Public health recommendations suggest that children and adolescents should accumulate at least 60 minutes of moderate to vigorous physical activity (MVPA) daily, yet epidemiological reports indicate that most youth are falling short of this recommendation (13,29). The Active Healthy Kids Global Alliance organized the preparation of report cards on the physical activity of youth in 38 countries and reported overall grades for physical activity around the world are D (low/poor) (29). The United States follows global trends, with less than 25% of children and adolescents meeting MVPA goals (14). Due to the extensive health- and fitness-related benefits associated with regular physical activity in youth (23), as well as the harmful effects of excessive sedentary behaviors such as television viewing (2), innovative ideas, creative programs and sustained efforts are needed to spark an ongoing interest in active games, exercise, and sport.
The Active Healthy Kids Global Alliance organized the preparation of report cards on the physical activity of youth in 38 countries and reported overall grades for physical activity around the world are D (low/poor).
In addition to improving aerobic fitness with running games and endurance activities, the importance of developing and maintaining strength fitness should not be overlooked. The term strength fitness became popular decades ago and continues to underscore the importance of developing a strong musculoskeletal system that is prepared for the physical demands of daily life and sport activities (33). Strength fitness is a global term that includes the phenotypes or observable characteristics of muscular strength, muscular power, and local muscular endurance. Because children need a certain amount of strength fitness to move their body to jump, skip, throw, and kick proficiently, fitness professionals should recognize the value of improving strength fitness throughout childhood and adolescence. Without interventions that include strength- and skill-building exercises that enhance strength fitness, current trends in physical inactivity among youth will likely continue and the gap between those with higher and lower levels of MVPA will likely widen across developmental time (21,25).
In this article, the importance of enhancing strength fitness early in life will be discussed to help reverse the troubling trends in youth physical activity. Concerns associated with low levels of strength fitness in modern-day youth will be addressed and the unique health- and fitness-related benefits of integrating strength and skill-building activities into youth programs will be explored. FUNdamental fitness ideas for designing and implementing youth programs that target strength deficits will be outlined in a child-friendly exercise program.
DYNAPENIA FOR KIDS
In addition to the loss of skeletal muscle mass associated with aging (i.e., sarcopenia), neuromuscular factors independent of muscle size contribute to muscle weakness, fall risk, and declining quality of life in older adults (28). Thus, the term dynapenia (dyna = power and penia = deficiency) was proposed to highlight the observable impact of muscle weakness and dysfunction on functional disability and mortality in older adults (3). Yet the life-changing consequences of low muscle strength and poor muscle power are not limited to older populations. Because children and adolescents also are vulnerable to the inevitable consequences of reduced strength fitness, the construct of dynapenia should be expanded to include youth. The term pediatric dynapenia describes an acquired and treatable condition in children and adolescents characterized by low levels of strength fitness and consequent functional limitations not caused by neurologic or muscular disease (8).
Because children and adolescents also are vulnerable to the inevitable consequences of reduced strength fitness, the construct of dynapenia should be expanded to include youth.
Global trends in strength fitness indicate that modern-day children and adolescents are weaker than previous generations. A 10-year study of English children found declines in bent arm hang, sit-up performance and hand grip strength (4), and similar trends were reported in Spanish adolescents (19). Other researchers noted worrying trends in selected measures of strength fitness in schoolchildren from the Czech Republic and Lithuania (20,32). Data from the National Youth Fitness Survey suggests that some measures of strength fitness likely decreased in American youth as well (15). For example, in the late 1980s, the 50th percentile for modified pull-ups ranged from 6 to 10 repetitions, but the present 50th percentile for 6 to 9 year olds in the United States is 2 to 4 repetitions (15). Collectively, these reports suggest that pediatric dynapenia in children is a contemporary corollary of modern-day lifestyles characterized by physical inactivity and a high degree of sedentary behavior.
In regard to the design of youth fitness programs, these findings underscore the importance of enhancing strength fitness during childhood before youth become resistant to interventions later in life. Because muscle weakness at any age predisposes individuals to functional limitations, activity-related injuries, and adverse health outcomes, targeted interventions are needed to enhance strength fitness and alter physical activity trajectories. If children are not exposed to an environment with regular opportunities to enhance their strength fitness, they will be less likely to develop the prerequisite skills and abilities that are needed for ongoing participation in active games and sport activities (12,18).
Years ago, Seefeldt (27) hypothesized that children with poor motor skills would not be able to break through a so-called proficiency barrier and, therefore, would be less likely to acquire mature movement patterns and engage in physical activity throughout the lifespan. At present, however, most modern-day youth seem to lack prerequisite levels of strength fitness that are needed to break through an observable strength barrier that would allow them to catch up with their peers with average or better levels of strength fitness. Regular participation in fitness programs that include resistance training can offer observable health and fitness value to children (7,16,17). The pleiotropic benefits of well-designed and sensibly progressed youth resistance training are shown in Figure 1.
