2. How Bones Actually Get Stronger: The Science Behind It

Here’s where things get interesting. Your bones respond to stress—specifically, the force of ground impact. Every time you land on your feet, you create a force called the “ground reaction force.” When it’s high enough, your body receives a wake-up call to build denser bone tissue. The magic threshold? Activities need to produce a force about three times your body weight to kickstart this process. That’s a lot more than most of our day-to-day movements provide!

3. Common Exercises and Their Bone-Building Limits

Let’s break down what you might already be doing:

• Walking gives a ground reaction force about 1.5 times your body weight—it’s great for your health, but not enough for building new bone.
• Running is better, at about 2.5 times your body weight, but still short of the magic mark.
• Jumping rope sits between the two—15% less force than running, and 40% more than walking. Amazingly, it’s still not quite optimal for serious bone-building, but it’s a step in the right direction.