Strides and Hill Sprints: The Cheapest Speed Work a Triathlete Can Do

Ask a triathlete about speed work and you'll usually hear about intervals: 1 km repeats, threshold runs, tempo sessions. Strides and hill sprints rarely get a mention. They look too short to matter. A few 20-second efforts at the end of an easy run hardly seem like training.

They've come back into the conversation partly through coverage of Norwegian coaching methods, which mix large volumes of controlled threshold work with small doses of fast running. TriForward's "Double Threshold, Single Reality" covers the threshold side. This article is about the other end: the shortest, fastest running you can do, what it may do for a long-course triathlete, and how good the evidence is.

The short version is that the idea is reasonable and cheap to try, but the evidence is thinner and less direct than its popularity suggests.

What strides and hill sprints are

The terms are used loosely, so it helps to be clear:

• Strides are short accelerations on flat ground, usually 15 to 30 seconds or around 80 to 120 m. You build up to a fast pace, often around mile or 1,500 m race pace, hold it relaxed, then ease off. They aren't all-out, and recovery is long enough that each one feels fresh.
• Hill sprints are short, hard efforts up a moderate to steep slope, often 8 to 15 seconds. The hill raises the effort and the muscular demand while lowering the speed and, for many runners, the impact on landing.
• Sprint intervals in research usually mean all-out efforts of around 30 seconds with several minutes of recovery. These are much more demanding than strides.

Strides and hill sprints sit at the light end of this spectrum. That's important, because almost all of the trials below used something harder.

Why fast running might help a slow race

A long-course triathlon run is slow compared with a sprint. So why should running fast for 20 seconds matter? There are three plausible reasons, drawn from running physiology rather than from a single study:

• Running economy. Economy is the oxygen cost of running at a given speed. Better economy means less energy for the same pace. Fast running may improve how stiff and springy your legs are and how well your muscles and tendons store and return energy.
• Neuromuscular qualities. Fast running trains you to produce force quickly and to coordinate faster movement. These qualities tend to fade with long, slow training and with age.
• A wider range of speeds. If your easy pace and your race pace are your only gears, your race pace is close to your top end. Raising your top speed may make race pace feel relatively easier.

These are mechanisms, not proof. The question is whether training studies show a real effect.

The explosive-training trial

The study most often cited for fast, short work is a 1999 trial by Leena Paavolainen and colleagues in the Journal of Applied Physiology. It involved 18 well-trained endurance athletes: 10 in an experimental group and 8 controls. The abstract doesn't report their sex.

• Both groups kept the same total training volume for 9 weeks.
• In the experimental group, 32% of training was replaced by explosive-type strength training, compared with 3% in the control group.

The results:

• 5-km time, running economy and maximal anaerobic running speed improved in the experimental group, with no change in the controls.
• Maximal 20 m speed and a five-jump test improved in the experimental group and fell in the controls.
• VO2max didn't change in the experimental group, but rose in the control group.
• Changes in 5-km speed were related to changes in running economy (r = −0.54) and maximal anaerobic running speed (r = 0.55).

The authors concluded that the improvement came from better neuromuscular characteristics, not a bigger aerobic engine. The trial is small, and "explosive-type training" isn't the same as strides. But it established the idea that fast, explosive work can make well-trained endurance athletes faster without raising VO2max.

A 2017 meta-analysis by Denadai and colleagues in Sports Medicine later pooled 16 studies of strength training in endurance athletes. Explosive training improved running economy by 4.83% and heavy weight training by 3.65%. TriForward's "Jumps or Iron?" covers plyometrics and lifting in detail, so this article stays with running itself.

The uphill interval trial

The closest trial to hill sprints is a 2013 study by Kyle Barnes and colleagues in the International Journal of Sports Physiology and Performance. It involved 20 well-trained runners. The abstract doesn't report their sex.

• Runners were randomly assigned to one of five uphill interval programmes of different intensities for 6 weeks.
• Before and after, they did a treadmill test, force-plate jumps and a 5-km time trial.

The results:

• 5-km time improved by 2.0% (±0.6%) on average, with no clear best intensity.
• Running economy improved most at the highest intensity, by 2.4% (±1.4%).

The authors concluded that, until more data are available, runners can assume that any high-intensity uphill interval training will benefit 5-km performance. That's encouraging for hill sprints, but the trial had no flat-running comparison group, so it can't show that hills beat other ways of running fast. With five programmes and 20 runners, each group was also very small.

The speed-endurance trial: economy up, race time flat

A 2009 trial by Iaia and colleagues in the Journal of Applied Physiology asked what happens if you replace most of your running with short sprints. It involved 17 endurance-trained runners: 9 in a speed-endurance group and 8 controls. The abstract doesn't report their sex.

