“How to improve VO2max?” Not a week goes by without one of my athletes asking this question. For good reason. Maximal aerobic capacity contributes 70 – 80 percent to any personal record performance in distance running events.
“If you want to race fast from the 5K to the marathon, you need a high VO2max.”
While a high VO2max alone is no stand-in for race performance, a low VO2max makes for slow running with certainty. Fortunately, you can improve your VO2max with intelligent training in a matter of weeks.
What is VO2max?
VO2max stands for the maximal amount of oxygen your body can use in 1 minute. In other words, it’s the rate of oxygen supply to your working muscles. The faster you can supply it, the more fuel can be burned to propel you forward. Making energy available fast in a sustainable way is the primary limiting factor of distance running. And that’s your aerobic capacity.
If you own an advanced running watch such as a Garmin Forerunner, you will have a rough idea about your VO2max. A precise measure necessitates a laboratory as a running watch can only compare your pace with your heart rate but is blind to your running economy. That may be a problem comparing the VO2max values of two different runners with wildly different running economies. But for you, as an individual, any increase in VO2max translates into a faster running performance.
Still, a perhaps better metric is vVO2max (velocity at VO2max). Here, your running economy is included in the equation. It is defined as the slowest pace at which you reach your maximal aerobic capacity. That’s approximately your 2000m – 3000m race pace, or a pace you could hold for about 6 to 11 minutes. Anything faster requires an additional contribution from the anaerobic energy system.
Yet your aerobic system contributes 90 percent of the energy in a 5K race, and nearly 100 percent in a marathon. Consequently, you don’t need to train your anaerobic energy system for the classic road races. Training paces exceeding VO2max (2000m – 3000m race pace) are purely for the sake of neuromuscular power, running economy, and lactate tolerance. Only 400m sprinters and middle-distance runners (800m, 1500m, the mile) require dedicated training for the anaerobic energy system.
Components of VO2max
So what does affect VO2max?
Scientifically speaking, the components impacting aerobic capacity are oxygen intake, oxygen transport, and oxygen utilization. Oxygen intake—the air intake into your lungs and its diffusion to capillaries—is not considered a limiting factor, unless you’re a hardcore smoker. Oxygen utilization—the oxygen uptake by the muscles—isn’t considered a major limiting factor either.
That leaves us with oxygen transport, which makes up the lion’s share of VO2max. Oxygen transport includes cardiac output (HRmax and stroke volume), blood adaptations (red blood cell count, hemoglobin concentration, blood plasma volume), and capillary density.
That means you have to select workouts that train the aforementioned parameters. Your maximal heart rate is largely genetic. But you can improve stroke volume, blood adaptations, and capillary density to a high degree with intervals at 3K and 5K pace.
This is not to say other workout modes don’t impact VO2max. A large volume of easy mileage itself is a potent enhancer of aerobic capacity. So are tempo runs. But intervals at or near VO2max pace are particularly effective at improving your cardiorespiratory fitness.
Pre-Conditioning for VO2max Training
It is tempting to head straight to the track and run 5x 1000m repeats at 5K pace. That is an effective VO2max workout after all and would result in a higher VO2max value on your Garmin watch. But while you would have some success with it, you would still fall far off your potential. If you want to maximize your VO2max interval training, you will first have to establish a solid foundation of mileage and neuromuscular power.
Mileage enables you to last through all intervals without tiring. A typical interval session for an intermediate/advanced runner is sandwiched by at least 2 miles of warm-up and cool-down on each end. Add the intervals themselves to it with recovery jogs in between and you’ll quickly accumulate 8 miles. If that mileage is a struggle for you as an easy run, then you can’t expect your best performance during an interval session where the intensity digs much deeper into your glycogen stores. Not to mention the higher mechanical impact on your tissues.
Equally important, you need the necessary strength and speed so that the typical VO2max training intensities of 3K and 5K race pace are a breeze for you. That means before you even think about VO2max training you will have to become comfortable at a 1500m pace. Better even, start out with hill sprints during the base period and then add a few surges at 1500m pace in the form of Fartlek runs. Though, there’s rarely a need for a dedicated track session running repeats at 1500m pace.
