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Running economy (RE) is typically defined as the energy demand for a given velocity of submaximal running, and is determined by measuring the steady-state consumption of oxygen (V̇O2) and the respiratory exchange ratio. Taking body mass (BM) into consideration, runners with good RE use less energy and therefore less oxygen than runners with poor RE at the same velocity. In highly trained runners, there are a number of physiological factors that determine running performance, with running economy (RE) identified as a critical factor in distance running performance. Given the importance of RE in performance, successful training interventions that improve RE would be advantageous for the athlete. Such interventions would benefit from including plyometrics (plyos) in.

Plyos, whereby the acceleration and deceleration of body weight is used as the overload in dynamic activities such as Drop Jumps (DJ) and Countermovement Jumps (CMJ), which involves stretch shortening cycle (SSC) components. Such exercises can be accomplished with or without an external load and both training modalities have shown to increase power and improve jump performance and sprinting abilities as a result. Plyos are believed to be an important component when developing the SSC and there is sufficient evidence proving that PT is effective at improving tasks that rely heavily on the SSC, such as the CMJ and DJ.

Schmidtbleicher, has suggested that the SSC can be classified as either slow or fast. The slow SSC (e.g. CMJ) is characterized by longer contraction times (>0.25 seconds) and greater angular displacements of the hips, knees, and ankles. On the other hand, fast SSC (e.g. DJ) is known to have shorter contraction times (<0.25 seconds) with smaller angular placements of the hips, knees and ankles. The muscle spindle reflex relies heavily on a fast rate of eccentric stretching and the elastic energy stored during the amortization phase may rely on a short transition between eccentric and concentric phases. As transition times between eccentric and concentric actions increase, these can be contributed to slow SSC Slow SSC plyos have a slower eccentric velocity and a longer transition period than that of fast SSC making them more relevant for longer distances.

Slow and fast SSC may represent different muscle actions that reply on differing biomechanical mechanisms having a differing effect on performance. Plyo’s also has the potential to increase the stiffness of the muscle-tendon system, which allows the body to store and utilize elastic energy more effectively. Both of these adaptations resulting from plyos could potentially improve RE by generating greater force production from the muscles without a proportionate increase in the metabolic energy requirement. Those who are new to the practice should keep intensity and eccentric loading low to begin with. If you’ve got any ankle, knee or hip pathology, seek medical advice prior to commencing. Let the running gains begin.

References
Anderson, T. Biomechanics and running economy. Sports Med. 22:76–89. 1996.
Bobbert M, Huijing P, and Van Ingen Schanau G. Drop jumping I. the influence of jumping technique on the biomechanics of jumping. Med Sci Sports Exerc 19: 332– 338, 1987.
Flanagan, E and Comyns, T. The use of contact time and reactive strength index to optimize fast stretch shortening cycle training. Strength and Conditioning Journal 30:32-38. (2008).
Markovic, G, Jukic, I, Milanovic, D, and Metikos, D. Effects of sprint and plyometric training on muscle function and athletic performance. J Strength Cond Res 21: 543–549. 2007.
Morgan, D, and Craib, M..Physiological aspects of running economy. Med. Sci. Sports Exerc. 24:456–461. 1992.
Paavolainen, L, Hakkiene, I. Hamalainen, A. Nummela, A and Rusko, H. Explosive strength training improves 5km running time by improving running economy and muscle power. J. Appl. Physiol. 86:1527-1533. 1999.
Saunder, P, Pyne, D, Telford, R and Hawlet, J. Factors affecting running economy in trained distance runners. Sports Med. 34:465–485. 2004.
Spurrs, R, Murphy, A and  Watsford, M. The effect of plyometric training on distance running performance. Eur J. Appl. Physiol. 89:1–7. 2003

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