Plyometrics have been used for many years as a tool to improve the performance of athletes in all sports. Even though these types of exercises are widely accepted by strength & conditioning coaches, the reasoning behind their use is largely misunderstood and/or not communicated to the athlete. So what makes plyometrics so effective? Understanding simple elements of the science behind these great exercises can greatly enhance their benefits from an athlete or coaching perspective.
Our nervous system is constantly collecting data from our muscles, including: position, amount of tension, rate of length change and even temperature. In this post, rate of length change is most important to the athlete. When the body senses a muscle is lengthening at too great of a rate, it forces the muscle to contract. This contraction of a particular muscle group is extremely powerful, and often uses a substantial portion of the muscle. This contraction is why coaches are interested in using plyometrics. By utilizing the body’s desire to protect itself, we can prime the athlete to use their muscles at a faster and more powerful way.
Imagine the landing position when performing a depth jump:
Where does this leave us from an athlete and/ or coaching perspective? The takeaway from this post should be, “You reap what you sow,” meaning, if you want your muscles to contract faster and be more powerful, you must voluntarily contract as fast and as powerful as you can during plyometric exercises. Otherwise, muscles will be trained to contract slower and less powerful than their full potential.
Advanced Uses of the Stretch-Shortening Cycle
Besides training our muscles to contract faster and more powerful, the principles of plyometrics can be used to change the makeup of a lift or even an entire workout. Below are two examples, one utilizes the strength-shortening cycle, the other does not.
Dip, Grip and Rip Deadlift
This technique for performing deadlifts takes advantage of the opposing contraction provided by the nervous system. When stepping up to a deadlift, dropping down quick, grabbing the bar and pushing as hard as you can with your legs/glutes can harness this contraction. Waiting too long in a bottom position before performing the lift can negate the stretch-shortening cycle.
Austin's Note: this technique can take awhile to get used to. Start practicing during your lighter warm up sets and when you feel comfortable give it a shot with the big weights. The hardest part is getting your breathing pattern down. Try one big breath and two big breaths, then see which one is more comfortable for you. Taking advantage of these small adjustments can pay off tremendously when trying to increase your deadlift PR!
Oppositely, pausing at the bottom of a lift can eliminate the stretch-shortening cycle. This technique creates more stress on the voluntary muscle contraction, and can make the lift more difficult depending on the percent of muscle groups able to be recruited by the athlete. Changing tempo and adding pauses is a great way to shake up a routine that is getting mundane.
Muscle Spindles vs. Golgi Tendon Organs
Earlier in the post, I mention that rate of change in the length of the muscle was most important when training the stretch-shortening cycle. We are now going to go into more depth as to why this is the case, and differentiate between another safety mechanism used by the body. When the nervous system senses a rate change that it declares as dangerous, the muscle fibers that are recruited to contract initially are called muscle spindle fibers. These spindle fibers surround the muscle belly, and their contraction couple with a voluntary muscle contraction creates the powerful biomechanical mechanism utilized in plyometric training.
Similarly, golgi tendon organs (GTOs) also help protect the muscles of the body, but by a different avenue. GTOs gather information about the tension placed on the muscle while performing any action. When too great of tension is placed on the muscle, the GTO will send inhibitory messages to the muscle, forcing it to relax. You can see why this particular mechanism would not be beneficial in a performance training session. GTOs are also the reason you will not see very much resistance or “weight” applied to an athlete performing plyometrics.
Whether you are performing plyometrics, olympic lifts or even basic static stretching, an athlete should understand the changes and adaptations caused by their training protocol. Having a solid base of knowledge in this area can not only improve the athlete, but the coach as well. Knowing how you will see improvement or why you are performing a certain exercise improves the knowledge and relationship between you as an athlete and your strength staff.