Strength Training Considerations for Youth

By

Randy W. Dreger, MSc, CSCS

Instructor, School of Health Sciences, Personal Fitness Trainer Program

The Northern Alberta Institute of Technology (NAIT) 11762 – 106 Street, Edmonton, Alberta, T5G 2R1 Phone: (780) 491-3098 Fax: (780) 471-7614 E-mail: [email protected]

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Introduction Resistance training for children has become very commonplace with a number of programs incorporating some form of resistance training into their curriculum. Programs such as summer camps, sport schools, and fitness centers are providing this type of training. As fitness professionals it is imperative that one understand the risks and benefits, underlying physiology, and training guidelines in order to safely and effectively develop resistance training programs for youths.

In this article youth will be defined as the period of life that includes both the prepubescent and adolescent (typically, 7 to 16 years of age). Resistance training will be defined as a form of conditioning that is used to increase one’s ability to exert force (typically referred to as strength). Although there are a number of modalities that fall under the broad category of resistance training, free-weights and weight machines will primarily be discussed in this article.

Benefits of Resistance Training Aside from an increase in strength there are a number of health and wellness benefits that are associated with resistance training, children. This section will describe the scientific findings associated with theses benefits.

Increased strength One of the main reasons for resistance training is to gain strength. There is plenty of evidence showing enhanced strength in children when engaged in resistance training, beyond the results of normal growth and maturation. Typically, a 30 to 50% increase in strength is found when children participate in a structured, supervised resistancetraining program from 8 to 20 weeks. However, one study demonstrated a 74% increase in strength after only 8 weeks of training (Faigenbaum et al., 1993). In another investigation (Ramsay et al., 1990), strength increased substantially in both the upper- (35% increase in 1 RM bench press and 60% increase in 1 RM elbow flexion) and lower-body (22% increase in 1 RM leg press). More recent studies continue to find similar results in strength gains after 8 weeks of resistance training among adolescents (Tsolakis et al., 2004). Clearly, resistance training can increase the strength of a child. 2

Sport Performance Sports such as gymnastics, hockey and basketball involve speed, power, and strength. In the adult literature, there is evidence demonstrating improved sport performance due to strength training intervention. Logically, it would seem the same would hold true for youths. However, the effects of resistance training on sports performance during pre pubescence and adolescence are less clear. Studies have shown both an improvement (Blanksby and Gregor, 1981; Queary and Laubach, 1992) in performances (swimming and gymnastics) as well as no (Ford and Puckett, 1983) improvement (basketball). Thus, resistance training to enhance sport performance among children is tenuous, and thus sport-specific skills should be the primary form of enhanced performance.

Injury Prevention Similar to adults, youths can benefit from the protective effects of strength training. One study showed a decreased number and severity of knee injuries in high school football players after a preseason-conditioning program (Cahill and Griffith, 1978). In another investigation, Hejna et al. (1982) examined injury rates for high school male and female athletes. Of the reported injuries, those who performed resistance training accounted for 26.2% compared to 72.4% for athletes who did not perform resistance training. Furthermore, the time required for rehabilitation was only 2.02 days for the strength-trained athletes versus 4.82 days for the non-strength trained. It is quite evident that resistance training is beneficial in the prevention and rehabilitation of injuries and should be a primary reason for such programs.

Health Related Benefits Inactivity among children is a rising trend across North America. Inactivity is associated with a number of health issues including obesity and diabetes. Among children who engaged in weight lifting there was a significant improvement in bone mineralization content (Conroy et al., 1993; Virvidakis et al, 1990), blood pressure (Hagberg et al., 1984), body composition (Faigenbaum et al., 1993) and blood lipid profiles (Fripp and Hodgson, 1987). Improvements in these factors are primarily related to an increased metabolic demand, which supports resistance training as a viable form of healthy activitiy. 3

Risk of Injury There are a number of myths regarding the safety of resistance training children. Most of which has been based upon unspecified hospital visits. Resistance training, as with most physical activities, has some degree of inherent risk for musculoskeletal injury. Yet this risk is no greater than other sports/recreational activities in which children regularly participate. Of the youth resistance training studies found in the literature, only two have reported an injury. One was a shoulder strain (Rians et al., 1987), which resolved itself within one-week, whereas, the other was an undefined “minor” injury (Brown et al., 1992).

