I ran my first marathon two springs ago, and – like many first-time marathoners – staggered through the last 10K or so. I wasn't bonking, and I didn't go out too fast. My problem, as I described in the brain training article I wrote about the experience, was muscle damage in my legs. After a couple hours of pounding, my quads were simply torn to pieces.
What could I have done differently? More mileage, and in particular more long mileage on hard surfaces (I did most of my training on the beautiful dirt trails of Canberra) might have helped. A less bouncy stride might also have helped (the anecdotal experience among my friends is that former middle-distance track runners, who tend to have springy strides, are at a high risk of struggling with muscle damage when they move up to the marathon). And The secret to achieving the elusive runners high European Journal of Applied Physiology, from researchers at Staffordshire and Chester universities in Britain, suggests another possible defense: the "repeated bout effect."
I've written about the repeated bout effect before. It's basically the idea that if you do a demanding workout that leaves you sore, you'll be less likely to get sore the next time you do the same workout, for reasons that aren't entirely clear but seem to involve factors both in the muscles and in the nervous system. What's particularly interesting about the repeated bout effect is that a relatively mild bout of exercise can give you subsequent protection against a much heavier bout; the new study explores this effect.
The researchers used a protocol that involved an initial workout designed to inflict muscle damage (a series of squats), followed by measurements of how sore the subjects were, as well as measurements of running stride, running economy, and a pair of 3000 meter time trials immediately after the squats and again 48 hours later. Then they did the same set of protocols again two weeks later to see how much protection they got.
The twist is that half of the 16 participants did a high volume of damaging exercise the first time (10 sets of 10 squats), while the other half did a lower volume (5 sets of 10 squats). Both groups did 10 sets of 10 during the second set of testing, two weeks later.
Here's how the measures of perceived soreness looked in the two groups (high-high and low-high). Not surprisingly, the high-volume group had more soreness than the low-volume group in the days after the first workout. But two weeks later, when the two groups did identical workouts, they both experienced equal protection from soreness. This has been shown many times before, but it's a really important message to bear in mind: you don't have to kill yourself to get the benefits of subsequent protection.
For runners, the interesting results are from the 3000-metre time trials, after the first workout, both groups suffered as soreness increased in the days after the exercise. And after the second workout, both groups were able to maintain their performance with no slowdown - running performance was protected even with a lighter workout.
So would this approach have saved my bacon during that marathon? There are a few key caveats. One is specificity: I'd probably be better off inducing soreness with a protocol that better mimics the demands of running a marathon, i.e. long runs at a relatively brisk pace. I did a couple of half marathons, but a 30K race (even if not all-out) might have been useful. Downhill running could also provide a shortcut to induce soreness more quickly and less exhaustingly.
The other caveat is that the study looks at the effects of delayed onset muscle soreness, two days after damaging exercise. In a marathon, I'm looking for protection against damage as it happens. I think there's reason to believe that some of the adaptations involved in the repeated bout effect would provide on-the-go protection, but that's just speculative at this point.
The bottom line for me is that if I do another marathon, I'll make sure to include some training that induces the kind of soreness I felt in those last 10K. I don't know how much it will protect me - but given how awful it felt, I'm willing to take some chances!
