Smigielski, Michael J. M.D.


Smigielski, Michael J. M.D.

Training Effects On A Growing Athlete

Training is an important to athletes. Excessive training, however, can place an undue amount of stress on the body, leading to tissue breakdown and injury especially in young athletes. Therefore, scheduling appropriate training is necessary.

The fact that children are still growing and their body system is under stress raises a couple of questions about the training of young athletes. First, how do young athletes respond differently to training than adults? Secondly, how does the growing tissues of young athletes respond to the stresses of early intense training?

Because children and young athletes are becoming involved in training programs once reserved for only high level athletes, understanding a growing child or young athlete's response to training is key. Measuring the body's response and performance responses to physical training in children is difficult. Speed, endurance, and strength normally improve as a child or young athlete grows and develops normally. Therefore, it is difficult to differentiate the effects of exercise from the normal improvement and motor skills development with growth. However, there is an increased amount of evidence in the medical literature that shows how children respond to short bursts or fast training (anaerobic), endurance training (aerobic), and resistance or strength training. I would like to talk about these three training areas.

In adults, who usually participate in regular endurance exercises such as running or long distance bicycling or cardiovascular workouts usually demonstrate certain benefits to the heart. This includes a lower resting heart rate, greater heart volume and greater cardio output. These changes allow the body to better use oxygen for aerobic or endurance purposes. A previously sedentary adult can improve the maximum oxygen uptake by 30% with a regular exercise program. Signs in children however, only show a maximum 10% improvement in both boys and girls with endurance training as far as utilizing oxygen and improving cardiac output. However, after puberty there is a much improved increase in endurance. This suggests that hormonal influences surrounding puberty certainly enhance trainability with endurance training. Getting in shape or endurance training for children or teenage athletes is beneficial for any sport; however, the heart benefits are difficult to measure.

Short burst sports activities such as sprints, jumping, skiing are anaerobic in nature meaning these events do not depend on oxygen for release of energy for muscle contraction. Sugar, which is stored in the body, is generally used for these activities. The most common means of measuring anaerobic fitness or short burst sports fitness are performance on field tests. Playing programs of short duration and high intensity exercise certainly improve anaerobic performance in adults. Studies have shown that sprint time in children and teenagers can be improved with anaerobic activity more so than with endurance training.

30 years ago children were felt to be incapable of improving muscle strength during weightlifting or resistance training. It is felt that testosterone is needed for such responses to occur. Since that time there has been abundant research, which has proven that this concept is false. A number of studies using free weights have shown significant improvement in strength up to 30% in children comparable to adults. Strength improvements have been similar in boys and girls. A question is asked whether free weights or weight machines are most appropriate for weight training programs in children. Proper technique and supervision are much more important in injury prevention than the type of resistance equipment that is being used. Strength gains up to 20-30% seen in both boys and girls before adolescence are not accompanied by increased muscle size. Thus, weight training to improve the appearance of muscle bulk in young boys will not be effective until testosterone becomes at a higher level. The feeling that strength is because of increased muscle size is not present in young children and it felt that other factors such as nerve adaptions or improved capacity of the muscle that is there must be involved. A number of studies have proven the false concept that strength-training programs are unsafe in children. Growth plates are not injured and there is no harm in the future for these young athletes if again proper technique and supervision are given to them.

Subsequently, of the three training concepts endurance training, short burst activity training, and strength training, it has been shown strength training has the greatest benefit in children before adolescence and in young athletes as well. The added advantage of strength training is improving bone material to prevent against future osteoporosis. One should differentiate between weight training and weight lifting. Weight training involves repetitive lifts of sub maximal weight. This is certainly safe and is proven effective in improving strength and subsequently making one a better athlete. Weight lifting, which is a competitive event involving single lifts of maximum weight, is probably not appropriate for children before puberty as growth plates and subsequent injuries are probably more prevalent.

In summary, endurance training and short burst anaerobic training is certainly of benefit to young athletes and even children before adolescence. The gain in endurance or short burst speed however is difficult to determine as children normally, improve as they grow and become stronger and more coordinated. Strength training however, certainly has been shown to improve strength 20-30% in both boys and girls and can certainly contribute to improved athletic performance. Proper technique and certainly parental and coached supervision on all these training activities is probably the more important thing that can be done to prevent injury and show them to enjoy their sport.