An Overview of Phycial Fitness Guidelines for Kids

Children

Children are shorter and weigh less than adults. Females are 98% of their adult height by the age of 16 or 17 and males by the age of 17 to 18. The heart rates in children decline as they age. During the toddler period, (1-3 yrs) it is 80 to 100 beats per minute, and by the time they are adolescents (12-20 yrs), it decreases to 50-100 b.p.m. Respiration (breathing) and blood pressure also decrease as children grow older, and children do not attain 20/20 vision until the age of seven. It is essential to remember however, that children of the same chronological age cannot be compared, as some children bloom earlier than others.

By the age of 6-12 yrs, children have greater strength, physical ability and coordination. Their balance and rhythm are also refined. By the age of 12, males have greater strength, endurance and agility, while females have greater flexibility and gracious movement. Children have lower oxygen consumption compared to adults. They have a great amount of local fatigue of muscle, a limited attention span and a low threshold for discomfort.

Adolescence

Children have lower anaerobic capacities than adults including the following:

• Anaerobic Activity
  The total amount of energy available to perform work in the absence of oxygen is referred to as the anaerobic capacity of the body.
  
  
• Capacity to Buffer Acidosis During Excercise
  Acidosis is a term applied to the lowered alkali reserve in the body which results from strenuous muscular exercise.

Thermoregulation

Children have difficulty in cooling, for they have great energy expenditure and lower sweat rates. They are at greater risk for hypothermia than adults, as the high surface area to body mass ratio can accelerate heat loss. When children are overheated, water is critical.

Strength Training for Kids_

It is only in the past 15 years that strength-training has been proven a safe activity for older children (ages 7-12 yr).

Children will not bulk but experience neural adaptations and better coordination of agonist and antagonist muscle groups. Motor unit activation and lean body mass will increase with fiber type differentiation.

Children should be monitored closely, since they are physiologically immature. Performing an optimal range of motion of multi-joint exercises is critical. The primary focus is learning proper technique and breathing. Ballistic movements, such as power lifting and bodybuilding should be avoided.

The American College of Sports Medicine recommends children weight train 20 to 30 minutes on 3 non-consecutive days per week. They should perform one to two sets of eight to ten repetitions of eight to ten different exercises. Rest intervals should be one to two minutes. As weight training is an excellent activity for children, it is essential that they are engage in other physical activities as well.

Children are more aerobic than any other time in life. They have a higher activity of aerobic enzymes and number of Type I muscle fibers than adults. Type I or ‘slow-twitch’ muscle fibers are responsible for long-duration, low intensity activity such as jogging, cycling, or any other aerobic activity.

Between the ages of five and 20 years, the number of Type II muscle fibers increase by 50%. Type II or ‘fast-twitch’ muscle fibers (divided further into A and B) are responsible for short-duration, high intensity activity. Type IIA fibers are designed for short to moderate duration of moderate-to-high intensity work, as seen in most weight training activities. Type IIB fibers are built for explosive, very short-duration activity such as Olympic lifts.