While I think that VDOT is perhaps the best thing you can do to improve your running, when combined with a training plan that takes advantage of it of course, we occasionally get the question about whether VDOT can be used by walkers. Part of this comes, I think, from the fact that the calculator I wrote which we use on Team Z allows for a number of different test distances, down to 1 mile. In general I recommend that people do the 5k whenever possible for test distances. If it wasn’t cruel and likely to be ultimately unsuccessful in getting people to do it, I’d actually recommend 10k distances for VDOT tests because that comes closer to true 1-hour pace for most people. Either way however, the existence of the 1 mile option isn’t really there for people who are not running, but for people who are.
VDOT was never designed with walkers in mind, as such at the lower end of the spectrum the paces become less likely to have meaningful effect if you tried to implement them in training. For example, someone who has a VDOT of 40 has an LRP of 10:01-10:26 and a TP of 08:08-08:12. Someone who walks at approximately 18:00 and has a VDOT of 14 has an LRP of 20:53-21:34 and a TP of 17:43-17:48. For the runner, there’s a substantial difference in the amount of effort required to maintain TP compared to LRP, and running at TP elicits certain muscular changes which help someone to get faster. For the walker however, I don’t believe that differentiating the walking paces helps; in fact rather than having someone walk 3-4 minutes slower than they’re capable of, is I believe actually counter-productive to a goal of making that person faster. I think if someone can walk a 5k in 55 minutes they’d be better off in their training by attempting to hold that same pace in all of their walks, than by intentionally slowing down. The physiological impact on runners of the different paces is substantially greater, which is the entire point of using VDOT to identify the paces associated with the areas one is attempting to alter. For walkers there is simply no, or very minor, physiological differentiation which occurs between the different paces.
In a sense this is why you’ll notice that many people who implement Jack Daniel’s VDOT paces usually have a cut-off value for the ‘floor’ of the VDOT. For many calculators, they won’t show VDOT values, and associated training paces, for anything below 30 or 20; which correlate to an extent with where running and walking paces intersect. I chose not to do this with my implementation of the calculator, but by leaving it open to any value you can see how the approach loses applicability at the slower end of the spectrum (i.e. sub-20 VDOT.)
The important thing in training is to get out and do everything you can and should be doing that day. If you’re at the point where you’re not able to run, then in my opinion you should walk the best you can for as long as you can. Rather than trying to figure out a way to make VDOT work for walking, I’d love to see folks walk their way to running and then get a VDOT value that they can use as new (or returned) runners for training, and I think the way to do that as a walker is to push your walking at every workout.