Some people are naturally better than others at pulling off the elusive pull-up, writes Kyle Hill at Scientifica American. For them, it's all about mass-to-arm-length ratio — ideally, you want a low mass and short arms to minimize the amount of energy it takes to pull your body upwards
. But Hill insists that the less genetically fortunate can learn to do pull-ups, too. It's just something that takes dedicated training.