Question: My boyfriend is doing a 300-hour regimen of slow riding (recommended by a coach) to build capillaries. The coach says if he rides harder during this period, he will prematurely destroy the budding capillaries. He rides three times a day — at dawn, lunch and dusk. Great for relationships! Is this a legitimate training technique? — Lynette C.
Coach Fred Matheny Replies: You pose a good question, Lynette. The theory that slow, high-volume training builds capillaries while fast training sets back the process is prevalent in some circles, especially among triathletes.
Also at issue is whether an increase in capillaries improves performance. The evidence is pretty firm that it does. The more capillaries you have, the higher your VO2 max and the greater your potential to perform well in endurance activities.
As for whether extensive slow training builds more capillaries, it’s difficult to get a direct answer. But it’s known that “capillarization” is proportional to VO2 max (the ability to consume and use oxygen during exercise).
The higher your oxygen uptake, the more capillaries you have. So it follows that workouts that increase VO2 max are the best workouts to increase capillaries. And guess what sort of workouts produce the biggest gains in VO2 max?
Not slow miles! Instead, the best results come from moderately long rides with relatively fast interval training included. The old adage that intense workouts are the best producer of fitness is still valid.
There’s nothing wrong with doing long, slow rides in the off-season. But they shouldn’t be your only mode of training. Mix in a smart amount of intensity, and you’ll be that much farther ahead come spring.