maximize our horizontal propulsion as we sprint, we need enough hip height to allow for us to reorient our limbs in the air and actively strike the ground each step. If our hips do not rise at all, we will simply crash into the ground and have to catch ourselves before we can apply propulsive forces in a forward and upward direction. Sometimes when we try to go too low, we end up popping up as a result of excessive braking or in an attempt by the brain to not fall or stumble.
Optimal hip height would be achieved when we project vertically enough to cycle our legs to prepare for the next ground strike, but no more than that. Excessively low hip height will lead to stumbling or side stepping, and excessively high hip height will lead to increased flight times without a proportional amount of horizontal movement. If you look like you are going up and down without much forward movement, you might be projecting too high each step. In contrast if you feel like you are sinking lower with each subsequent step, you likely fired out too low.
To wrap things up, I do believe it is worth training in a way that can lead to you being able to orient forces horizontally during early acceleration, also known as staying low. We can use resisted sprinting in the form of sled towing to familiarize the body with applying force horizontally, and over time this can help train the brain to be comfortable firing out of the blocks in an aggressive, forward manner.
In the gym, we can include exercises which strengthen our legs through large ranges of motion, including deep knee flexion, and this can lay down a foundation of general strength which will be beneficial for us so that strength in certain positions is not a limiting factor of our sprint ability.
When we sprint, we can aim to keep our torso flexed at the hips, such that it is easier to produce horizontal force and our weight is distributed in a way that is effective for acceleration. Just make sure that you are not going so low that you crash and stumble, and also be sure that you are actually flexing the torso, not just tucking your chin and keeping your head down. It may be counterintuitive, but sometimes it is easier to flex the trunk if we keep our head neutral, or even tilted slightly upward.
Over time as you transition from an emphasis on heavy sleds to focusing more on moderate loads and unloaded sprints, you can attempt to sprint with an overall lower position.
- Relationships between ground reaction impulse and sprint acceleration performance in team sport athletes, Naoki Kawamori, Kazunori Nosaka, Robert U Newton; https://pubmed.ncbi.nlm.nih.gov/22531618/
- Technical ability of force application as a determinant factor of sprint performance, Jean-Benoît Morin, Pascal Edouard, Pierre Samozino; https://pubmed.ncbi.nlm.nih.gov/21364480/
- Effect of Velocity-Based Loading on Acceleration Kinetics and Kinematics During Sled Towing, Bentley, Ian; Sinclair, Jonathan K.; Atkins, Steve J.; Metcalfe, John; Edmundson, Christopher J; https://journals.lww.com/nsca-jscr/Abstract/2021/04000/Effect_of_Velocity_Based_Loading_on_Acceleration.21.aspx
- Impact of Harness Attachment Point on Kinetics and Kinematics During Sled Towing, I. Bentley, S. Atkins, C. Edmundson, J. Metcalfe, J. Sinclair; https://www.semanticscholar.org/paper/Impact-of-Harness-Attachment-Point-on-Kinetics-and-Bentley-Atkins/e7bd60a3688efb1b6acb4f8d79d4d5714fe80567