• For 4 weeks, the speed-endurance group replaced its usual training of about 45 km per week with frequent sessions of 8 to 12 30-second sprints with 3 minutes of rest.
• Their weekly running fell to 5.7 km of sprints plus 9.9 km at low speed. Inference: about 15.6 km in total, roughly a third of their usual volume.
• The controls carried on with normal endurance training.

The results:

• Oxygen uptake at submaximal speeds fell by 6.6%, 7.6%, 5.7% and 6.4% at 11, 13, 14.5 and 16 km/h in the sprint group, a clear improvement in economy. The controls didn't change.
• VO2max and 10-km time didn't change in either group.

This is the most useful trial for setting expectations. Short sprints improved economy and maintained performance on a fraction of the usual volume. But better economy didn't translate into a faster 10 km within 4 weeks. Inference: for a triathlete, short fast work looks like a useful addition, not a shortcut around aerobic training.

Two sprint-interval trials

Two more trials tested 30-second sprints in trained runners.

Trail runners, six sessions

A 2018 study by Koral and colleagues in the Journal of Strength and Conditioning Research involved 16 trained trail runners, 12 men and 4 women.

• They did 4 to 7 all-out 30-second shuttle runs with 4 minutes of recovery, 3 times a week for 2 weeks: six sessions in total.
• 3,000 m time trial performance improved by 6%, maximal aerobic speed by 2.3%, and time to exhaustion at 90% of that speed by 42%.

There was no control group, so some of the improvement could reflect familiarity with the tests or normal training. It's a striking result from a short intervention, but it needs to be read with that limitation.

Well-trained young men, six weeks

A 2025 randomised trial by Jin and colleagues in Frontiers in Physiology involved 20 well-trained male distance runners aged around 19 to 20, with an average 5,000 m best of about 14 minutes 38 seconds.

• The sprint group did 10 all-out 30-second sprints with 3.5 minutes of recovery, twice a week for 6 weeks.
• The control group did traditional distance training, including longer intervals and tempo runs.
• Both groups also ran 40 to 60 minutes easy on 4 days a week.

The results:

• 3,000 m time improved from 527.48 to 522.61 seconds in the sprint group, and by 5.31 seconds more than in the control group, a large effect (d = 1.53).
• VO2max and oxygen cost improved slightly in the sprint group, but neither change was statistically significant.

The authors flagged their own limits: a small sample, men only, a narrow age range and only 6 weeks.

What the studies have in common

Taken together, the trials point in a consistent direction:

• Short, fast running can improve running economy in trained runners, by 2.4% in the uphill trial and by 5.7% to 7.6% in the speed-endurance trial.
• Short-distance performance (3 km to 5 km) improved in most trials.
• VO2max usually didn't change. The benefit seems to come from economy and neuromuscular qualities, not the aerobic engine.
• The doses were small. Six to twelve sessions over 2 to 9 weeks.

But there are important gaps:

• No trial tested classic strides. Most used all-out 30-second sprints, which are harder and more fatiguing.
• No trial studied triathletes, and none measured performance over a half or full marathon, let alone off the bike.
• Most participants were young and male, and several abstracts didn't report sex.
• Samples were small, from 16 to 20 people, and one trial had no control group.

Why it may matter more for triathletes

Inference: there are reasons to think short, fast running may be particularly useful for triathletes, even though no one has tested it in them.

• Most triathletes run slowly most of the time. Long-course training is dominated by easy running and long bricks. Many age-groupers rarely run faster than threshold pace.
• Run volume is limited. Triathletes often run three or four times a week. Strides add a stimulus without adding much load.
• Fatigue cost is low. A few relaxed strides at the end of an easy run are unlikely to compromise the next day's swim or bike session.
• Speed declines with age. Sprint ability and fast force production tend to decline faster with age than endurance. TriForward's "Strength Training After 50: Why Power Matters More Than Strength" covers this from the gym side.

The counter-argument is that a long-course triathlon run is limited by durability, fuelling and heat far more than top-end speed. TriForward's "Why the Ironman Marathon Falls Apart After 25 km" covers those factors. Strides won't fix a fade caused by under-fuelling or an overpaced bike.

How to add strides and hill sprints

The following is practical inference from the trials and common coaching practice. It's not a tested programme.

Strides

1. Start with 4 to 6 strides of 15 to 20 seconds at the end of an easy run, on flat, even ground.
2. Build up smoothly, hold a fast but relaxed pace for a few seconds, then ease off. If it feels like a sprint, slow down.
3. Walk or jog for 60 to 90 seconds between strides, so each one starts fresh.
4. Do this once or twice a week. Strides also work well as part of the warm-up before a harder session or a race.

