If taking up running is one of your New Year's resolutions but you haven't quite managed to get started, you might be pleased to hear that a gentle jog is less tiring than a power walk.
A new study has found that running helps a key calf muscle to work more efficiently than it does when walking briskly.
The research team, from North Carolina State University, found that running helps the muscle release more momentum-boosting energy, increasing stamina levels.
The study, published in the National Academy of Sciences, analysed volunteers while walking or running on a treadmill.
The results showed that the medial gastrocnemius muscle attached to the Achilles tendon adjusted according to the movement and speed of the participants, enabling them to shift into a different gear, acting in the same way as a car clutch.
The researchers found that walking fast was less efficient, making the muscle work harder while providing less energy.
Jogging at a speed of two metres per second prompted the muscle to change its length more slowly, providing more power even though it isn't working as hard.
Study author Dr Gregory Sawicki said: "Other than Olympic race walkers, people generally find it more comfortable to run than walk when they start moving at around two metres per second - about 4.5 miles per hour.
"The muscle can’t catch up to the speed of the gait as you walk faster and faster.
"But when you shift the gait and transition from a walk to a run, that same muscle becomes almost static and doesn’t seem to change its behaviour very much as you run faster and faster."
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