There are many types of workouts you can include in your training to get faster: tempo runs, interval workouts, and hill repeats. Interval workouts are a broad term that can encompass many different types of workouts. When most runners think about intervals, they think about challenging reps at VO2max. While VO2max is not the sole predictor of running performance, there are benefits to including VO2max interval workouts in your training.
What is VO2max?
VO2max is a technical term that refers to how much oxygen you consume during a run. (This article explains more about VO2max and its relationship to running.) The higher your VO2max, the more oxygen you consume and deliver to your muscles, and the faster you run.
VO2max itself is not a pace. Instead, VO2max refers to the maximum amount of oxygen intake (measured in mL/kg/min) you can have during exercise. You may also hear it called “aerobic capacity.” For most runners, VO2max is an intensity you can only sustain for seven to 11 minutes.
Velocity at VO2max (vVO2max) is the pace that corresponds with your VO2max. vVO2max is sport-specific. You may have a high VO2max and a fast vVO2max in running, but if you are inefficient at swimming, your vVO2max in swimming is low.
VO2max can plateau even with training. However, repeated research (as summarized in articles such as this 2023 review in Sports Medicine) indicates that vVO2max can improve – and with that, bring improvements in performance.
We still do not fully understand how much vVO2max correlates with performance outcomes at various distances (half marathon, marathon, etc), as discussed in a 2020 review in the International Journal of Environmental Research and Public Health. However, most training theory supports the concept of training all physiological systems – including vVO2max. While it should not be the sole emphasis, we cannot ignore it in training.
How Can You Improve vVO2max?
Research demonstrates several effective approaches to improving vVO2max. Strength training can improve vVO2max. Most changes to running economy will improve vVO2max. One common and effective approach is VO2max interval workouts.
VO2max interval workouts are short intervals at or near your maximum oxygen uptake – or roughly at 10-15 minute race effort. For elite runners, that is 3K to 5K pace. For most recreational runners, VO2max is around mile to 3K pace. However, you do not have to be precisely at your exact VO2max pace to benefit. Approximately 95-105% of vVO2max will elicit the same physiological stimulus. So, recreational runners could pace these intervals at 5K effort and still benefit.
Training at VO2max triggers several training adaptations. As outlined in a 2023 study in International Journal of Environmental Research and Public Health, intervals at VO2max have both cardiovascular and neuromuscular benefits. Maximum cardiac output, plasma volume, heart mass, and stroke volume all increase. These central adaptations mean that your heart can send more oxygen-rich blood to working muscles. Peripheral adaptations include increased recruitment of motor units, increased capillary density, enhanced enzyme activity, and more mitochondrial activity in fast-twitch muscle fibers. Together, these changes help you produce more energy in the working muscles. Some neuromuscular changes to muscle fiber recruitment can also improve power output and fatigue resistance.
VO2max Interval Workout
When most runners think of VO2max intervals, they think of workouts done the track, such as 6 x 800m (½ mile or two laps around a standard track). However, you don’t need to hit the track in order to run fast. Time-based VO2max intervals on the road will still elicit the same adaptations.
Time-based VO2max interval workouts offer two benefits. First, the time-based interval removes the temptation to race the workout. You may feel tempted to run 800m as fast as you can to get it over with sooner. You can’t do that with a time-based interval.
Secondly, time-based VO2max interval workouts can be done in various locations. You can run them on a track, the roads, or even trails. Trail runners can even take these workouts onto hills.
Finally, time-based intervals ensure the workout triggers the appropriate physiological response. At this high intensity, distance-based workouts could actually elicit different physiological responses from different levels of runners. Sub-elite athletes may complete 1K repeats at in less than 4 minutes, while back-of-the-pack runners may take over 6 minutes to run 1K. The sub-elite runner is running an appropriately hard VO2max workout. Meanwhile the slower runner will be running a workout that risks overtraining or injury.
Research indicates that intervals lasting 2-4 minutes are optimal for improving your vVO2max. A 2022 review by top physiologists in Sports Medicine defines VO2max intervals as lasting 2-4 minutes in duration. Running at VO2max for less than 2 minutes and you may not fully reach your VO2max in the workout, while running at over 4-5 minutes makes it too strenuous to hold the appropriate pace.
