Speed & Agility Training Zone!

Is It Time to Rethink Power Development?

By: Bill Parisi, BBA, CSCS

The goal of any athlete is to maximize their force production in the shortest amount of time. How high someone can jump is directly determined by how fast they can apply force into the ground. The same holds true for acceleration. It is all about the ability to put force quickly into the ground in the opposite direction you wish to move.

So how does an athlete maximize the speed of force production, better known as power? Power is defined as (Force)*(Displacement) = (Work )÷(Time). Or an easier equation is (Work)÷(Time). And even easier… (Force)*(Velocity).

So how do we maximize power? There are many approaches and training methodologies to accomplishing this goal. If you follow Dr. Stuart McGill, the first place to start is by creating a stiff core. Dr. McGill describes the core as being between the two shoulder and two hip joints. By creating tremendous stiffness at the core, the hips and arms have the ability to produce a greater amount of force with minimal energy leaks. An example commonly used to depict core weakness or instability is shooting a cannon out of a rowboat and comparing it to shooting a cannon that is bolted down to a block of cement. The core needs to act like that block of cement for the limbs to generate explosive force with minimal blow back.

Let's assume we have appropriate core stability. The four limbs (arms and legs) are securely anchored to this strong foundation. These four joints themselves have to have both stability and mobility. The dynamic stabilizer muscles around the shoulder and hip play an important role in doing that. For instance, the scapular stabilizer muscles, such as serratus anterior, latissimus dorsi, rhomboid major/minor, upper middle and lower trapezius, provide proximal stability to the scapula. These serve as an anchor for the muscles of the glenohumeral (shoulder) joint to create movement. A strong rotator cuff acts as a dynamic stabilizer, meaning it both creates movement and provides the stability within that movement, which is necessary for power production at the shoulder.

Similarly, the muscles of the spine, quadratus lumborum, erector spinae, mutifidi, obliques and psoas to name a few, attach to the pelvis, check spinal motion and provide that anchor for the muscles of the hips. The deep external rotators, commonly called the rotator cuff of the hip, along with glut medius and minimus (deloids of the hip), help to provide that dynamic stability for power production in the lower body.

These stabilizer muscles not only need strength and endurance to maintain core stiffness, but they need to have the neuromuscular coordination to “fire” and “relax” quickly. Yes, to maximize power you have to be able to shut off muscles as fast as you turn them on.

Movement patterns of the body result from muscle synergies. A synergy is when different muscles work together to coordinate movement. Even muscles that oppose one another can work together to achieve movement and stability. These opposing muscles are termed agonist and antagonist. For example, a flexor muscle group (agonist) may work together with an extensor group (antagonist) to stabilize a particular joint, while another muscle is in motion.

The ability to control how fast we turn muscles on and off also plays a very important role in power development. We need to have the neuromuscular coordination to fire muscles quickly, in the correct sequence, as well as relax them just as fast to maximize power production.

Let's use the vertical jump as an example. To maximize performance in this event, an athlete quickly descends and flexes at the hip, knees and ankles right before the takeoff to maximize vertical jump height. This action helps to create the pre-stretch in the extensor muscle group, such as the glutes, hamstrings and calves. Specific muscles need to fire to allow the body to come down fast. Then opposing muscles need to fire to reverse this action to jump up as high as possible. There is an element of coordination involved in this event that most people do not realize. Power generation, even during the simplest moves like a vertical jump, involves a specific amount of skill and neuromuscular coordination.

The specific skill I am referring to is the ability to turn on and shut off motor units. A motor unit is a measure of motor neurons that are activated in a particular muscle that contract a specific number of muscle fibers. The ability to recruit and turn on and off motor units is a foundational component to power development.

Let's focus the rest of this discussion on motor unit recruitment. When we perform traditional isotonic weight training, we are recruiting a specific amount of motor units based on the amount of force needed to lift the weight.  Also, how fast we lift the weight will determine if we recruit fast twitch motor units or slow twitch motor units. Research has shown that an increase in the speed of a contraction will result in a higher level of fast twitch motor unit recruitment. This helps power development.

Let's use the squat exercise as an example here. As we go through a range of motion with a bar on our back, we pass through mechanical advantages and disadvantages at different ranges of motion. We are stronger at certain points and weaker at others. So as we squat down deeper, we are not as strong in the bottom position, compared to when we rise up. We have a natural, greater mechanical advantage and are stronger when our muscles are at the mid range of contraction, which is the optimal length of the muscle for force generation.

What does this tell us? When lifting, we will fatigue and eventually fail at our weakest point of the lift. In the squat, it would be near the bottom. So this means the weight we are using may be enough to challenge us at the bottom position, but not enough to challenge us at the midrange or higher positions.

This is where the addition of chains and bands can come into play to help create dynamic strength. By applying a band or chain to both ends of the bar, it allows for lesser tension at the bottom position and greater tension at the top position. This helps to maximize motor unit recruitment. Also, using bands on the bar with less than your normal weight can allow for slightly faster movements, which help recruit the fast twitch motor units we spoke about earlier.

I have seen the use of chains and bands help athletes break through strength and power plateaus time after time. They are a great way to mix up your athlete's workouts and I like incorporating chains and exercise bands 1X every 1 to 2 weeks. These are great tools for your more advanced athletes that have a training age of at least 3 or 4 years. As always, athletes using chains and bands should always be properly supervised. Check out all the great products offered at Perform Better in this category.

In closing, it was my goal to have you better understand power development and maybe think about it a little differently. In my opinion, power development is about a strong core, stable joints, neuromuscular coordination and maximizing motor unit recruitment.

For more information about Bill Parisi and the Parisi Speed School, check out www.parisischool.com/businessopportunity.

(July 2015)