Researchers have come up with an unusual tip for walkers looking to burn more calories: rather than trudging steadily from start to finish, consider taking rest stops.
The advice comes from a study of volunteers who were put through their paces in the laboratory to measure the oxygen and energy demands of short walks versus longer walks.
Tests on the participants found that walking or climbing stairs in 10- to 30-second bursts required 20 to 60% more oxygen, a proxy for energy expenditure, than covering the same distance in one continuous session, mainly because walking is more efficient after several minutes in motion.
“When we walk for shorter bouts, we use more energy and consume more oxygen to cover the same distance,” says Francesco Luciano, a researcher at the University of Milan and first author of the study. “It’s like having a car that uses more fuel during the first few kilometers than it does afterwards.”
The team launched the study after noticing that many estimates of the energy required to walk are based on data from people exercising at a metabolic steady state. This is when the heart rate is constant and the body’s energy production and consumption are balanced, a state compared to a car traveling at cruising speed.
To learn more about the energy requirements for different walks, the scientists recruited 10 healthy volunteers who were monitored while they exercised on a stair climber and a treadmill. The exercises covered three different speeds with bouts lasting from 10 seconds to four minutes.
During the training sessions, the researchers recorded how much oxygen each person consumed and worked out the metabolic needs for the different walks. They found that more energy was needed at the beginning of each step, to get going and warm up the body, than later in the exercise when the body was already moving and working more efficiently.
“When we start walking, we can incur some fixed costs at the beginning of the game,” Luciano said. “By analogy, driving a car requires fuel to start the engine or get the car out of the garage. We found that when you start from rest, a significant amount of oxygen is consumed just to start walking. We incur this cost regardless of whether we run for 10 or 30 seconds, so it weighs proportionally more for shorter rather than longer bouts.”
Measurements of the participants on the exercise machines also revealed that in the earliest stages of a stride, people are less efficient at converting oxygen and energy into effective movement, but this improves as they get into their stride.
The work reinforces knowledge of the health benefits of short walks and climbing stairs, particularly for people who are largely sedentary, and may explain the improvements in fitness associated with popular “exercise snacks”. It involves short bursts of activity that often last no more than two minutes each. The study is published in Proceedings of the Royal Society B.
Beyond the implications for healthy people, the work will help inform the design of rehabilitation programs and exercise advice for those with limited mobility, such as people with obesity and those who have had strokes.
“Researchers have usually measured energy requirements over walking bouts lasting many minutes. However, many people are not even able to walk that long. Think of elderly individuals or people with walking disorders,” Luciano said.
“If we want to design programs to promote physical activity or exercise for these people, we need to rethink how to estimate and adjust their energy needs. Understanding the energy needs of short walks can help us promote physical activity in a more inclusive way.”
