Podcast, Science, Training

The Great Debate: Intensity vs. Volume | EP#16

 April 26, 2017

By  Mikael Eriksson

The Great Debate: Intensity vs. Volume | EP#16

What's the relative importance of training intensity versus training volume?

The answer could be simply "it depends", but let's try to dig a little bit deeper and get at least some guidelines.

In this Episode you'll learn about:

  • What levels of triathletes should prioritise volume over intensity and vice versa?
  • How should you increase training volume?
  • What kind of intensity should you add to your program?
  • What does prioritising one over the other mean in practice - what does it look like in your training program?


01:14 -​

  • For beginner triathletes, the priority should be training frequency. In a sense, volume but not as workout duration, but as frequency. 
  • This might be increasing workouts from four times per week to six times per week.
  • This is because beginner triathletes have not necessarily built up the durability to withstand intensity and stay injury free when they embark on a training program.
  • Even though there are a lot of studies that show that the fitness benefits that can be gained from high intensity training are huge, there is a risk associated with that kind of training program. The same goes for higher training volume that consists of workouts of higher duration instead of more workouts in a week.
  • They may be shorter but the total volume increases when you increase the frequency. But again, let me reiterate that intensity can give huge fitness benefits for beginners - it is just that there is a risk to it.

02:59 -

  • When you train at a sub-maximal level, which is also called low intensity training, you get an increase in both utilization of oxygen by your working muscles as well as delivery of oxygen to the muscles. You also get central adaptations, for example you get a decrease in resting heart rate, increase in blood and plasma volume and greater cardiac output so your heart can beat with larger stroke volume. There is also increased capillary density which means more capillaries that will deliver oxygen to your muscles and mitochondrial volume. The mitochondrias are the part of your cells that produce energy. 
  • Although the actual work capacity has been shown in research to be increased in just a few days’ time when doing continuous low intensity training but before you see any physiological variables increase like VO2 max, it may take three to five weeks or so.

04:25 -

  • For intermediate triathletes, there is still a lot of improvements to be made by increasing volume but increasing the duration of workouts at this point will probably be more important than frequency.
  • You have a base level of fitness that is quite good and at this point the duration of workouts is what is going to challenge your muscular system and your physiology. Just adding more short workouts is not necessarily going to do that for you.
  • You can recover quickly enough, especially when you are a multi-sport athlete who has a couple of days between run, bike and swim. So this is why you should increase the volume by increasing the duration and not necessarily the frequency.
  • The relative importance of intensity also increases when you get to a higher level. Generally, it is taken that 10 weeks or so is the maximum time that you usually should be doing a high intensity training program and you would need short period to recover from and not do high intensity program at all. You need to make room for that recovery in between programs.
  • Intensity becomes more and more important but there is still much to be made from volume because you still haven’t reached your potential in how much you can get your cardiac output for example to increase or your mitochondrial size and so on.
  • There is a little bit of both intensity and volume, with volume being slightly more important simply because there are so many triathletes who are injury prone.
  • This is where real life comes into play as well because most age groupers are time constrained in the amount of training that they can do. So in all likelihood, you might not be able to do the training volume that is required for you to get any additional adaptations and fitness improvements from just increasing volume. So at this point, your only option is to basically to start doing more high quality intensity training.​

07:20 -

  • I was recently reading a very good research paper on High intensity interval training by Paul B. Laursen and David G. Jenkins from the University of Queensland in Brisbane, Australia.​ You can read the publication here.

08:00 -

  • High intensity training is the way to go if you have 10 weeks to work with and you need to be as fit as possible after 10 weeks. But you need to take a long term view as well at the same time, which is why you need to be a bit cautious with intensity even though research studies definitely would show that high intensity training would get you more fitness benefits.​

09:08 -

  • In the review by Laursen and Jenkins, there was mention of a study that compared different kinds of high intensity training programs and their effect on a 40k time trial on the bike, and peak power at an incremental bike test. They compared five different programs for high intensity training and two of them produced very good, similar improvements, and the others did not.
  • One of the programs that produced improvements was a commonly used program with aerobic type intervals that were 8 times four minutes at 85 % of peak power (from an incremental bike test) with 90 seconds recovery. This has been shown in many studies to improve endurance performance.
  • A comparable improvement in performance was seen from intermittent supramaximal training. That protocol was 12 times 30 seconds at 175% of peak power with four and a half minutes of recovery.


