Stride Length and Stride Frequency

When discussing sprinting mechanics in young athletes, there needs to be an understanding of the components involved. Sprinting mechanics are determined by 4 factors:

1. Mechanics
•Posture
•Leg cycle
•Arm/hand actions
•Shoulder position and relaxation
2. Force
•Generation into the ground
•Getting body into proper position
3. Central nervous system’s ability to fire quicker and more efficiently
4. Arm/leg length

Numbers 3 and 4 are influenced by stride length (SL) and stride frequency (SF). What are SL and SF? Stride length is the distance the center of mass (generally the hips) travels during one running stride. Studies have shown that optimal stride length is approximately 2.5 times the athlete’s leg length. Stride frequency is the number of steps taken in a given amount of time or over a given distance. Based on these definitions, any athlete who wants to lessen sprinting times should seek to improve SL and SF.

Young athletes sometimes make the mistake of “over striding” to try to improve SL. They need to understand that increasing the strength in the muscles that determine proper leg cycle mechanics will give them a better result. SF is largely determined by the athlete’s unique muscle make up. Fast twitch muscle fibers allow faster movements, thus if an athlete’s muscle tissue consists of more fast twitch fibers, they will have an advantage over an athlete (with all other factors being equal) with more slow twitch fibers. It is important to understand, though, that an athlete, with practice, can improve the efficiency of muscle firing.

However, with young athletes the most important thing to remember is that his or her running technique should be taught at a young age so that the muscle pattern will be created. During development there will be adjustments made because of the changes of bone length and nervous system adaptation, but a young child who is allowed to run during the earliest stages of development will have the best possible foundation.

In Health,
Len

Puberty and Developing Athletes

Puberty usually occurs between the ages of 13 - 15 for girls, and 14 -17 for boys. The pubertal growth spurt lasts about 2 years and is accompanied by sexual development - growth of pubic hair, development of sex organs, beginning of menstruation in girls and deepening of the voice in boys. Specific bodily changes are:

•Bone development
1.Bones develop at each end of the bone shaft. The bone lengthens as cartilage is calcified into bone. Growth ends when the epiphysial plate eventually calcifies.

•Muscle
1.Muscle mass increases steadily in both sexes until puberty
2.Boys show faster muscle growth

•Fat
1.At birth, approximately 10 to 12% body fat in both sexes
2.Pre-puberty, 16-18% body fat in both sexes
3.Post-puberty, approximately 25% body fat in girls while boys have approximately 12 to 14% body fat


Just as toddlers start to walk at different ages, youths develop athletic skills at different rates. By age 10, the differences in athletic development can be profound. Some children are nearing puberty while others are not. There could be as much as a three to four year difference biologically between youths of the same age and their athletic development. The great leveler in athletic ability is puberty.

Because of the differences puberty can bring, sometimes parents and coaches evaluate this as a less talented athlete rather than what it truly is, not beginning puberty at the same time. Parents, coaches, and sometimes even the young athletes may feel they aren’t cut out for sports. It is important that everyone involved realizes that there isn’t any cause for alarm and that some youths begin puberty sooner and therefore may have a temporary advantage initially. However, it is imperative that all young athletes are trained appropriately based on their prevailing level of development so that they continue to progress to their own personal best.

In Health,

Len