To have a solid backbone, practice sport and adequate dietary calcium as well as vitamin D is needed . The calcium is a major component of the skeleton, which is the reservoir of the organism. Almost 99% of body calcium is found in bones. In case of deficiency, your body draws on reserves of calcium in the skeleton, which weakens it.
You need to eat about 900 mg of calcium per day if you are an adult. To cover your needs, then you must eat 3 dairy products per day. If you do not like milk, you can also drink water rich in calcium (Contrexeville... eg). Some fruits and vegetables and also meat and fish contain calcium but at levels lower levels.
Apart from dietary intake of calcium, practice sport (that's your case!) and exposure to sunlight promotes good bone density. If you practice indoors exercise and you're rarely more than 1 / 2 hours outside, you can seek advice from your doctor for vitamin D supplementation.
