Human tendons act like springs to boost jumping power

When an NBA player like Austin Reaves prepares for a forty-inch vertical leap, his muscles aren't doing all the heavy lifting. Instead, his legs act as biological catapults. During the split second his feet touch the floor, his tendons stretch like heavy-duty rubber bands, capturing kinetic energy that would otherwise be lost. This stretch-shortening cycle allows an athlete to explode upward with fifty percent more force than they could generate by using their muscles alone.