Types of physical activity that can improve bone density include weight-bearing and resistance exercises. Activities like running, walking, hiking, and dancing apply stress to the bones, stimulating them to become denser. Resistance training, through weights or body-weight exercises, enhances bone strength by activating muscles that pull on bones, further promoting bone health. Additionally, activities such as gymnastics and sports involving jumping contribute positively to bone density, particularly when started during childhood and adolescence when bone development is most crucial.