Local ski knowledgeables might be surprised to know that 20 years ago (and give or take 3 or 4) I was a better at classic skiing than skating. Now it's the opposite and if this year's races are any indicator, the relative difference (compared to other ranked racers) is close to 8 or 10 percent.
I think it comes down to V02 max, heart rate, and muscle strength. Maybe skis.
V02 max, the amount of oxygen you can process at an all out effort (usually measured at 12 to 15 minutes) drops about 12% per decade in men. Based on 5K times, from the different eras (1989 to 2009) I've actually done pretty well: 67 down to 58, a drop of 13% in two decades. A decline for sure, but I'll take it.
I think the big drag is heart rate (HR), and the maximum I can handle. Back in the day, I didn't use a HR monitor (and just picked one up last year), but I could find a long (400 to 800 m) fairly steep (6 to 10%) climb and hammer intervals, where I could get that HR over 200, hold it for several minutes, and repeat four or five times. On race days I can remember just digging in and grinding up big hills.
Now as a M5 (50-54) age grouper, that is simply impossible. What I'm best at anymore is getting into the high 150s and low 160s and holding for a long time. Relatively speaking I'm now a much better ski marathoner, but 5K and 10K type distances are torture. I can hold a HR of 170s for a few minutes before going under, and if I push into the 180s for more than 30 seconds at time (or low 190s as in the 5K night race last week), boom it's over. I shut down and rig up.
Which brings us to muscle strength. Upper body wise, I'm as strong as I've been, and have been consistent with weight training for the first time ever for more than a year now. However, back in the early 1990s my strength to weight ratio was no doubt better. Now I'm heavier--about 12 to 15 pounds so, some of it muscle, some not. Back then I had 5% body fat, now probably 10%. So now I can power up a hill skating (using my upper body) while keeping my percent V02 max at a reasonable effort. But with classic striding, which has higher oxygen demands, it's easy to go into overload and tilt!
I need to change race strategy to accomodate these limitations and excesses. Working on it.
Now about skis. In 1987, when classic skiing was hanging on by an FIS induced thread, I picked up a pair of brand new Fischer RCS (Air Carbon Klister) skis, 210 cm, soft klister flex for $50 in Boulder. Yes $50. Those were fast skis and they carried me well for 10 years. Ever since then I haven't found quite the right fit, and I've gone through 5 pairs since 2004. My newest pair (Atomic World Cups, 201 cm medium flex) seem promising, but I had to stone grind the bases already because the factory p-tex was uneven.
January Jaunt on Saturday. Won that in a freakish sprint over the last km at -20 F in 2006. Not looking for a repeat, but if it's -10 or warmer I'll give it a go and hopefully vie for an age group W. Helps that Edic is in Hawaii but there will be other challengers.