Once you have developed a foundation of endurance and speed, you are ready for VO2max intervals. At that point, discontinue Fartleks with speed surges but continue hill sprints once a week after an easy run.
How to Improve VO2max with Effective Workouts
The effective range of VO2max intervals falls between 2 and 6 minutes. Anything shorter than 2 minutes won’t be enough time to raise your heart rate to desired levels unless the jog recoveries in follow-up intervals are very short. Intervals longer than 6 minutes won’t be intense enough to elicit the desired adaptations. The argument for the shorter intervals at 3K race pace is the ability to hold 100 percent of VO2max. Longer intervals at 10K race pace are run at 90 percent of VO2max, which is still an effective intensity to raise maximal aerobic capacity. The advantage here is more training time spent near VO2max.
I recommend taking advantage of the full range of VO2max workouts. Here are 3 examples of classic VO2max workouts of different intensities and duration:
Warm-up: Precede each workout with 1 – 2 miles of easy running followed by dynamic stretches, drills, and a few accelerations.
Short intervals: 6x 600m at 3K pace with 2:00 – 2:30 min jog recoveries
Medium intervals: 5x 1000m at 5K pace with 3:00 min jog recoveries
Long intervals: 4x 1600m at 10K pace with 3:00 min jog recoveries
Cool-down: End each workout with at least 1 mile of easy running to return your body to homeostasis, followed by static stretching.
As you may have noticed the work-to-rest ratio is skewed toward shorter rest periods for longer intervals in comparison to the interval duration. That’s because 3K race pace is about 30sec/mile (20sec/km) faster than 10K pace and requires more recovery between intervals. But consider the aforementioned examples as rough guidelines. Intervals can be manipulated by frequency, intensity, duration, and recovery time.
VO2max Training for the 5K and 10K
VO2max training is crucial for fast 5K and 10K times as both distances are raced near-maximal aerobic capacity, at 95 and 90 percent of VO2max, respectively. Although the lactate threshold is also a variable for 5K and 10K events, lactate tolerance is a more important factor. And that, too, you can improve with fast intervals exceeding lactate threshold pace. Since VO2max training pace is also race-specific for these shorter races, performing 2 such workouts a week is not unusual. Except for the base period at the beginning of a training plan.
For both the 5K and 10K the lines blur between what constitutes VO2max training and race-specific training. The latter is characterized by increasingly longer intervals and/or reduced recovery jogs. Hence, a 5x 1000m at 5K pace with 3:00 min recoveries could become a 4x 1200m with 90-sec recoveries. For the 10K, 4x 1600m at 10K pace with 3:00 min recoveries could become 3x 2000m at 10K pace with 2:00 min recoveries.
What’s important here is that you progress your VO2max workouts carefully as I mentioned before. You will run only your best 5K race-specific intervals if you excel at 3K pace intervals. Likewise, you will perform only at your best in 10K race-specific intervals if you have mastered intervals at 5K pace. For best results, you should even include hill sprints and surges at 1500m pace in Fartlek runs early in your training plan.
VO2max Training for the HM and Marathon
A high VO2max is also important for longer events. But while shorter events are centered around maximal aerobic capacity, training for the half-marathon and marathon leans equally on tempo runs and longer long runs.
In addition—contrary to 5K and 10K training—VO2max workouts in the final stages of HM and marathon training can be detrimental. For one it’s not race-specific for longer events. You need to emphasize lactate threshold training (at around 15K pace for most intermediate/advanced runners) and longer segments at HM/marathon race pace. The other reason is that intensities at VO2max teach your body to rely heavily on glycogen as a fuel source, instead of training the fat metabolism.
You can circumvent this by emphasizing VO2max training in the middle of an HM/marathon training cycle and discontinuing it about 4 weeks from race day. But even then you will need only a single VO2max workout per week. Finally, you don’t need to mess around much with training intensities faster than 5K pace for longer events.
Having said all that, don’t conclude VO2max training for the half-marathon or marathon is insignificant. VO2max workouts in the right amounts and at the right time may be exactly what you need in your training plan for a big personal record at your next race.