By Daniel G. Graetzer, Ph.D.
Faculty Member, School of Health Sciences
Modern society’s demand for greater competitive performances from young athletes poses a controversial question: When and how much should young athletes participate in strength training? Strength training through weight resistance increases athletic performance and strength gains help athletes to avoid injury, especially in sports where explosive power, speed, anaerobic muscle endurance, and quick recovery from tiredness are necessary.
During strength training, the muscles are enlarged (hypertrophy) due to the increased storage of intramuscular proteins actin and myosin in response to stressing muscles. Atrophy (muscle size reduction) due to the depletion of actin and myosin reserves develops when strength training is reduced or stopped.
Competition often motivates unsupervised young athletes to increase the amount and intensity of their strength training. However, this type of training often goes beyond what is safe and beneficial.
Young Athletes’ Strength Training Needs to Be Supervised by a Qualified Adult
Strength training can be effective for everyone from children to the elderly, but it is highly advisable that strength training for young (especially prepubescent) athletes is supervised by a qualified adult. That adult can tailor workouts appropriate to a child’s age and individual stage of maturity.
James Tanner, a British pediatrician, created the Tanner Scale in 1969 to define the stages of physical development in males and females. Prepubescent is defined as boys or girls who have not yet developed secondary sex characteristics, according to Tanner’s classification of physical development.
But because pubertal development is so variable, giving a reliable age to begin strength training is difficult, but the early teen years is a good estimation.
Epiphyseal Injuries in Young Athletes
Excessive strength training that is unsupervised or improperly supervised can be detrimental to a growing child’s musculoskeletal system. For example, it can cause physical problems such as epiphyseal fractures and lower back injuries.
The epiphyseal plate (a disk of cartilage located near the ends of long bones) is responsible for bone growth and reaches its mature strength through ossification. Young athletes who have reached Tanner’s stage 5 of development of secondary sexual characteristics have passed their period of maximum velocity of height growth, when the epiphyses are especially vulnerable to injury.
Overhead lifts performed with improper technique appear to cause the vast majority of epiphyseal injuries. These weightlifting exercises generally cause the most injuries, especially when they are performed with heavy weights:
- Clean and jerk
- Dead lift
- Power clean
- Horizontal and incline bench press
- Overhead press
The Sports Medicine Committee of the American Academy of Pediatrics recommends that young athletes who lift weights perform a high number of repetitions using light weights. This organization also discourages young athletes from participating in bodybuilding or power lifting (a low number of repetitions performed with heavy weights) until the child reaches Tanner’s Stage 5 of growth.
Exercise Machines Are Not Designed for Use by Young Athletes
Another concern with strength training for young athletes is that exercise machines designed for adults are often badly oversized for young athletes. As a result, the weight on these machines encourage improper weightlifting techniques by creating an inappropriate force on the young athlete’s torso, arms and legs.
Additionally, the lowest weight on many machines is 10 pounds. Even this amount of weight may be too high for some young athletes.
Effective Strength Training Can Occur in Young Athletes
Early debate about the usefulness of strength training for young athletes centered on whether an increase in muscle mass is possible because of their low levels of circulating androgens (naturally produced sex hormones, such as testosterone). However, strength training can significantly increase the amount of weight a child can lift. However, most of the strength gain is not due to muscle hypertrophy but increases in neuromuscular coordination.
Proper and safe strength training can benefit athletic performance (particularly in vertical jumps) and result in fewer injuries. Also, participation in regular strength training can be safer than participation in other sports, such as football, basketball and soccer.
Guidelines for Strength Training in Young Athletes
To help young athlete safely get stronger through strength training, I recommend following these guidelines:
1. Before a young athlete begins strength training, he or she should have a thorough medical examination by a physician who is knowledgeable in sports medicine. Organizations such as the National Academy of Sports Medicine, National Strength and Conditioning Association and the American College of Sports Medicine have excellent certification programs to aid parents who want to hire a personal trainer for their young athlete.
2. Be sure that the child is emotionally mature enough to follow directions. Proper lifting techniques must be explained and reiterated in a manner that an individual child can understand. Supervision by an adult must be full time and encompass all young athletes in the weight room using a ratio of about 8 to 10 children per supervisor at one time.
3. A young athlete should always lift free weights while being observed and aided by a spotter. Spotters should offer assistance while weights are removed or replaced on machines or racks, if the young athlete asks for help, or if assistance is needed getting past the “sticking point” of the range of motion. The young athlete should also wear a weight belt to increase safety during heavier lifts to stabilize the small, supporting muscles of the lower back. The belt should be tightened immediately prior to each lift and loosened it immediately after each lift.