​These two programs resulted in similar performance improvements:

The first program was 8 times 4 minutes, 85% of peak power, 90 seconds recovery. 

The second program was 12 times 30 seconds at 175% of peak power, with four and a half minutes recovery.

So in the second program you have a five minute cycle with 30 seconds of very hard work. The first one was a five and a half minute cycle with four minutes of hard work.​

11:22 -

  • For advanced athletes, intensity is the most important variable. Going back to that review by Laursen and Jenkins, the conclusion stated that:
"It does not appear that additional sub-maximal endurance training volume improves endurance performance or related physiological variables in this particular population [highly trained endurance athletes]”.
  •  High intensity training in many forms can elicit significant improvements in endurance performance in already highly trained athletes.
  • Another example is something Joe Friel (who was on the show in Episode 1), wrote on his blog:
"How well such an athlete [advanced triathletes] performs on race day is determined 60% by the intensity of their recent training and 40% by their recent volume."

12:44 -

  • Sedentary individuals are generally defined as those that have a VO2max of less than 45 (millilitres O2 per minute per kilogram of bodyweight). Recreationally active individuals have a VO2 max of 45-55 millilitres per kilogram per minute. Intermediate athletes fall around 55-60 and beginners would be below 55. Highly trained athletes would have at least 60, maybe even 65+ as VO2 max, depending on how you define it.

13:24 -

  • If you are a highly trained athlete then you need to do high intensity training. It is important to remember, I am not saying that all of your training should be high intensity, but you really have to make that high intensity count. If you need to drop some training sessions, maybe a couple of easy training sessions, to really be able to perform in and hammer those intense workouts then that is what you should do, because the intense training is what is going to be the biggest determinant in your racing success, endurance improvement and physiological improvement. In other words, do as much volume as you can but don’t let that interfere with ability to really smash and hammer your high intensity workouts.​

Key takeaway

Do as much volume as you can but don’t let that interfere with ability to really smash and hammer your high intensity workouts.​

14:22 -

  • ​Many advanced triathletes focus way too much on training volume because it is easy to measure and brag about. Just because it is easy to measure does not mean that it is the right thing to measure.

Key takeaway

Do as much volume as you can but don’t let that interfere with ability to really smash and hammer your high intensity workouts.​

14:55 -

  • ​For the advanced athletes, the intensity that you do your high intensity workouts at does matter. It has been shown that actually since the slow component of VO2, the volume of oxygen utilization that your muscles use during exercise, is reduced once endurance increases. A sub-VO2max effort or intensity is less effective for highly trained athletes because you can’t reach VO2max by relying on the slow component the way intermediate athletes can. The idea here is that for some athletes if you go at an intensity that is slightly lower than your pace or power at your maximum aerobic capacity or your VO2max, then if you repeat that and your recoveries are reasonably short, let us say a 2 to 1, even a 1 to 1 work to recovery ratio, then after a few intervals your VO2 has a slow component that rises steadily and does not decrease to its baseline during the recovery. So you will reach that VO2max anyway and that way you can do more work at VO2 max. But when you get highly fit, that slow component gets reduced so going at a sub VO2max pace becomes less effective the more fit you get.

​17:09 -


  • If you are a beginner, you should focus mostly on increasing your volume by increasing the frequency of workouts. Do more workouts, they don’t need to be too long, just do a bit more than what you are doing now by increasing more workouts.
  • ​If you are an intermediate triathlete and you don’t train too much and you have time, you can add a couple of workouts but primarily you should increase the duration of your workouts.
  • For advanced triathletes, if you have a VO2 max of 65 or above, definitely you need to include about 10 to 20% of your training that is the kind of high intensity workouts that you really try to smash. The kind of intense training that is going to be the most beneficial for you are performed at an intensity level that corresponds to your VO2 max or your maximum aerobic capacity. Power at VO2 max can be 120% of your functional threshold power on the bike or something like intervals at your 5k pace or slightly faster than 5k pace, maybe 10 seconds per kilometer faster than 5k pace on the run.

Links and resources

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Mikael Eriksson

I am a full-time triathlon coach, founder of Scientific Triathlon, and host of the top-rated podcast That Triathlon Show. I am from Finland but live in Lisbon, Portugal.

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