What is Acceleration?

What is Acceleration?

Acceleration is the rate at which velocity increases over time, and in sport it is the physical quality that lets you go from standing still, or jogging, to top running speed in the fewest possible steps. Physicists define it as change in velocity divided by change in time, and Newton's second law explains where it comes from: a net force applied against the ground.

In sprinting, that force comes from the legs, and acceleration is what happens in roughly the first 10 to 30 meters of a sprint, before an athlete shifts into the max-velocity phase. It is a distinct athletic quality from top-end speed. A 100-meter sprinter with elite max velocity can still be an average accelerator, and a lineman with modest top speed can be devastating over the first three steps because he produces enormous force fast.

Team-sport athletes rarely reach true max velocity during a game — a basketball closeout, a soccer press, or a loose-ball scramble rewards whoever gets moving hardest from a static or rolling start, not whoever eventually runs the fastest over 40 meters. That is why coaches train acceleration as its own skill, with its own mechanics, its own drills, and its own strength demands, separate from max-velocity sprint work.

How it works

Acceleration works through triple extension: the hip, knee, and ankle extend in sequence at each ground contact, driving force down and back into the ground so the ground pushes the body forward and up in return. Early strides are dominated by force production, not leg speed. Ground-contact time on the first steps runs roughly 150 to 220 milliseconds, two to three times longer than the 80 to 100 milliseconds seen at max velocity, because the athlete needs time to drive large horizontal force into the ground rather than simply cycling the legs fast.

Sprint scientists Jean-Benoît Morin and Pierre Samozino quantify this with the ratio of force, the share of total ground-reaction force that points horizontally instead of vertically. Elite sprinters sit around 45 percent ratio of force early in the acceleration phase, and that ratio declines in a predictable, measurable way as velocity rises and the body becomes more upright; the rate of that decline is itself used as a marker of sprint quality.

Stride length and stride frequency both climb through the acceleration phase, but stride length rises faster at first. A sprinter typically opens with strides in the 1.2 to 1.5 meter range that lengthen past 2 meters by 20 to 30 meters in, while trunk angle progressively rises from a strong forward lean at the first step toward a tall, near-vertical posture as max velocity approaches.

The formula

a = Δv ÷ Δt (change in velocity ÷ change in time); Newton's second law, F = m × a, explains where that force comes from

Coaches rarely calculate acceleration in m/s² on the field. Instead they track it indirectly through short sprint splits — a 0-10 m or 0-20 m time — because a faster split over a fixed distance means a higher average acceleration across it.

How to apply it

• Resisted sled sprints: Push or pull a sled loaded to roughly 10 to 20 percent of body mass, or dosed to a 10 to 15 percent velocity decrement, for 10 to 30 meters. The added resistance overloads horizontal force output per stride without letting mechanics fall apart, the exact quality acceleration depends on.
• Heavy strength training: Squat, deadlift, and hip-thrust variations in the 1 to 5 rep range raise the force ceiling acceleration draws from. Technique work alone plateaus quickly without a strength base, since the ground can only push back as hard as you push into it.
• Drill the start position: Practice 2-point standing starts and 3-point hand-down starts with a strong forward lean of roughly 42 to 45 degrees at the first step, driving the rear knee through low and pushing back into the ground rather than popping upright early.
• Plyometrics for rate of force development: Broad jumps, bounds, and depth jumps train the nervous system to express force inside the short 150 to 220 millisecond ground-contact windows acceleration demands, building power that heavy lifting alone does not.
• Sprint-specific technique drills: Wall drills, A-skips, and falling starts groove the front-side mechanics — a dorsiflexed foot, an aggressive knee drive, and full ankle, knee, and hip extension at toe-off — that keep force directed backward instead of leaking vertically.
• Practice at near-maximal intent: Run true acceleration reps of 10 to 30 meters at 95 to 100 percent effort with 2 to 3 minutes of rest between reps. Acceleration is trained fresh and fast, not as conditioning, so fatigue defeats the purpose of the rep.

Worked example

A simplified, phase-by-phase picture of what changes as a trained sprinter accelerates from a start toward top speed. Exact numbers vary by athlete and level, but the pattern — longer ground contact and a bigger forward lean early, then progressively shorter contact and a taller posture — holds up across sprint biomechanics research.

Ground contact time roughly halves from the drive phase to max velocity while trunk angle swings from a strong lean to fully upright. Acceleration training targets the first row of this table, not the last one — that is why sled work and short sprints, not flying 40s, build a faster first step.

Acceleration vs max velocity

Most field-sport actions — a defensive break, a closeout, a loose-ball scramble — never leave the acceleration window, which is why team-sport athletes should spend far more training time on 5 to 20 meter sprints than on flying 40s.

By goal

• Team-sport athletes (soccer, basketball, football): Prioritize 5 to 15 meter sprint reps from varied starts — standing, rolling, reactive — since most sport actions never reach max velocity. Layer in resisted sled work at 10 to 20 percent body mass twice a week.
• Track sprinters: Train the full 0-30+ meter acceleration curve with block starts, build-ups, and heavy sled pulls, then bridge into max-velocity work once drive-phase mechanics stay consistent under fatigue.
• General strength and conditioning clients: Two short sessions a month of 10 to 20 meter sprints from a standing start, paired with squats or trap-bar deadlifts, build usable acceleration without needing a track or a sled.

