You Are Not a Car: Why Distance Runners Have to Sprint

By Alex Lyons


When you were a kid, what was your first introduction to the world of running?  Was it a tempo run?  A fartlek?  Some sort of complicated heart rate zone workout?

Probably not.

My guess is you sprinted.

That’s what we did in my neighborhood: first one from the front step to the mailbox wins.  Line up and throw down for 8-10 seconds, and that was it.  It was pretty awesome.

But then we got older.  We got (supposedly) smarter and more sophisticated with our training.  We learned all these cool things about how global volume/mileage mattered, and that if we just ran more and more we would get better and better.

So we stopped sprinting, and thereby made a critical physiological error in our training.

The human body does not function like the engine of a car.  A car always has access to its same horsepower and cylinders.  It just runs at a higher or lower RPM depending on the speed.  Your body is different.  It’s comprised of an amalgam of muscle fibers that have distinctly different characteristics.  The most basic distinction is the categorization of muscle fibers on a continuum of “fast twitch” to “slow twitch”.  A primary difference between these fibers is how they respond to different intensities.  Slow twitch fibers become activated at lower intensities, while fast twitch fibers do not.

Let’s look at a real world example of this: on a normal easy run, research estimates that a runner will access roughly 20-30% of the muscle fibers in his or her body.


This is a staggeringly small number.  So if all we do every day is go for a nice easy jog, we may be slightly bolstering our cardiovascular system and burning some calories, but we are leaving a solid 70-80% of our fiber pool untrained and unchallenged.

Results don’t improve as much as you’d think with regular track workouts either.  A hard track session of 400m repeats will net you a fiber activation rate closer to 70 or 80%, but that’s still a long way from 100%.  Traditional tempo or lactate threshold runs are even lower, down closer to 60-65%.  This all makes sense if we contextualize these workouts in terms of power output.  We’re never really going as fast as we can from the get-go.  Sure, the last rep may be all out, but that’s because we’re tired from the previous ones.  We are never using our true maximal velocity.

The question then becomes how we can recruit all these normally untouched fibers.  It’s impossible for someone to recruit all available muscle fibers in the body during exercise.  A central governor exists that, for safety reasons, prevents this from happening.  But we can still get way closer to our max than most people ever do.

And we get there by SPRINTING.

It’s a simple cause and effect problem:  to recruit more fibers, we need greater intensity.  The most basic way to achieve the necessary intensity is by sprinting.  There are other ways to recruit additional fiber pools:  high intensity weight lifting, circuit training, some crossfit workouts, etc.  But we will focus on sprinting for two reasons:  it’s the simplest and most readily available activity, and it recruits fibers in the most running-specific way.

Hill Sprints

***Important:  I recommend that anyone interested in sprint work, or any type of consistent run training, receive a professional gait analysis.  This can identify muscular weaknesses and imbalances, as well as poor motor patterns, and can turn you into a healthier and more efficient runner.

So how do we start to incorporate sprinting into our training plan?

We need to do this in a conscientious way that bolsters our muscular and neurological fitness while also keeping everyone healthy.  The best way to start, therefore, is with the hill sprint.  Hill sprints provide all the benefits of neuromuscular recruitment, they add an increased strength component to the exercise because you are working against gravity, and THEY ARE VERY SAFE.  In fact, high profile elite coaches such as Brad Hudson, Steve Magness, Jay Johnson and Renato Canova prescribe sets of hill sprints to their chronically injured athletes in order to REDUCE injuries.

Hill sprints are substantially safer than flat sprints because the angle of contact reduces loading rate.  The contact angle cuts down impact forces that travel up through the body, and therefore the activity is much safer than a traditional flat sprint.  If we look at the angle of the leg from hip to knee and knee to ankle, the angle will be smaller going uphill.  The vast majority of injuries, Canova explains, are triggered when that ground contact angle is wider (closer to 180 degrees).

The one exception to this rule is a runner experiencing Achilles tendon issues or similar lower leg problems (peroneal tendon, calcaneus, etc).  The increased vertical nature of the hill sprint places loads more directly on the Achilles and lower leg structures.  If you have issues in this region, hold off for a bit on the hill sprints until the area has calmed down.

In terms of frequency in your training plan, one hill sprint session a week will suffice.  These can be incorporated either at the end of an easy run or in the midst of one, depending on where you have a hill available.  Find a relatively steep hill to use to start out with.  The steeper hill elicits greater fiber recruitment and involves a larger muscular strength component.  As the hills become more gradual, the exercise becomes specific, but the recruitment level goes down.  So it’s best to start on a steeper hill to gain access to a larger fiber pool, then progress to a more gradual hill to train those newly recruited fibers in more a specific manner.   Examples of a hill sprint workout:

– 40 min easy run finishing at a hill, set of hill sprints


-30 min easy run to hill, set of hill sprints, easy jog home

The Actual Hill Sprint Set:

For those of you new to hill sprints, a set of 2-4 during your first time is plenty.  Add a rep each time until you reach 8-10 reps.  Each sprint should last roughly 5-10 seconds. Do not go much longer than this.  If you miss the window by a second or two, no big deal, but extending too far beyond the window will incur a lactate uptick that isn’t part of the plan.

Basically, if you sprint for too long, you’re changing the nature of the workout away from what we want to get done.

A good rule of thumb for sprint work is that VELOCITY HAS TO RULE.  

That means you need to pick a duration short enough that you can maintain your sprint speed all the way through it.  If at the beginning, that’s only five or six seconds, sprint for five or six seconds.  As you become more adept and can extend the sprint to the full eight, ten or twelve seconds, feel free to do so.  THE REST BETWEEN THESE REPS IS CRITICAL.  DO NOT REST LESS THAN 2 MIN (3 minutes is the ideal rest period).  Because the goal here is motor recruitment, you have to be fully recovered before you start each rep.  That means resting for 2-3 minutes between reps.  Sprint up the hill, WALK slowly down, and chill out at the bottom until the appropriate recovery time has elapsed.  Then go again.  And remember, this is a SPRINT uphill, not a jog or an uphill stride or regular hill reps.  They are short and intense, so you need to let it rip and fly up that hill.

Try out the hill sprint and have fun running fast.


“Sprint Training” by Steve Magness

Run Faster from the 5k to the Marathon by Brad Hudson

Renato Canova’s “Training for the Mile”

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