Noah Hoffman’s Pacing

I was interested (rather than offended) to read about Noah Hoffman’s pacing strategies in Sunday’s classic WC race. I have a limited supply of data on split times (what I do have is thanks to Jan over at worldofxc.com, though) so the following data is definitely incomplete.

Hoffman seemed determined to not start too fast, something that apparently he does quite often. Since pacing interval start races is so much different than mass start or pursuits, we’ll only look at his splits for interval start races. I only have split times from a total of eight WC-level interval start races for him (of varying lengths). Here’s a simple graph showing them all together, with Sunday’s race highlighted with the black dashed line:

This is a very crude representation of split times, where I’ve simply plotted how fast Hoffman skied each timed section compared to the field. So, for example, the y-axis means he had the 20th fastest, 40th fastest, etc. split time on that section.

In order to compare races of different length I’ve converted the x-axis from raw kilometers to a percentage of the total race distance. (This may be dubious, since pacing strategies will be markedly different in a 15k versus a 30k. However, these data consist of two 10k’s, five 15k’s and only one 30k, so I think we’re on fairly safe ground.)

Certainly Noah’s first split was slower than his subsequent splits on Sunday. And it was the 3rd slowest initial split of the eight I have. But it seems to me like he proceeded to ski the rest of the race fairly consistently, rather than gradually accelerating. At least, until he faded a bit on the last section.

This is in contrast to several of the other lines here that begin with fairly quick initial splits, but by mid-race he’s clocking only ~60th fastest time on each section or so. So whatever he did seemed to work.

I should say that I’m fairly cautious about my ability to analyze split times. I’m sure the coaches are keeping more detailed data on this sort of thing than I have access to. But it’s interesting, nonetheless.

Should You Start Fast Or Slow?

Pacing is a frequent topic of conversation in skiing, or really any endurance sport. Typically, the refrain is ‘don’t start to fast‘. In fact, I feel like I hardly ever hear people recommending that one should start a race harder. It must happen occasionally (and I’ll share a story about this later), but I suspect endurance athletes have a general bias towards worrying about going too hard early in a race rather than too easy.

If someone tells me that I shouldn’t start a race ‘too fast’, my first question is ‘Too fast compared to what?’ There are only two things skiers could compare themselves to: (1) the maximum speed that you, personally, could sustain during an entire race, and (2) the speed your competitors are travelling at.

Split times from races give you direct information about (2), which in turn gives us only indirect information about (1). Think for a moment about how runners can learn to tell how fast they’re going based on how they feel. Runners can run on a fixed course (e.g. track, fixed road or trail course) and glance at their watch every lap or every mile and get instant feedback on the connection between how they feel and how fast they’re running. Even with the aid of GPS devices, skiers don’t have a concrete, objective measure of speed to compare themselves to that’s independent of weather, snow conditions, wax, etc. They can’t look at their watch, see that they skied 1km in 2:47 and have that mean something to them. Obviously, skiers do develop a sense for pacing, and probably a pretty good one, too. It’s just harder and they have to do it mostly be feel.

Let’s think carefully about how we’d show with data that someone started ‘too hard’ in an interval start race. The first thing we’d look for is their split times slowing down during the later stages of the race, right? But how do we know for sure that this race tactic would be slower compared to the alternate universe in which the skier started at a slower pace? It’s possible that the time they lost late in the race is balanced out, or even outweighed, by the time they gained early in the race. Ultimately, it’s tough to know for sure without a time machine that let’s us go back and repeat the race using different tactics. Runners (particularly track runners) can experiment with these sorts of tactics with a fairly high level of precision, but skiers have to use whatever innate sense they develop over time.

Obviously, I’m not saying that it’s impossible to tell when you’ve started too hard. I’ve bonked in races myself, you know. My point is that while the extreme cases of poor pacing in either direction are easy to spot, there’s probably a large grey area that’s difficult to navigate with any certainty, at least in skiing.

Let’s get back to the old adage, ‘Don’t start too hard’. My point with this post is that this advice only makes sense compared to yourself (1) not your competitors (2). As I said above, how fast you’re going compared to everyone else is surely correlated with how fast you can go relative to own potential, but if you start too hard in a race against Petter Northug and bonk, it isn’t Northug that caused your body to shut down, it’s your own limitations.

In fact, we can easily flip this around and say that compared to everyone else, you can never start too fast. What do I mean by that? Well, one of the first things that has jumped out at me while digging through the split times from the past WC season is how closely correlated early splits are with final performance, particularly in interval start races: Read more

Men’s Sprint Heats Tend To Be More Tactical

I’ve mentioned this from time to time in other posts, but one thing I’ve noticed from the sprint heat times that Jan at WorldOfXC.com has been providing me is that the women’s heats are more likely to increase in speed as the day progresses. I’ve said it enough that I should probably provide some evidence:

In blue I’ve shown the median value (and error bars representing the interquartile range, or middle 50%) for each heat. As you can see, the men’s heats tend to remain roughly flat, or slightly slower as the day wears on. The women, on the other hand, see more of a trend toward faster times as we progress through the quarters, semis and finals.

There could be fitness or physiological reasons for this, or it might be related to how competitive each gender’s qualification round happens to be. For instance, it may be that qualifying in the women’s sprints is enough easier (by this I mean that there is a tendency for the men’s field to be somewhat deeper) which allows many of the women to back off somewhat in qualification.

But another possibility I’d like to suggest is that as the men move into the semis and finals, they are less willing to hammer right out of the gate in an attempt to break their competitors. Instead, they’ll tend to play more of a waiting game.