In the running world, there are many workout options to choose from if you want to get faster – think race-pace repeats, tempo runs, threshold runs and VO2 max efforts.
But lots of runners tend to overlook one type of workout that can do wonders for your performance: critical velocity training. According to exercise physiologist and running coach Tom Schwartz, PhD, founder of Tinman Coaching who popularised the approach, critical velocity training is key to boosting your speed without beating up your body.
Here’s how to slot it into your training.
What is critical velocity training?
Critical velocity training raises your lactate threshold, which is 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 to feel easier, which allows you to not only run faster, but also hold those faster paces for longer.
As a general rule of thumb, lactate threshold is a pace that you can sustain for roughly 60 minutes. So, although it isn’t something that you can hold all day, it also isn’t 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 that he was already experimenting with – a metric that he first called critical value but would later refer to as ‘critical velocity’ when he started using it in coaching.
Critical velocity running feels a little harder than running at lactate threshold. If lactate threshold is the pace that you can maintain for one hour, critical velocity is one that most runners can sustain for 30 to 35 minutes, or a little longer or shorter depending on fitness levels and distance experience, says Schwartz. ‘Critical velocity is about 4-5% percent higher,’ he says.
In terms of effort, critical velocity 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 2000m 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 that you can maintain before your body starts to struggle due to the fatigue-related byproducts of exercise. Another way to think about it is this: critical velocity is the fastest you can run comfortably and in control without having to gasp for air.
The benefits of critical velocity workouts
Many beneficial physiological changes occur when you do critical velocity training. It recruits your fast-twitch muscle fibres, develops more energy-producing mitochondria and stimulates more capillaries that can help to bring nutrients and oxygen into your cells and take exercise byproducts out of them, says Schwartz.
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,’ says Schwartz, 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. However, the intensities tested in some studies overlap with what critical velocity looks like in practice, according to Schwartz.
A study published in Medicine & Science in Sports & Exercise, for example, looked at performance outcomes for four groups of runners performing different training protocols lasting eight weeks: long and slow (70% of maximum heart rate), lactate threshold running (85% of maximum heart rate), short and fast intervals of 15 seconds on, 15 seconds off (90-95% of maximum heart rate), and longer high-aerobic intervals of four minutes on, three minutes off (90-95% of max heart rate).
The interval groups improved their VO₂ max more than the long and slow and lactate threshold groups, while the longer-interval group – a protocol that closely mirrors the physiological responses seen in critical velocity training, per Schwartz – did so to the greatest extent.
Another study in the Journal of Science and Medicine in Sport found that runners who trained with hard-but-sustainable three-and-a-half-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, says Schwartz.
Critical velocity training seems to work your body in a highly effective ‘middle zone’, adds Schwartz: you’re going hard enough to help with oxygen delivery and utilisation, but it’s still controlled enough to allow you to put in your reps without burning out too quickly.
If you stick with slower work like lactate threshold, Schwartz says that you’ll still demand a lot of oxygen at a given pace. ‘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,’ he says.
All in all, Schwartz says that ‘critical velocity provides more return on investment’ compared to lactate threshold training. 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.’
Which race distances does critical velocity training benefit the most?
‘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,’ says Schwartz.
In fact, he’s seen runners have success with critical velocity training in race distances from 3000m 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 that you should consider adding to your training.
The workout that you need to try
The amount of total time that you spend running at critical velocity pace during your workouts depends on your fitness level, says Schwartz. Beginners may want to stick to 12 to 15 minutes, intermediate runners 18 to 21 minutes and advanced runners 21 to 24 minutes, or even up to 27 minutes or so.
Here’s what this could look like for an intermediate runner:
Warm-up
- Easy jogging for six to eight minutes
- 6 x 20-second strides, with 20-second recoveries in between
- Easy jogging for two minutes
Critical velocity work
- 6-7 x 3 minutes at critical velocity pace, with one-minute recoveries (slow jogging or fast walking) in between
Cooldown
- Easy jogging for 12 to 15 minutes
‘Think of critical velocity as your aerobic cruising speed,’ says Schwartz. ‘It’s comfortably hard, but not where you get to the point where it starts getting out of control and you’re gasping.’
When to do these workouts
The beauty of critical velocity workouts is that 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 advises runners to do a critical velocity workout nearly every week of the year, particularly when a race is 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.
Critical velocity workouts can check the ‘speed day’ box in your training plan. And if you’re worried this will make you miss out on other types of workouts, like hard, breathless efforts where you’re running at 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 ensure that you’re challenging your body in a variety of ways.
For example, Schwartz will often programme shorter sprint repeats after critical velocity work, like three to six reps of 30-second intervals with one-minute jogs in between. Alternatively, you can do a handful of 30-second hill repeats before your cooldown. This helps you to work on your speed and power, in addition to the aerobic efficiency component of critical velocity. ‘You check off all kinds of boxes,’ says Schwartz.
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