In one prospective study that evaluated the incidence of sports-related injuries in school children, over a 1-year period (Zaricznyj et al., 1980), resistance training resulted in 0.7% of all the injuries reported whereas football, basketball, and soccer resulted in approximately 19, 15, and 2%.

Physiological Mechanisms for Strength Gains It is apparent that youths can safely derive a number of health and fitness benefits from resistance training. However, many practitioners are interested in how to design a safe and effective program. To best understand the program variables it is important to know what physiological mechanisms are underlying the strength increases.

A number of studies have shown dramatic increases in strength within as little as 8 weeks of training. This is similar to adult populations. The primary mechanism is an enhanced neural muscular system as there is no evidence showing signs of muscle hypertrophy in children. It is generally accepted that is takes approximately 8 to 12 weeks for morphological changes to occur in the muscle, which might explain why children engaged in short term (8-weeks) resistance training studies do not show muscle hypertrophy. In order to address this issue, Ramsay et al. (1990) resistance-trained children for duration of 20 weeks, they demonstrated significant strength gains without any change in upper arm or thigh muscle hypertrophy. Furthermore, they utilized EMG techniques to examine the neurological

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adaptations showing a trend toward increased motor unit activation, coordination, recruitment and firing rate. In addition, they speculated there were possibly intrinsic muscle adaptations, as evidenced by increases in twitch torque.

A possible reason why children do not show morphological changes in the muscle may be related to inadequate levels of circulating testosterone. Although, a recent study (Tsolakis et al., 2004) demonstrated that resistance-trained boys increased the circulating testosterone levels they did not measure aspects related to muscle mass (hypertrophy).

Training Guidelines It is evident that resistance training is very beneficial for youths. A number of organizations, such as the American College of Sports Medicine, National Strength and Conditioning Association, and the Society for Pediatric Orthopedics endorse the concept of resistance training for children. In doing so, many of the organizations and experts in the field have developed a series of recommendations for the implementation of a youth resistance training program (Table 1). The most common component emphasized in the guidelines is technique, regardless of age or training status. In addition, acute training variables such as sets, repetitions, and rest intervals are also important for the design of a safe and effective training program. Table 2 describes the guidelines for these variables.

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References Blanksby, B. and Gregor, J. (1981). Anthropometric, strength, and physiological changes in male and female swimmers with progressive resistance training. Austral. J. Sport Sci. 1: 3-6.

Brown, E., Lillegard, W., Henderson, R., Wilson, D., Lewis, E., Hough, D. and Stringer, K. (1992). Efficacy and safety of strength training with free weights in prepubescent to early post pubescents. Med. Sci. Sports Exerc. 24: S82.

Cahill, B. and Griffith, E. (1978). Effect of preseason conditioning on the incidence and severity of high school football knee injuries. Am. J. Sports Med. 6: 180-184.

Conroy, B., Kraemer, W., Maresh, C., and Dalsky, G. (1992). Adaptive responses of bone to physical activity. J. Med. Exer. Nut. Health. 1: 64-74.

Faigenbaum, A., Zalchkowsky, L., Westcott, W., Michell, L. and Fehlandt, A. (1993). The effects of a twice per week strength training program on children. Pediatr. Exer. Sci. 5: 339-346.

Ford, H. and Puckett, J. (1983). Comparative effects of prescribed weight training and basketball programs on basketball skill test scores of ninth grade boys. Percep. Mot. Skills. 56: 23-26.

Fripp, R. and Hodgson, J. (1987). Effect of resistive training on plasma lipid and lipoprotein levels in male adolescents. J. Pediart. 111: 926-931.

Hagberg, J., Ehsani, A., goldring, A., Hernandez, D. and Holloszy, J. (1984). Effect of weight training on blood pressure and hemodynamics in hypertensive adolescents. J. Pediatr. 104: 147-151.

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Hejna, W., Rosenberg, A., Buturusis, D. and Krieger, A. (1982). The prevention of sports injuries in high school students through strength training. NSCA Journal. 4: 28-31.

Kraemer, W. and Fleck, S. (1993). Strength training for young athletes. Champaign, Il: Human Kinetics, page 5.

Queary, J. and Laubach, L. (1992). The effects of muscular strength/endurance training. Technique. 12: 9-11.

Ramsay, J., Blimkie, C., Smith, K., Grarner, S., MacDougall, J. and Sale, D. (1990). Strenght training effects in prepubescent boys. Med. Sci. Sports Exerc. 22: 605-614.