4. Young athletes should never hold their breath while lifting weights. The young athlete should exhale during the most difficult part of the lift and inhale while returning the weight to the starting position. The Valsalva Maneuver (trying to exhale against a closed glottis) causes a temporary reduction in blood flow returning to the heart followed by a sudden surge of blood back to the heart, which can cause an abnormal heartbeat.
5. The young athlete should warm up properly before a strength training workout. All strength training workouts should be preceded by least five minutes of stretching and 10 minutes of calisthenics, stationary bicycling, rope skipping, or even kicking a hackysack.
Warming up increases the young athlete’s body temperature, circulation and muscular efficiency while preparing the muscles for overload stress. Cooling down after a workout using the same exercises as a warm-up routine will reduces post-workout soreness. Some delayed soreness will occur after exercise, but it will fade in time.
6. The young athlete should rest for 48 hours between workouts involving the same muscle groups. For instance, if a young athlete lifts weights on consecutive days, the lower body muscles should be trained on Monday and the upper body on Tuesday. A muscle that is not properly overloaded at least every 72 hours will begin to atrophy.
7. The young athlete should keep an individual workout log and set short- and long-term goals. The log and goals will be interesting and motivating to children who are serious about a particular sport. A heavy focus on competition between adolescents, however, should be avoided.
8. The young athlete should lift the weights slowly and be aware that using some exercise machines sometimes causes the dominant leg or arm to be used much more than the non-dominant. It’s important to strain equally hard with both limbs and to use free weights in a workout, which force laterality and balance better than machines.
9. A young athlete should initially perform basic, multi-jointed exercises – like squats, bench presses and military presses – that simultaneously involve several muscle groups. These exercises improve body strength and coordination between muscle groups. Once the child is strong enough, other exercises that isolate and strengthen single-joint muscles can be added to the workout in order to develop sport-specific skills.
10. The young athlete’s weightlifting routine should work out the larger, stronger muscle groups first. For example, the bench press should be conducted before the lateral pulldown. Strength balance between muscle groups should be ensured by conducting an equal number of repetitions with the triceps as the biceps, quadriceps as the hamstrings and so on.
Lifts are most effectively performed using the same range of motion utilized by the sport for which a young athlete is training. These lifts should generally be conducted throughout the entire range of motion of the joint with the exception of half-squats and half sit-ups.
11. The amount of weight a young athlete lifts should leave the child completely tired after a certain number of repetitions. For example, the young athlete should use a weight that would allow the child to perform at least 12 repetitions but no more than 15 repetitions. If 12 repetitions cannot be completed, the amount of weight should be decreased; if more than 15 repetitions can be performed, the amount of weight should be increased.
The exact amount of weight varies substantially by individual. Some exercisers are able to lift a higher amount of weight due to previous conditioning and differing percentages of fast- or slow-twitch muscle fibers.
12. The young athlete should rest two to three minutes between sets. A workout can be completed in 45-60 minutes if the child keeps moving from one exercise to the next and does not get distracted.
13. With guidance from a trainer, the young athlete should try to focus on isolating a muscle group during the lift as much as possible. It’s important to not cheat by “hitching” the weight with other muscle groups; lifting in this way promotes bad form, can result in injury, and provides less stress to the muscle group to be strengthened. There should be a momentary pause at the end of both the raising and lowering of the weight to ensure a proper lift and not a “throw.”
14. It is often recommended that athletes get periodic body composition checks via underwater weighing during training to record progress. In addition to getting percent body fat, a “body comp” check will also indicate the percentage of weight that is fat-free. Any changes in fat-free weight are due almost exclusively to changes in muscle weight because the weight of the other fat-free parts of the body parameters (such as bone or connective tissue) remain relatively constant during training. Scale weight alone does not indicate gains made through strength training.
15. If desired, young athletes can supplement their strength training workouts with plyometrics, rope skipping or running in a swimming pool. These exercises are very beneficial when they are conducted in combination with strength training but are not nearly as effective as using weights.
16. The young athlete should also eat a nutritious diet, consisting of proteins, fiber, healthy fats and carbohydrates. An adequately balanced diet provides the RDA requirement for protein (about 0.8 grams of protein per kilogram of body weight), and any additional protein intake will only be stored as fat.
17. The young athlete should be given appropriate education regarding anabolic steroids, growth hormones and other performance-enhancing drugs. Expect that young athletes will have access to these dangerous, illegal and unethical drugs, which should be avoided at all costs.