Why cyclists and rowers train high cadence over power

HostI was watching a bike race the other day and noticed something that felt a bit off. There were these riders whose legs were moving so fast they were almost a blur, like a kitchen blender on high. But then there were other people just pushing down slow and hard. To me, the fast spinners looked like they were working way too hard for no reason. Why do they choose to move their legs like that instead of just pushing harder?

GuestIt looks totally frantic from the outside, like they're wasting energy just to stay in place. But what those cyclists and rowers are doing is actually a clever trick to shift where the stress of the workout goes. They're moving the load away from their leg muscles and putting it onto their heart and lungs instead. Think of your body like a car. If you stay in a low gear and try to go fast, the engine screams. If you shift up, the engine goes quiet but you have to push the gas pedal much harder. For humans, our legs are like a small gas tank that runs out of fuel really fast if we push too hard. But our heart and lungs? Those are like a big solar panel that can keep the lights on as long as the sun is up. By spinning fast, we're letting the heart do the heavy lifting.

HostSo you're saying it's better to have a screaming heart than tired legs? That sounds like a tough trade. If I try to spin my legs that fast, I feel like I'm going to run out of breath in ten seconds. It feels much more natural to just push the pedals down with my weight.

GuestThat's the big trap. Pushing hard feels easier at first because it uses your big strength muscles. Those muscles are great for jumping or sprinting, but they're like matches. They burn bright, they give you a ton of power, but then they're gone. Once those big muscle fibers are tapped out, they take a long time to recover. If you spend your whole bike ride or your whole rowing session grinding away with that raw power, you're burning through those matches one by one. By the time you get to the end of the trip, you have nothing left. But when you spin fast with less pressure, you use a different kind of muscle. These are the slow and steady parts of your body. They don't have as much power, but they can go all day as long as you keep breathing. So, yeah, you'll be huffing and puffing, and your heart will be thumping, but your legs will still be fresh miles down the road.

HostI guess that makes sense for a long ride, but what about rowers? They're in a boat for maybe six or seven minutes in a race. It's a total sprint. Surely in a short burst like that, you would want to just use all the raw power you have?

GuestYou would think so, but rowing is actually where this gets even more important because of how the body handles waste. When you squeeze a muscle really hard, like you do when you're trying to move a heavy weight, you actually pinch off the blood flow for a split second. It's like putting a kink in a garden hose. If you're doing these long, slow, heavy strokes, you're cutting off the oxygen to your muscles over and over again. That causes all that burning acid to build up in your legs and arms. When rowers keep the stroke rate high, the muscles are snapping on and off much faster. That quick snap keeps the blood moving. It flushes out the junk before it can settle in and make your muscles quit. It's like the difference between trying to push a heavy car ten feet in one go versus giving it a bunch of quick, little shoves. The little shoves keep the car rolling without killing your back.

HostBut there has to be a limit, right? If I move my legs at a hundred miles an hour with zero weight on them, I'm still going to get tired just from moving the weight of my own limbs.

GuestYou hit on the exact reason why everyone has a different sweet spot. If you spin too fast, you're wasting energy just tossing your legs up and down. That's called internal work. You're working hard, but none of that energy is actually moving the bike or the boat. It's just moving you. If you go too slow, you break your muscles. The pros spend years trying to find the point where their heart can handle the speed but their muscles aren't being crushed by the weight. For most people on a bike, that's usually around ninety circles a minute. If you watch a pro, they look like they're floating because they have trained their brain to handle that fast rhythm without bouncing in the seat.

HostIt sounds like it's more about being a smooth machine than a strong one. Is it something that actually changes how your body works over time, or is it just a choice you make while you're out there?

GuestIt actually changes you. When you train at those high speeds, your body starts to build more of those little power plants inside your cells that use oxygen. You also get better at clearing out that burning feeling. Your heart actually gets bigger and stronger so it can pump more blood with every beat. People who always push the heavy gears usually just end up with big leg muscles, but they hit a wall because their heart can't keep up with the demand. The people who spin fast might have smaller legs, but they have an engine under the hood that never quits. It's why a pro cyclist can eat a sandwich while their legs are moving like crazy. Their body has become so good at that fast rhythm that it feels like resting to them.

HostThe next time I see someone spinning their legs like a blender, I'll think of them as a car that found the perfect gear to keep the engine from blowing up.

GuestThose fast legs are just a sign that the heart is doing the work the muscles were never meant to finish.

HostIt turns out that looking like a blur is actually the most relaxing way to go the distance.