Rians, C., Weltman, A., Chill, G., janney, C., Tippet, S. and Katch, F. (1987). Strength training for prepubescent males: Is it safe? Am. J. Sports Med. 15: 483-489.

Tsolakis, C., Vaenas, G. and Dessypris, A. (2004). Strength adaptations and hormonal responses to resistance training and detraining n preadolescent males. J. Strength Cond. Res. 18: 625-629.

Virvidakis, K., Georgiu, E., Korkotsidis, A., ntalles, K. and Proukakis, C. (1990). Bone mineral content of junior competitive weightlifters. Int. J. Sports Med. 11: 244-246.

Wilmore, J. and Costill, D. (2004). Physiology of sport and exercise (3rd edition). Champaign, Il: Human Kinetics, page 529.

Zaricznj, B., Shattuck, L., mast, T., Roberston, R., and Ella, G. (1980). Sports-related injuries in school-aged children. Am. J. Sports Med. 8: 318-324.

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Table 1. General guidelines for youth resistance training. Age (years) 7 or younger

Considerations Introduce and teach basic exercise techniques with little or no weight. Develop the concept of a training session (warm-up, cool-down, sets, repetitions). Progress from body weight calisthenics (push-ups, sit-ups) to lightly resisted exercise. Keep volume low (i.e., 1 exercise per body part).

8 – 10

Gradually increase the number of exercises and training volume. Practice exercise technique in all lifts; keep exercise simple (e.g., bicep curl). Start gradual, progressive loading of exercises, carefully monitoring toleration to the exercise stress (i.e., proper form)

11 – 13

Teach all basic exercise techniques, emphasizing technique. Continue progressive loading of each exercise. Introduce more advanced exercise with little or no resistance (e.g., deadlift, high pull).

14 – 15

Progress to more advanced youth programs in resistance exercise. Add sport-specific components. Emphasize exercise techniques. Increase volume.

16 or older

Move child to entry-level adult programs after all background knowledge has been mastered and a basic level of training experience has been gained.

Modified from Kraemer and Fleck (1993)

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* = increase load when all sets and Table 2. Acute program variables for youth resistance training. repetitions can be completed with correct Training session duration (min)

20 – 30 form.

Frequency (sessions/week)

2–3 Modified from Wilmore and Costill (2004)

Repetitions (per set)

6 – 15

Sets (per exercise)

2–3

Rest between sets (min)

1–2

Rest between exercises (min)

3–4

Load progression (kg)*

0.5 – 1.4

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Strength Training Considerations for Youth: Randy W. Dreger, MSc, CSCS Name: 1.

2.

3.

4.

5.

Address: What is the average strength increase for resistance trained youths? a.

10 to 15%

b.

70%

c.

30 to 50%

d.

25%

Is the main function of strength training youths a.

Improved sport performance

b.

Improved strength

c.

Reduced risk of injury

d.

b and c

Resistance training can cause which of the following? a.

Excessive bone damage

b.

Improved blood lipid profile

c.

Increased cardiovascular fitness

The risk of injury from physical activity is inherent. Based on the literature which activity has the highest incidence of injury? a.

Basketball

b.

Volleyball

c.

Weight lifting

d.

Football

The primary mechanism for strength gain in adolescents is? a.

Neural-muscular

b.

Hormonal

c.

Hypertrophy

d.

Psychological

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6.

7.

Childhood resistance training programs should emphasize this variable: a.

High loads

b.

Low volume

c.

Technique

d.

High frequency

Which of the following would be the most appropriate set of training variables for a 14 year-old with some resistance training experience.

8.

a.

2 sets; 10 reps; 4 times/week

b.

3 sets; 6 reps; 1 time/week

c.

1 set; 15 reps; 3 times/week

d.

3 sets; 15 reps; 3 times/we

e.

ek

Load progression should only be applied when the youth is able to complete all sets and repetitions with correct form. How much of an increase should one use?

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10.

a.

0.5 lbs

b.

0.5 kg

c.

5 lbs

d.

5 kg

The main reason why children do not experience muscle hypertrophy when resistance training is due to? a.

Age

b.

Fiber type

c.

Inadequate circulating testosterone

d.

Neural

Resistance training involves which modalities? a.

Free weights

b.

Machine weights

c.

Calisthenics

d.

All of the above

Please mail finished Exam Attn: Kristin Flewell Provincial Fitness Unit C/o Faculty of Physical Education & Recreation University of Alberta Edmonton, Alberta. T6G 2H9 11