IMPORTANCE OF STRENGTH FITNESS
The general health goal of accumulating at least 60 minutes of MVPA daily seems to undermine the critical importance of developing prerequisite levels of strength fitness that are needed to move and play with energy and vigor. Children who do not develop sufficient levels of muscular strength and movement skill competency may be less efficient jumpers, throwers, kickers and runners on the playground and sports field (11,12,30). Without opportunities to learn, practice, and reinforce desired movement patterns while enhancing strength fitness, boys and girls are less likely to engage in the recommended amount of MVPA and more likely to experience negative health outcomes (7).
Although enhancing the muscular strength and power abilities of young athletes is not a novel concept, concerted efforts are needed to enhance strength fitness in all boys and girls to provide a logical, timely, and evidence-based approach for long-term physical development (16). Yet all too often, contemporary thinking related to the pandemic of pediatric physical inactivity focuses on time spent in MVPA and neglects the foundational importance of strength fitness. In support of this observation, the venerable youth physical activity pyramid for kids places muscle fitness exercises on the second-to-last rung of the ladder below flexibility exercises (5). Although there is value in aerobic games and endurance activities, this model is not consistent with the fundamental needs and physical abilities of modern-day youth. As illustrated in Figure 2, strength is the staple that holds other fitness components together. That is, without adequate levels of strength fitness, it is unlikely that children will be able to optimize performance gains in other important components of physical fitness. Observing children in a beginner gymnastics class or martial arts program supports the premise that adequate levels of strength fitness are needed to move with style, grace, and precision.
Strength is the staple that holds other fitness components together.
Because children with low levels of strength fitness often lack confidence and competence in their abilities to participate enthusiastically in physical education and after-school sports, fitness professionals should recognize the potential benefits of exercise training that is purposely designed to improve strength fitness. Developmentally appropriate exercise interventions that target strength deficits are needed to prevent the accumulation of risk factors, functional limitations, and pathological processes that may eventually appear. In the long run, children who participate regularly in strength- and skill-building activities will be better prepared for physical activities and more eager to learn more complex movements and sport skills.
FUNDAMENTAL INTEGRATIVE TRAINING
Children are less mature than adults, and therefore, training programs designed for older populations are typically inappropriate and potentially unsafe for youth. Although enhancing aerobic fitness and improving body composition are notable goals for exercising adults, most children simply want to have fun, make friends, and learn something new. This is where the art of designing youth programs comes into play because the principles of pediatric exercise science need to be balanced with games and activities that are engaging and enjoyable. Watching children on the playground supports the premise that the physical activity behaviors of boys and girls are characterized by short bursts of high-energy physical activity interspersed with brief rest periods as needed (24).
Although enhancing aerobic fitness and improving body composition are notable goals for exercising adults, most children simply want to have fun, make friends, and learn something new.
FUNdamental Integrative Training or FIT is a method of conditioning that incorporates developmentally appropriate exercises into youth programs with the aim of improving strength fitness and, in turn, increasing participation in daily MVPA (1,6). FIT provides all participants with an opportunity to enhance their strength fitness while improving their movement vocabulary. By keeping the FUN in FUNdamental, children will have an opportunity to gain confidence and competence in their physical abilities while performing a series of exercises that are challenging, rewarding, and consistent with their physical abilities. With qualified instruction and enthusiastic leadership from certified fitness professionals who understand the physical and psychosocial uniqueness of youth, participants can learn how to perform different strength-building exercises while participating in a program that includes variety, progression, and game-like activities.
FIT does not require expensive equipment. Although medicine balls, elastic bands, punch balloons, and other training modalities can be incorporated into FIT, the exercises are designed so that participants learn how to move and control their own body, which forms the foundation for future participation in context-specific sports and games. This type of preparatory conditioning early in life can help to reduce the incidence of activity-related injuries while encouraging participation in exercise and sport as an ongoing lifestyle choice (21). Because the decline in MVPA seems to begin at approximately 7 years (10), early childhood seems to be an opportune time to intervene with developmentally appropriate exercise interventions that enhance strength fitness and prepare youth for a lifetime of physical activity. Although adolescents can certainly benefit from FIT, concerted efforts are needed to prevent the decline in MVPA that begins early in life. Furthermore, unlike adolescents, most children are not as self-conscious about making a mistake in front of their peers, and young children often are more willing to try new activities and games.
