Sorry, this one’s totally true. You can ride 5,000 miles a year, but if you only go one easy speed, you’ll get fitter, but you won’t get much faster. You need those easy base miles, yes. But cycling ultimately rewards suffering. Hard efforts that make your legs burn and insides ache raise your lactate threshold—the point at which your body creates more lactate than it can use and you’re forced to slow down. A higher threshold means that you can cruise longer at a faster pace before slamming into your ceiling. Cyclists also prize suffering; as the rider who is willing to suffer the most is often the one who stands on the top of the box in the end.
Equally important, a little pain lets your brain know you can handle hard efforts, so when it comes time to race, you’re more likely to start and finish fast. “The brain paces you based on past experience,” says South African exercise researcher Dr. Timothy Noakes. “It wants to protect you. So if you’re going harder than it’s used to, it’ll shut you down before you want or before you even have to. Training hard lets it know you’re safe.”
Get comfortable in the pain cave with LT intervals like under-overs. After a good warm up, increase to a steady, tempo pace for five minutes. Accelerate to VO2 (about 90 percent max) for a minute. Take it back to tempo for five minutes. Continue back and forth for 20 to 30 minutes.