Basically, the muscle behaves as if it were elastic, and this is difficult to explain if you only know actin and myosin. But the titin stiffens compared to the strength of muscle contraction, which corresponds to the bill: the titin is „loose“ and allows an extension when the muscle is relaxed, but when you turn on the muscle, it stiffens and resists stretching more and more as you clump together. Intelligent. Eccentric contractions are not the same as „dropping“ a weight after lifting. It is a controlled movement in which you move towards an opposite force instead of moving away from it. Thompson, H. S., Clarkson, P.M., and Scordilis, S. P. (2002). The repeated fighting effect and heat shock proteins: intramuscular expression HSP27 and HSP70 after two eccentric workouts in humans.
Acta physiol. Scanned. 174, 47–56. Coactivation exercises (with slow balance and control activities) use isometric, eccentric, and concentric contractions to increase CNS proprioception and awareness, thereby improving wrist stability.35 A simple method of coactivation training is to perform balance ball exercises (Fig. 22.4). The client`s hand(s) are placed on a weighted ball. The customer is asked to move the ball slowly around the table, which allows the simultaneous activation of the extenders, flexors and deflectors of the wrist. Coactivation rehabilitation with hidden vision and vision improves wrist stability by increasing proprioceptive awareness during movement, with better muscle control. Exercises by litter and with resistance with free weights or elastic bands increase sensorimotor feedback and reciprocal and recurrent muscle action. Activities of limited level and scope (e.g., B toy hammer or imitation of a dart throw) activate stabilizers with a graduated load.49 Movements that use eccentric contractions include walking down stairs, descending, lowering weights, and moving down squats, push-ups, or pull-ups. Friden, J., and Lieber, R. L.
(1998). Segmental lesions of muscle fibers after repetitive eccentric contractions. Cell Tissue Res. 293, 165-171. On the other hand, nothing is so orderly in sports medicine. Even if it helps, recent results show that EE may not really change the tendon,8 which is probably what most people hope for and assume – a new stimulus with an interesting and useful tissue response would be of great interest. Mueller, M., Breil, F. A., Vogt, M., Steiner, R., Lippuner, K., Popp, A., et al. (2009). Different response to eccentric and concentric training in older men and women. Euro. J.
Appl. Physiol. 107, 145–153. doi: 10.1007/s00421-009-1108-4 Other possible cellular adaptations include increased protein synthesis, adaptation of excitation-contraction coupling, and increased stress proteins (i.e., heat shock proteins) (McHugh, 2003). In particular, the role of heat shock proteins (HSP) in protecting against muscle damage represents an exciting new area of research. Small HSPs (sHSPs) named HSPB1 (Hsp27) and alphaB-crystalline appear to play an important role in cell adaptation, as they are involved in accompanying unfolded proteins, stabilizing the cytoskeleton, as well as regulating the cellular redox state and inhibiting apoptosis (Orejuela et al., 2007). After eccentric exercise, sHSPs move from the cytosol to the cytoskeletal/myofibrillary compartment, presumably to stabilize and protect the organization of the myofibrillar filament (Paulsen et al., 2007, 2009; Frankenberg et al., 2014). Such an observation was not found after a concentric exercise (Frankenberg et al., 2014). AlphaB-crystalline interacts with the intermediate filaments of desmine and Hsp27, as well as alphaB-crystalline, has been proposed to interact with various microfilaments (Orejuela et al., 2007). These data strongly support the idea that alphaB-crystalline and Hsp27 are crucial for the preservation and conversion of myofibrillary structures. Therefore, in accordance with the strengthening of cytoskeletal/myofibrillary structures, adequate adaptation of HSP protection systems may also be important (Paulsen et al., 2007).
Since HSPs are involved in developing stress tolerance for several stressful insults, it is likely that the HSP response triggered by a first episode of damage will give resistance to a potentially harmful second exercise. Few studies have examined the response of HSPs to repeated eccentric exercises. Paulsen et al. (2009) found that two episodes of maximum eccentric stress separated by 3 weeks resulted in comparatively high levels of HSP in the cytoskeletal fraction, although less damage was caused during the second seizure. The large amount of Hsp27, crystalline alphaB and Hsp70 in the cytoskeletal compartment after repeated fights suggests that a more efficient translocation of these HSPs is likely a mechanism behind the RBE. Similarly, Thompson et al. (2002) reported a similar relative increase in Hsp27 and Hsp70 2 days after the first and second eccentric seizures, but it is interesting to note that the basal levels of these HSPs appeared to be lower before the second fight. This raises the question of HSPs as important players in the RBE. .
