Examining the Stretch Shortening Cycle by Larry Strong

[Larry Strong is a Senior at East Carolina University and is currently enrolled in the Athletic Lab Coach Apprenticseship Program]

Have you ever wondered why you can jump so much higher when you quickly bend your knees before jumping? Or why baseball pitchers wind up their throws before throwing 100mph fast balls? Or why you got pinned under that heavy squat the other day? The mechanism in play is something that you and I use every day and don’t even realize it, this spectacular mechanism of the human body is called the stretch-shortening cycle (SSC). Would you believe me if I said that you could train the SSC to improve your athletic proficiency? Well you can and here is how

SSC occurs when a muscle stores elastic energy as a muscle lengthens. The stored up energy is used when the muscle shortens (Dupont). It is seen in many sports and exercises like bench press, squats, Olympic lifting. In Laymen’s terms I describe the muscles as a rubber band. When you stretch the rubber band used for a slingshot it builds up tension and potential energy. Putting an object in that slingshot and releasing it is like the muscles releasing stored force and energy to produce powerful movements. A “Supercharged Rubber band effect” as Dalton Oliver a professor of Sport and Exercise Science at the University of Central Florida, would say.

Why the SSC is important.

The SSC has 3 phases. Those phases are the eccentric phase (also called the lowering phase) such as in bench press when you are lowering the bar to your chest, the concentric phase where you powerfully contract your muscles to move the bar back up to the lockout position and the portion of the lift called the Amortization phase which is where you change direction going from eccentric to concentric. As I was doing my research, I learned the counter movements are a perfect of example of how we use the SSC in sports. Counter movements perfectly illustrate athletes tapping energy from their SSC (Oliver). These counter movements are especially important because of a stance most people know as the universal athletic stance. With knees and other joints slightly bent, straight back, and square shoulders, this stance is seen in many sports such as basketball, hockey, weightlifting, and football. As an example, the next time you are watching a football game pay close attention to the linebackers stances before the ball is snapped. According to Dalton Oliver “From this position, the athlete can more readily transmit force to a greater extent with a counter-movement than he or she could from a standstill” (Oliver).

Ways to Train the SSC.

During my research, I found that plyometric training had extremely positive effects on training athletes. In a study titled Stretch-shortening cycle exercises: an effective training paradigm to enhance power output of human single muscle fibers published in the Journal of Applied Physiology. Their training program was as follows: All subjects completed the whole SSC exercise training program consisting of 24 sessions performed three times per week for a total of 5,228 jumps. All exercises were performed without overweight and included different types of jumps, presented here in order of increasing difficulty: static jump (vertical jump starting with knees flexed at 90 without prior countermovement), vertical countermovement jump, drop jump (height of 40 cm), double-leg triple jump, single-leg triple jump (starting alternatively with left and right leg, final landing on two legs), double-leg hurdle jump (1 repetition = 5 hurdles), and single-leg hurdle jump (similar leg, 1 repetition = 5 hurdles)( Malisoux et al). The authors concluded after their study based on their results that short-term SSC exercise training enhances functional performance of all muscle fiber types through improvements of both shortening velocity and force.

Another way to train the SSC is to limit the “bounce” effect. The bounce effect allows us to use the elastic energy stored to our advantage to initiate contraction and this is often times seen used in exercises such as squats and bench presses. This does two things: first according to Dalton Oliver, it makes the exercise more difficult which then requires the recruitment of more motor recruitment and force production which essentially leads to better performance and muscle hytrophy if that is your goal. Second it can reduce the risk of injury as The point that the athlete changes direction in a lift is the point where he or she must produce the most torque. If an adverse event is going to happen, it is more likely to do so in stretched positions, especially when engaging the bounce effect. We can train not using the bounce effect by utilizing methods such as the stop and go, pauses at the eccentric portion of lifts and even training the eccentric phase only.

Conclusion

As you can see, the Stretch-Shortening cycle is a vitally important part of everyday life and the key to improved athletic performance and efficiency. Training the SSC will transform you into a better athlete. As discussed above sufficient plyometric training is a great way to improve your SSC, this results in improved ability to transfer all stretch to the tendon through maintenance of muscle stiffness, which results in the energy conservation of locomotion(movement) and enhanced propulsion forces (Turner). It is even recommended that plyometric training be preceded by strength training to reduce the risk of injury to the MTC and increase the quality and quantity of type II fibers (Turner). I’ll leave you with a final though, a quote from Dalton Oliver: Plateaus and injuries are right around the corner for those who don’t account for the SSC’s impact on their training and performance.

References

• Dupont, Doug. “Using the Stretch Shortening Cycle for Improved Efficiency.” Breaking Muscle. Web. 10 Sept. 2015.
• Malisoux, Laurent, Marc Francaux, and Henri Nielens. “Stretch-shortening Cycle Exercises: An Effective Training Paradigm to Enhance Power Output of Human Single Muscle Fibers.” Journal of Applied Physiology 100.3 (2006): 771-79. Web. 10 Sept. 2015. <https://jap.physiology.org/content/100/3/771>.
• Oliver, Dalton. “Why You Need to Understand the Stretch-Shortening Cycle.” STACK. 9 June 2014. Web. 10 Sept. 2015.
• Turner, Anthony N., and Ian Jeffreys. “The Stretch-Shortening Cycle: Proposed Mechanisms and Methods for Enhancement.” Strength and Conditioning Journal 32.4 (2010): 87-99.
• ProQuest. Web. 10 Sept. 2015. <https://search.proquest.com.jproxy.lib.ecu.edu/docview/847389694 pq-origsite=summon>.