Hill sprints

1. Find a moderate hill where you can run 8 to 12 seconds without your form breaking down.
2. Start with 4 to 6 efforts at a strong, not maximal, effort.
3. Walk back down and rest fully, around 2 minutes or more.
4. Build up over several weeks, both in number and effort, before going close to maximal.

The uphill trial found that any high-intensity uphill work helped 5-km performance, and the most intense work gave the biggest economy gain. Inference: you don't need to go all-out from the start.

Fitting it into a triathlon week

Short, fast running is easy to fit around other training:

• Attach strides to an easy run rather than adding a separate session.
• Keep hill sprints away from your hardest bike session, so tired legs don't spoil either.
• Keep them in the base phase. Fast running is often dropped in winter, which is when a triathlete has the most time for it.
• Keep a few strides in race weeks. They're a common part of taper and pre-race routines, though that's coaching practice rather than tested.

If you want to see whether it helps, TriForward's "Critical Speed for Runners" describes a field test you can repeat after 6 to 8 weeks.

A triathlon scenario

The following example is illustrative, not drawn from a study. A 44-year-old age-grouper training for a 70.3 runs three times a week: an easy run, a long run and a brick. Their 10 km pace has stalled for two seasons, and they never run faster than threshold.

Based on the evidence above, they might:

• Add 4 to 6 relaxed strides to the end of the easy run each week.
• After 3 or 4 weeks, add a short set of hill sprints to the same run every other week, starting at a strong rather than all-out effort.
• Keep the long run and brick unchanged, because those are what the race depends on.
• Retest after 6 to 8 weeks using the same field test.

If their economy or 5 km pace improves, that's useful. If not, they've spent a few minutes a week finding out.

Common mistakes

• Treating strides as sprints. Strides should feel fast and relaxed. Straining to go flat out raises injury risk without clear benefit.
• Too little recovery. Short rest turns strides into an interval session. The fatigue cost goes up and the speed goes down.
• Starting with maximal hill sprints. Build up effort over weeks, especially if you're older or new to fast running.
• Expecting a faster Ironman marathon from strides alone. The trials measured 3 km to 10 km performance, not long-course racing.
• Replacing aerobic running. In the speed-endurance trial, replacing most running with sprints improved economy but didn't change 10-km time.
• Doing them on tired legs. Strides after a hard bike session are unlikely to be fast or well-coordinated.

What we don't know

• Whether classic strides work. No trial has isolated 15 to 30-second submaximal strides.
• Whether gains transfer to long-course racing, or to running off the bike.
• The effect in women and older athletes, who were few or absent in these trials.
• The minimum effective dose. No trial compared, say, four strides a week with ten.
• Whether hills beat flat sprints. The uphill trial didn't compare them.

TriForward's "Do 30-Second Sprints Belong in a Triathlete's Week?" covers the bike equivalent of this question.

References

• Paavolainen L, Häkkinen K, Hämäläinen I, Nummela A, Rusko H. Explosive-strength training improves 5-km running time by improving running economy and muscle power. Journal of Applied Physiology, 1999;86(5):1527–1533. doi:10.1152/jappl.1999.86.5.1527
• Barnes KR, Hopkins WG, McGuigan MR, Kilding AE. Effects of different uphill interval-training programs on running economy and performance. International Journal of Sports Physiology and Performance, 2013;8(6):639–647. doi:10.1123/ijspp.8.6.639
• Iaia FM, Hellsten Y, Nielsen JJ, Fernström M, Sahlin K, Bangsbo J. Four weeks of speed endurance training reduces energy expenditure during exercise and maintains muscle oxidative capacity despite a reduction in training volume. Journal of Applied Physiology, 2009;106(1):73–80. doi:10.1152/japplphysiol.90676.2008
• Koral J, Oranchuk DJ, Herrera R, Millet GY. Six sessions of sprint interval training improves running performance in trained athletes. Journal of Strength and Conditioning Research, 2018;32(3):617–623. doi:10.1519/JSC.0000000000002286
• Jin K, Cai M, Zhang Y, Wu B, Yang Y. Effects of 6-week sprint interval training compared to traditional training on the running performance of distance runners: a randomized controlled trial. Frontiers in Physiology, 2025;16:1536287. doi:10.3389/fphys.2025.1536287
• Denadai BS, de Aguiar RA, de Lima LCR, Greco CC, Caputo F. Explosive training and heavy weight training are effective for improving running economy in endurance athletes: a systematic review and meta-analysis. Sports Medicine, 2017;47:545–554. doi:10.1007/s40279-016-0604-z