In the running world, there are lots of workout options to have at the ready if you want to get faster: race-pace repeats, tempo and threshold runs, and VO₂ max efforts.
But there’s another option lots of runners tend to overlook. It’s called critical velocity training—and it’s key to boosting your speed without beating up your body, according to exercise physiologist Tom Schwartz, PhD, a running coach and founder of Tinman Coaching who popularized the approach.
Here’s how to slot it into your training.
What Is Critical Velocity Training?
Critical velocity training raises your lactate threshold, the level at which a byproduct of exercise called lactate accumulates in your blood faster than your body can clear it. Improving this metric is important, because it can help hard paces feel easier, which allows you to run faster, and it helps you hold those faster paces for longer.
The general rule of thumb for lactate threshold is that it’s a pace you can sustain for roughly 60 minutes. It’s not something you can hold all day, but it’s also not a pace that’ll leave you totally breathless.
Schwartz read about lactate threshold training when he was in college, and decided to give it a shot in an attempt to improve his own running.
“I found that it did okay,” he tells Runner’s World. “I felt that it gave me good endurance, but I just didn’t have the leg power necessary to sustain the kind of pace [needed] in a race. I felt like I had one gear, so to speak. I couldn’t move any faster.”
So he decided to dig a little deeper into something he was already experimenting with, a metric he called critical value but would later refer to as “critical velocity” when he started using it in coaching.
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Critical velocity running feels a little harder than running at lactate threshold. If lactate threshold is the pace you can maintain for one hour, critical velocity is one that most runners can sustain for 30 to 35 minutes, a little longer or shorter depending on fitness levels and distance experience, Schwartz says. “Critical velocity is about 4 to 5 percent higher,” he says.
In effort level, CV falls between lactate threshold pace and your all-out VO₂ max pace. To find it, you can input your race results at distances ranging from 2,000 meters to the 10K in the calculator on Schwartz’s site to find your critical velocity pace.
The crux of critical velocity training is that it has you running at the hardest pace you can maintain before your body starts to struggle due to the fatigue-related byproducts of exercise. Another way to think about it: CV is the fastest you can run comfortably and in control without having to gasp for air.
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A bunch of beneficial physiological changes occur when doing critical velocity training, including recruiting your fast-twitch muscle fibers, developing more energy-producing mitochondria, and stimulating more capillaries that can help bring nutrients and oxygen into your cells and take exercise byproducts out of them, Schwartz says.
By running slightly faster than your lactate threshold, you can also efficiently improve that metric: “Critical velocity improves your lactate threshold more than running at lactate threshold,” Schwartz says, based on his experience. It can boost your VO₂ max and running economy, too, he adds.
It’s tricky to dig into research on critical velocity because many studies don’t use the term “critical velocity,” but the intensities tested in some studies overlap with what CV looks like in practice, according to Schwartz.
For example, a study published in Medicine & Science in Sports & Exercise looked at performance outcomes for four groups of runners performing different training protocols lasting eight weeks: long and slow (70 percent of max heart rate), lactate threshold running (85 percent of max heart rate), short and fast intervals of 15 seconds on, 15 seconds off (90 to 95 percent of max heart rate), and longer high-aerobic intervals of 4 minutes on, 3 minutes off (90 to 95 percent of max heart rate).
The interval groups improved their VO₂ max more than the long and slow and lactate threshold groups did; the longer-interval group—a protocol that closely mirrors the physiological responses seen in CV training, per Schwartz—did so to the greatest extent.
Another study, published in the Journal of Science and Medicine in Sport, found that runners who trained with hard-but-sustainable 3.5-minute intervals for 10 weeks improved their speed at lactate threshold, whereas those who performed 30-second sprints and those who did recovery runs didn’t experience an increase. This supports the idea that high-aerobic interval work triggers a broader endurance-development stimulus than sprints or slower running alone, according to Schwartz.
Critical velocity training seems to work your body in a highly effective “middle zone,” per Schwartz: You’re going hard enough to help with oxygen delivery and utilization, but it’s still controlled enough so you can put in your reps without burning out too quickly.
If you stick with slower work like lactate threshold, “you’ll still demand a lot of oxygen at a given pace,” he says. “So you’ll be a one-trick pony; you’ll have a pace that you can sustain, but you can’t go any faster than that.”
All in all, in comparison with lactate threshold training, “critical velocity provides more return on investment,” Schwartz says. And because it has you running more slowly and controlled than you would in very high-intensity workouts like VO₂ max routines, it’s a more sustainable practice for runners in the long term, he believes.
“They’re not gasping for breath, their legs are not heavy, and they can do enough repetitions of it, enough minutes of it [to elicit change],” he says. “They can repeat it week after week and basically the body starts transforming.”
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“If you can improve the speed at which you’re running along at a submaximal heart rate or submaximal lactate, it’s very likely that pretty much everything that you’re racing will improve,” Schwartz says.
In fact, he’s seen runners have success with critical velocity training in racing distances from 3,000 meters all the way up to the marathon—and even with some ultramarathoners, too.
So whether you’re racing a 5K, 10K, or going longer, critical velocity is something you can consider adding to your training.
The Workout You Need to Try
The amount of total time you spend running at critical velocity pace during your workouts depends on your fitness level, per Schwartz. Beginners may want to stick to 12 to 15 minutes; intermediate runners 18 to 21 minutes; and advanced runners 21 to 24 minutes, up to 27 minutes or so.
Here’s what this could look like for an intermediate runner:
- Warmup: 6-8 minutes of easy running, followed by 6 x 20-second strides with 20-second recovery, and finished with a 2-minute easy jog
- CV work: 6-7 x 3 minutes at CV pace, with 1-minute recovery between (slow jog or fast walk)
- Cooldown: 12-15 minute jog
“Think of critical velocity as your aerobic cruising speed,” Schwartz says. “It’s comfortably hard, but not where you get to the point where it starts getting out of control and you’re gasping.”
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The beauty of critical velocity workouts is you can—and should—do them year-round, says Schwartz. Because they’re not overly stressing your body, your recovery time is lower than it would be for workouts with harder efforts where you’re really pushing.
“You can do them week after week, which is unlike VO2 max training, which you cannot do for multiple weeks in a row because your body would get destroyed,” he says.
He recommends runners include a CV workout nearly every week of the year, particularly when you are in a competitive season or have a race on the horizon. “You need to include it, in my opinion, if you really want to be serious about reaching your potential,” he says.
Regular critical velocity workouts allow you to see continued progress, he believes, including increasing your average speed.
As for when to slot it in during your week? CV workouts can check the “speed day” box in your workout plan. And if you’re worried this will have you missing out on other types of workouts—say, hard, breathless efforts when you’re running VO₂ max pace or running up hills—one of the benefits of critical velocity training is that you can tack on other workout components to it to make sure you’re challenging your body in a variety of ways.
For example, Schwartz will often program shorter sprint repeats after CV work, like three to six reps of 30-second intervals with a 1-minute jog in between. Or you can do a handful of 30-second hill repeats before your cooldown, too. This helps you work speed and power, in addition to the aerobic efficiency component of CV. “You check off all kinds of boxes,” Schwartz says.
For nearly 10 years, Christa has created health, fitness, nutrition, and wellness content that’s steeped in science but engaging enough that people actually want to read it. She’s tuned in to all the latest research that people with an athletic lifestyle need to know, and prides herself on helping her readers apply it to their everyday lives.