A Great Plyometric Exercise to Build Downhill Speed

The search for the secrets to improving speed in downhill mountain bike racing has left relatively few stones unturned in the last decade. From weight training to supplements to building muscle.

The selling point of these of mechanical and chemical approaches to speed improvement is a major increase in strength. We all know that greater strength and power means greater speed, so how about plyometrics and specific sprint training? Applying these to your weight training program, and you'll have all the components you need to increase downhill speed.

Plyometrics for Power

One problem for many downhill cyclists is the inability to fully utilize their muscular leg strength in explosive-type actions, such as sprinting up a short rise or accelerating quickly out of a turn. What is needed is a training procedure that increases power (i.e. strength divided by time).

In addition to your resistance-training program, there is an additional training modality to increase your power, a system known as plyometrics that emphasizes the "explosive-reactive" power of training.

Plyometrics, simply defined, is a series of training drills that place the muscles in the pre-stretched position before they shorten during contraction.

Research into plyometrics and muscle physiology shows us that a muscle will contract more forcefully and quickly from a pre-stretched position, and the more rapid the pre-stretch, the more forceful the concentric contraction.

If you have trouble relating to this, picture a rubber band and how it responds to a stretch. Then think of the muscles as a structure of elastic tissue that shortens when you contract your muscles.

The elastic component can be stretched, thereby developing tension due to its elastic resistance to that stretch. Again, think of stretching an elastic band. As you increase the stretch on the band, the tension and velocity of shortening is also increased.

Muscles have receptors that are sensitive to stretch (referred to as the stretch reflex or myotatic reflex). This reflex is activated when a muscle lengthens quickly and causes the muscle to contract. Inducing the stretch reflex in conjunction with the voluntary muscle contraction results in a more vigorous contraction.

Therefore, the elastic component and the stretch reflex contribute to the total force generated in contraction. In a plyometric exercise like a bounding jump, the rapid stretching (loading) of the muscles activates their stretch receptors and sends a very strong stimulus via the spinal cord to the muscles, causing them to contract powerfully.

A excellent book offering elementary drills is Jumping into Plyometrics by Dr. Donald Chu, which underlines the basic concepts of plyometrics and suggest the following when developing a plyometric training program:

1. The maximum amount of tension is developed when active muscles are stretched rapidly.

2. The faster the muscle is stretched the greater the tension it exerts.

3. The rate of the muscle's stretch is more important than the magnitude of the stretch.

4. Utilize the overload principle of training, which dictates that increased strength results only when work is performed at an intensity greater than that to which the muscle is accustomed.

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