Running is a power sport

Try this. Stand on one leg and hop. Land on the other leg and hop again. Now keep going for 40 minutes. That’s a run.

We usually think of running as an endurance sport, all heart and lungs. Those matter a lot. But what actually moves you forward is your foot pushing into the ground, thousands of times, for a fraction of a second each time. One classic study compared a runner to “a rubber ball bouncing along.”1

Coach and ultrarunner David Roche has been making this point for years on his podcast, Some Work, All Play. “I think that fast strides are the most powerful training stimulus for runners,” he wrote. We wanted to see how well the research backs that up. Here’s what we found, including where it falls short.

What does power mean in running?

Power is how hard you can push, and how quickly. Running gives you very little time to do it. In one study, athletes running at top speed had each foot on the ground for about a tenth of a second. In that moment, they pushed down with an average of 2.08 times their body weight, peaking at 3.62.2

The same lab tested 33 people with top speeds from 6.2 to 11.1 meters per second, roughly 4:20 down to 2:25 per mile. The fastest people didn’t swing their legs through any quicker. They pushed into the ground harder.3

Why should distance runners care?

Nobody sprints at mile 19. But two things carry over.

A higher top speed makes race pace feel easier, because race pace becomes a smaller share of what your legs can do. In elite 800 m runners, sprint speed was strongly linked to race times.4 In well-trained 5K runners, faster 5Ks went along with faster sprints and less time on the ground with each step.5

It can also make you more efficient. Running economy is how much energy it takes to hold a given pace. The less you need, the easier that pace feels. Roche has a good way of picturing it:

“Instead of forcing the bus to go fast, I’d rather upgrade to a Porsche.”

David Roche, in a 2017 interview with Andrew Skurka

A Finnish study from 1999 shows how this works. For nine weeks, well-trained runners kept their total training the same, but one group swapped about a third of it for explosive strength work. That group ran faster 5Ks and used less energy at the same pace, without any change in VO2max. The other group raised their VO2max, but their 5K didn’t get any faster.6

Do sprints really help distance runners?

This is the study Roche has called his all-time favorite. Danish researchers had 20 trained runners do 10 sprint sessions over 40 days, mostly 10 × 30 seconds all-out with 3.5 minutes of walking in between. Meanwhile, they cut their weekly running by 36%, from 25 to 16 km. Afterwards, the runners used about 2% less energy both at 10K pace and at an easy pace, and they ran their 10K 3.2% faster, from 45.2 down to 43.7 minutes. VO2max didn’t change.7

Other studies found something similar. Here they are, from the smallest cut in training to the biggest.

Look at the last two rows. When training was cut by more than half, 10K times held steady instead of improving. Sprints don’t replace regular running. They work best as a short block on top of it.891011 Even six sessions over two weeks made trained trail runners about 6% faster over 3K, though that study had no comparison group.12

A 2025 review of this kind of training came to the same conclusion, and added that you don’t need much of it: twice a week worked as well as four times.13

What about strides, hills and weights?

Strides, about 20 seconds of fast but relaxed running, are a gentler version of these sprints. We couldn’t find a good study of strides on their own, so the case for them comes from the sprint research plus a lot of coaching experience. They take five minutes and carry little risk. Roche’s advice: “Going faster than you’ll ever race–but not as fast as you absolutely can–will make you faster overall at all effort levels.”20

Hills and the gym help too. Six weeks of hard uphill intervals made well-trained runners about 2% faster over 5K.14 Eight weeks of heavy squats cut the energy they needed at the same pace by 5%.15 Jumping drills helped in some studies,16 but heavy lifting seems to help more.17 Across 24 strength-training studies, runners typically needed 2–8% less energy at the same pace, though not in every study.18

How much hard running do you need?

Less than you’d think. A 2026 review of 69 studies looked at how long interval sessions need to be to improve VO2max, a common measure of fitness. Most of the benefit came early. Interval sessions of about 11 minutes, rests included, got 80% of the biggest gain. That’s only around 5 minutes of actual hard running. Steady, moderate running needed about 52 minutes to get there.19 The Roches covered it in an episode called, in part, “Why You May Not Need Much Intensity.”

The likely range is wide, from 9.5 to 40 minutes, so 11 isn’t a magic number. And VO2max isn’t the same thing as your race time. But the takeaway holds: after the first few minutes of hard work, each extra minute adds less. Other researchers have suggested that 5 to 7 minutes near your maximum effort per session may be enough for team-sport athletes, while trained endurance athletes may need more than 10, though that isn’t proven.21

For most people, five-ish minutes of real effort is a proper workout, and the amount can grow as you get fitter. That’s how we approach speed sessions in Strides plans.

Should your reps be short or long?

Both, because they do different jobs. A 2026 review of 102 studies found that in an all-out effort, your body switches from mostly anaerobic to mostly aerobic energy at about 78.6 seconds.22

So a 20-second stride mostly trains your muscles and nerves to move fast, while a 4-minute rep mostly trains your heart and lungs. In one study, 4 × 4 minutes hard raised VO2max by 7.2% in eight weeks.23 Short reps build speed, long reps build your aerobic fitness, and easy running supports both.

What should I actually do?

Start small. Here are four options, from easiest to hardest. The last two are based on what the studies used, so treat them as ideas rather than rules.

Go easy on all-out sprints. The runners in these studies were trained and supervised.13 If you haven’t run fast in a while, start with strides. As the Roches said on another episode, you should rarely be pushing as hard as you possibly can.

What are the limits of this research?

Our take: keep most of your running easy. Once or twice a week, add a few minutes of fast running. It doesn’t take much, and it can make every pace feel easier.

Common questions

Sources

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Further listening

This article is general information, not medical advice. Check with a doctor before starting hard training if you have a health condition or are coming back from an injury. Strides isn’t affiliated with David Roche or Some Work, All Play.