Question: In three weeks I will ride my first 300K (186-mile) brevet. A friend told me that the rule for pacing long rides is: Never go anaerobic. Sounds like smart advice, but how can I tell when I’m in danger of doing it? – Bud S.
Coach Fred Matheny Replies: You’re talking about the “anaerobic threshold,” a phrase used for many years. Nowadays, the more common term is lactate threshold (LT).
To simplify the physiology, as you increase intensity, your body produces lactate. At relatively low workloads, the lactate is cleared readily. But at higher intensities, it builds up and you slow down rather dramatically.
The term “lactate threshold” refers to the intensity at which your body can no longer clear the lactate accumulation. Fit cyclists can sustain a threshold heart rate (about 90% of their maximum) for an hour. On longer rides, like your 300K, you’ll need to reduce your average heart rate considerably below that figure to last the distance.
You don’t need a heart monitor to do it. The trick is to ride at a pace that keeps your breathing regular. When breathing becomes forced it’s a sure sign you’re asking your system to clear a lot of excess lactate. Doing so uses muscle fuel and almost certainly means you’ll ride slower later in the event.
The trick is to keep your enthusiasm under control, especially on climbs or in pacelines where you might be forced to ride too hard.
That said, you can gain quite a bit of time on hills if you carefully elevate the pace to just below your LT and recover on the descents. But in a long event, you need to be extremely careful with this strategy because a foray or two over LT can cost you dearly.
Bottom line: If you’re breathing hard during a long ride, you’re probably in trouble – unless you’re so fit that extended efforts near your LT are possible. But riding that hard usually exacts a high price later in the event.
The only way to learn your maximum safe pace is to get experience in longer events. This is one of the educational benefits of a brevet series. With progressive distances of 200, 300, 400 and 600K, riders learn plenty about pacing and endurance.
Lots of us know what it’s like to push too hard early in a century or double century, then pay the price. But that’s actually an effective way to learn for sure where the limit is.
Fred, wouldn’t you also recommend a pace slow enough that the rider is primarily burning fat, rather than glucose? Standard wisdom (correct me if I’m wrong) is that none of us has enough glucose stores to last more than, oh, two hours. So for most of the ride, you need to burn fat. Since “fat burns in the flame of glucose,” and you need to burn some glucose throughout the ride, you don’t want to exhaust your glucose stores. Also, a rider who has gotten fit via hour-long training rides hasn’t trained his/her body to burn fat. I’d suggest that Bud S. ride a few really long training rides, certainly well over 100k and if possible 200k,, to introduce his body to heavy-duty fat burning. That will also give Bud first-hand experience of how his body feels at the end of such a ride, and that experience will inform his early-ride pace.