Dancers & Bone Health

“The harder the demand placed upon the structure, the stronger the foundation must be.” Our bones – they protect our organs, they manufacture red blood cells, they store calcium, they provide a place for muscles to connect, they permit movement and they provide the framework for our bodies.  Without our skeletal system, we could not exist, yet we rarely think about how our bones develop or bone health. Although our bones appear sedentary, bone tissue is very active and each week 5-7% of our bone mass is recycled, or remodeled.  The outer surface of our bones is compact bone, which is composed of a web of proteins that hardens into a tough structure.  The inside of our skeletons is made of spongy bones with spaces in between the bone cells. Our bones grow from the outside in.  Specialized cells called osteoblasts build bone by travelling to the surface of the bones and depositing collagen molecules between the structural cells to form a matrix and that hardens into layers of compact bone. Meanwhile, other cells called osteoclasts resorb, or breakdown, the mineralized matrix from the inside.  The bottom most layer is dissolved and calcium is released into the bloodstream. This process serves to renew our bones and occurs in a balanced manner most of the time.  During growth spurts, and especially during adolescence, the creation, or modeling, of new bone occurs in addition to the remodeling process, resulting in a surplus of new bone. It is also important to know that osteoblasts (the builders) respond to increased loads that are placed upon the bones such as weight training or weight bearing activities like walking, running and jumping.  When the body recognizes an increased load, or stress, on the skeleton, the osteoblasts are called in for overtime and begin to model more new bone to protect the body against the increased strain. Bone cells grow old like any other cells, and, unfortunately, osteoblasts (the builders) age quicker than the osteoclasts (the dissolvers).  Between the ages of 30 and 40, the osteoblasts begin to slow down while the osteoclasts continue to resorb bone tissue.  A deficit of bone mass is naturally created which can lead to osteoporosis.  People with osteoporosis have brittle, fragile bones which can fracture easily. The best defense against osteoporosis is encouraging the body to create as much bone mass as possible during the formative years and to stimulate the osteoblasts with weight bearing physical activity. Since dance is a weight bearing activity, it would seem that dancers have nothing to worry about, right?  Next week’s post will explain why dancers have to be concerned.