Being physically active has always been part of the human experience. We were designed to be physically active. We were not designed for organized sports, bodybuilding, or Olympic level competition. What we humans did best and most was walk. We are the great walkers. We are designed to walk almost anywhere, climb over downed tress, down Children at Playhills, up mountainsides, and across grasslands. We also ran short sprints then stopped. We exerted ourselves then rested. We were very fit. No one was fat. We fasted much of the time. We had no choice back in ancient times. If our ancestors had access to the vast quantity and quality of food each of us has today and all the labor saving machinery then they would be confronted by the same exact obesity and its associated health issues as we do today. Remember, we are they.

If you watch children at play, you will see that they naturally follow this pattern. They need no coaching or adult supervision to play actively. It comes naturally. They chase each other with gusto; they hide and seek, the crawl through the bushes, and walk through the woods. Children on the playground are the same. Our task is to facilitate this play, encourage it, and interfere only to prevent harmful behavior not to interrupt its spontaneity.

Avoid Contact SportsBoxing or any “sport” that involves violent physical contact is no longer appropriate in my opinion. I strongly suggest discouraging your child from participating in any physical activity where there is a risk of the child suffering closed head injury. Boxing, football, and ice hockey head the list in my view. Closed head injuries result in permanent brain injury that affects intelligence, mood, physical coordination, and the ability to be independent and form meaningful interpersonal relationships.

Soccer, track, Lacrosse, volleyball, tennis, basketball, baseball are all sports that are fun, aerobic, do not often cause significant injuries. Of course, no sport is completely safe but neither is life and unless you want to put your child in a protective bubble their whole life then being normal involves there being some risk. These sports rarely cause head or spine injuries unlike football and ice hockey.

Team Sports are BestThe team sports not associated with closed head injuries are traditional sports that are offered broadly, expertly coached, and popular. They are appropriate for older girls and boys interested in both team and individual sports. There are adolescent versions offered at the middle and high school level and beyond.

Studies show that the strain of children’s play on bone does two vital
things. First, it shapes the bone along the lines of force placed upon it by the exercise. This shaping force informs the bone where to grow in the best way to manage the strain placed upon it by the physical stress of the play. The play also directly affects the shape, form, and health of the muscles that overlie and attach to the bone. The sites of muscle attachment also shape the bone.

The Biologic Force Sensor and the Piezoelectric Effect
The second benefit exercise has on the growing skeleton is transmitted when the collagen bundles that are at the center of all mineralized bone are stretched they generate an electrical potential through the piezoelectric effect. The force applied to the bone causes the buddle within to be stretched. In this way, the mechanical energy is stored in the bundle. When the pressure is released the special physio-chemical properties of the collagen bundles convert the stored mechanical energy into electrical energy when it returns to its normal shape. This special material property is called the piezoelectric effect.

As a result, electrons are released from the surface of the bundle and adjoining bundles and travel as a weak current across the bone surface. These electrons are being released in pulses related to the stress and strain placed upon the bone the bundles reside within. Since the bone crystals form a matrix surrounding aligned collagen fibers and multiple collagen containing bones are being strained and released in unison, there are multiple electrical impulses being generated simultaneously. There is a pattern to this release, a rhythm, and intensity. These characteristics have been shown to affect the bone remodeling system positively. The flow of electrons along the lines of force generated in the bone informs the osteocytes where to reinforce bone. This electrical information is translated into biological instructions to the BMU or bone-modeling unit of bone cells instructing them where to go and what to do (see the Skeletal Cycles sections for more on normal bone cell biology and physiology). Because life continues, information from this biologic force sensor system is continuous. It provides real-time updates to the BMUs assigned to the task of reinforcing the femur for example on whether to keep working and when to stop. Once a mechanically sustainable equilibrium is reached, singling from the sensor changes and addition of bone halts because it is not required.

The same sensor system is involved in bone loss seen due to inactivity. It detects the biomechanical demands you place on your skeleton and gives you what you really ask for, not what you want. Your body precisely senses the physical demands you place on it and responds accordingly.

Exercise stimulates the bones to grow stronger and to form more bone where it is needed most. Children and teens that are physically active, and eat a healthy diet rich in calcium, magnesium, have good vitamin D levels, adequate protein, calories vitamins, and other trace minerals have the best chance of reaching the peak bone mass potential.