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Why Smart Cyclists Train With Watts

These 3 workouts show you how to use power to maximize your performance.

Watts don't just brighten your indoor existence; they can light up your ride, too. The same energy used to make bulbs glow is similar to what you can create on your bike (stationary, road or mountain) without a plug. Your manmade power comes from within—or more specifically, the combination of RPMs (i.e., your cadence) plus how much torque you put on the pedal, explains seven-time Ironman triathlete and Equinox cycling instructor Robert Pennino.

In simpler terms, watts measure how hard you work. One horse, for example, can produce 746 watts. One super human, like six-time Tour de France stage winner Andre Greipel, can create a charge of 1,900 watts in a single sprint. Most pro cyclists produce about 200 to 300 watts on average during a four-hour tour stage. The recreational rider, on the other hand, might be only able to sustain this wattage during a 45-minute or hour-long spin class.

Used correctly, watts can help you better understand how your energy is being transferred to the bike. Perceived exertion changes based on several factors such as your stress levels, how well you ate or slept before your ride, and the temperature outside. Watts are unbiased. “That's what's great about wattage. It takes out of all the variables,” Pennino says. “If you're training off your heart rate,” he explains, “when you're stressed, tired, dehydrated or sick, your numbers are always different. Watts, however, are always watts.” 

The challenging part about watts is understanding what, say, 150 watts mean for you. Because one's individual number is very subjective—meaning it derives from a combination of bodyweight, leg strength and overall fitness—there's no clear-cut answer.

Look at it this way: “If a 200-pound man and a 125-pound woman are producing the same wattage, the female will go faster because she's pulling less weight,” says Pennino. The advantage women have over men, who are generally bigger and stronger, is that they're lighter and, therefore, if they are strong, too, then they can produce a lot of power and ultimately go faster. 

To find your personal power numbers, start by determining your baseline with a 20-minute time trial on a stationary bike. “Hit the gas to see what's your average watts. Once you get that number, take off 10 percent to calculate your baseline number, or functional threshold power (FTP),” says Pennino. So if your average power is 200 watts, then your FTP is 180. From there, follow these three workouts to determine your training levels for interval, tempo and easy endurance rides.