Brian Grasso, CEO of the International Youth Conditioning Association, travels extensively throughout the world as a guest lecturer on the topic of youth athletic development and fitness. You can find dozens of free articles, sample programs and resources on his Web site, www.DevelopingAthletics.com.

As the youth fitness market continues to expand and opportunities for personal trainers to work with kids ranging from ages 6 to 18 grows, fitness professionals must understand the science and application of training this unique demographic, including how it differs from working with adults.

Aerobic-based training is somewhat of a contentious issue these days. Many pundants say it is a necessary piece of the adult "fat loss" puzzle while others disagree, arguing that diet and strength training are the causative factors for effective weight management.

One thing that cannot be debated, however, is the health benefits associated with aerobic-based training. The efficiency of the heart and lungs to circulate oxygen throughout body cells and tissues is a critical factor for promoting health and staving off illness and disease.

The reality of working with young people, however, is that the biomotor improvements you are trying to create must be held in context with the veracity of human growth and development. Unlike adults, children and teenagers are experiencing significant changes as they approach and ascend through puberty. These changes involve structural, neural and muscular-based developmental patterns. Through the phase of peak height velocity, for example, bones are growing quickly and placing the corresponding musculature under considerable strain. This growth results in the common diffuse pain that many young teenagers feel through prominent joints, such as the knees and hips. Standard adult-based aerobic training, such as running or jogging, becomes contraindicated due to the laborious repetitive pounding these exercises place on the very same joints which are currently under tension. Non-impact forms of aerobic exercise, such as Spinning, are equally contraindicated but for a different reason.

An important consideration with respect to the issue of human growth and development involves neural maturation. Starting from birth and extending through adolescence, the human central nervous system is a highly evolving system that is constantly learning and being enhanced via physical experiences.

The ability of the central nervous system to continually learn and evolve with ease is a state specific to the ages between birth and the mid-teens. During this time frame, the central nervous system is said to have high amounts of plasticity. Plasticity, or adaptability, infers that the central nervous system is craving new stimulus, and when that stimulus is encountered, it will be able to retain it as a skill for life.

For that reason, personal trainers must understand that static or stationary forms of aerobic training, while adequate from a pure health benefits perspective, are actually limiting — if not detrimental — to the craving-physical-stimulus state that children and teens are in.

Simply stated, kids need to move, and they need to move in functional ways that promote multi-directional and multi-planar forms of body interaction. This integrative form of aerobic training is critical for ensuring that children and teens experience the right kind of stimulus related to filling their central nervous systems with high quality and diverse movement skills that will become talents for a lifetime.

Rather than just relying on the basic aerobic training equipment housed in your local health club, think outside the box by creating fun, interactive and movement-oriented drills that challenge the aerobic capacity of your young clients.

Here are some examples:

1. Obstacle Courses.
Create an obstacle course that involves various movements, such as crawling, running, throwing, hopping, jumping, skipping and climbing.

Have your young clients navigate through the course at different speeds and using different paces. This interval-style participation serves as a wonderful form of aerobic training.

2. Relay Races.
If you are working with groups of young clients or athletic teams, this is a fantastic way of increasing the aerobic base of your participants while having a great time.

Be sure to incorporate varying movements into your races — don't stick to the basics of running. Lunge walks, sideways walks, one-legged hops — use your imagination and keep your young clients working in very functional ways.

3. Jump Rope Games.
Using a jump rope doesn't have to mean that you just jump in place. Skip Loop, for example, is a great game that promotes central nervous system development as well as quality aerobic development.

Have your young clients jump/skip using a basic two-foot pattern. But rather than jumping in place, have them move forward, traveling roughly 20 to 25 feet. At that point, they can turn around and jump back to where they started using the same or a different jumping pattern.

These types of aerobic training styles are incredibly effective and are much more developmentally sound for the young client than most standard adult-based health club aerobic activities.