Children grow at different rates and in a group of 10 year-olds some players might be significantly taller or heavier than others. Inevitably such differences will have a great influence on a child's ability to develop football techniques and skills. For example, the co - ordination difficulties that puberty causes in boys aged between 10 and 14, with legs and arms growing out of kilter with the rest of their bodies and the difficulties associated with growth spurts can cause some players to appear clumsy, uncoordinated and awkward.

There can be as much as a four year difference in physical maturity in young people of the same age. Football tends to highlight these differences because of the emphasis on the way football is structured by age and age group reliability for team competitions for example, Under-10s, Under-12s

It is important that as coaches, we organise our groups when coaching to take into account the ability and size differences amongst players of similar age. For some technical, less physical practices you might consider grouping by ability, for example, dribbling and ball control skills and techniques. For other more physical training activities such as running and physical fitness games, defending and 1 v 1 and 2 v 2 the groups should be determined by the size and physical fitness of the players

Physical Development Characteristics amongst Young Players

When coaching young players between the ages of 6-12, coaches should be aware that:

• There is the likelihood that growth spurts can bring quite dramatic and traumatic increases in height and weight, and changes in body shape
• In adolescent boys the growth spurt can begin as early as 12, though it normally reaches a peak at ages 14 to 15
• In girls the growth spurt can start earlier (10-11) and normally peaks at 12
• For young players between the ages of 6-10, boys and girls show gradual increases in height and weight and there is little physical difference between them - though boys might tend to be taller
• Children who mature early have a greater proportion of fat in their bodies than those who mature more slowly
• Players who physically develop early will often look better players and perform better but this might not continue as later maturer's catch up during adolescence.
• Children who tend to be taller and heavier children in the 9-12 age range have a tendency tend to stop growing earlier and are likely to become shorter, more heavily built adults.
• Children who mature later and have a leaner build, tend to become taller, thinner adults.

Strength in young players

As young players will have not reached adolescence and have immature bodies, with weaker muscles and bones, it is important that they should not be subjected to intensive strength training. A sensible amount of training using the players own body weight, such as sit ups and press ups can have a beneficial effect on the blood supply and development of muscles. But in these young players, weight training should never be used as it can do a lot more harm than good, as in growing children, the growth areas at the end of long bones (such as those in the upper and lower leg) and around joints can be damaged by excessive stress and strain, and growth can be impaired.

Flexibility in young players

Believe it or not, after the age of ten, children begin to lose flexibility. Therefore it is important that the players develop good habits with regards to their warm-up and cool-down habits and attitudes as stretching and mobility exercises can help maintain this flexibility.

Before undertaking stretching exercises to develop or maintain flexibility, it is important for the muscles to be warm and general body movements are useful to prepare for stretching. Flexibility in players is defined as the range of movement around a joint (eg the hips), mobility is concerned with a player's general ability to co-ordinate forward, backward and sideways body movements, which are crucial for players.

For example, wind milling arm circle movements are mobility rather than flexibility exercises, whereas upper leg stretches, such as hamstring stretches should promote better flexibility around the hip joint. Increases in flexibility around the hips should improve a player's general mobility in that part of the body, allowing them to twist and turn more effectively.

Stretching

To improve flexibility through stretching, coaches should ensure players:

• Have a good warm-up routine including mobility exercises before starting a stretching routine (read more)
• Pay specific attention to stretch the muscles which are involved in football a€¦(read more)
• Use static stretches not bouncy stretching (ie ease into each stretch to a point of mild tension and then hold for 15 seconds). Pain is a sign of overstretching
• Stretching should be always be kept within the control of the player. Under no circumstances should external force, such as the coach other player or parent be applied
• Static stretching is a vital factor in improved flexibility in young players. This form of stretching involves a slow sustained movement in which a muscle is lengthened and then held in position for 15-20 seconds. Each stretch should be repeated 2-3 times, and stretching should form part of a regular warm-up and cool-down routine.
• Players might use the same stretches for their warm-up and cool-down but should hold stretches for longer in the cool-down, as long is there is no damage as a result of the game.

Young Players and exercise

As children start to play football their need for energy grows. To meet this need, oxygen supply to the blood and blood supply to the muscles must improve. Children breathe more quickly but less deeply than adults and extract oxygen less effectively. Because of this, young children (6-12 years) must work harder than adolescents or adults to provide the oxygen their muscles require when playing football. Therefore as responsible coaches you must consider this in any training routines and provide plenty of rest periods

Physical Training

Aerobic energy is the term used when oxygen is the main energy source for the body. Players rely on oxygen as a major source of energy since it enables them to maintain constant activity. Before adolescence, children get a higher proportion of their energy from the aerobic energy system than adults.

Moderate continuous exercise (eg small-sided games) can improve young players' aerobic energy systems and enable them to sustain longer periods of activity before fatigue sets in. However, this improvement is governed by each child's physiological maturity and only after puberty will children become more efficient in their use of aerobic energy.

As a guide, coaching sessions should last between 45 and 60 minutes for children below the age of twelve, and approximately 90 minutes with older children (12-15 years). Within sessions, periods of long physical activity (eg small-sided games) should last no longer than 25-35 minutes and should still allow sufficient time for drinks and recovery periods.

Below the age of 12, players should play and practice for no more than three football sessions per week (eg two practice sessions and one game), with the emphasis on personal development, not team success.

Coaches should remember that:

• Children do not have the physical ability to tolerate exercise as well as adults and do not understand their limitations
• Children need to breathe more often than adults and as a result they lose more water through their breath
• Children are more susceptible to both hot and cold environments
• Children get a higher proportion of energy from the aerobic system but their system is less efficient at extracting energy than adults
• Up to the ages of 10-12, boys and girls do not differ significantly in aerobic efficiency after puberty, boys generally have a higher aerobic capacity than girls
• Young children (6-10 years) work better at low intensity continuous exercise (up to 30-40 minutes duration) and this should be taken into consideration when considering training programmes