Every day you get up out of bed, put your feet on the ground and casually walk around your house. You go up stairs, reach for cereal boxes from the top shelf, change lightbulbs and carry things from here to there.
And all the while, you are blissfully unaware of the fact that the mass of the entire planet is generating violent gravitational forces that ceaselessly drag at your bones.
Lucky for you, your skeleton is amazing. Like the proverbial optimist making lemonade with lemons, your bones are using that massive planetary force for moving furniture, gardening and twerking instead of collapsing into a useless carbon-based heap.
Gravitational acceleration clocks in at about 9.8 m/s2; that translates to a mind-blowing 21.9 mph/s, which, for perspective, is just a little bit faster than the 2011 Ferrari 458.
This means that every second of every day, the planet is trying to flatten you with an acceleration that wasn’t beaten by a supercar until 2007, and your skeleton just keeps walking around like it owns the place.
And the coolest part? You’re bipedal, meaning that you’re doing all this with only two legs while the vast majority of other mammals strut around with four legs and a tail. Your feet manage forces equal to nearly 150% of your bodyweight with every single step—or 300%, while running—and even inactive lifestyles include around 3000 steps a day. For active folks? 10,000 steps or more.
You do this using an arsenal of insanely powerful and versatile structures: structures like your iliofemoral ligament. It’s the strongest ligament in your body with an ultimate tensile strength—the weight it can support before breaking—of 350 kg. For those of you not currently wearing a lab coat, that’s a little under 800 lbs (or, if you prefer, the bodyweight of a particularly large grizzly bear).
In fact, almost all of your joints are outfitted with ligaments that are capable of carrying many times more force through their longitudinal axes than you will probably ever need; the iliofemoral ligament is just the biggest beast of the bunch. You don’t have to “sculpt” it, you don’t have to earn it; until now, you probably didn’t even know you had it. But you do—and it’s another reason why you are stronger than you think.