Strengthening children's muscles

Most adult exercise programs aim to increase the trainee’s muscle size with the notion that the bigger the muscle, the stronger it will be. Yet, muscle size is not the only element that plays a role in its strength. While Neurological adaptation increases muscles abilities during the first two weeks of adult exercise programs, this adaptation is the main reason for the increase in a child’s strength throughout childhood. Hence the aim of children's exercise programs is to optimize their neurological system to make their muscles stronger rather than merely bigger. Neurological adaptation improves through:

Muscle learning

The skeletal muscle contracts by receiving signals from nerves that are connected to it on one side and to the spinal cord at the other end of the nerve.

The grouping of the nerve and the muscle fibers connected to it is called Motor Nerves or Motor Unit; hence muscle contraction is actually a recruitment of motor units. Therefore, the heavier the weight needed to be moved, the more motor units needed to be recruited.

When a muscle is used recurrently, movement becomes ingrained in the nervous system and thus becomes able to contract by playback reflex. This reflex eliminates the need to receive orders from the brain. As signals start going through the motor unit faster, the rate of muscle contraction becomes higher producing a higher outcome.

The phenomenon of an increase in muscle strength without or before an increase in muscle size is known as muscle learning.

Stretch reflex mechanism

In untrained muscles, a specific mechanism known as a stretch reflex is found to protect the muscles from injury. This mechanism causes the nervous system to react slowly when muscles repeatedly contract, such as during jumping, throwing or kicking.

As muscles get trained, they become stronger and require less reflex protection. A proprioceptor present within the muscles learns to adjust automatically to differences happening to the muscle length without receiving messages from the brain. Again, this means a higher rate of muscle contraction and thus higher outcomes.

Additionally, the reaction occurring from stretching muscles is like when you stretch a rubber band.

The potential energy stored in the stretched muscles can add more strength to the next movement if the muscle contracts fast enough. Conversely, if the movement is delayed after the stretch, the energy produced from it will get lost as heat.

Skills

From the aspect of sports, skill is the ability to orchestrate the movement of skeletal muscles along with the movement of the involved joints while having the right body position all channeled towards performing a specific motion. Skill allows little to none of the exerted power to get “wasted” away from the goal. Skills need time and perseverance of recurrent right practice to learn and develop, keeping in mind that a child who was highly skilled in a sport a month ago can suddenly look less skillful. This happens as the nervous system was programmed to perform the task within the weight and the height of the child, but the rapid growth happening to children’s bodies can confuse their nervous systems. However, this should not be a problem as, after a period of adjustment, the neural system “catches up” with the physical growth and continues to improve.

There is a limitation to how far we can increase strength through neural adaptation (muscle learning, stretch reflex and skills). A fatty sheet surrounds the nerve, known as myelin, which helps transmit nerve impulses faster. This sheet does not get fully developed until after puberty, with the effect of training being constrained by the level of myelination.

Muscle size

Muscles get bigger by having the amino acid (which is supposed to be readily available in the blood) pushed into the muscle. This happens by putting tension on the muscle through heavy lifting. Also needed for muscles to grow bigger are high levels of hormones like the growth hormone testosterone.

However, children can have fragile bones and undeveloped body systems, which makes them unable to handle considerable weight and the hormonal system starts to be effective only when children enter adolescence.

For these two reasons, children might exhibit minimal to no increase in muscle size above what is expected in the normal growth chart. So, instead, to help children develop optimal muscle strength:

1. Provide them with suitable well-balanced nutrition with an emphasis on protein intake.
2. Avoid overtraining through extended exercise sessions or relatively high weightlifting.
3. Provide enough recovery period between sessions. Equally important, allow for enough rest time during the same session.