This work is in progress. I realised I was just keeping it as such forever as my will to continue it comes and goes. I decided to just put it on the internet, though without being readily linked. If you get to this page, beware.

Critical velocity (CV for short) in running is defined by Tom ‘Tinman’ Schwartz (Citation needed. He does seem to have popularised it at least). It is a pace you can race for 30 minutes. Tinman calls it “somewhat hard”. Comparing it to some Jack Daniels paces, it would be faster than Threshold (hour race pace), but slower than Intervals (~VO2max, 11ish minutes race pace). See it as yet another pace you can decide to train at. Tinman says it is helpful from 800m to definitely 10 km, though he suspects it helps all the way to the marathon.

What Does It Improve

Improves aerobic capacity of Type IIA muscle fibers. These fibers can be specialised to be more aerobic or more anaerobic, depending on what training you throw at them. CV makes them “consumers of oxygen and producers of power”. Helps with sustaining pace for 800m and more races. Tinman argues it helps all the way up to marathons.

The muscle improvements lead to the following two noticeable effects. First, it elevates the average cruising speed during races. This means you can stay cruising for a longer time without increasing fatigue. Second, it improves your kick. Specifically, it improves from how far from the finish line you can start your kick, i.e., the length you can sustain the kick.

Finding Your CV Pace

You could go out for a fully rested 30 minute race effort, but that is probably harder to plan in. You likely have somewhat of an idea of the range to go for, but if you want more precise numbers, Tinman provides an online calculator. Just enter any recent or representative race time. Others12 have suggested doing a 3 minute all out run. That is, after a sufficient warmup, you start running all out from the start. You just keep going as hard as you can for 3 minutes. Your pace will flatten out somewhat eventually. The pace in the last 30 seconds is your critical velocity. This last method is useful if you do not have race efforts to go by.

You could also try by feel, of course, though that may prove much trickier. As mentioned in the intro, Tinman describes CV pace as ‘somewhat hard’. I have also heard it described as being right between comfortably hard (a description often attributed to the 1 hour race pace, T pace in Daniels speak) and on the edge. In that context a VO2max workout (I pace, ~11 minute race pace) feels like “a little to a lot under the edge”.3

How to Train at CV Pace

The eventual goal seems to be repetitions of around 2 to 5 minutes with recovery lasting about one third of the repetition’s duration. The maximum total duration at CV pace would be around 25 minutes (as mentioned in a video of tinman). From what I have heard, us average runners may be happier at 20 minutes maximum. Another more precise number I have heard, but one for which I did not look for a proper source, is dividing 420 by your 5 km time in minutes. This gives you maximum time at CV, also in minutes.

Getting to this eventual point may take you several sessions though. Start out with longer recoveries or shorter repetitions. Post workout recovery is about 2-3 days. Add a few extra recovery days in case a race follows.

You can do CV workouts year round. There is no specific CV phase in your build-up. Limit yourself to one a week or one every other week.

An Example

As an example, planning and analysing my first CV session went as follows. To make up a workout, I just picked a duration on the lower end of the 2 to 5 minutes range, considered my CV pace, and picked a distance that fit with things. In my case, Tinman’s calculator put my 800m time in a CV training at the 2:5x neighbourhood. Under 3 minutes seems like a safe place to start. Finding a distance to aim at will make it easier to do this correctly on a track. I like the precision versus GPS. I started with just 4 reps, and used a recovery of ~1:30 rather than the ~1:00 you would expect in the ideal situation (i.e., a third of just shy of 3 minutes). In my case, this workout felt a bit too easy, though of course a first workout is to get used to things. Your mileage may vary.

How to improve from here to the theoretical maximum is pretty obvious, there are not a whole lot of variables to play with. Either increase the repetitions, increase the repetition duration, or decrease the rest. In all three cases, you evidently do not want to cross the maxima mentioned above (maximum 25 minutes total, maximum 5 minutes per rep, minimum a third of duration recovery). I will likely bump my next CV workout up to 6×800 next time with a little shorter rest.

As always, if it takes you too long to recover in the days following a workout, then you probably overdid it.

More

TODO: I had some sources dumped into my onedrive. Ensure their information is incorporated.

  • Letsrun has (at least) two articles about/with Tinman and CV. Though I believe they were the more boring muscle talk.
  • There are some scientific papers

Further Reading

I did not come up with anything in this blog post, I am combining information from various other sources. Give them a read to ensure I correctly distilled information.

  1. Pettitt, Robert W., “Applying the Critical Speed Concept to Racing Strategy and Interval Training Prescription”, in International Journal of Sports Physiology and Performance, 2016. DOI: 10.1123/ijspp.2016-0001 ↩

  2. Science of Ultra podcast, episode 68: Avoiding the Mediocrity of the Middle ↩

  3. As described by user run_INXS on ARTC Slack’s #training channel ↩