You don’t want to skimp on the recovery intervals during VO2max interval workouts. Recovery intervals in VO2max interval workouts will last 50-100% of the interval duration (or roughly 2-3 minutes).
VO2Max Interval Workouts
As with any speed workout, you want to be running at least 15-20 miles per week before adding in speedwork. Be sure to include a sufficient warm up, including dynamic stretches.
The number of intervals you do will depend on your training volume and background. Beginner and/or low-volume runners may only do 10 minutes total of VO2max intervals. Intermediate runners might complete 12-16 minutes. High-volume and elite runners may do up to 15-20 minutes total across the intervals.
Beginner:
10 minute warm up at an easy, conversational effort
5 x 2 minutes hard, 2 minutes recovery jog or walk
5-10 minute cool down at easy pace
Intermediate/Experienced:
15-20 minute warm-up at easy run pace
3-4 x 4 minutes at 3K-5K race effort, 3 minutes recovery jog in between
15-20 minute cool down at easy run pace
For the hard intervals, you want to run about a 8-9 on a scale of 1-10 (1 being a light jog, 10 being an all-out sprint). The pace should feel like something you could sustain if racing a 3K to 5K race. Jog as lightly as you need to during the recovery intervals to bring your breathing back to normal.
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17 Responses
Ive been running by time a lot more lately- it seems less intimidating for some reason. These are great workouts that seem tough but manageable.
Running hard for 3-4 minutes is definitely less intimidating than running hard for 0.5 mile, even if they cover the same distance. And thank you!
I’m usually a run for distance type gal but I started doing run for time intervals and kind of liked it. Those workouts were on the road but on the track I like distance. It’s more measurable to me which feels like there’s an end in sight!
Running by time works so well on the roads, at least for shorter intervals. Plus with the track it’s measured out – no staring at the watch to countdown distance!
Great article, Laura. I have been running by time for years now, and at age 67 now do some of my interval workouts on my old Nordic Track ski machine to get great cardio while sparing these old legs the pounding.
Ah speed – so elusive and we work so very hard to get it! I love how you explain the right way to chase it here. I’m a big fan of time and not distance – my coach has taught me that. I’ve also become a master at HR zones so it’s like training in a whole different way and I love it!!
It is so much work – months and months just to save some seconds off of each mile! I’ve noticed that about your workout when you share them and think it’s awesome – and clearly it pays off for you!!
Good old VO2 Max. I prefer running economy and lactate threshold runs, but VO2 max is obviously important to developing better running economy. I just like the longer efforts of lactate threshold runs. I’m a curmudgeon, let me be 😀
I’m a curmudgeon too when it comes to my preference, but I know that VO2max stuff works. It’s not the only factor, but it is a factor!
Great tips! I almost always run for distance, rather than time, but I love the idea of focusing more on time and effort. I’m hoping to get some VO2 max workouts in the next few weeks… I did very few over the last month or two, but shorter intervals are my favorite!
I imagine you’ll do great at those workouts after such a fast half! I like the longer stuff over the shorter intervals but they really do pay off.
Dang, I miss these types of workouts! I should write up a post specifically about how to run speed work safely during pregnancy. It’s hard because there’s no black and white rule. They used to say nothing over 140 bpm for heart rate, but of course you know that everyone’s heart rate is different. Then they say that as long as you’re able to hold a conversation (that you’re not breathing too hard) then you’re okay. But, man, I think it boils down to knowing our own bodies. I know I’m going off on a pregnancy tangent here, I’m sorry! I just really miss those REALLY hard workouts. I mostly like doing intervals by distance, but once in a while I’ll do them by time, and only on the treadmill.
You should write a post about that! I bet there’s some research out there that supports running faster during pregnancy. The heart rate rule seems archaic and arbitrary.
I first started running by time when I trained with you! I got really into those types of workouts for a while even after the half marathon! then I fell off with doing them by time but I am sort of back to those workouts again. they are great!
I really like them because you can go with how you’re feeling that day – cover more or less distance in the time – and there’s not the pressure of a certain pace. Thank you!
I’ve never trained using vo2max. I’m interested to try it!
It’s definitely an effective form of speedwork!