Speed performance is a complex of a person’s functional abilities, ensuring the fulfillment of motor actions in the minimum time interval for these conditions. There are elementary and complex forms of speed performance. Primary forms include four types of speed abilities: the capacity to respond quickly to a signal and perform single local movements with maximum speed. Moreover, these are the skills to start moving fast and to perform actions at a maximum pace. Several scientific facts have been accumulated that show that these abilities have a complex structure. The maximum rate of elementary high-speed movements cannot be considered a single form of manifestation of speed performance. One of the approaches that can enhance it is strength training, mainly focusing on eccentric muscle traction. It is an activity when a tense muscle lengthens under load. Due to it, the muscle-tendon complex stretches and absorbs mechanical energy (Chaabene, Prieske, Negra, & Granacher, 2018). When no muscle shortening occurs after stretching, the power is dissipated in the form of heat.
The central benefit is the improvement of muscle coordination. With eccentric training, the cortex’s activation is high and covers a large area. Besides, the electromyographic activity is lower, comparing a similar level of effort in terms of concentric contraction (Chaabene et al., 2018). EMG muscle activity shows the number of motor units in a muscle that is involved in contraction (Chaabene et al., 2018). The higher the electromyographic potential, the more muscle fibers contract. Since the EMG activity during eccentric strength training with the same load intensity is lower, the mechanical loading on individual muscle fibers is higher. According to research, improvement in contractile functions is observed mainly in rapidly twitching fibers (Chaabene et al., 2018). It is believed that some of the fastest muscle fibers are activated only during high-intensity eccentric contractions.
Reference
Chaabene, H., Prieske, O., Negra, Y., & Granacher, U. (2018). Change of direction speed: Toward a strength training approach with accentuated eccentric muscle actions. Sports Medicine, 48(8), 1773-1779.