How do ultrarunners (or any athletes who go through vigorous training) know when/how much to rest?
As in politics, sports, and life in general, athletic training/racing has all kinds of rhetoric that gets wrapped up in the mix. An example of this is the notion that our bodies will tell us when we need rest. This is a bit of rhetoric that I have been trying to prescribe to for most of my days as a runner. It seems like such a simple thing. So much so that I've never actually thought much about it, and I'm certain that I've even told others that this is how I know when to rest. The problem is that in the case of ultrarunning this couldn't be further from the truth.
In this manner it reminds me of the idea in baseball that a runner should never dive into first base because not only is it potentially dangerous, but also that you actually get there faster by running through the base rather than diving for it (something about losing forward motion by coiling up for the dive? Even though with every stride we basically coil up as we bend at the knee and ankle). For most of my childhood (in which I always played baseball) I simply accepted this as the truth because every coach and all announcers on TV would always point this "fact" out. It never occurred to me that it could be any other way until one random day as a young adult when my brother and I were watching a game where a player dove into first base and the announcer went off with the typical bottled rhetoric about the stupidity of doing such a thing. This time something went off in our minds though and for some reason we just didn't really trust the rhetoric anymore. We talked about the reality that probably none of these coaches or announcers who always said this had ever actually done any research to back up these claims, and that in all likelihood this notion came about decades ago and was simply passed on as "fact" without anyone really even thinking much about it, let alone testing it. A few minutes later we were out in the yard with a stop watch, a tape measure, and an old glove for a base. We measured off 90 feet and my brother ran while I timed. I don't remember the exact times but what I do remember is that after about a half dozen tests both ways his fastest time without diving was slower than his slowest time with diving for the base. In other words everything that we'd ever been told about this notion was wrong, and to this day I still get annoyed when I hear an announcer on a game mention this "fact" about it being stupid to dive into first base.
Anyway, back to running. The most obvious problem with this notion about our bodies telling us when they need rest is that our bodies don't "speak" such a clear language. When I'm in the midst of serious training (100+ miles per week) I often feel like my body is telling me that it wants rest everyday. How do I know though if it really needs rest or if it's just telling me that it's going to need to have a nice long warmup before it's really ready to go strong? The question is how do we tell when our bodies really need rest and aren't just telling us that they want the rest? For the most part this only applies to those seeking to get the highest level of performance out of their bodies, not so much to those running simply for recreation/general fitness. In other words, the reason we have this dilemma is that we're not training with the intention of our body feeling as strong as possible throughout our training but rather with the intention of our bodies being as strong as possible for a specific event at some point in the future. Thus there are days that you simply have to go out and struggle through fatigue that has accumulated from previous days. You're not always going to want to run every day, but on almost all of these days you will need to or you'll never get as fast as you otherwise could have.
At some point we do benefit from days off, but I really don't think that our bodies are as precise at telling us this as we give them credit for. Rather we have to have a mind that takes over and forces us to grind out a couple hours of running when our bodies are saying that they just want to sit on the couch and sip coffee.
None of this answers the question of how we know when we really do need a day off though. For me I don't feel like there is any specific answer. I think it's something that we have to slowly learn over time. Certainly if my body is saying rest for several days in a row then I know something is up that I should probably be listening to, but otherwise I tend to just get out and grind out some mileage, knowing that my body will almost always feel better after my run than it did before it. When I'm really in good shape I pretty much don't take days off, but that doesn't mean that there aren't plenty of days (typically about one in every 7-10 days) when my body is telling me to. Usually with an active recovery day or two though my body feels great again and over the long haul I think this is more beneficial than a day off would have been.
I'd be interested to hear the opinion of other competitive endurance athletes on this idea... Obviously different people subscribe to (and likely need) very different ideas about training techniques, including rest. How do you all feel about the importance of days off vs. active recovery days?