"Winter miles, summer smiles."
If going slow might makes you strong, shouldn’t going fast make you that much stronger? Wouldn't hard intervals in November, give me a leg up in summer? Allow me to try to convince you otherwise, and help you get fast the slowest way possible.
Let’s start by looking at VO2max. It’s a measure of the body’s ability to take up and use oxygen—an important measure in an aerobic sport like cycling. VO2max is actually a bad predictor of performance, but it’s a great tool for looking at training.
For decades, scientists have researched which factors are most important in determining VO2max, and it’s still a hot debate whether “central” or “peripheral” factors are most important. Central conditioning refers to the heart’s ability to deliver blood to working muscles. Peripheral conditioning, on the other hand, builds the muscle cells’ ability to take up and use that oxygen.
Central conditioning
The concept of central conditioning accounts for up to 80 percent of the improvements in a trained cyclist. It’s what we’re focused on in the base season. Two things affect your heart’s ability to deliver blood: how fast it can beat and how much blood it can pump per beat (called stroke volume.)
Sadly, our max heart rate is genetically set and it only gets lower with age. We can’t train it. Stroke volume, on the other hand, can be trained. When we talk about improving central conditioning, we’re talking about stroke volume.
Thus, the question becomes, how do you train stroke volume? To train a system you must hit it hard. Fortunately, stroke volume has a low ceiling—it peaks at about 60-65 percent of your max heart rate. In other words, if you’re killing yourself at 190 beats per minute (bpm) up a climb, your maximum stroke volume topped out at 123bpm. Going harder may feel good, but it doesn’t add any gains to your central conditioning.
Training stroke volume increases the size of the heart’s left ventricle. Because it’s a structural change, it takes time to come about. Therefore, the key isn’t about going hard, but about doing this training often and for a significant length of time. It takes months to see gains in a single season and up to 10 years to reach your personal potential.
Peripheral conditioning happens fast
Your working muscles’ ability to use oxygen is affected by two things. The first is the capillary density of your muscles. This structural change is trained like stroke volume; from a training perspective, think of it as part of central conditioning.
The other is the mitochondrial density of your cells. As the powerhouses of your cells, mitochondria use oxygen to produce energy. For cyclists, mitochondria are a powerful component of our physiological engine. To improve your peripheral conditioning, you must go hard. However, unlike central conditioning that takes years to develop, it takes only six weeks to fully develop mitochondrial density.
Sounds great, right? You might be thinking: Why not do it as soon as possible? Well, unless you just bought your first bike, most of your peripheral improvements are in your fast-twitch fibers. Forcing them to work aerobically is what allows you to set personal bests on that 10-minute climb. But it also makes your fast-twitch fibers cranky. They don’t like working aerobically.
It takes just one week of detraining for fast-twitch muscle fibers to lose 50 percent of their mitochondrial density. Once you start building your peripheral fitness, you have to keep working it, or you lose it. (Which would mean doing several high intensity rides per week.)
The catch is that fast-twitch fibers won’t remain aerobic indefinitely. Eventually, you will be forced to let them detrain; often this takes the form of burnout. Building your peripheral conditioning in November is a great way to be the fastest rider in the February group ride—and be cooked by April.
How to go slow to be fast
The 80/20 principle
Following the well-established polarized training model, 80 percent of your gains come about through central conditioning. As any good businessperson would tell you, you’d be wise to spend most of your time focused on what produces 80 percent of your gains. Training your peripheral systems by going hard in November detracts from the critical central work; additionally, you’ll lose all of those gains if you don’t keep up that intense, stressful training.
Lots of long slow rides
Central conditioning comprises long slow distance (LSD) riding. For even new riders, three or more hours are needed for an effective ride. Training at about 65-70 percent of your max heart rate is a good target. However, for the most elite riders, stroke volume continues to increase up to higher intensities. Sorry pro riders, but your base work needs to remain as high as 80-85 percent of your lactate threshold.
Train by heart rate
On long rides, there’s an effect called cardiac drift where your heart rate will steadily increase over the course of a consistently metered ride. That means that while 180 watts may be a good LSD pace to start, it’s going to be too hard after four hours. Train by heart rate, not power.
Back-to-back days
Many athletes will complain that LSD rides simply don’t hurt enough. That’s why I’ll often prescribe several LSD days in a row. By the third day, you’ll have all the “hurt” that you need. To train a system, you must stress it. The best way to stress your central system isn’t with intensity but volume. On your big weeks, do several LSD days in a row. Then make sure you follow it up with recovery days.
A little threshold work never hurt anyone
A little interval work in the off-season can be good, just be sure to make them threshold intervals. These are intervals of about 4-8 minutes at your threshold power. A total of 25-30 minutes at threshold, once or twice per week, is all you need.
Watch your heart rate drop
Think of your heart like a billow: A bigger billow can pump a lot more air with each stroke. Now try to quickly pump that big billow. Notice anything? As your central conditioning improves, and your heart gets bigger, you should see a gradual drop in both your resting and max heart rate.
The six-week rule
Remember that it takes six weeks to develop your peripheral conditioning. So, start the high intensity intervals about six to eight weeks before your first important race.
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