The benefits and possible detriments of resistance training have been noted extensively in the literature. Although the benefits of resistance training are well known, many professionals fail to heed scientific advice or follow appropriate recommendations for resistance training in adolescents. When developing a resistance training program for adolescents, be cognizant of any pre-existing health conditions and experience level of the adolescent. For strength training, the adolescent should begin with exercises that involve all major muscle groups with relatively light weight, one to three sets of 6 to 15 repetitions, 2 to 3 non-consecutive days per week. As the adolescent becomes more experienced, gradually increase loads and add multijoint exercises. Each exercise session should be properly supervised for safety, and to provide feedback on technique and form, regardless of the resistance training experience of the adolescent. This article reviews the guidelines for resistance training for health-related fitness for adolescents.
The term resistance training (RT) refers to a method of physical conditioning that uses progressively increasing resistive loads and various training techniques to achieve desired muscle strength, power, muscle hypertrophy, local muscular endurance, or a combination thereof ( Table 1 ). Various techniques are used in RT to increase work demands of the muscles ( Table 2 ). Often, the terms resistance training, strength training, weight training, and weight lifting are used interchangeably and inappropriately. Strength training is one of the specific goals achievable through various RT techniques. Weight lifting is a competitive sport that includes the snatch and clean and jerk lifts, not recommended for adolescents. Similarly, participation in competitive power lifting and body building is not recommended for adolescents.
| Strength | Maximal force that a muscle or muscle group generates at a specific velocity of movement |
| Power | The rate (how fast) a muscle or group of muscles can perform a given task. (Power = work/time; work = force exerted on an object × the distance the object moves in the direction in which the force is exerted) |
| Hypertrophy | Increase in the size (cross-sectional area) of the muscle; primarily results from hypertrophy of muscle fibers |
| Local muscular endurance | The ability of a muscles or muscle group to continue to perform contractions against a submaximal resistance |
| Techniques | Examples |
|---|---|
| Load-bearing exercises | Climbing |
| Specific bodyweight exercises | Curl-ups, press-ups, jumping, hoping |
| Use of resistive materials | Stretch or elastic bands of various resistance, weight machines, free weights |
RT is recommended as an integral component of any regular exercise program. The design of a RT program depends up on the specific goals of RT. The goal of a RT program can be to improve muscle strength, increase power, increase muscle bulk or size, enhance muscle endurance, or a combination of any of these goals. A RT program that is specifically designed as part of sport-specific training and conditioning takes into consideration the relative aerobic and anaerobic demands of the sport, and relative importance of achieving muscle strength, power, muscle hypertrophy, or local muscular endurance. Therefore, sport-specific training and conditioning is more complex, and the training program should be designed and supervised by appropriately qualified professionals. This article reviews the general recommendations for RT for health-related physical fitness. Health-related physical fitness generally consists of various aspects of regularly recommended exercises that result in good health. In addition to RT, other components of health-related physical fitness exercises include aerobic exercise, flexibility exercises, and stretching. The discussion here focuses on adolescents aged 13 to 18 years who have reached Tanner stage 3 and above.
Safety of resistance training
If appropriate for the emotional and developmental stage, RT poses minimal risk of injury to adolescents. Some studies have reported injuries resulting from RT; however, these are minor or occurred as a result of improper load or exercise technique. Although there are acknowledged risks with RT for adolescents, these risks are no greater than the risks of participation in sport and recreational activities. Injuries reported in RT do not occur any more frequently in youth than in adults. Zaricznyj and colleagues reported that RT accounted for less than 1% of all injuries, while football and basketball accounted for 19% and 15% of injuries, respectively.
Injuries from RT to growth plates, articular cartilage, and apophysis remain a concern in children and adolescents, because these areas are relatively weaker and therefore more susceptible to injuries from excess stress. The likelihood of growth plate or cartilage damage may be higher in adolescents than in preadolescents, because the growth cartilage is more resilient to shearing forces in preadolescents. Although the potential risk of injury to growth cartilage may exist, RT has not been shown to adversely affect skeletal growth or maturation in adolescents.
The potential for soft-tissue overuse injuries is also a concern in adolescents. Overuse injuries associated with RT in adolescents are not adequately documented; however, the incidence of lower back pain in adolescents is significant enough to warrant concern. A properly designed RT program that focuses on strength and flexibility may help alleviate lower back pain.
Most published reports suggest that the benefits of RT in adolescents far outweigh any concerns for potential injuries. The use of weight machines, elastic bands, or body weight all have been shown to be effective in RT. Resistance training in children and adolescents has been shown to increase strength by 13% to 30%. In addition to improved physical fitness, a well-designed RT program can contribute to improved psychosocial well-being and help establish and promote beneficial exercise habits at an early age.
