Many of us grew up in a time when fitness was all about cardiovascular endurance. As youngsters, we were encouraged to perform volumous cyclic activities like running, cycling and swimming as means of conditioning for sport or for general fitness adaptations. These recommendations came regardless of chronological age, physiological age, structural differences, psychological development and individual functional efficiency. If you wanted to be fit, you had to be performing aerobic exercise. There was little regard for other physical stimuli. Unfortunately, this dogma continues to permeate the youth fitness industry today. This article will review the key components of fitness as it relates to our children.

Strength Training

It was believed for years that strength training in pre-pubescent children was futile due to a lack of circulating androgens in these youngsters (24, 26). Current research has been effective in overcoming this myth. There is a large body of evidence to suggest that resistance training in children is not only safe but also quite effective (9, 10, 11, 24, 26). Much of the research suggests that children respond better to higher repetitions (12-15) than lower repetition protocols (6-8). However, before accepting all this research for factual evidence, we must consider how the majority of this research is being conducted and measured.

The fact that children respond more positively to higher repetition protocols can be misleading as most of these studies were conducted on beginners, children with no previous resistance training experience. It has been well established that beginners respond better to higher repetition brackets initially due to the degree of motor learning involved in the movement (often the same movements being used to test) (6, 12, 14, 27, 29). That is, the majority of strength gains in the initial stages of a resistance program are associated with increased efficiency of the nervous system (i.e., increased inter and intramuscular coordination). Therefore, the only conclusion we can draw from these studies is that higher repetition brackets demonstrate greater increases in strength in young children with no previous training history. Would the results be different if the nervous system was already efficient in these motions?

The vast majority of research conducted on children’s strength training makes use of machines designed for adults (26). These same machines are often used to measure the outcomes of the studies themselves (i.e., test exercises). While the results demonstrate increases in local strength, they can not be used to draw conclusions on the children’s functional strength and efficiency. This is simply due to the fact that machine-based training provides a fixed axis of rotation and requires little input from our stabilizers. Muscles that generally work synergistically to produce functional movement are exercised in isolation. Over time, this will have a detrimental effect on the natural force couple relationships and significantly decrease functional efficiency. Therefore, the fact that these children are getting stronger in these studies demonstrates that strength gains are possible in children, but they can not be extrapolated to suggest that these children are “more fit” – particularly from a functional standpoint. Functional efficiency is a critical component of the long term health and fitness of a child and should be prioritized above and beyond strength adaptations in isolated movement patterns.

This research demonstrates a fundamental problem with the way we think about strength training in relation to children. We must get away from thinking about strength training in relation to specific muscular changes or isolated strength gains. Instead, we must recognize the benefit of strength training from a motor skill and movement pattern perspective. Protocols that focus on mechanical efficiency in gross movement patterns have demonstrated lasting benefits in functional efficiency (1, 4, 6, 7, 20, 24, 28). Strength training in prepubescent children must focus on the development of general motor skills such as lunging, bending, pushing and pulling (4, 5, 6, 7, 20, 21), the goal of which is to develop sound motor skills and optimal movement coordination. These adaptations will contribute to long term musculoskeletal health, fitness and performance.

Energy System Training

The same can be said for energy system training (i.e., aerobic vs. anaerobic). Contrary to popular belief, the focus should not be placed on anaerobic activities (4, 5, 20) as opposed to building the “aerobic base.” Research has concluded that children’s physiology is not sufficiently developed to differentiate specific adaptations from various energy system training. That is, aerobic exercise has been proven to alter anaerobic performance factors of force and power (2, 3, 13, 23). The anaerobic approach shifts the focus to quality above quantity, thereby avoiding the inherent risk of developing poor movement patterns and ingraining suboptimal neural pathways that, according to the above research, produce non-specific adaptations (20).

