You Don't Need More Speed Work

I ran a 16:58 5K on Thanksgiving. That's 5:28/mile pace.

In the six months before that race, do you know how many times I ran faster than 6:00/mile in training?

Twice. Both were 5K races.

Every single step of training, other than strides, was slower than 6:00 pace. Most of my interval work was done at 6:10-6:30. Easy runs were 8:00-8:30.

And yet race day I ran 5:28s.

I wouldn't have believed it unless I experienced it myself. But you really don't need high-end speed work to run fast. And you'll feel way better. Less beat up. Less injured. More consistent.

The truth

If you want to run a faster 5K, the answer is almost certainly not more speed work.

I know. Sounds backwards. If you want to run faster, shouldn't you practice running fast?

Here's the problem with that logic: the 5K is not a sprint. It's not even close to a sprint.

The mile is roughly 80% aerobic. The 5K is 90%+ aerobic. Your finishing time is determined almost entirely by your ability to sustain effort, not by your raw top-end speed.

Think about it this way. If I put you on a track and said "run one 400 as fast as possible," you could probably hit a pace that would be respectable for a 5K. Maybe even a good 5K. The speed is there.

But could you hold that pace for 12 more laps? Not a chance.

The limiter isn't your speed. It's your endurance. Your ability to hold a hard pace without falling apart. Your aerobic system's capacity to deliver oxygen and clear waste for 20-plus minutes of sustained effort.

For almost everyone, that's the bottleneck. Not speed.

The test

Here's an easy way to check.

Go to any race equivalency calculator online and plug in your current 5K time. Look at what it predicts for your mile time.

I'd bet that for at least 95% of you, your actual mile time is faster than the prediction. Probably significantly faster.

If your 5K is 25 minutes, the calculator might predict a 7:20 mile. But I'd bet that if your 5K is 25:00, you could run a sub 7:00 mile.

That gap between your predicted mile and your actual mile tells you something important. You have more speed than your endurance can support. Your engine is the problem, not your legs.

Adding more 200s and 400s won't fix that.

What actually works

If speed isn't the limiter, what do you train instead?

Two things: your aerobic base and your lactate threshold.

Your aerobic base is your foundation. It's your body's ability to produce energy using oxygen, which is what you're doing for the vast majority of any run over 800 meters.

You build it with easy running. Lots of easy running. Heart rate under 75% of max. The kind of running that feels almost too slow to be useful.

Your lactate threshold is the pace you can sustain before things start to fall apart. It's roughly the pace you could hold for an hour in a race: much faster than easy, but not so fast that you're gasping and dying.

This is where the real gains happen for most runners. When you push your threshold up, your 5K pace drops with it. You're not getting faster by sprinting harder. You're getting faster by raising the ceiling on what "comfortably hard" means.

You build threshold with sub-threshold and threshold intervals. Hard but controlled efforts in the 85-92% max heart rate range. Sets of 4-8 minutes with short rest. The kind of work where you're pushing but not dying. Where you finish and think "I could have done one more."

These two adaptations, a bigger aerobic base and a higher threshold, are what actually make you faster at the 5K. Not hammering 400s until you puke.

Why speed work feels productive

I get it. Speed work feels like real training.

You're running fast. You're breathing hard. You're suffering. You finish the workout drenched in sweat, hands on your knees, feeling like you accomplished something.

Easy running doesn't feel like that. You finish and you're barely tired. It seems too easy. Like it can't possibly be doing anything.

Sub-threshold work sits in the middle, and that's part of why people skip it. It's hard enough to require focus, but you're not destroyed afterward. You don't get that dramatic collapse at the finish line. You just feel... worked. Solid. Like you put in effort but could do it again tomorrow.

That lack of drama tricks people. They think if they're not wrecked, they didn't train hard enough. So they skip the threshold work and go straight to all-out intervals. Or they run their easy days too fast because "easy" doesn't feel productive.

But the adaptations from easy running happen slowly, invisibly, over months. Your capillary density increases. Your mitochondria multiply. Your heart gets more efficient. None of this shows up in a single workout. It accumulates over time.

And the adaptations from threshold work (teaching your body to clear lactate, pushing up the pace you can hold without falling apart), those require consistent, controlled effort. Not max effort. Controlled effort.

Speed work gives you an immediate sense of accomplishment. Easy running and threshold work give you long-term results. Most people choose the thing that feels productive over the thing that actually is.

The other problem with speed work

There's a practical issue too: injury risk.

Running hard 200s and 400s puts enormous stress on your body. The forces are higher. The impact is greater. Your connective tissue takes a beating.

If you're a lifter adding running to your training, you're already asking a lot of your body. Your joints and tendons aren't adapted to running yet. Throwing in high-intensity sprint work before you've built that foundation is asking for trouble.

I've seen it happen over and over. Guy decides to get serious about running. Does a few weeks of intervals and tempo runs. Feels great. Then his Achilles flares up, or his knee starts aching, or his shin splints come back. He's out for a month. Starts over from scratch.

Easy running builds durability. Speed work tests it. You need the first before you can safely do the second.

What to do instead

Here's the formula that works for most people:

• About 80% of your running should be at easy pace. Heart rate under 75% of max. Slow enough that you could hold a conversation. This builds your aerobic base and lets your body adapt to the impact of running without breaking down.
• About 15-20% should be at threshold or sub-threshold pace. Efforts that are hard but controlled. This pushes your lactate threshold up so you can sustain faster paces.
• A small amount, maybe 5%, can be true speed work. Strides after easy runs. Short hill sprints. The occasional set of 200s when you're sharpening for a race.

That's the ratio. It doesn't make for good Instagram content. But it works.

Build the engine first. The speed will follow.

Lift heavy. Run fast (but not too fast).

Capacity Training

I built Capacity Training to teach you how to build up your mileage slowly by learning how to run easy, with your lifting planned around it. Once you build that base, you get into the fun stuff: intervals and running faster.

Run faster. Get stronger. capacitytraining.app

Mike