Minimum effective dose
13 days to 100 miles
If X achieves the desired result, with no added benefit from doing more than X, then the most efficient option is to stick to the minimum effective dose. There may even be a tipping point where doing more than necessary becomes harmful.
In medicine, it makes a lot of sense and is fairly easy to measure: gradually increase the dosage of a drug until the problem goes away. What about running, though?
A few days ago I read an article by Cliff Pittman about minimum effective dose in the context of heat training.1 Runners training for events in hot weather have long incorporated methods such as running on a treadmill in a heated room, to prompt the adaptations that can make it easier to run well in the heat. These adaptations include plasma volume expansion, reduced core temperature at rest, earlier onset of sweating, and other measurable variables. Pittman cites research that demonstrates all it takes to achieve these desired adaptations is six days of taking a hot bath after your run. That is all you need.
(I’ve not been adding hot baths after my runs during the heatwave this week, as that would be horrible, but it will be a feature of the next two weeks, to prepare for running 100 miles in mid-June)
No doubt elite runners such as Tom Evans, who has trained in a heat chamber at Loughborough University before hot ultras, take a confidence boost from knowing they’ve done a really hard thing. That might give them a mental edge, but it’s not physiologically necessary. A few baths would have sufficed.
When it comes to determining the minimum effective dose of training to attain the required fitness to achieve a running goal, it’s impossible to define a one-size-fits-all approach. There will be a point beyond which adding more miles, or increasing the number of reps leads to diminishing returns, but identifying that point, for each runner and each race goal, is tricky.
Everybody responds to training stimulus differently and has their own personal history of sport participation, fitness, physiology, and lifestyle factors that may influence what works.
Prescribing a minimum effective dose of training for an endurance athlete, when there are so many complex inter-related physiological processes to consider, is always going to require some guesswork.
Yes, there are common principles (run a lot, mostly slow, sometimes fast), but the precise composition varies from runner to runner and season to season. Personally, I’ve frequently run almost identical race-times off very different training plans. My four best 5K times are within 10 seconds of each other, run over a seven year period, implying there’s more than one way to reach one’s own peak.
When this unknowability is combined with research that shows a clear correlation between more mileage and lower race times, the approach for many runners becomes “train as much as you can before something breaks.” Before a big race, it’s reassuring to be able to think “I’ve done all I could” beyond the bare minimum.
I’m OK with this during the majority of a training cycle, because I like running. The more running, the better. But then you get to the taper and things change.
All that training takes time to recover from if one is to feel fresh on the start line. The amount of time needed is hard to pin down. Are we talking about muscle soreness, glycogen stores, hormones, or neurological adaptations? Because they are all very different and recovery could vary from a few hours to a number of weeks.
I think there is a lot to be said for the wisdom of what feels right. Typically, for me, two to three weeks is enough to morph from an achey, tired training state to race-ready.
This taper period is where I’m at now. As much as I appreciate the extra rest and the feeling of freshness returning, there’s often a worm of doubt in my brain that questions whether I’ve done enough and pushes me to squeeze in a little extra.
That’s not helpful. There is no time left to add fitness, but plenty of time to mess it all up with an injury or illness. The taper is the period for the minimum effective dose. I just have to hold my nerve, resist the temptation for one more long run, and do no more than I need to.
This is volume one, issue thirty-four of ¡Venga!, a running journal by Jonathan S. Bean.
Volume one: ‘326 days to 100 miles,’ documents Jonathan’s preparation for, and participation in the South Downs Way 100 mile race on 13 June 2026. The journal is published on Substack and as a paper newsletter sent by post.
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Read on for another couple of posts about training principles…
Soffrito: the training plan base
There is a danger this could prove to be the least interesting issue of ¡Venga! Certainly, it may be the one of least interest to a wider audience, because it’s going to focus on a very specific question: how will I use the time between now and June next year to train to run the
https://ultrarunning.com/featured/heat-training-optimization-not-maximization/