10 reasons why ultra runners need speed work (even if you’re not chasing fast)

(Photo courtesy of HOKA)

By Henry Howard

If you’ve spent any time in the ultra running community, you’ve probably heard some version of this advice, “Run slow to run fast.” There is real wisdom in that but it’s only part of a solid training plan philosophy.

Base mileage and time on feet are the foundation of ultramarathon training. But if that’s all you’re doing, you’re leaving a significant amount of performance on the table. Speed work is a critical part of any training plan, whether you are training for a 5K, half marathon, marathon, ultra or any other distance.

As an experienced, Road Runners Club of America certified coach, one of the most common mistakes I see ultra runners make is treating speed work like it belongs to a different sport entirely. “I’m not training for a 5K,” they might think. “I don’t need to go fast.”

But speed work isn’t about going lightning fast on race day. It’s about making your race day pace feel more sustainable, your body more resilient and your fitness ceiling dramatically higher.

10 reasons why ultra runners need speed work as a staple in their training plan

1. Speed work for ultra runners makes race pace feel easier.

This is the big one, and it’s the reason I push every athlete I coach — regardless of their goal distance — to include some form of high-intensity work. Running economy is essentially how efficiently your body uses oxygen at a given pace. When you train your body to move fast, your pace during an ultra represents a smaller percentage of your maximum capacity.

As your top-end speed increases, your ultra shuffle becomes less of an effort, therefore you are more likely to move faster. What felt hard before now feels controlled. That’s not magic, it’s physiology working in your favor.

2. How speed work boosts your aerobic capacity

VO2 max — your body’s maximum oxygen uptake — is one of the strongest predictors of endurance performance. Speed work, particularly intervals and tempo runs, is one of the most effective ways to increase your VO2 max.

The higher your aerobic ceiling, the more runway you have before you hit your limits. For an ultra runner grinding through the latter stages of a race, that extra runway isn’t a luxury, it’s a fitness boost that routinely pays off.

3. Speed work improves how your body handles lactate

Lactate is often misunderstood. Speed work, especially tempo efforts run at or just above your lactate threshold, teaches your body to process and recycle lactate more efficiently.

The practical result? You push fatigue further back. Efforts that used to make your legs feel like concrete start feeling manageable. In an ultra, where the game is always about delaying the inevitable breakdown, this is a massive advantage.

4. How speed work develops fast-twitch muscle fibers

Ultras are slow-twitch dominated. However, dismissing fast-twitch fibers entirely is a mistake. When your primary muscle fibers are depleted and exhausted deep into a race, your body begins recruiting fast-twitch fibers to pick up the slack.

If those fibers have never been trained, they have nothing to give. But if you’ve done strides, hill repeats, short intervals in training, those fibers are conditioned and ready. They serve as your reserve tank when everything else is running on fumes.

5. Speed work strengthens muscles and connective tissue

The repetitive, low-impact shuffle of ultra training is one of the things that makes the sport sustainable — and also one of the things that creates overuse injuries. When you do the same movement pattern thousands upon thousands of times, certain structures get chronically overloaded while others are barely used.

Speed work forces your body out of that groove. The more powerful, dynamic strides required for faster running recruit different muscles, strengthen tendons and ligaments, and build the structural resilience that helps you stay healthy through high-mileage training blocks. Variety, in this case, is genuinely protective.

6. How speed sessions improve your running form

A drawback to slower running for some athletes is that it can lead to poor form. Heel striking, excessive vertical bounce, low cadence, and weak arm drive all tend to get worse the slower and we run. Speed work demands better mechanics simply because sloppy form at faster paces feels terrible and wastes energy noticeably.

The neuromuscular patterns you reinforce during speed sessions carry over to your longer efforts, even if only subtly. Over months of consistent training, that adds up to a more efficient, more injury-resistant stride at all paces.

7. Speed work builds mental toughness

This is one that doesn’t get talked about enough. Speed work is uncomfortable as you push your limits on hard efforts. Learning to manage discomfort, to breathe through hard efforts and to stay controlled when your lungs are burning all build mental toughness.

Ultra running is as much a mental game as a physical one. Athletes who regularly practice sitting with discomfort in training develop a different relationship with suffering on race day. They’ve been uncomfortable before. They know it ends. That confidence is worth more than any single workout.

8. Use speed work to become a more versatile runner

Most ultra courses aren’t just flat and runnable. They have technical climbs, fast descents, runnable sections and everything in between. Speed work makes you capable across a wider range of terrain and intensity.

An athlete who only trains slow is often caught off guard when a course demands a quick surge to pass someone, a faster descent pace, or a hard push over rolling terrain. Speed-trained athletes have more tools available and can respond to what the course and the race demand in real time.

