Building functional threshold power is one of the biggest objectives of most competitive cyclists. Cyclists everywhere like to brag about how many watts they put out at threshold. Coffee shop talk is dominated by phrases like “watts per kilogram” and “threshold intervals” in the pursuit of more cycling power. Interval training programs are based on the concept of how much power you can put out at threshold.
I'm telling you that functional threshold power is indeed one of the biggest goalposts we measure fitness by. The way we've consistently tried to train it has evolved over the years, but the basic concept remains the same: increase aerobic power at and under your threshold. There are a few ways to improve your functional threshold power without having to spend hours, days or weeks doing 20 minute threshold efforts.
Quite simply, if you want your functional threshold power to grow, you can either train longer, train smarter or train harder. Click through the jump to listen to my latest podcast. You'll learn two keys that will help you train smarter, giving you a jump on building functional threshold power in the base phase.
What is Functional Threshold Power?
First of all, I recommend you check out my post “What is FTP and how do we train with it?” to get a better idea of what FTP is all about.
Functional Threshold Power is simply the maximal power your body can maintain under aerobic conditions. It is typically determined by the average power over a 60 minute (typically around 40K) time trial.
In many cases, cyclists don't have the ability to perform a 60 minute time trial (due to the lack of a closed course, motivation, etc etc). Most estimations of functional threshold power come from a calculation. Riders will take 95% of a 20 minute all out time trial as an estimation.
The 5% calculation error takes into account some anaerobic contribution over 20 minutes. Alternatively, doing a couple of 5-minute all out efforts first will empty the tank. Then the average power is taken as an estimation of FTP.
FTP as a percentage of VO2 Max
Functional Threshold Power is actually a percentage of your overall VO2 max capacity.
The ceiling analogy: if you put a plant in a room with a short ceiling, once it hits the ceiling it can't grow taller. Same with your fitness: once you hit the ceiling, you can't raise it more without raising the ceiling. See Podcast #66: HIIT 1 The Science.
Building functional threshold power depends on raising your VO2 max ceiling and allowing room to grow.
You need to raise your VO2 max ceiling to allow room for building functional threshold power. Why? Because FTP is a percentage of VO2 max, raising VO2 max utilization helps in building functional threshold power.
Most untrained people can only utilize 50% of their genetic VO2 max. This increases with training. So increasing VO2 max allows extra room for building functional threshold power.
VO2 intervals: Designed to raise VO2 max ceiling and create room for functional threshold power growth.
Start with longer duration (5-8 minutes) @110% of FTP. Move toward shorter 3 minute intervals @120% of FTP as you progress. Initially, start with 3-4 reps, increasing towards 5-6 reps for longer duration intervals. With the shorter, more intense intervals, start with 4-5 reps and move towards 9 reps.
Frequency should start around 1x/wk in base, increasing towards 2x/week in build. In peak periods, move to 3x/wk (and move to shorter, more intense intervals.)
Check out my VO2 max workouts post for a couple other awesome options.
FTP intervals: Building functional threshold power is more a case of building endurance at high percentages of VO2 max.
The standard “FTP interval” is a 2×20 minute interval set. Starting off, intensity should stay around Sweet Spot intensity (for repeatability sake.) Work your way up to 100% FTP, or the traditional FTP interval intensity. As you progress, move towards 3×20 and 2×30 minute intervals. When you change interval durations, switch back to sweet spot intensity and work back to FTP levels.
Frequency should start at 2x/wk in the base phase, increasing to 2x to 3x/wk in the build phase. If your specific goals dictate it, you can perform 1 interval workout per week in the peak phase.