Properly supervised RT is an integral component of health-related and sport specific training and conditioning. RT can be initiated at almost any age for children as long as they are emotionally and physically ready to undertake such a program—generally 7 to 8 years of age. Supervision and instructions should be provided by qualified professionals who have training and background in RT techniques and an understanding of the unique needs, both physical and psychological, of children and adolescents. Supervision should include feedback about form, speed of movement, breathing techniques, and proper lifting or performing the movements. Instructions in developing correct resistance training techniques will assist adolescents in achieving RT goals, limit the potential for injury, and promote program adherence. In instances where instruction in complex techniques is included, more than one supervisor may be needed, thereby increasing the supervisor-to-adolescent ratio in the weight room. Supervisor or instructor to adolescent ratios of 1:10 to 1:25 can be appropriate, depending upon the complexity of exercises and the maturity of the adolescents being supervised.
Evaluation before starting RT
Before starting RT, the adolescent should be evaluated to identify any medical conditions that may require appropriate modification of the RT program. History should include information about nutrition and use of supplements such as creatine and drugs such as anabolic–androgenic steroids.
It is important to assess the physical, cognitive, and psychosocial developmental status of the adolescent. The adolescent should have realistic expectations from RT. The adolescent should understand that to achieve the desired goals of RT, exercises need to be done on a regular basis for a long period of time. The adolescent should understand the importance of correct form and techniques of RT exercises and appropriate supervision and guidance by qualified professionals should be provided to reduce the risk of injury and to progress toward desired goals.
Before beginning an RT program, it is essential to ascertain the adolescent’s RT status, so as to design a program that matches the adolescent’s experience and current physical fitness. Adolescents can be placed into one of three groups based on their previous level of RT experience: novice or beginner, intermediate, and advanced. Novices or beginners are adolescents with limited (<2 to 3 months) to no resistance training experience; adolescents in the intermediate group are those who have had approximately 3 to 12 months of training experience. Adolescents with 12 or more months training experience are considered advanced. When determining the exercises for the RT program, it is imperative that the exercises are appropriate for the adolescent’s physical development, fitness level, and RT status.
Evaluation before starting RT
Before starting RT, the adolescent should be evaluated to identify any medical conditions that may require appropriate modification of the RT program. History should include information about nutrition and use of supplements such as creatine and drugs such as anabolic–androgenic steroids.
It is important to assess the physical, cognitive, and psychosocial developmental status of the adolescent. The adolescent should have realistic expectations from RT. The adolescent should understand that to achieve the desired goals of RT, exercises need to be done on a regular basis for a long period of time. The adolescent should understand the importance of correct form and techniques of RT exercises and appropriate supervision and guidance by qualified professionals should be provided to reduce the risk of injury and to progress toward desired goals.
Before beginning an RT program, it is essential to ascertain the adolescent’s RT status, so as to design a program that matches the adolescent’s experience and current physical fitness. Adolescents can be placed into one of three groups based on their previous level of RT experience: novice or beginner, intermediate, and advanced. Novices or beginners are adolescents with limited (<2 to 3 months) to no resistance training experience; adolescents in the intermediate group are those who have had approximately 3 to 12 months of training experience. Adolescents with 12 or more months training experience are considered advanced. When determining the exercises for the RT program, it is imperative that the exercises are appropriate for the adolescent’s physical development, fitness level, and RT status.
Components of an RT program
Proper warm-up and cool-down periods, level of intensity, frequency of training sessions, order of exercises, volume of exercise, and rest periods are main considerations in designing a RT program. RT programs for adolescents also should include specific educational objectives, instructions in weight room etiquette, and desired performance outcomes.
Warm-up
Warm-up consists of movements that prepare the body before the desired activity. A warm-up period is recommended to increase the range of joint motion, raise body temperature, and enhance awareness of body position. The warm-up period usually consists of two phases: general and specific. The general phase consists of 5 to 10 minutes of general activities to increase the heart rate, muscle temperature, and respiratory rate, and decrease joint viscosity. The specific warm-up consists of activities similar to the movements performed during the resistance training exercises, lasting for approximately 8 to 12 minutes. Dynamic activities during the warm-up period have been shown to assist in enhancing power performance for youth.
Cool-down
The cool-down period occurs after the exercise session and consists of dynamic exercises similar to the warm-up period. The aims of the cool-down period are to facilitate the elimination of waste products from the muscles, and to return the heart rate and respirations to preactivity levels. In addition, a cool-down period should include a flexibility component that includes static stretching. Stretching exercises after activity can increase flexibility while increasing performance and reducing the risk of injury over the long term. Typically, the cool-down period lasts approximately 5 minutes and is also an appropriate time to reflect on the day’s activities and focus on training objectives for future exercise sessions.
