It’s not enough to just prescribe specific movements in your program, you have to dig below the surface level of training to develop these athletes. CHAPTER FOUR: MUSCLE SPINDLE ENGAGEMENT
Okay, so first thing...I am NOT a scientist. So for any alpha-dominant frat daddy who wants to chime in and critique my perspective, chances are you aren’t a scientist either. When working with explosive athletes, I want to employ movements that required reactive strength to close the gap between the eccentric stretch and the concentric reaction. What we are technically talking about here is manipulating the three phases of the “stretch shortening cycle”. Phase one is the “stretch” of the eccentric contraction, followed by the third phase (the “shortening” phase) created through a tightened concentric contraction. What occurs between phase one and phase three is the second phase, the “amortization” phase that is known as the transitional period between the stretch and shortening motions. That transitional period is what defines the explosiveness of an individual (how fast can you react and quickly develop movement). When considering this information, there are various types of movements you can program for your athletes to help cater to this mindset of creating a more efficient execution of the stretch shortening cycle:
-Traditional resistance training to help strengthen the musculature
-Plyometric training to take this strength and incorporate power
…the list could go on!
But besides the information expressed above, there are even MORE variables that could have an effect on dynamic ability to being an explosive athlete. It’s not enough to just prescribe specific movements in your program, you have to dig below the surface level of training to develop these athletes. To do this, you have to incorporate science and literature to your program. To bring in more science to this discussion, not only are we working to close the gap on the stretch shortening cycle, but we are also trying to cause the body to quickly respond to the overloading stretch by focusing and improving the muscle spindles response. The biggest problem with this process, though, is to understand “what the hell are the muscle spindles”?
So at this current moment, we are talking about how to produce more highly explosive athletes, but the kind of athlete I want to now focus on are sprinters. Adding this focus to my post will allow me to be able to incorporate specificity to the conversation and show how these principles can apply to a realistic athlete.
Anders Jelvéus (2011) defines the muscle spindles as small, spindle-shaped sensory receptors located in skeletal muscle tissue, and they run parallel to the main muscle fibers (extrafusal fibers). A muscle spindle consists of several differentiated muscle fibers (intrafusal fibers) that are enclosed in a spindle-shaped connective tissue sac. The ends of the intrafusal fibers are contractile, but the central portion is noncontractile and innervated by special neurons named gamma motor neurons. These gamma motor neurons are involved with involuntary movement when an external force acts upon the stimulated muscle, which is engaged during the stretch reflex. Stimulation of muscle spindles elicits a contraction in the stretched muscle (myotatic reflex, i.e. stretch reflex) and at the same time inhibits action potentials to antagonistic muscles (Jelveus, 2011).
Sensitivity, stimulation, activation, we are using all these terms to explain the same phenomenon: get the muscle to respond! Ross, Leveritt and Riek (2001) discuss that improved temporal sequencing of muscle activation and/or improved fast twitch fibre recruitment may contribute to superior sprint performance. So what does this mean to us? This means that our program needs to elevate muscle spindle response and recruitment in order to internally generate a quicker response of the CNS to our musculature for producing quicker reaction. Reviewing the movements we talked about before (strength movements and plyometric movements), if we can incorporate specificity to the program and do movements that relate to sprinting mechanics and incorporate quickness in these tasks, we begin to see adaption that is showcased by quicker neural activation and physiological adaptation. By embracing science in this discussion, we are now more mindful of what the body’s response is by incorporation of neural activation that might not be seen through the naked eye, but does occur internally. Ross, Leveritt and Riek (2001) also discuss that the speed of impulse transmission along the motor axon may also have implications on sprint performance, which we discussed just before. Through the use of this previously discussed information, we can continue to see growth and development in our athlete’s ability to create faster movement externally and internally. So what kind exercises are we talking about?
To discuss these movements would take time, but the overall theme of this program is to create stronger hip flexion, hip extension, and utilizing explosive movements that match this strength. The program has specific movements that relate to sprinting, and through the use of the explosive movements we are working to promote muscle spindle sensitivity so when the “stretch” occurs of the movements, we quickly react and develop a tightened contraction for a faster response. This step also supports the concept of neural activation between the various phases of movement.
As I said before, science rocks! Our ability to discuss these concepts and incorporate them in programming can elevate our athlete’s ability tremendously. You can’t just “do things” because they look to work, you have to justify and understand the purpose of each movement in a program. Take time, research your facts, and keep developing the correct programs for the correct athletes. Don’t become the hunted, become the HUNTER!
Sources:
Walker, O. (2016, January 23). Stretch-Shortening Cycle. Retrieved from https://www.scienceforsport.com/stretch-shortening-cycle/
Ross A, Leveritt M, & Riek S. (2001). Neural influences on sprint running: training adaptations and acute responses. Sports Med, 31(6):409-25.
Jelveus, A. (2011). Soft tissue stretching in sports massage. Integrated Sports Massage Therapy.