John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
CityLab investigated this workout showdown.
The cyclist: quick, sleek, often clad in fun aerodynamic costumes. The walker: steady of foot, plodding, relentless. But who, in fact, is getting the best form of exercise?
This question came up between myself and the significant other as we prepared for our poor excuse for weekend exercise—traveling about 1 mile to drink at a bar. My point, from something I probably misremembered from high-school physics, was it doesn’t matter what kind of transport you use, because the energy required to get from point A to B will always be the same, and the briefer-but-more-intense bike workout will equal a longer-but-less-intense stroll. Also, how many images of sweaty, straining cyclists have you seen, compared to pedestrians going hard as a mofo on the sidewalk while dripping bullets? Walking just seems like a lazier mode of transit.
Her view: For the same distance, you burn more calories walking, because the bicycle does some of the work for you.
To settle this debate, I’ve taken the avenue traveled by many arguing couples: contacting Berkeley physics professor Joel Fajans. Fajans is the winner of the American Physical Society’s Simon Ramo Thesis Prize and the National Science Foundation’s Presidential Young Investigator Award. He’s also an avid cyclist, having cracked many frames in his life over the course of biking thousands of miles.
For another perspective, we also reached out to Liz Letchford, who in 2015 was chosen as one of the best personal trainers in San Francisco by Thumbtack and The Bay Area A-List. When she’s not getting bodies ripped in Fog City, Letchford is at the University of Hawaii at Manoa pursuing a Ph.D in kinesiology and rehabilitation science.
Here’s the scenario: You’re journeying a mile over flat terrain. If you want better exercise, should you hop on the Trek or slip on some sneakers?
Best for getting ripped: cycling
The two options are fundamentally different in terms of the strain you put on your body. “With biking, you have the pedals moving down, but not 100 percent of your weight is on that pedal. It’s classified as non- or partial-weight-bearing activity, as opposed to walking,” says Letchford. “You’re weight-bearing when you’re walking, so you’ll be training your bones to be stronger.”
Both activities use nearly all of your muscles. But when biking, you’re really working out your glutes and quadriceps (also muscles in the lower legs/feet, if clipped into the pedals). Do this enough and you’ll come out with a pretty toned lower body. If you really push it, you could build those cyclist calf muscles that look like you’re smuggling two beer growlers in your Lycra.
Walking is more chill for your muscles, putting a bit of stress on the calves, core, gluteus medius, and—if you’re the power-walker-type who swings their arms like they’re in a military parade—the shoulders. “You’re essentially just falling forward if you're walking at your casual, preset pace, like how we go to get snacks from the fridge,” says Letchford. “It’s a very efficient biomechanical activity.”
Walk many miles over a couple decades, and you’re going to look pretty much the same, though with strong calves and foot muscles. You might even become a bit scrawnier. “Initially, as you adopt this training regimen, you may lose body fat and gain muscle mass as your body adapts to the new demands being placed on it,” Letchford says. “However, after several months of the same daily routine, your body may continue to lose fat without additional gains in muscle, causing a decrease in total body weight. Since walking is simply carrying your body weight across a specific distance, you may actually begin lose muscle mass as you continue to carry less and less weight across the same distance each day.”
Better slow burn: cycling, if you crank it up
However! As efficient as walking is, biking is more efficient, having the lowest energy cost of all transportation options, including walking, swimming, driving, ride-sharing, taking the train, and trotting through a sun-dappled meadow on a horse, according to San Francisco’s Exploratorium. “There is legend and lore out there—that I have never independently verified—that a person on a bicycle below 10 mph or something like that is the most efficient transportation system known,” says Fajans. “It gets you the farthest for the least energy. Which is surprising, because things like fish might be efficient in their own ways, and so are birds. Obviously this doesn’t count with, say, an eagle dropping out of sky—we’re talking about horizontal travel.”
Biking takes a certain amount of energy to get moving, but once you’re on the go on a flat surface (from a pure-physics perspective) you no longer have to put in energy to maintain speed. The way you can coast for short distances on bikes takes away some of their workout power. Unless you’re on an ice rink, you can’t glide as a pedestrian; you’re constantly putting one foot in front of the other and burning calories. People who favor this age-old form of exercise might want to try chugging along like one of those ridiculous Olympic race-walkers, though at that point they might as well be running, which is probably better exercise than biking and walking.
If you really cranked that mile—pedaled so hard the wind felt like sofa cushions slapping your face—the frenzied physical activity paired with air friction would make for a great workout. “You would be utilizing more anaerobic and aerobic energy systems,” says Letchford. “So, yeah, that would be a much better kind of exercise than just leisurely walking the same distance.” (You’d also get to your destination much faster, a big plus for people who think walking is boring.)
Stop signs can also turn biking into hard exercise. Constantly braking and re-starting, as cyclists know, devours a lot of energy, and could push biking over walking as better exercise. On one kinetic-energy scale, it takes 16 times more energy for a bicyclist to get up to speed from a halt than a pedestrian. “That’s why stop signs are devastating, because if you can just keep on going, you put energy in the first time and it’s in,” says Fajans, who co-wrote an article on the phenomenon. “If you have to stop at a stop sign every block, you’re losing it every single time you come to a stop.”
The verdict—walk or bike to quaff that brew?
“Whenever you walk, you’re lifting your body up and down, and that’s going to expend energy,” says Fajans, coming down for Team Walk as better exercise. “Now, there’s a little bit of springiness in your system, so some of your muscles act like springs when you put your foot down, and you kind of spring back up. But nonetheless, it adds energy. Bicycling doesn’t have that—your body isn’t moving up and down—so at slow speeds bicycling is going to be more efficient than walking.”
“I would walk there, for two reasons,” says Letchford. “One, it’d be more exercise. And two, if I’m going to a bar, I’ll be drinking, and I don’t want to want to be driving drunk on my bike.”