Young (2006, p. 74) reported that exercises involving bilateral contractions of leg muscles for vertical movements, like squats and jump squats, are not effective in improving performance. In contrast, according to Young (2006, p. 74), plyometric training can lead to “significant increases in sprint acceleration performance, thus highlighting the importance of movement pattern and contraction velocity specificity.” Further, Harris et al. (2008, p. 691) reported that based on an experiment they conducted among thirty elite rugby athletes, the correlation between sprint ability and jumping ability is generally positive and of moderate to strong magnitude. Adopting the definitions reported by earlier works, Ploeg et al. (2010, p. 39) explained that plyometric exercises or plyometrics are exercises in phases that begins with intense eccentric muscular contractions followed by rapid concentric muscular contraction.
Drawing on various works, Ploeg et al. (2010, p. 39) explained that when muscle is stretched, the muscle stores elastic energy briefly and plyometric exercises use the stored energy to assist the concentric contraction to produce more force than what can be provided by a plain concentric action or a concentric contraction....
(2010, p. 40) clarified that alpha motor neurons transmit signals to the muscle group in a ploymetric exercise. The amortization phase in the plyometric activity is crucial in developing the production of power (Ploeg et al. 2010, p. 40). Craig and Judge (2009, p. 75) explained that several studies have shown consistently that overloading the body with a progressive training program will increase muscle size and strengthen the bone. Based on the results of their experiments, Villareal et al. (2008) concluded that moderate plyometrics training programs are more efficient than higher plyometrics training volume but the although their study was limited to short-term or 7-weeks of training and may be applicable for that class of training programs, particularly short-period training programs. In contrast, the evidence reviewed by Craig and Judge (2009, p. 75) covered l training programs with longer time periods. 2.0. Training and Conditioning Appropriate and Physiological Adaptation In designing training programs, Craig and Judge identifed three important aspects of designing a training program: periodization, resistance training, and training sets (2009, p. 75-76). Turner (2011, p. 34) emphasized on the importance of periodization as an “optimal strategy for organizing strength and conditioning programs.” Periodization involves the variation of training methods and volume loads for the purpose of “potentiation of biomotors and the management of fatigue and accommodation” (Turner 2011, p. 34). Turner pointed out that periodization manipulate volume loads and progresses from general to sport-specific training (2011, p. 34). For Turner, although scientific studies are required to establish the use and