Order of Exercises
Generally, the exercises selected should start with single-joint, simple movements and progress to multijoint and complex movements. Progression to the complex exercises should be based upon demonstration of proper exercise technique, confidence, and attainment of goals and objectives. In more experienced adolescents, multijoint exercises, performed using proper techniques and lower weights, can be initiated in early exercise sessions. Within a training session, large muscle groups typically should be exercised before small muscle groups, while multijoint exercises should be performed before single-joint exercises. This pattern helps reduce the risk of injury by stressing neuromuscularly demanding exercises at the beginning of a session when fatigue is minimal.
Load or Intensity
The training load refers to the amount of weight lifted for that specific resistance exercise. As the load becomes heavier, the number of repetitions decreases. Conversely, more repetitions can be accomplished with lighter loads. The load usually is described as a percentage of 1 repetition maximum (1 RM) or as the maximum weight lifted in 1 repetition. The weight should be lifted through the entire joint range of motion. The use of a 1 RM to determine the load is more appropriate for experienced resistance trained individuals, whereas, a 5 RM or up to 10 RM method is preferred for less experienced individuals and adolescents. Determining the RM depends upon the goals and demands of the sport.
Another method used to determine the percent of maximum load lifted during an exercise session is the RM equivalent. The RM equivalent is calculated as : RM equivalent = (weight lifted × number of reps × 0.03) + weight lifted. For example, an RM equivalent for an adolescent who lifted 125 lb during an inclined bench press exercise a total of 8 times would be calculated as: (125 × 8 × 0.03) + 125 = 155. Although not as accurate, the RM equivalent procedure may be best suited for inexperienced adolescents.
The relationship between possible RM and percentages of 1 RM varies with the amount of muscle mass needed to perform the exercise (eg, a leg press requires more muscle mass than a knee extension). Because different muscles or muscle groups exert different amounts of force depending up on their mass and strength, the load for a given number of repetitions can vary depending upon the muscles or muscle group involved in a particular exercise. The velocity of muscle contraction, that is how fast or slow a muscle contraction is achieved, during dynamic muscle action is inversely related to the exercise load during maximal muscle contraction. The velocity of muscle contraction affects the neural, hypertrophic, and metabolic adaptations to RT exercises.
Sets and Repetitions
Repetitions refer to the number of times a weight is lifted in a set; conversely, a set consists of the number of repetitions performed between rest periods. In RT programs, the number of repetitions and sets are manipulated according to the goal of the RT and desired outcomes for the adolescent. The number of sets and repetitions may vary for different muscles or muscle groups. For example, it generally is recommended that adolescents perform three sets of six to eight repetitions for multijoint exercises, and two sets of 10 to 12 repetitions for single joint exercises. Generally, multiple sets of RT exercises have been shown to be more effective than single-set exercises. The number of sets and repetitions do not have to be the same for all muscle groups or exercises.
Frequency
The term training frequency refers to the number of training sessions completed in a given time period. Training frequency depends upon the experience, maturity, and training status of the adolescent, and sport or outcome requirements. Adolescents should begin RT with one to three sessions a week on nonconsecutive days. As the adolescent becomes more experienced, sessions can increase up to three times per week, but the load and rest periods may need to be manipulated for optimal recovery between sessions.
Rest between two RT sessions should not exceed more than 3 days. A split-routine regime allows for more frequent RT sessions. In a split routine, exercises involving different muscles or muscle groups are performed on different days. Exercises can be divided, for example, into upper body and lower body, in which upper body exercises are done on days 1 and 3, and lower body exercises are done on days 2 and 4. Similarly, exercises can be divided as push exercises (bench press, triceps extension) or pull exercises (lat pull down, biceps curl) and done on different days of the week.
Factors such as training volume, exercise intensity, exercise selection, nutrition, and sleep habits should be taken into consideration when determining the optimal recovery period between RT sessions. As the number of training sessions increases, attention should be given to maintaining appropriate training habits, with less intense workouts interspersed throughout the week.
Rest Periods
The duration of rest periods between sets varies according to the specific goal of the RT, load lifted, and training status of the adolescent. For adults, the duration of rest periods between sets varies from 2 to 5 minutes for multijoint exercises, depending upon the goal of the training. The duration of rest periods in adults may not be applicable to adolescents, however, because of differences in maturity, growth, and development. Studies have shown that adolescents may recover more quickly than adults for high-intensity, short-duration exercises. Rest periods of approximately 1 to 3 minutes may suffice in adolescents for moderate-intensity RT depending upon the goal of resistance training.
Volume of Exercise
The volume of exercise refers to the total amount of weight lifted during an exercise session. Volume or load volume equals the total number of sets multiplied by the number of repetitions per set multiplied by the weight lifted per repetition. If each set is performed using a different weight or load, the volume is calculated for each set, and then the volume for each set is added to obtain the total volume of the exercise session. Thus, the volume of the exercise session can be manipulated by altering number of sets, number of repetitions per set, or weight lifted per repetition. Variation in training volume is essential during long-term training for those who are more advanced in their training. Constant-volume exercise sessions may result in staleness and decreased adherence to training.
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