Weight Training Stunts Growth?
The human body contains many types of bone. Long bones, flat bones, short bones and sesmoid bones. For the purpose of this explanation we will focus on one of the long bones of the leg, the femur (or the thigh bone). Bone itself is made up of spongy bone (found within the bone), compact bone (the material that gives bone it's strength) and the marrow cavity found within.
Figure 1. Image of a long bone (femur) and it's components.
Other important areas of the bone are the diaphysis which is the long shaft and the epiphysis, the proximal and distal ends of the long bone. The metaphysis is the area in between as can be seen in the image above. The epiphyseal growth plate is a layer of cartilage that allows the diaphysis to increase in length, this process will be described briefly later. Once a person stops growing, between the ages of 18-21, the epiphyseal growth plate hardens and is converted into the bony epiphyseal line.
There are two important cells involved in the formation and maintenance of bone (figure 2 below). The first is osteoblasts. These are the building cells as they deposit the material needed for bone to form. Secondly, osteoclasts carve out the bone to break it down and resorb the minerals. A process that is necessary to grow new bone tissue, especially during puberty or the healing process after a break. Easy way to remember these are B for blast and build, and C for clasts and carve. The process of remodelling bone continues throughout a person's life. Once a person reaches full maturity the rate of bone deposition and bone resorption are evenly matched. At any one time, roughly 5% of bone is being remodelled, with approximately 4% of compact bone being remodelled every year. This is a vital process that keeps your bones healthy and strong.
There are two important cells involved in the formation and maintenance of bone (figure 2 below). The first is osteoblasts. These are the building cells as they deposit the material needed for bone to form. Secondly, osteoclasts carve out the bone to break it down and resorb the minerals. A process that is necessary to grow new bone tissue, especially during puberty or the healing process after a break. Easy way to remember these are B for blast and build, and C for clasts and carve. The process of remodelling bone continues throughout a person's life. Once a person reaches full maturity the rate of bone deposition and bone resorption are evenly matched. At any one time, roughly 5% of bone is being remodelled, with approximately 4% of compact bone being remodelled every year. This is a vital process that keeps your bones healthy and strong.
Figure 2. Life cycle of bone tissue.
As a youth's skeleton develops, there is a vital area of growth around the epiphysis, the growth plate. This is the area in which all the lengthwise growth of bone occurs. Through a series of process and reactions, cartilage is laid down, calcifies and is then converted to bone on the diaphysis side of the growth plate. On the epiphysis side of the growth plate, cartilage continues to proliferate and multiply and lay down more cartilage. This process of bone remodelling continues until full maturity is reached. As mentioned above, the growth plate then becomes the epiphyseal line and no more lengthwise growth occurs. 25% of total adult bone mineral content is developed during the early years of a child's life, pre-puberty. Thus, showing the importance of fully optimising a child's potential for peak bone mass, not only to produce improvements in sporting performance later in life but more importantly to provide them with the opportunity to live a safe and healthy life by reducing their risk of fragility later in life.
This article wouldn't be much good to people if I finished it just there without explaining how exercise, involvement in sport and resistance training can influence the growth of bone, or how resistance training (provided it is safe and supervised) does not stunt your growth.
Bone has incredible adaptive qualities and reacts to many different mechanical loading stimuli such as compression, shear, tension etc. External load from exercise stimulates osteogenesis (the formation of new bone). Research has shown that pre-pubertal skeleton is more repsonsive to exercise training which involves high intensity loading, without the need for high volumes of training < 3 hours/week. Think weight-bearing activities such as gymnastics, soccer and rugby. Exposing children to weight bearing activities in which the load is placed in several different directions is critical to produce new, healthy and stronger bone. Sport participation increases peak bone mineral density (harder bone) by 10-20% compared to non-physically active people. This is relevant especially for females as some literature has shown a reduction in the rate of increase of bone mineral content after the onset of their menstrual cycle. Essentially meaning that once females hit puberty, their body begins to slow down the rate at which it deposits material for new bone growth. To combat this females needs to be involved more in exercise at an early age to reduce the risk of becoming fragile later in life.
This information should highlight the need for more unstructured physical activity in schools. More weight bearing activities in which the skeletons are stimulated to develop beyond that of which they would under normal circumstances. The skeleton will adapt to the prevelent level of the exercise intensity and no further. On the flip side of this, structured resistance training for youth athletes must be carefully monitored during all phases of development. It must be stressful enough to stimulate osteogenesis, but not too intense as to provoke a negative reaction or increase risk of getting injured.
Bone has incredible adaptive qualities and reacts to many different mechanical loading stimuli such as compression, shear, tension etc. External load from exercise stimulates osteogenesis (the formation of new bone). Research has shown that pre-pubertal skeleton is more repsonsive to exercise training which involves high intensity loading, without the need for high volumes of training < 3 hours/week. Think weight-bearing activities such as gymnastics, soccer and rugby. Exposing children to weight bearing activities in which the load is placed in several different directions is critical to produce new, healthy and stronger bone. Sport participation increases peak bone mineral density (harder bone) by 10-20% compared to non-physically active people. This is relevant especially for females as some literature has shown a reduction in the rate of increase of bone mineral content after the onset of their menstrual cycle. Essentially meaning that once females hit puberty, their body begins to slow down the rate at which it deposits material for new bone growth. To combat this females needs to be involved more in exercise at an early age to reduce the risk of becoming fragile later in life.
This information should highlight the need for more unstructured physical activity in schools. More weight bearing activities in which the skeletons are stimulated to develop beyond that of which they would under normal circumstances. The skeleton will adapt to the prevelent level of the exercise intensity and no further. On the flip side of this, structured resistance training for youth athletes must be carefully monitored during all phases of development. It must be stressful enough to stimulate osteogenesis, but not too intense as to provoke a negative reaction or increase risk of getting injured.
Like, comment and share. We want to know what you think!
RSS Feed