The 4 Main Phases of Sprinting Mechanics

For many athletes (and for most sports), speed is one of the most sought-after athletic qualities. Whether it be the speed of a swimmer completing laps in the pool or the quick-footed agility of a soccer player, it’s no question that speed garners high praise from athletes and spectators alike.

Consider the element of speed in running — people are always on the lookout for info on how to run faster, trying to shave a few extra seconds off their next workout or race. And even if you yourself aren’t a natural speed demon, just about everyone recognizes the name “Usain Bolt” for his lightning fast running records.

Granted, most of us can’t live up to his record-breaking speeds, but it certainly illustrates how coveted speed is in the world of athletics.

Witnessing such impressive feats of speed can act as a great motivator for our own running goals, especially for those who are so inclined to master the sprint.

And, as with any other runner, sprinters often wonder: how can I go even faster?

The Difference Between Running and Sprinting

Before we dive into the nitty gritty details of sprinting biomechanics, let’s first define what exactly sprinting is and why it’s so different from its cousin, running.

Well, technically, it’s less of a cousin and more of an umbrella term; running, by definition, theoretically encompasses all types of gaits that generate forward propulsion by foot at a speed faster than walking. (Or, per Wikipedia’s humorous definition, it’s a method of “terrestrial locomotion” wherein humans and other animals “move rapidly on foot.”)

Per this definition, both jogging and sprinting are of the same breed — but, they’re quite distinct from one another in practice and demand entirely different training needs.

Differences in Power Output

One of the main distinctions is the power output: with activities like jogging or running, you’re bound to be moving for much longer durations than a sprinter would, so your power output will be comparably much lower than the maximal effort needed for a full-on burst of sprinting.

To put it in more “science-y” terms, we can compare the rates of oxygen consumption between a lighter running pace and a high intensity sprinting pace. According to the American College of Sports Medicine, if a person weighing approximately 130 lbs ran at about 6 mph (which is considered a comfortable jogging pace), they’d be consuming about 2140 mL of oxygen per minute. This would land them at about 719 watts of power.

But, for that same person to sprint at approximately 15 mph, their oxygen consumption would more than double to 5050 mL per minute, generating about 1690 watts of power. You don’t have to be mathematically adept to recognize how big a difference that oxygen demand and power output becomes when you switch from running to sprinting.

Differences in Energy Systems

As you can infer from the intensity and demand for oxygen, sprinting isn’t a sustainable pace for longer durations, nor was it meant to be. Running and sprinting each come with their own set of demands, so they rely on different sources of energy to fuel your muscles and maintain that forward motion.

With running, you’re moving for much longer distances or times than you do with sprinting, so your body has to ration its energy over the duration of your run. In this case, your body recruits slow twitch muscle fibers and uses its aerobic system to produce and consume oxygen at a sustainable rate.

But with shorter, higher intensity workouts like sprinting, your aerobic energy doesn’t generate quickly enough to fuel your fast-paced activity. This is when the body turns to the anaerobic system, relying on fast twitch muscle fibers and utilizing glycogen stores for quick-release bursts of energy.

(Think of it this way: it’s basically the difference between the way your body provides energy for a long distance run versus a speed interval.)

Differences in Form

Finally, we have the most visibly apparent difference (apart from rate of travel): the form of a runner vs. a sprinter.

The differences between a running gait versus a sprinter’s form is heavily influenced by the activity itself. After all, when we talk about proper form for long distance running, we’re discussing the ideal posture and joint angles that will ultimately conserve energy and absorb shock over a longer period of time. (It’s all in the name of sustainability, folks.)

One of the biggest form differences is the joint angles.

Biomechanics

Compared to sprinters, runners will present with much less hip flexion and triple extension during the propulsion stage of their gait. They will also have prolonged stance times, where they’ll typically demonstrate deeper hip, knee, and ankle flexion during the midstance and peak knee flexion phases. From a theoretical standpoint, this is likely because long distance running places a bigger emphasis on sufficient shock absorption to preserve your joints through long-term, repetitive impacts.

Sprinting form, on the other hand, is much more aerodynamic; the primary focus here is to achieve the biomechanics that will make for the fastest, most powerful strides. This includes increased hip flexion/knee drive; decreased flexion in the hips, knees, and ankles during midstance; and “exaggerations” of triple extension to generate maximum power for propulsion. You’ll also see sprinters moving with higher degrees of shoulder flexion/extension and faster arm swing to supplement the forward velocity of the movement.

But we’re getting ahead of ourselves — let’s take a beat and break down sprinting biomechanics, one phase at a time.

The Phases and Biomechanics of Sprinting

For many athletes, sprinting can start from an upright or standing position, especially during sports where a player has to spring into action (think soccer or football). But, for those whose primary sport is sprinting, your form is prepped for optimal biomechanics right from your initial starting position.

After all, the goal of sprinting is to generate sufficient forces and drive them through the ground, allowing a stationary body to achieve peak acceleration. It takes a massive amount of deliberate training and effort to accomplish that kind of biomechanical feat.

So, without further ado, the biomechanical phases of sprinting!

Phase #1: The Start

One of the first things people envision when they think of sprinting is the starting position itself: that lowered stance, legs staggered behind the body, and hands anticipatorily waiting to lift off the track just as you launch into full speed.

This is where it all begins — both literally and biomechanically speaking.

You first start out in the 4-point stance position (i.e., when all four of your limbs are making contact with the ground). With your feet against the starting blocks, your legs will be in an offset position, and your center of gravity should be geared towards your leading leg. Your arms should be shoulder-width apart, and both the head and spine should be in straight alignment to ensure sufficient stability and power transfer as you propel yourself forward.