9. How speed work bolsters recovery between training efforts

This one is counterintuitive but well-supported: fitter athletes recover faster. By improving your cardiovascular efficiency and lactate clearance with speed training, your body becomes better at bouncing back. You are better prepared to tackle the next hard training day.

If you’ve ever done a 100-miler or a stage race, you know that the ability to recover during the race itself — at aid stations, during night sections, on runnable flats — is a defining factor in your finish. Speed work quietly improves all of it.

10. Why masters athletes need speed work

If you’re over 40 like me, this section is for you — and speed training is for you. The research on this subject is clear and it’s something I actively work into the training plans I build for my masters athletes.

We know that aging brings a natural decline in fast-twitch muscle fiber recruitment and overall neuromuscular power. What’s less commonly recognized is sprint and speed-based training is one of the best interventions available for countering that decline. A study published in the Journal of Aging and Physical Activity in 2017 found that sprint training was both a safer and more effective way to preserve physical function in older adults than moderate-intensity exercise alone.

For masters ultra runners, speed work can improve performance and lengthen longevity in the sport. Preserving your neuromuscular capacity keeps you moving well, recovering efficiently and racing for years longer than athletes who avoid intensity training.

Frequently Asked Questions: Speed work for ultra runners

Question: Won’t speed work increase my injury risk if I’m already running high mileage?

A: It can, if added too aggressively. The key is keeping speed work volume low — typically no more than 10–15% of your weekly mileage — and treating it as a replacement for some easy running, not on top of it. Introduced carefully, speed work actually tends to reduce certain overuse injuries by breaking up repetitive movement patterns.

Question: How fast is “fast” for an ultra runner doing speed work?

A: It depends on the workout. Strides are run at roughly mile to 5K race effort — controlled but quick. Tempo runs are typically at your 10K to half-marathon effort: comfortably hard, but sustainable for 20 to 60 minutes. VO2 max intervals are harder — around 3K to 5K effort — but short (usually 2 to 10 minutes) with recovery in between each set. You don’t need to be a fast runner to benefit from any of these. Effort is what matters, not pace.

Question: I’m training for a 100-miler. Shouldn’t I be focused entirely on time on feet?

A: Time on feet matters enormously. But “only time on feet” is an incomplete approach. One quality speed session per week, balanced against your long runs and easy volume, won’t compromise your endurance. What it will do is make your long runs more productive, your aerobic capacity higher, and your legs more resilient for race day.

Question: I’m a masters runner in my 50s. Is speed work safe for me?

A: As a runner in my 50s, I say yes, absolutely! It is arguably more important for you than for younger athletes. The research increasingly supports speed training as an effective and safe modality for older adults. That said, masters athletes generally need more recovery between hard sessions, so spacing quality workouts further apart and listening carefully to your body is essential. I always recommend building in at least 48 to 72 hours between longer speed sessions for athletes over 50. But regular speed work “snacks” 4x20 seconds fast, 5x30 second hill repeats, etc. are core staples of my training plans.

Question: What’s the simplest way to start adding speed work?

A: Strides. After your next easy run, add 4–6 strides: 20–25 seconds of smooth, controlled acceleration to about 85–90% effort, with a full recovery jog back to your starting point. You can do them anywhere, and they start waking up your neuromuscular system immediately. From there, you can layer in more structured work over time.

Question: How do athletes who run high mileage add speed work?

A: I know what some of you are thinking: “I’m already running 60, 70, 80 miles a week. Where does speed work even fit?” The answer is: carefully, intentionally and in small doses.

One or two quality speed work session per week, in addition to strides and hill repeats can deliver most of the benefits without meaningfully increasing your injury risk. The key is keeping the volume of speed work low while protecting the quality of those sessions.

Start where you are. If you’ve never done structured speed work, begin with strides: 4–6 x 20-second accelerations at the end of an easy run, twice a week. Over time, build toward more structured intervals. And as always — listen to your body, progress gradually, and prioritize consistency over intensity.

Question: How long before I notice a difference from speed work?

A: Most athletes start to feel a shift in 4 to 6 weeks, easier breathing at moderate paces, a little more snap in their legs, less perceived effort at their usual training paces. Measurable fitness adaptations (VO2 max, lactate threshold) typically show up after 8 to 12 weeks of consistent work. Patience and consistency are everything.

Editor's note: This article on why ultra runners need speed work is one of many I've published about training and coaching tips. For questions about integrating speed work into your ultra training or other topics, reach out through my RunSpirited coaching page — I work with athletes at every level and distance.