There are fundamental differences between eccentric and concentric contractions in terms of energy costs. Early observations by Bigland-Ritchie and Woods (Bigland-Ritchie and Woods, 1976) showed that at the same speed of movement (cycling), the energy costs of positive work (shortening) are about six times higher than with negative work (extension). Thus, eccentric contractions have been advocated as particularly suitable for restoring muscle mass and strength in elderly and clinical populations (Hoppeler, 2014; Mitchell et al., 2017). The characteristics of the metabolic and energy costs of ECC in relation to CON contractions were recently examined by Professor Hoppeler (Hoppeler, 2016). Muscle contraction is not just muscle strength. It`s not just the mass that allows bodybuilders and weightlifters to perform Herculean lifts. Muscle contraction and strength in general is much more than size, but also involves the muscular response to resistance training. Martineau and Gardiner (2001) observed that MAPK activation is quantitatively related to tension, with ECC providing the greatest stimulus compared to shortening muscle actions. It is well known that mechanical stress is one of the crucial factors affecting muscle growth (Goldberg et al., 1975; Fry, 2004) and also that eccentric contractions are associated with greater stress development compared to concentric contractions (Katz, 1939). Interestingly, a successive study in which the ×-time force integral (FTI) was manipulated by modifying the contraction force showed that p38 and FAK phosphorylation correlates with FTI (Rahnert and Burkholder, 2013), indicating a possible close relationship between these targets and the type of mechanical stimulus exerted on the muscle. This observation led us to understand the role of FAK activation (at the tyrosine site y-397) between different contractions (elongation vs.
shortening). B) and at different muscle sites (mean muscle vs. JT): Preliminary analysis of the data showed that activation of y-397FAK was greater after a single session of ECC-RT compared to CON (Franchi et al., 2016b). In addition, such activation appeared to be site-dependent on muscle (MTJ > MID), supporting the regionality/heterogeneinity of hypertrophic adaptations and structural remodeling to different load modes. Schoenfeld, B. J., Ogborn, D. I., Vigotsky, A. D., Franchi, M.
V., and Krieger, J. W. (2017). Hypertrophic effects of concentric vs. eccentric muscle actions: a systematic review and meta-analysis. J. Strength. Res. 31, 2599–2608.
doi: 10.1519/JSC.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 muscle pain and muscle function after resistance exercises. J. Sports Med. 18, pp. 431-437. Regarding morphological adaptations of muscle to CON and ECC training, Blazevich and colleagues suggested that training at a greater than normal range of motion of the joints could explain similar structural remodeling in response to both modes of exertion instead of the type of contraction. This hypothesis appears to have been supported by other studies (McMahon et al., 2014; Guex et al., 2016), who noted a greater increase in the length of the VL fascicle during training with a larger ROM of the knee joint. Nevertheless, Noorkõiv et al. (2014) showed that isometric training can induce a significant increase in Lf at longer muscle lengths (i.e. almost the reproduction of an ECC contraction scenario).
With regard to the results of blazevich`s (2007) study, the authors therefore raise the question of whether more pronounced mechanical stress could have been applied to individual sarcomeres (and thus fascicles) during the large ROM CON RT at a higher articular knee angle (counting the complete leg extension as anatomical zero = 0 degrees) and whether this is the distribution of the serial sarcomere and, ultimately, architectural adjustments, which were presented by the above studies. Jones, D. A., Newham, D. J., Round, J.M., and Tolfree, S. E. (1986). Experimental human muscle damage: morphological changes compared to other damage indices. J. Physiol. 375, 435–448.
Roig, M., O`Brien, K., Kirk, G., Murray, R., McKinnon, P., Shadgan, B., et al. (2009). The effects of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: a systematic review with meta-analysis. Br. J. Sports Med. 43, 556–568. doi: 10.1136/bjsm.2008.051417 Chen, T.C. (2003).
Effects of a second attack of maximum eccentric exercise on muscle damage and electromyographic activity. Euro. J. Appl. Physiol. Occupy. Physiol. 89, 115–121. McHugh, M. P. (2003).
Recent advances in understanding the repeated fighting effect: the protective effect against muscle damage caused by a single eccentric exercise attack. Scan. J. Med. Sci. Sport 13, 88-97. To turn the rod and lower the weight pile, all these muscles must be elongated afterwards and the rod must return to its starting position above your head. You don`t just let go and let the bar fly away and crush the pile of weights. Instead, slowly bring the stem back by contracting these muscles and letting them lie down. It is an eccentric contraction that involves shortening and tension in the muscle associated with lengthening. Brown, S. J., Child, R.B., Day, S.
H., and Donnelly, A. E. (1997). Exercise-induced damage and adjustment of skeletal muscles after repeated attacks of eccentric muscle contractions. J. Sports Sci. 15, 215–222. Croisier, J. L., Camus, G., Venneman, I., Deby-Dupont, G., Juchmes-Ferir, A., Lamy, M., et al.
(1999). Effects of exercise on exercise-induced muscle damage and interleukin-6 production. Muscle nerve 22, 208-212. Looking at muscle thickness as an index of muscle hypertrophy in response to ECC vs CON RT, a total of six studies were identified. Five of the six studies reviewed found no significant differences between exercise paradigms on knee extenders, long-headed femoris biceps or supraspinatus muscles. One study (Farthing and Chilibeck, 2003) showed that for midpoint and distal elbow flexors, high-speed ECC RT resulted in a higher increase in TM compared to high- and slow-speed CON RT. However, when the slow speed ECC RT was compared to the slow speed CON RT, no difference in MT switching between the training programs was found. Nevertheless, the proximal site study showed significant superiority of high-speed ECC RT in generating major changes in TM. However, while similar “whole muscle” growth is often observed as a result of both types of RT, the structural remodeling mechanisms by which hypertrophic reactions are achieved seem to really differ between ECC and CON load. Our laboratory has recently shown that various architectural adjustments (measured with the B-mode ultrasound technique, Figure 4)4) between ECC vs CON: ECC contractions leads to a significantly greater increase in fascicle length (Lf), while CON promotes larger changes in pennation angle (PA), probably reflecting the differential addition of sarcomeres in series or in parallel (Reeves et al., 2009; Franchi et al., 2014, 2015) (Figures (Figures5,5, ,7).7).
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