elitefts™ Sunday Edition

Muscular contractions can be characterized by two primary actions—concentric and eccentric contractions. When the force produced by the muscle exceeds the force applied to the muscle, the muscle will shorten or act concentrically, which typically occurs when you drive up from the bottom of a squat. When the force applied to a muscle exceeds that produced by the muscle, it will lengthen or act eccentrically, which occurs during the descent of a full squat.

Eccentric contractions describe muscle elongation or the active lengthening of muscle fibers under load. It’s the negative phase of an exercise which gives you the most bang for your buck. Those seeking maximum results should incorporate training methods on eccentric overload. Eccentric muscle actions can be performed at greater absolute muscle force levels, albeit lower levels of activation, than concentric ones (Seger 2005). Some research has suggested that subjects may be as much as 20–60 percent stronger eccentrically than concentrically (Hollander 2007). After all, who doesn’t want to get strong(er), right?

Considering that eccentric muscle action involves a reduction in muscle fatigue, a lower cardiorespiratory component, and more metabolic efficiency, you can train eccentrically for a longer period of time compared primarily with concentric contraction. Now, a few things to keep in mind—velocity of movement is a key factor. From a hypertrophy perspective, movement speed may play a larger role on the eccentric portion of a rep. Essentially, the speed of movement should be controlled during eccentric actions. Otherwise, strength and hypertrophy gains will be negated. Moreover, intensity plays another role. You need to train heavy enough and understand and take advantage of the fact that you can use supramaximal loads.

Eccentric resistance training incorporating submaximal, maximal (100 percent 1RM), or supramaximal (>100 percent 1RM) training loads may lead to greater increases in maximal muscle strength (Higbie 1996, Hortabagyi 1996, Hortabagyi 2001, Norrbrand 2008, Seger 1998) in part due to greater or a more pronounced degree of muscle hypertrophy following eccentric training (Higbie 1996, Hortabagyi 1996, Hortabagyi 2001). Despite the fact that concentric and isometric muscle contractions have been shown to elicit a hypertrophy response, numerous studies have reported that eccentric actions have the greatest effect on skeletal muscle growth (Hortabagyi 1996, Nickols-Richardson 2007, Hortabagyi 2001, Roig 2009, Hather 1991).

Higbie and colleagues (1996) found a combined strength increase (concentric strength improvement plus eccentric strength improvement) of 43 percent with an eccentric-only training protocol, compared to one of 31.2 percent with a concentric-only regimen. In addition, Farthing (2003) concluded that eccentric training resulted in greater hypertrophy than concentric training for the biceps over eight weeks. Furthermore, LaStayo and colleagues (2003) found accentuated eccentric training to cause 19 percent more muscle growth than traditional strength training over an eleven-week period. Recently, Carothers and colleagues (2010) evaluated the strength benefits of an eccentric-only protocol compared to a standard and concentric-only protocol using the bench press performed for two sessions a week for six weeks. The subjects were randomized into one of three groups—eccentric-only (ECC), standard (STN), and concentric-only (CON). Participants were tested for concentric, standard, and eccentric 1RM pre- and post-training. The subjects performed four sets of 4–8 repetitions with 80 percent of their 1RM. Subjects progressed up five percent when four sets of eight repetitions were achieved successfully, and 3–5 minutes of rest was used between sets. The results demonstrated that the eccentric group (ECC) showed a significantly greater increase in strength over the standard group (STN) in the eccentric 1RM (22 percent versus nine percent). This suggests that eccentric-only protocols favorably increase strength development over standard protocols. These findings are even more meaningful with respect to the level of gain (22 percent in only six weeks) with recreationally trained individuals. Although increases to this degree are normally associated with neural adaptation in untrained subjects, the results suggest that eccentric muscle actions are undervalued in resistance training protocols.

There are a whole host of reasons why eccentric exercise training is effective for stimulating greater strength and hypertrophy compared to pure concentric training:

  • There’s a greater force output produced during a maximal eccentric action because you can use a higher external load. Research focusing on the effects of overload training (100–120 percent of the maximal repetition) during the eccentric phase of an exercise demonstrates greater strength gains than during resistance training using lighter loads.
  • There is significant neural adaptation to eccentric training compared to concentric training (Hortobagyi et al. 1996). In addition, the energy cost of eccentric exercise is low, despite the high muscle force being generated. This response is exhibited through significant alterations in strength, power, and hypertrophy (Lindstedt et al 2001).
  • Exercise-induced hypertrophy from eccentric exercise is manifested by greater muscular tension under load. It's postulated that this is a result of a reversal of the size principle of motor unit recruitment, resulting in fast twitch motor units being recruited (Shepstone 2005). In addition, eccentric exercise is also linked to increases in protein synthesis (Moore 2005), as well as a larger rise in IGF-1 mRNA expression (Shepstone 2005) when compared to concentric muscle action.
  • There is a current trend toward an agreement in the literature that eccentric training sessions elicit greater muscle damage compared to concentric training (Nosaka 2002a, 2002b). The response to damage from eccentric training is thought to be associated with a mechanical disturbance of the actomyosin bond versus ATP-dependent detachment, leading to greater stress and strain on the contractile apparatus compared to other muscle actions (Enoka 1996).

Although strength and hypertrophy take precedence for most of us, there are even further benefits to training with eccentrics. These include an increase in muscle cross-education effect. Cross-education describes the transfer of strength gains from one limb/side to the other. Simply, if you train your right arm using eccentric training, the left would get stronger by transferring the strength gains. The muscle group is also thought to contribute to the magnitude of muscle damage from eccentric contractions in that the degree of muscle damage is greater following eccentric exercises in the upper limb than the lower limb (Jamurtas 2005). It appears that fusiform muscles (e.g., biceps brachii) are more susceptible to eccentric-induced damage than penniform muscles (Jamurtas 2005). Pennate muscles have short fascicles attaching obliquely to a central tendon that runs the length of the muscle (e.g., rectus femoris). In addition, type II muscle fibers are more vulnerable to damage during eccentric exercise than type I muscle fibers (McHugh 2002, Vijanian 2001) 3). Eccentric exercise is commonly employed in functional rehabilitation given the increase in collagen synthesis and improvements in overall bodily function (Gerber 2009).

The bottom line is that resistance-training protocols, specifically when the eccentric is emphasized, appear to result in greater strength and hypertrophy than concentric exercise alone.


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