An example of a FIT program is outlined in Table 1. Although there is not a minimal starting age, participants should be able to accept directions and follow safety rules. In general, most 6 and 7 year olds are ready for some type of structured fitness training. However, it is important to remember that the goal of FIT is not just to spend time in MVPA, but rather to teach children how to perform and properly progress different exercises in a supportive class environment. The FIT program in Table 1 consists of a series of animal-like movements that are purposely designed to capture the imagination of the children. Although there are literally hundreds of exercises that can be performed, the program in Table 1 follows a simple progression so participants can experience small successes. Most of the FIT exercises challenge the body to function as a unit instead of separate parts and therefore require participants to use their mind as well as their whole body.
The FIT program includes animal movements because this type of training offers a point of reference for boys and girls who may otherwise be unfamiliar with complex movement patterns and multijoint exercises. For example, the fitness instructor can ask participants how a flamingo stands or how a bunny jumps. This introductory discussion can be followed by a demonstration that highlights proper technique and body position. Linking animal movements with proper exercise technique allows the instructor to “talk the child’s talk” and creatively paint a picture of the desired movement patterns. The game-like approach of this teaching style places an emphasis on having fun, which is an important critical component of youth fitness programs (26).
Each session should begin with approximately 5 minutes of dynamic warm-up activities and calisthenics. Sample dynamic warm-up exercises include high knee marches, arm circles, side steps, and jumping jacks (9). Children can perform FIT exercises in a circuit for a predetermined number of repetitions (e.g., 8 to 15) or time interval (e.g., 30 seconds). Initially, it may be appropriate to start with only a few exercises so children can learn proper technique and begin to understand the concept of a fitness circuit. Over time, new exercises can be added to the program depending on exercise performance and available time. Of note, the primary focus of FIT should not be to complete as many exercises or repetitions as possible but rather, to perform each movement with proper technique and enthusiasm.
At the start of the class and throughout the program, fitness professionals should provide clear instructions and clear demonstrations to reinforce proper exercise technique. Although FIT tends to be engaging because the exercises are challenging, the importance of taking time to teach children something new while offering ongoing support and encouragement should not be overlooked. Because young children are still learning how to move their bodies through space, fitness professionals may need to slow down selected exercises so movements can be performed with proper technique in a controlled manner. Also, before every session, instructors should review program expectations and safety rules (e.g., proper footwear, shoelaces tied, no gum chewing).
Children should receive constructive feedback, which can positively influence skill development, fitness performance and motivation. When offering constructive feedback, address what was seen (descriptive feedback) and identify what changes or improvements should be made (prescriptive feedback). Keep descriptive feedback short and simple so children can easily understand comments and suggestions. For example, during the performance of the swaying cobra exercise, an instructor notices 8-year-old Ricardo is quickly twisting his torso so that he can touch the ground as many times as possible. Instead of telling the child to stop, feedback might sound like this, “Ricardo, I see you twisting your body (descriptive feedback). I want to see you sway like a snake would move (prescriptive feedback). Can you slither or sway your upper body? Much better! Can you make a snake hissing sound while you move? Excellent!” By offering simple, yet specific, feedback along with clear demonstrations of desired movement patterns, instructors can enhance the learning experience, which will ultimately improve performance, motivation, and adherence.
Children can begin with a single set for each exercise at each station, and as confidence and competence improve, they can progress to the next level. Depending on available time and program goals, additional sets of selected exercises (with a 30-second transition period between sets and exercises) can be performed in a circuit manner. Although there is no set order of FIT exercises, it is reasonable to alternate more challenging exercises with less taxing activities. In addition, after several weeks of FIT, children can be asked to create a new exercise at a “mix and match” station. The purpose of this activity is to provide an opportunity for children to apply the skills they learn in a mastery-oriented climate. As children use learned skills to create new animal exercises, they control the type of task engagement and are more likely to overcome challenges that are self-determined. Over time, children will be able to display mastery of learned motor skills on basic exercises and gain new knowledge by performing novel movements on other exercises that require higher levels of strength fitness.
Current trends in physical inactivity among youth highlight the need for developmentally appropriate exercise interventions that build a strong foundation for ongoing participation in free play, exercise, and sport activities. Physically active lifestyles tend to develop early in life, and without adequate levels of strength fitness, it is likely that the gap between those with higher and lower levels of strength fitness will widen throughout childhood and adolescence. Fitness professionals can raise awareness about this important public health concern and champion community efforts to design and implement youth fitness programs that support the integration of meaningful and enjoyable physical activities into the lives of children.
BRIDGING THE GAP
Regular participation in resistance training offers unique health- and fitness-related benefits for children. A well-developed musculoskeletal system is less susceptible to injury, and stronger girls and boys will be better prepared for sport and for life. New insights into the design of youth exercise programs continue to highlight the importance of improving strength fitness early in life by integrating resistance training into fitness programs. A FUNdamental approach to youth fitness training provides an opportunity for all girls and boys to enhance their strength and improve their motor skills while making friends, having fun, and learning something new.
The authors thank Erica Siemer for her graphic art expertise creating Figure 2.
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