“Exercise capacity and aerobic power increase gradually throughout childhood,” according to a paper published by Borms (8). He found that an increase in VO2 max (a measure of the ability to uptake oxygen - a common adaptation from endurance training) was unchanged in children aged 10 years or younger. He further concluded that the “trainability” of endurance was largely dependent on biological maturity, and endurance adaptations in children following puberty were consistent with those found in adults. Based on the above research, it would seem that long duration cardiovascular training is an unnecessary component in youth fitness programs. Still, the aerobic dogma permeates today!

The anaerobic approach also stresses the importance of technique at a very young age and contributes to a greater understanding of the training process as the athlete matures (20). Children do not have the strength-endurance to maintain functional efficiency in complex cyclic activities such as running over long durations. Running is a complex motor task involving intricate neuromuscular coordination. Their ability to maintain postural efficiency and segmental stability is negligible until they develop a general strength base. You must have strength prior to building the capacity to endure it (20)! Therefore, exercises that challenge the strength and coordination of these young athletes should be prioritized above the more metabolically driven stimuli.

Flexibility Training

Of equal concern is the way in which flexibility training is being handled in our youth. Despite the fact that young children are already quite flexible by nature (4, 6, 7, 16), they are constantly being encouraged to engage in long duration static stretching. Have a look at the movement patterns of a young child; it is nothing for them to get down on their haunches in a full squat position. Their bodies naturally drop into that position with ease. Generally speaking, flexibility is maintained until the latter prepuscent stages (ages 10-12) (4, 7), at which point they will slowly begin to decline – particularly around the hips and shoulders (13).

General flexibility is easily maintained throughout the prebuscent stage with dynamic activities like deep BW squats, deep BW lunges, high knees, high knee skips, buttkickers, shoulder circles, hip circles, trunk rotations and body circles. These movements promote active flexibility which relies heavily on motor control, proprioception and range of motion. Dynamic movements that encourage coordination, synchronization and balance are also recommended in the prebuscent stage; an example is shoulder circles with contralateral (opposite side) hip circles. This approach works to maintain natural flexibility and improve general athletic qualities.

It is also becoming common practice to involve our young children in Yoga and other specialty classes of the like. Once again, there are some fundamental issues with this approach. Children are full of energy – they were meant to move and explore their bodies in large dynamic ranges of motion that encourage flexibility, strength and proprioception. Their nervous systems have not developed to the point that they can handle the fine motor skills involved in many of these classes, and they simply do not have the mental focus to handle long duration static stimuli. The focus should instead be placed on dynamic flexibility exercises that encourage active range of motion, strength through range, coordination and proprioception.

As with anything in the fitness industry, there are exceptions to every rule. There are times when a corrective flexibility program including static, PNF and active isolated techniques will be called for in prebuscent children. Take for example a 10 year tennis player and alpine skier I recently assessed. This young athlete demonstrates the classic signs of pronation distortion syndrome (33) with associated frontal plane pelvic imbalance and minor scoliosis. These imbalances developed secondary to an acute foot injury (4 broken metatarsals) when the child was five years old and have been exacerbated by his movement patterns on court. There is an obvious movement impairment around the ankle and foot on the previously injured side that will require a corrective strengthening and repatterning approach. A multidisciplinary flexibility protocol is also called for in this case to address the isolateral imbalances, particularly around the pelvis, hips and trunk. The point is, when dealing with prebuscent children that demonstrate significant structural imbalances outside those associated with a child’s development, the flexibility protocol will have to be modified in recognition of those needs.

Static stretching and specialty classes like Yoga and Pilates can be introduced in the pubescent and post pubescent stages when the maintenance of range of motion is becoming increasingly challenging. Focus should be placed on stretching the restricted tissues and strengthening the positionally weak muscles in an effort to encourage the development of structural and functional efficiency. It should be noted that the adult model of body posture should not be applied to children (16, 25). Their bodies will demonstrate natural postural deviations throughout the developmental process. For example, children will demonstrate a significant lordosis primarily due to common movement patterns in early childhood (34). Aggressive stretching methods to correct these issues can cause significant damage to the joint structures. Anyone working with this population is encouraged to educate themselves on the natural postural development patterns of children so they are better able to decide whether intervention is required.

