Physiology of Plyometrics

The definition of plyometrics is any exercise involving repeated rapid stretching and contracting of muscles (as by jumping, medicine ball throwing, and rebounding) to increase muscle power.

Regardless of the plyometric exercise chosen, it will involve three phases.

1.The first phase is the pre-stretch or eccentric muscle action. Here, elastic energy is generated and stored.

2.The second phase is the time between the end of the pre-stretch and the start of the concentric muscle action. This brief transition period from stretching to contracting is known as the amortization phase. The shorter this phase is, the more powerful the subsequent muscle contraction will be.

3.The third and final phase is the actual muscle contraction.

This sequence of three phases is called the stretch-shortening cycle.

Muscles can be compared to rubber bands to an extent. A cycle stretched rubber band will go farther than a non-stretched rubber band. To better understand the effect of the stretch-shortening cycle, perform two vertical jumps. During the first vertical jump bend the knees and hips (eccentric muscle action or pre-stretch) and hold the semi-squat position for 3-5 seconds before jumping up vertically (concentric contraction) as high as possible. The 3-5 second delay increases the amortization phase.

During the second jump, bend the knees and hips to the same degree but immediately jump up without a delay. This keeps the amortization phase to a minimum and makes best use of the stored elastic energy. This will produce a jump that is higher.

Plyometric training programs are effective. However, they are best determined by a qualified sports trainer who not only understands the physiology, but can match it to an athlete’s current level of development and fitness.

In Health,
Len

The Need for Agility

Generally, agility means being able to move your body quickly and without difficulty while maintaining control and balance of the body. In athletic terms, agility is often more specifically defined as the ability of an athlete to quickly start and stop, as well as, to change directions without losing motor control.

Agility is a highly valued ability for young athletes, and it is an important skill in sports such as soccer, lacrosse, tennis, football, and basketball. It is important for adolescent athletes and their coaches to know that it is an attribute that can be improved upon by using properly designed athletic programs. Programs can include:

•Perform drills that require rapid body changes. Change quickly from forward to backward movement, from side to side and up and down. Do several sets of the drills, focusing on moving quickly and efficiently.
•Transition runs involve alternately walking, jogging and running in 5- to 10-yard increments. Transitions runs can include running forward and backward, changing direction and stopping and starting quickly.
•Cones can be set up in rows, squares, circles, triangles or other shapes such as letters and numbers. Athletes can jump over the cones, run around the cones in different patterns, weave between the cones or run to the cones. Cone drills can improve an athlete's ability to stop and start quickly and to change directions without losing balance or speed.
•Jump-rope drills for agility include a basic jump with feet together, jumping with alternate feet, and jumping side to side or back and forth.

Remember that young athletes need to understand that agility is actually many skills (core activation, hip mobility, ankle mobility, arm movement, ect.) that when combined produce the desired movement. Teaching each component can give the athlete the power to understand that each is necessary to move safely and efficiently.

In Health,
Len

Hip Mobility In Youth Athletes

Mobility at its most basic definition is to accomplish the desired movement or position under specific conditions. Our limbs, joints, and muscles represent a collective of individual pieces, all working together to move the body. Mobility in all areas is crucial. The most common mobility deficiency resides in the hips.

When considering hip mobility in young athletes it is important to remember the following:
Unfortunately, most of their day is spent sitting, which may result in:

• Kyphosis (excessive curvature of the thoracic spine, causing a "C" shape instead of a "S" shape of a normal spine. This curvature causes the lumbar spine to flex, negating its natural extension. The shoulders are rounded forward and the pelvis is tipped backward (posterior pelvic tilt), causing the rectus abdominus and chest muscles to shorten and tighten and lack thoracic mobility and therefore proper scapular function).
• Tight, weak hips that lack function.

Most don’t have proper strength and conditioning care, which may result in:

• Range of motion in joints is weakened.
• Form and function of lift technique is unknown to them.

It is important that hip mobility is continuously trained in a young athlete. Because the bodies of adolescents are constantly changing, so are their pathways to coordination and movement. Disregarding mobility during periods of physical development can set back an athlete's performance as well as set him or her up for potential injury.

Training hip mobility in adolescents will help in several areas:

• Reduce or eliminate lower back and/or knee pain stemming from overcompensation
• Increase power and performance in hip extension, vertical lifts, sprinting and other explosive movement training (squats, deadlifts, Olympic lift, etc.) while making them safer
• Improve rotational strength, such as swinging a golf club, or tossing a ball
• Improve speed while changing directions, specifically sprinting speed

In Health,
Len