A Sample Stretching Routine
Stretches are most effective (and less likely to cause injury) when the muscles are already warmed-up. An increase in core body temperature increases the pliability of muscles and tendons. It takes about 5 minutes of moderate exercise to raise the core body temperature. Therefore, before you begin the stretching routine, let the players do a pass-and-move type exercise or some other football drill of moderate intensity involving continuous motion.

The reason to stretch pre-adolescent athletes is to begin good training habits. Therefore, emphasis should be placed upon developing a consistent routine, rather than which individual stretches are performed. Although the order of stretching is probably not very important, establishing a consistent routine (i.e., doing the same stretches in the same order each practice) is important.

Joint Rotations (3 minutes)
Begin the routine with some simple, slow joint rotations:

Ankles and Knees:
hands on knees; knees bent; rotate knees in a circle in one direction 5 times; repeat in the opposite direction

Hips:
stand straight; hands on hips; rotate hips in exaggerated fashion in a circle in one direction 5 times; repeat in the opposite direction

Torso:
stand straight; lock hands in front of body; bring hands forward so they touch the chest; use arms to twist body in one direction (try to look at something behind you and hold the position for 5 seconds); repeat in the opposite direction;

Shoulders:
stand straight; Right arm extended straight up and Left arm at side; rotate arm in a circle in one direction 5 times; then repeat in the opposite direction; repeat for Left arm/shoulder

Neck:
stand straight; rotate head in exaggerated fashion in a circle in one direction 5 times; then repeat in the opposite direction
Lower Extremities (5 minutes)
Since it is the muscles of the lower extremities that are more commonly injured in football, focus the remainder of the stretches on the following leg muscles: calf, thigh (quadriceps, adductors and hamstrings), and the hips. All of the muscles can be stretched while in a standing position (there is no need, therefore, for players to get on the ground). Players should be instructed to bend only to a point where they feel their muscle being stretched (if the stretch becomes painful, they have bent too far).

Lunge (stretches calf muscles of the front leg and the quads of the rear leg)
Stand straight up and extend (lunge) the right foot forward as far as possible. The toes of both feet need to be pointed forward. Bend the right knee slightly while keeping the truck upright. The left heel needs to stay on the ground. Hold for 15 seconds. Repeat with left foot extended.

Toe Touch (stretches hamstrings)
Stand straight up with feet shoulder width apart and the toes of both feet pointed forward. Bend forward and touch toes (if a player cannot touch her toes with the knees unbent, let her bend her knees first and then slowly straighten her legs as much as possible). Hold for 15 seconds.
Stand straight up with feet double shoulder width apart and the toes of both feet pointed forward. Bend forward and touch the ground between the legs. Hold for 15 seconds.
Stand straight up with feet double shoulder width apart and the toes of both feet pointed forward. Bend to the right and try to touch the right foot with both hands. Hold for 15 seconds. Straighten up. Repeat for left side.

Groin Stretch (stretches adductors and quads)
Stand straight up with feet double shoulder width apart and the toes of both feet pointed forward. Keeping the right leg straight, bend the left knee and try to sit on the left heel. Hold for 15 seconds. Straighten up. Repeat for left side.

Standing Quad Stretch (stretches quads)
Stand straight up. Put left hand on a partner's shoulder. Grab the right ankle with the right hand (NB: many people prefer to teach players to use the opposite hand, which is more likely to keep the player's knees together and avoid stressing the knee joint) and pull upwards toward the buttock, keeping the knees together, the hips rotated forward, the trunk fully upright and the standing foot pointed forward. Hold for 15 seconds. Repeat for left side.