Common misconceptions

• "Acceleration and speed are the same thing." Acceleration is how fast velocity changes; speed, or max velocity, is how fast you are moving once it stops changing. A sprinter can have elite acceleration and only average top speed, or the reverse, and the two are trained with different drills and loads.
• "You get faster off the line just by sprinting more." Acceleration is force-limited, not just skill-limited. Without a strength base — squats, deadlifts, hip thrusts — to raise how much force you can drive into the ground, technique-only work plateaus quickly regardless of how many sprints you run.
• "Staying low longer always improves acceleration." A forward lean helps direct force horizontally in the first steps, but holding that lean too long past 10 to 15 meters wastes the stride length and stiffness needed to transition into max velocity; the trunk should rise progressively, not stay pinned down.
• "Heavier sled loads are always better for acceleration." Loads much above 20 to 30 percent of body mass slow the sled enough to change stride mechanics into something closer to a heavy push than a sprint. Most research supports 10 to 20 percent body mass, or a 10 to 15 percent velocity decrement, to overload force without breaking technique.

Related terms

Acceleration FAQ

What is acceleration in sports?

Acceleration in sports is how quickly an athlete increases running velocity from a stop, jog, or change of direction, rather than how fast they eventually run. It is measured over short splits like 0-10 or 0-20 meters and depends on how much horizontal force the legs drive into the ground each step.

What is the difference between acceleration and speed?

Speed, or max velocity, is how fast you are moving once velocity stops increasing, usually reached 30 to 60 meters into a sprint. Acceleration is the rate of getting there. An athlete can have elite acceleration and only average top speed, and the two are trained with different drills and loads.

How long does the acceleration phase last in a sprint?

For elite 100-meter sprinters the acceleration phase lasts roughly 30 to 60 meters before max velocity is reached, with the fastest sprinters extending it closer to 60 meters. Recreational and team-sport athletes typically stop accelerating much earlier, often somewhere between 10 and 20 meters.

How can I improve my acceleration?

Improve acceleration with resisted sled sprints at 10 to 20 percent body mass, heavy lower-body strength work like squats and deadlifts, plyometrics for rate of force development, and short 10 to 30 meter sprint reps at full effort with long rest. Technique drills that groove a strong lean and full hip extension help too.

What muscles are used in acceleration?

Acceleration relies mainly on the gluteus maximus and hamstrings for hip extension, the quadriceps for knee extension, and the calves for ankle plantarflexion, working together in a triple-extension pattern at each ground contact. The hip flexors also drive the recovery leg forward between strides.

Why is acceleration important in team sports?

Most actions in soccer, basketball, and football never reach max velocity — they last only a handful of steps. A player who accelerates faster off the mark wins the race to the ball, the closeout, or the gap, which is why coaches train short sprints and resisted starts far more than long sprints.

What is a good 10-meter sprint time?

Elite male sprinters cover the first 10 meters in roughly 1.7 to 1.9 seconds from a block start. Well-trained team-sport athletes typically run a few tenths slower, and recreational athletes commonly need 2.2 seconds or more over the same distance from a standing start.

What is the force-velocity profile in sprinting?

The force-velocity profile is a method, developed by researchers including Jean-Benoît Morin and Pierre Samozino, that estimates how much horizontal force and velocity an athlete produces across a sprint from simple timing data. It flags whether an athlete needs more force or more velocity work to accelerate faster.

Should I train acceleration and max velocity differently?

Yes. Acceleration work uses short distances of 10 to 30 meters, resisted sled loads, and a forward-lean start, while max-velocity work uses run-in distances of 30 meters or more so the athlete is already near top speed before the timed section begins. Mixing the two blurs both adaptations.

Does resisted sled sprinting actually improve acceleration?

Yes, when loaded correctly. Research generally supports sled loads around 10 to 20 percent of body mass, or a 10 to 15 percent velocity decrement, to overload horizontal force production without changing sprint mechanics enough for the sled push to become a different exercise entirely.

References

1. Rabita G, et al. Sprint mechanics in world-class athletes: a new insight into the limits of human locomotion. Scand J Med Sci Sports, 2015. PubMed 25640466
2. Cross MR, Brughelli M, Samozino P, Morin JB. Methods of Power-Force-Velocity Profiling During Sprint Running: A Narrative Review. Sports Medicine, 2017. PubMed 27896682
3. Morin JB, et al. Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production. Frontiers in Physiology, 2015
4. Stavridis I, et al. Differences in the Force-Velocity Mechanical Profile and Sprint Performance Between Sprinters and Hurdlers. Frontiers in Sports and Active Living, 2019
5. Rieger M, et al. Effect of Weighted Sled Towing on Sprinting Effectiveness, Power and Force-Velocity Relationship. PLoS ONE, 2018
6. Acceleration vs. Maximum Speed. NSCA, Kinetic Select
7. Sprinting Mechanics and Technique. NSCA, Kinetic Select