Daniel Lieberman at Harvard University and colleagues compared the gait of endurance runners in the US and Kenya and found that more than two - thirds of those who grew up running barefoot or had trained themselves to do so as adults
ran on their tiptoes, landing on the balls of the feet first (Nature, DOI: 10.1038 / nature08723).
«Synchronous functioning» of the tendon and calf is crucial for many activities, including standing
on tiptoe,
running, jumping and climbing stairs (Bhimji 2016).