Sports Medicine for Youth Soccer Coaches
Jonas T. Holdeman, Jr.
Knoxville, Tennessee
Draft 1/30/91
Introduction. Soccer is a contact sport demanding power and speed. Your responsibility as a coach, in addition to teaching the technical demands of soccer, is to assist the players to meet the physical demands of the game by guiding them in the development of their physical fitness and to react prudently when they are injured.
While injury rates in soccer are low, especially for younger players, to deny the possibility of serious injury would constitute negligence on the part of the coach, as would the failure to take reasonable steps to avoid dangerous situations and conditions. Deliberate ignorance on the part of a youth coach is in itself a form of negligence. The failure to act quickly to mitigate the effects of a serious injury when the condition demands prompt, responsible action is as negligent as an overzealous, imprudent response.
The coach should have a rational basis for all training regimens. This unit will attempt to introduce you to some physiology and anatomy, along with a few governing principles to establish that rational basis.
Common sense. There are a few "common-sense" measures the coach can take reduce the chance or severity of injury or "complications" in the case of an injury. Responsibilities will vary with the age of the players.
1. Make sure practice, playing and surrounding areas are safe. Remove obstacles around and objects from the field before practice or games. Problems which cannot be immediately corrected should be reported to the proper responsible authority. Insist they be corrected.
2. Have a first aid kit at all practices and games. Kit should include coins for emergency telephone call if necessary.
3. Have an assistant or other responsible person at all practices and games. One can go after help or transport an injured player while the other supervises the remaining players. With older players (U19), the players can assume some responsibility.
4. Keep the medical release forms with you at all practices and games. These may be useful if emergency treatment is required and the parents cannot be located.
5. Do not allow horseplay or disruptive behavior.
6. Be sure fluids are available, especially in warm, humid weather.
7. Train proper techniques. Develop fitness in a systematic, progressive manner.
8. Prepare the players for practice and games, both physically and mentally with warmups and static and dynamic stretching.
9. Train players that in the case of an injury to any player, to force a stoppage of play by kicking the ball over the touchline.
10. In many minor injuries, the pain subsides quickly and the player is ready to play again. If there is any doubt about fitness to continue, remove the player from the game and temporarily play short (your team must be trained to do this). Then after further observation, either return the player to the game or call for an injury substitution.
11. After recovery from an injury, do not allow a player to return to competition until they are comfortable executing all of the physical demands of the game.
Fundamental concept. The fundamental concept we shall apply to all training is that the natural state of any living organism is homeostasis, or equilibrium or balance with its environment. If an organism is under stress, its response is to adapt in such a way as to balance the effects of the stress. Examples of this would be the development of resistance by insects to insecticides or resistance of microbes to antibiotics, tanning of skin in response to exposure to strong sunlight, and development of muscles in response to the force of weights or work.
There are some restrictions though, summed up in the "SAID" principle. When exposed to stress the organism or human body responds by a Specific Adaptation to the Imposed Demand. For example, if an athlete trains with a weight by doing curls with a dumbell with the right arm, the right biceps muscle will enlarge and get stronger, but not the left biceps nor any other muscle not involved in the exercise. Pure weight training does not increase endurance, nor does endurance training increase speed.
On the other hand, since living organisms seek balance with the environment, if a muscle, for instance, is stronger than necessary under usual conditions (say the muscle is unused), it will shrink or atrophy until balance is achieved. If an athlete, trained for endurance, stops exercising, he will lose approximately one tenth of his endurance per week. This is important to remember off-season or at the start of the season, or for an athlete who is recovering from an injury.
When training, the rate of development or improvement is proportional to the unbalanced stress. Thus when training starts, improvement is rapid, but eventually levels off as the athlete's body adapts to the demands. To sustain a rate of improvement it is necessary to keep increasing the demands. Thus it is necessary to overload in training sessions, to impose demands greater than would be expected in normal athletic activity.
A note of caution is necessary. If the work demands are increased too rapidly, the body may not have time to adapt, minor injuries occur in succession which do not have time to heal, and chronic stress injuries can develop. In this case the work load must be reduced until recovery is complete.
These then are the principles we shall apply to training to decide which training exercises are appropriate to each of our athletes at any particular time.
Training for U10 and U12. While the physiological basis for training is applicable to youth, its application to power development must be limited. Bone growth in children takes place at the ends of the bones at growth plates. The growth plates are weaker than bone and can be damaged by excessive loads or use. Damage to the growth plates in the extreme case result in cessation of growth and consequent deformation of the limbs. Any weight training involving repeated lifting heavy weights should be discouraged by the coach, as should any activity which results in repeated extreme stress on the joints (such as occurs in baseball at the elbow of pitchers).
At this age the coach should stress stretching so that muscles and tendons keep up with bone growth so that flexibility is retained. It is a time to emphasize the development of technique and skill. Strength will come easily with time as they grow older. To this end, small sided teams on smaller fields lessen the need for great strength and place greater premium on dribbling and short, accurate passing and good ball control.
Energy systems. The muscles require a continually available source of energy in order to operate. At the most basic level, the most important source of energy is the phosphate bond in the molecule adenosine triphosphate (ATP). Each ATP molecule releases a relatively large amount of energy when it decomposes into adenosine diphosphate (ADP) plus phosphate. Note that no oxygen is involved in this process. Without ATP, muscles become rigid and immobile. A small amount of ATP, enough for 10 to 20 seconds of intense activity, is stored in the muscle. For continued activity, the ADP must be transformed back into ATP using energy from other sources.
Under conditions of limited activity, the energy to reconstitute ATP can be supplied by "burning" glycogen (or sugar) and lipids (or fat) in the presence of oxygen. A certain amount of glycogen along with fat is stored in the muscle tissue. Additional glycogen is stored in the liver. Lipids are stored in fat cells. These materials along with oxygen are carried to the muscles by the circulatory system. When glucose and lipids are "burned" with sufficient oxygen, the waste products produced are water and carbon dioxide. The limiting factor in the resupply of energy is the oxygen. Thus the maximum volume of oxygen V(02) which an athlete can take in by respiration in a given time is a measure of the maximum work rate the athlete can sustain.
If activity is temporarily greater than can be sustained, another energy source is available, the transformation of glucose into lactic acid. The duration over which this higher level of work can be sustained is limited by the buildup of lactic acid in the muscle, which causes a decrease in performance and discomfort. Because of the debilitating effects of lactic acid in the body, this energy regime should be avoided in the game of soccer.
The energy sources can be classified by two factors: whether or not lactic acid is produced (lactic or alactic) and whether or not oxygen is necessary (aerobic or anaerobic).
In summary then the three energy rate regimes are:
Anaerobic alactic: Highest work rate but only for about 20 seconds, energy source is ATP stored in muscle. Example of activity would be 50 or 100 meter sprint, jumping or throwing.
Anaerobic lactic: Moderately high work rate for about 60 to 90 seconds, energy source is glucose, oxygen is not required, waste product lactic acid is toxic. Example of activity would be 400 meter run.
Aerobic, alactic: Modest, sustained work rate, energy source is glucose + lipids + oxygen, waste products, water and carbon dioxide, are innocuous. Example of activity would be a marathon run.
Note that soccer involves sustained activity (aerobic alactic) with bursts of high intensity work (anaerobic alactic).
Training the energy systems.
That’s all folks. I never finished this. JTH