Bone stress injuries are common in running and jumping sports, and calcium intake is one piece of the puzzle, alongside vitamin D and, above all, eating enough overall.
Things worth knowing:
Typical adult recommendations are around 1000 mg of calcium a day, and higher (often 1300 mg) during adolescence when bone is being built
Dairy is an easy source; fortified plant milks, tofu set with calcium, tinned fish with bones and some greens also help
Low energy availability undermines bone health even if calcium intake looks fine on paper
Some research suggests a calcium-rich meal before long sessions may reduce bone breakdown markers, but this is still emerging