I have just seen two people exercising together. She was running while he cycled beside her. She was only moving herself, but he was moving the bike too. Who expended more effort?
Tony Green
Ipswich, Suffolk, UK
Advertisement
A bicycle is a supremely efficient tool for converting muscle power into motion. So much so that while I can happily ride 130 or more kilometres, even a 1-kilometre run is utterly beyond me.
So, the runner is undoubtedly expending more effort than the cyclist in my view.
Peter Slessenger
Reading, Berkshire, UK
If level or downhill, the runner is definitely using more energy because lifting the body off the ground is hard work.
I recently used an 鈥渁nti-gravity鈥� treadmill, which uses air pressure to reduce your weight on the track. Running at 70 per cent bodyweight (about 25 kilograms lighter) was easy, at a speed I could never manage for more than a minute normally.
When running uphill, though, I have several times overtaken struggling cyclists.
Ron Dippold
San Diego, California, US
The cyclist is expending less effort, even if he weighs twice as much.
Every rotation of the cyclist鈥檚 feet is going directly into forward motion, minus only the friction of the wheel and chain.
The runner, on the other hand, wastes much of her energy on producing vertical forces every time her foot hits the ground.
Studies show that cycling on flat, firm ground uses about one-third the effort of walking or running at the same speed. I need to bike 32 kilometres for the same workout as fast-walking for 8 km.
The best resource for such comparisons is the , which regularly incorporates the latest studies into its list of Metabolic Equivalents (METs). A MET of 1.0 corresponds to resting level. An activity with a MET of 2.0 burns twice as many calories as that.
The formula for these values is MET 脳 weight (kg) 脳 time (hours) = calories burned (kilocalories).
For instance, leisurely biking at 8 kilometres per hour has a MET of 3.5, while running at 8.4 kilometres per hour has a MET of 9.0. Those values are directly comparable. This shows that cycling is burning about 2.5 times fewer calories (3.5/9.0).
Note that a cyclist going at a moderate cycling speed (MET 7.5) will burn around twice as many calories as someone walking at a moderate walking speed (MET 3.5), but, of course, the cyclist is going much faster and further. In the example given, the cyclist is held back to a snail鈥檚 pace, so that doesn鈥檛 apply here.
Of course, the cyclist puts in zero effort on a downward slope, but they put in more effort on a steep, upward slope. On a sufficiently bad trail, the cyclist will be walking 鈥� or flat on the ground! Terrain matters.
But in the example given, it is the cyclist who is slacking.
Dave Jackson
Telford, Shropshire, UK
Like a lot of 快猫短视频 readers鈥� questions, this is less straightforward than it would appear.
I am an ex-runner who now cycles at my previous running pace. Speed, weight and fitness will factor in, but bikes are a very efficient way of turning human energy into speed, so I suspect in most cases the runner is expending more energy. However, we are asked about effort rather than energy expenditure.
When I was running fit, it was more comfortable to maintain a 1000 kcals per hour energy expenditure while running than while cycling or using gym equipment. So, burning energy isn鈥檛 directly related to effort. I suspect, for the people in this situation, a smartwatch would answer the energy question, but not the more complex and less objective question of 鈥渆ffort鈥�.
Eric Kvaalen
Les Essarts-le-Roi, France
Definitely the person who was running. There was an examining the efficiency of various modes of transportation, including walking, running and cycling, and it showed that cycling was by far the most efficient. Riding at a moderate speed takes no more energy than walking.
To answer this question 鈥� or ask a new one 鈥� email lastword@newscientist.com.
Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.
快猫短视频 retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.
听