Sprint Acceleration Mechanics: Everything To Know
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Sprinting can be really frustrating.
You think you’re doing the right technique until you watch your form back on video.
So if you are looking to work on your acceleration, it’s worth understanding the mechanics of sprint acceleration.
Developing Your Speed
Speed development includes these subcategories:
Starting Speed
Acceleration
Absolute Speed
Speed Endurance
Each of these qualities play a vital role in how fast you can be.
Starting Speed
This is the initial burst from a stationary position.
Acceleration
This is your increase in speed up to the maximum velocity.
Absolute Speed
This is the top speed you can achieve.
Speed Endurance
This is the ability to maintain a high speed over a distance.
Sprint Acceleration
This is not just about how fast you can run, but how quickly you can increase your speed.
Mastering acceleration involves a blend of proper posture, effective mechanics, and optimal energy utilization.
This changes as you progress from a starting stance to an upright position reaching your maximum speed.
On average, trained athletes take about 5 seconds to reach their top speed.
During these 5 seconds, a typical 13-year-old might cover around 35 meters
A world-class male sprinter could exceed 40 meters
The distance covered and the acceleration achieved depends on:
Your biomechanics
Rate of force development
Surface conditions
How ready you are
Concepts of Acceleration
Acceleration is the positive change in velocity. It’s the change in the speed of movement.
Deceleration is a decrease in velocity.
Acceleration is crucial from the moment you start moving.
View the start and acceleration phases as interconnected elements of a single process rather than isolated parts of your race.
Things to look for when working on your acceleration:
Attack angles
Contact times
Flight times
Stride length
Stride frequency
What Should You See When Accelerating?
Attack angles should decrease with each step. The body becomes more upright by about 4-6 degrees with each ground contact
Stride rate and length increases
Ground contact time decreases
Flight time increases
Your ability to raise your center of mass and increase your stride frequency is a testament to how well you can accelerate.
Force
As you accelerate, your goal is to exert the maximum amount of force possible in the shortest time and in the right direction.
Dr. Ken Clark breaks down the mechanics of this process.
During acceleration, you need to focus on two major types of forces:
Vertical force, helps support your body weight and propels your center of mass into the next step
Horizontal force pushes your center of mass forward
To generate horizontal force, position your center of mass slightly ahead of your foot throughout the ground contact phase.
As you pick up speed and get to your top end speed…
Your body should gradually straighten up, and your force application shifts to more vertical directions.
The time your feet are in contact with the ground changes as you accelerate.
When starting, the ground contact time is relatively longer, around 0.15 to 0.20 seconds
As you approach your top speed it drops to about 0.08 to 0.12 seconds
Acceleration is not just about moving fast; it's about committing fully to each step with a clear understanding of the mechanics involved.
From your initial push off the blocks, force is met with an equal and opposite force.
This force travels in a straight line from your ankles through your shoulders…
Ideally at a 45-degree angle relative to the ground.
Pushing hard through your heels from the start gives the necessary tension to minimize any unnecessary movement in your knees and shins.
As you rise from the blocks and continue to move forward, an imaginary straight line should be able to be drawn from your ankles through to your ears.
The front shin of your swing leg should align parallel to your body's angle.
From this position, focus on pushing your feet back towards the track so that ground contact occurs at or just behind your hips.
Projection
Projection refers to how you move your hips forward.
This alignment is crucial for maximizing your projection while allowing your feet to strike the ground directly under your center of mass.
Avoid projecting too low as it can lead to inefficient movements like casting out or skating side-to-side.
Rhythm
Sprinting is rhythmic.
You move from slower steps to faster steps, and you’ll be able to hear this on the track.
Rise
The rise should be smooth and continuous with each step you take until you are fully upright.
It's crucial to avoid staying low as your speed increases.
Each step should come with a rise in your hips and shoulders.
Visualize running up a flight of stairs or taking off like an airplane.
These cues can help you maintain the correct posture and momentum as you transition from starting acceleration to reaching your top speed.
Foot Strike
Optimizing your foot strike is crucial.
During the initial steps of a sprint, your foot should strike the ground slightly behind your center of mass (CoM).
As you progress through each step, this contact point should gradually shift from behind, to directly beneath, and then slightly in front of your CoM.
Make sure the foot does not strike too far behind the CoM.
If your shin swings out too far during the leg's forward motion, it can land ahead of your hip.
This position forces you to "pull" forward using your hamstrings.
This is inefficient and can lead to injury.
If your foot lands too far in front of your CoM, it will compromise the rigidity of your ankle.
This increases the time your foot is in contact with the ground, leading to energy and speed loss.
Conclusion
Mastering the mechanics of your acceleration in sprinting is essential for enhancing your speed and efficiency.
By reading this blog you can avoid the common pitfalls, optimize your sprint performance and reduce your risk of injury.
Want help running and accelerating faster?
See how an Unstoppabl Sprint Coach can help by clicking here.
Frequently Asked Questions
How do you do acceleration sprints?
When doing acceleration sprints, you start from a stationary position and gradually increase your speed to the maximum.
The focus should be on powerful and controlled movements, pushing off the ground with great force, and maintaining a high knee lift.
Proper warm-up and technique are crucial to prevent injuries and achieve the best performance.
What is the mechanics of acceleration?
The mechanics of acceleration involve a complex interaction of biomechanical processes.
These include the correct posture, the angle of the body leaning forward, powerful leg thrusts, high knee lifts, and quick ground contact times.
Efficient acceleration mechanics ensure maximum forward momentum and minimal energy wastage.
How do you accelerate in a 100m sprint?
To accelerate in a 100m sprint, focus on exploding out of your starting blocks with high force.
Maintain a forward lean and use short, quick strides to gradually increase your stride length as you build up speed.
Keep your movements smooth and controlled, and concentrate on pushing off the ground forcefully with each step.
What is biomechanics in sprinting?
Biomechanics in sprinting refers to the study of how the body moves during a sprint.
This includes analyzing the forces exerted by muscles and the movements of joints during the sprinting process.
Understanding sprint biomechanics helps in improving performance, technique, and reducing the risk of injuries.