As you move into the second portion of the 4-point stance (that moment when you see all the sprinters lift their hips into the air just before taking off), it’s imperative to maintain that same spinal alignment from your head down to the low back. Per the National Strength and Conditioning Association, this should allow your front leg to be near a 90 degree angle and the back leg around 120-125 degrees.

Many athletes will select their dominant leg to position up front, which you can determine with some assistance from a coach, trainer, or physical therapist. (Interestingly enough, you may assume your dominant leg is the same as your dominant hand, but many studies have shown that people are actually more left-leg dominant when it comes to jumping or taking off. So, if you’re unsure, the left leg may be a good place to start.)

Once your position is set, you’ll move into the dynamic take-off. As you launch into your sprint, you’ll push directly off the blocks with both feet; specifically using the blocks at the start will allow for the maximum amount of horizontal forces you can channel into your propulsion. From there, your back leg will swing forward first in tandem with your contralateral arm — and now, you’re off!

And that takes us into the next stage…

Phase #2: The Acceleration

Otherwise known as the “transition phase” of your sprint, the point of acceleration is when your body shifts from running with horizontal forces to primarily vertical forces. This phase happens extremely quickly in real-time, and adhering to proper form is imperative for your body to maximize its force generation as you move from a crouched, stationary position to an upright sprint.

For a successful acceleration phase, the key is to achieve full leg extension for maximal force production into the ground. Which, theoretically, sounds simple, but comes with a bit of a balancing act…

Higher force production requires longer ground contact times, yet sprinting demands as little ground contact time as possible.

It can certainly pose quite the dilemma, but hey — if sprinters didn’t like the challenge, they wouldn’t be in it at all, right? Plus, the solution is all in the biomechanics (as usual!).

To achieve as many forces as possible, lean forward as much as possible (typically around 40-50 degrees) throughout the acceleration phase. Doing so will increase the angle of your shin, which keeps the back end of your foot further off the ground, and voila: your body produces the same amount of force, but has minimal ground contact time through the balls of your feet!

Maintaining this forward lean is mostly relevant for the acceleration phase, so you don’t have to hold it for too long. The cue is to stay low as you’re moving out from the start position and to keep your forward lean just until you reach a fully upright position for the remainder of your sprint.

Phase #3: The Drive (Top Speed)

Once you move past the initial acceleration phase, you transition into the stride phase of your sprint where you begin to run in a more upright position. Here, your head starts to rise, your spine elongates and straightens out, and your eyes are locked onto the end of your sprint lane.

During this phase, you’re reaching maximal velocity, typically somewhere between the 40-80 meter mark. At this point, you’re using a combination of momentum and muscle power to carry you through to the end of your sprint.

Sprinting means you’ll present a high cadence/frequency of strides. With faster stride turnover, your feet make more contact with the ground, so it’s important to maintain a footstrike underneath the hip (i.e., your center of gravity). This will ensure that you minimize any braking forces upon landing and continue at top speed.

And that’s the main gist of the drive phase — to minimize any potential braking forces or points of deceleration that could slow you down! It’s all about harnessing those vertical forces with each step you land and driving yourself forward.

Phase #4: The Deceleration

Last but not least is the final phase of your sprint: the deceleration.

The name of this last phase is a bit misleading; you aren’t trying to actively decelerate from your sprint. More so, this is typically the point in a sprint where athletes run low on power and have to work harder to stave off any fatigue or factors that may cause slow-down.

Your deceleration phase is essentially the same as the drive phase, just with the added difficulty of having to keep up your anaerobic endurance. To help maintain that maximal force output, in your final stretch of the sprint, be sure to achieve high knee action and plenty of arm drive (keep those elbows bent at 90 degrees). 

These sharper joint angles will reduce external deceleration as you charge your way to the finish line! That last 20 meters can pose quite a challenge for both your physical and mental fortitude, so be sure to dial in and apply all your effort to that final portion of the race.

Sprint to the Finish Line

And there you have it, folks: a comprehensive breakdown of how the human body sprints.

The physiological and biomechanical demands of sprinting are entirely unique to the sport. In addition to being a high intensity, anaerobic activity, it also requires muscle recruitment and joint angles that parallel the complexity of a running gait. When combining the nuances of both, you end up with a highly nuanced and demanding exercise that leads to impressive feats of strength, speed, and power.

Sources:

  1.  American College of Sports Medicine. Guidelines for Exercise Testing and Prescription, 4th edition. Philadelphia: Lea & Febiger, 1991, p. 285-300.
  2. Haff, G., & Triplett, N. T. (2016). Essentials of strength training and conditioning. Fourth edition. Champaign, IL: Human Kinetics.
  3. Young, M. Maximal Velocity Sprint Mechanics. United States Military Academy and Human Performance Consulting. 
  4. Hoffman, J. R., & National Strength & Conditioning Association. (2012). NSCA’s guide to program design. Champaign, IL: Human Kinetics.
  5. https://trackandfieldnews.com/track-coach/sprinting-technique-the-key-to-increasing-your-speed/
  6. MACKENZIE, B. (2001) Sprinting [WWW] Available from: https://www.brianmac.co.uk/sprints/index.htm [Accessed 10/9/2021]
  7. https://www.mydailystatic.com/post/three-phases-of-sprinting

By Dr. Josh Tatsuno DPT

Dr. Tatsuno is passionate about high-level sports training and rehabilitation and is dedicated to educating his clients of proper maintenance and care for their bodies. After graduating from the Chapman University Doctorate of Physical Therapy Program, Josh explored his passion for developing and implementing vertical jump, strength and conditioning, and speed and agility programs for all levels of athletes. Josh stays active through his personal passions of backpacking or playing a variety of sports, though he also enjoys traveling, photography, and being a foodie in his spare time.

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