What do weight-bearing activities primarily increase?

Weight-bearing activities primarily increase bone density, which is crucial for maintaining strong, healthy bones. These activities place stress on the skeletal system, prompting the body to adapt by strengthening the bones and increasing mineral density. This process helps to prevent bone-related issues such as osteoporosis and fractures. Activities like running, jumping, and resistance training are prime examples of weight-bearing exercises that effectively promote this adaptation.

In contrast, while weight-bearing exercises can contribute to muscle strength, flexibility, and cardiovascular endurance through various mechanisms, their most significant specific effect is on bone density. Therefore, the focus on improving bone health is what sets weight-bearing activities apart in the context of increasing bone density.