It is well known that the most sport specific exercise athletes can do is the sports skill itself although this will lead to muscular imbalances and will not provide a sufficient overload. The goal of specificity within a program therefore is to adhere to the principle of dynamic correspondence (Appendix one). This term was first used by Dr Yuri Verkoshansky of the former Soviet Union who did extensive research with athletes in the area of what was then referred to as specialized exercises, to improve performance. From this evolved the principle of dynamic correspondence which says the aim of specificity is to include exercises that are very similar or duplicate specific joint actions or has the same biomechanical and motor characteristics seen during execution of the competitive sport skill. Total body exercises performed explosively could be considered to have similar joint actions to sports involving running, jumping and changes of direction. A large proportion of sporting movements are like those used in weightlifting. Jumping and related weightlifting movements in which the athlete produces force against the ground, are total body movements involving multiple muscle groups and are closed kinetic chain (Ajan & Baroga, 1988) so should be trained that way (Armstrong, 1993; Stone & O’Bryant, 1987)
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Weightlifters are arguably the most powerful athletes and so many strength and conditioning coaches look to the training methods and modalities of weightlifters to improve performance in power and speed based elite sport (Chiu & Schilling, 2005; Janz, Dietz, & Malone, 2008). Power is one variable that correlates positively with athletic success (Chiu, Moore, & Favre, 2007; McBride, Triplett-McBride, Davie, & Newton, 1999; Haekkinen & Komi, 1985). Power = force x velocity and so optimum power must come from both force and velocity training (Chiu et al., 2007). Another explanation for power is speed strength, which has been termed, “any capacity that contains both a force (strength) and speed component to muscular actions” (Young, 1993) and this should be improved when working in power oriented sports if the athlete is to be successful (Hedrick, 1993). Optimizing the transference of gym-based strength and power gains to sporting performance necessitates a physiological and biomechanical understanding of the weight-training exercise as well as the sporting activity (Cronin, Jones, & Hagstrom, 2007). For greatest possible efficiency of training and transfer of the training exercises, it is necessary to do special strength training (Weineck, 2004). To maximise this transfer of training effect, Verkoshansky and Siff (1988) suggest that the criteria of “dynamic correspondence” be considered when selecting specialized exercises-delete this- (Siff, 1998).
The weightlifting lifts are snatch and clean and jerk and importantly the derivatives such as the pulls which can be referred to as Olympic-style lifts (Hydock, 2001). These movements all require great balance, coordination and flexibility which are some of the physical qualities required in sports (Chiu et al., 2007) that have been found to be improved as a result of weightlifting (Tricoli, Lamas, Carnevale, & Ugrinowitsch, 2005). The use of multiple joints and major muscle groups in weightlifting and the resultant improvements in neuromuscular co-ordination may lead to a reduction in injury risk due to the strengthening of connective tissues and improved balance. Indeed Hamill (1994) showed that injuries in weightlifting are less than in other common sports such as basketball, football and gymnastics (delete) (Hamill, 1994).
The Olympic-style lifts can include pulls from hang, below the knee and other various heights but all have the commonality of high velocity, leading to high power output (Hoffman, Cooper, Wendell, & Kang, 2004). The pull section of the lifts are responsible for the majority of the power production (Stone, 1993) and are quite similar in kinetics and kinematics to jumping and other movements (Hori, Newton, Nosaka, & Stone, 2005). During the pull phase the athlete never decelerates the barbell and conversely, accelerates the bar until full extension of the ankle knee and hip is complete (Janz et al., 2008). The angles at ankle, knee and hip are similar to those involved in sports and although an athlete will never lift a barbell above themselves in competition the overload at these joint angles will create an adaptation. Also training with the pulls may allow an athlete to train without apprehension of the catch or drop phases (Hydock, 2001) which often impair development.
The anatomy and teaching of the pull phase is a highly researched area beyond the scope of this paper but the important second knee bend will be discussed as this relates to the transfer of training that occurs through improving jumping performance and providing a specific overload to the ‘athletic position’. The athletic position is characterized by an athlete standing with slightly flexed hips and knees similar to that of a vertical jump start (Chiu et al., 2007). After picking the barbell up from the floor, the termination of knee extensor activity and activation of the knee flexors as the barbell passes the knees causes the second knee bend action (Baumann, Gross, Quade, Galbierz, & Schwirtz, 1988) in weightlifting movements. The net joint moment in favour of knee flexion is brief as the knee extensors reactivate to perform the second pull (Baumann et al., 1988). The second knee bend is important as it allows the second pull to fully utilise the major muscle groups (Hydock, 2001) thus creating maximum force and thus power outputs.
For athletes in sports such as rugby it is far more important to generate force quickly than to just display as much force as possible, indeed success often depends on the rate at which force is developed (Janz et al., 2008; Chiu et al., 2007). Rate of force development is vital in weightlifting and without an adequate attempt to accelerate, the lifter will normally fail. It is often said in strength and conditioning that for optimal athletic development, athletes must train across the force velocity spectrum (Appendix 2).
Also the energy pathway for weightlifting is primarily the PCr system (Plisk, 1991) but adaptations to the oxidative and glycolytic energy systems can be explained via the recovery processes (Schuenke, Mikat, & McBride, 2002). The initial use of the fast glycolytic system is followed by the oxidative metabolism to restores the high energy phosphates (Plisk, 1991) during training. In addition to the musculoskeletal and mechanical adaptations, cardio-respiratory, and psychological adaptations also result from weightlifting training (Chiu & Schilling, 2005) and the muscle fibre adaptations include transition of fibre types and hypertrophy of fibres (Hakkinen, Pakarinen, Alen, Kauhanen, & Komi, 1988; Fry et al., 2003). With training the fibres containing the protein, myosin heavy chain, which is primarily responsible for muscle contraction force and velocity will change from type IIb to type IIa and importantly the fibres containing myosin heavy chain type IIa proteins have the greatest capacity for growth.
The weightlifting movements and there derivatives have the potential to produce some of the highest average power outputs (Garhammer, 1980; Garhammer, 1991) and are significantly higher than the traditional power lifting exercises (Hoffman et al., 2004) (Table 1). Rugby is a sport that involves multiple changes of direction and intermittent sprinting therefore explosiveness is a key to success. There is an abundance of research that high velocity; high force specific movements improve sports performance (Garhammer, 1991; Garhammer, 1981; Stone, 1990) and more specifically Olympic style lifts (Garhammer & Gregor, 1992; Jaric, Ristanovic, & Corcos, 1989), although Brzycki (1986) opposed this view (Brzycki, 1986) albeit with little factual basis.
Absolute Power (W)
Outputs Table 1
Note: Modified from (Stone, 1993)
Vertical jump is often used as a standard measure of athletic strength and power in the lower body