This page is an evergrowing library of sports science and strength & conditioning infographics.

Stretch-Shortening Cycle

This strength & conditioning infographics outlines the stretch-shortening cycle (SSC), including what the SSC is, the underlying mechanisms, the difference between a slow SSC vs fast SSC, the energy storage and the neurophysiological model.

What is the SSC

The stretch-shortening cycle involves three stages. Firstly the muscle undergoes an eccentric action, secondly, the muscle undergoes a transition (also called amortization) phase, this is the time between stage one and three. Stage three is the concentric phase. An example of this would be stepping off a box, and landing, then immediately jumping to a second box.

Provided that the eccentric and amortization phases are fast, the corresponding concentric phase can utilize stored elastic energy like a spring. The faster the first two phases, the more elastic energy can be produced.

It is worth noting, that it is debated, whether the muscles involved, actually work eccentrically and concentrically, or whether the muscles contract isometrically and the recoil is provided by the stretching and shortening of the tendon.

Fast vs slow SSC

The speed of the SSC depends on the action occurring, with actions below 250ms described as fast stretch-shortening cycle, and actions over 250ms are described as a slow stretch-shortening cycle. Synonyms are a short stretch-shortening cycle for the fast SSC and long stretch-shortening cycle for the slow SSC.

Mechanisms of the SSC

The mechanisms which underpin this effect are still not fully understood, however, a range of hypotheses have been suggested, with varying levels of evidence to support them.

Mechanisms include elastic energy storage in the muscle-tendon unit (MTU) during the eccentric phase and amortization phase, that allows an additional propulsive force during the concentric phase. The engagement of the muscle spindles during the eccentric phase, which leads to an augmented firing frequency and stronger recruitment of muscle fibers and the active state, which refers to the time available for the cross-bridging formation, which improves the concentric force output.

Stretch-Shortening Cycle Conclusion

In conclusion, understanding the SSC is an essential component of plyometric training. The SSC is a spring-like mechanism, that can enhance athletic performance in explosive sports, as well as endurance based sports. Well trained athletes often have highly developed SSC capacities, it is therefore worthy of attention in any training program.

This sports science infographic is taken from the article Stretch-shortening Cycle (SSC) from Science For Sports.

Chain Resistance Training

Chain resistance training involves adding heavy chains to your lift, generally at the end of the bar. It is a form a variable resistance training which increases the weight added as the chain moves off of the ground.

Benefits of Chain Resistance Training

Generally speaking, this ensures that a lift is heavier in the easier portion(s) of the movement. Chains have a linear mass displacement, and therefore for each link added, there is an equal amount of weight added to the bar.

An example of Chain Resistance Training

Take the example of a bench press, as the bar is moved further from the ground, more links of the chain come off of the ground, adding more weight to the bar. In the bench press, generally, people are strongest at the top of the movement, as the bench press has an ascending strength curve the use of chains here ensures that the top range of movement receives a larger stimulus than a traditional bench press.

The practical application of using chains

Understanding how chains can influence the kinetics of your movement is important, chains have been shown to increase both peak force and impulse, but you must also consider that they have been shown to reduce peak and average barbell velocity, peak and average power, and peak rate of force development.

Using chains with weight above 15% of your 1RM has been shown to elicit changes similar to those described above. Despite these results, there is still a lot we need to learn about chain resistance training, if this taster has got you interested, this Sports Science infographic is a summary of the article Chain-Resistance Training from Science For Sports.

Matt Solomon

The infographics are created by Matt Solomon.

Please check out Matt’s contributor page

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