Conclusion

Working with developing young children can be a daunting task for coaches, trainers and parents due to the individual rates of maturation, structural development and functional efficiency. Children will experience physiological changes such as growth spurts and puberty at different ages (i.e., physiological age).

Throughout this development, their bodies will often feel foreign to them and they may experience difficulties with balance, coordination, strength and flexibility (16, 20). These physical qualities must be challenged in a manner that creates success for these individuals. Exercises and drills must be programmed in a manner that recognizes the individual needs of each child at their relative stage of development.

The number one rule to creating lasting success from young people’s fitness protocols is – keep it FUN! Consistency is the key to any successful fitness program, and keeping it fun has been proven to increase adherence over the long term (31, 32, 35).

Practical Application

Coaches, trainers and parents must consider chronological age, physiological age, individual structural development, psychosocial development and functional efficiency when designing exercise protocols for children. While the relevance of each of these factors is beyond the scope of this article, some generalizations are presented below.

Pre-Pubertal

• Energy system stimulus should concentrate on anaerobic activities such as short distance speed work focusing on coordination, agility and the development of running technique (4, 5, 20). Children must learn proper running mechanics and changes in direction over short distances prior to introducing longer duration aerobic work. This approach will significantly reduce the incidence of injury secondary to faulty motor sequencing. Coaches should aim to slowly progress the intensity of the exercise as ligament strength is still developing and bones are still calcifying (4, 7).
• Strength work should focus primarily on gross movement patterns that challenge strength and balance. These movements have a high degree of motor coordination and therefore contribute greatly to active flexibility and movement efficiency. Children should be taught to optimize movement mechanics and build motor control and joint stability around every joint in the body; however, fine motor skills should be avoided as their neurological systems and cognitive abilities are not developed enough to handle them (4).
• Children should be encouraged to develop balanced levels of overall flexibility in gross movements designed to increase active range of motion and proprioception. These kids were meant to move, so flexibility should focus on dynamic flexibility that exercises their bodies through large ranges of motion. Focus on movement patterns around the hips and shoulders as these areas will demonstrate limitations as the child progresses toward puberty (13).
• Children that participate in multiple sports have a tendency to develop balanced motor skills (4, 7, 18, 30, 35). Therefore, our youngsters should be encouraged to participate in multiple sports that initiate fitness adaptations naturally.
• Coaches, trainers and parents must look for opportunities to create success in the training arena and in sport for these young children. The development of their self esteem relies on it. So focus on fun, non competitive activities that offer opportunities to teach valuable life lessons such as teamwork, fair play and respect (31).
• All modes of training should prioritize variety as prepubertal children will lose focus quickly (31).

Pubertal

• Throughout puberty, the focus on movement efficiency and motor control is maintained as their functional efficiency can be significantly challenged during a growth spurt. Proprioception and kinesthesia, particularly the qualities of spatial awareness, motor coordination, balance and kinesthetic differentiation will be challenged. What was once a fairly simple drill or exercise can become quite challenging for them as they reacquaint themselves with their new body. A prudent coaching tactic at this point is not to introduce new stimulus, instead focus on re-patterning the already familiar movements (13).
• Growth spurts coupled with social and emotional development can set off structural aberrations; therefore, a strong focus should be placed on body posture and muscle balance.
• Static and dynamic balance can be challenged through ground-based exercises. Stability-based equipment (wobble boards, rubber discs etc.) should be avoided as children this age do not have the proprioceptive control or the segmental stability to handle them.
• Neurological development permits the use of fine motor patterns within the confines of the athlete’s cognitive development (4, 7, 8).
• The anaerobic approach can slowly shift toward longer duration exercise; however, a strong focus on technique must be maintained throughout (4, 5).
• Flexibility training should slowly shift toward longer duration structured stretching such as static, modified PNF techniques and active isolated stretching. Some dynamic flexibility should be maintained as well; this will often form the majority of a quality warm up (13, 14, 16, 18, 20).
• Recognition of the physiological changes on psychosocial development is very important throughout this stage.

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