The Five Biggest Contradictions in Fitness
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The Five Biggest Contradictions in Fitness

Itís no secret that when people contradict themselves, it has the effect of making the flaws in their actions or statements seem glaringly obvious. But what about when WE ourselves get caught contradicting ourselves by someone else?

By: Nick Tumminello Added: January 6th, 2014
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  1. #1
    Gonnabebig Member JuniorMint6669's Avatar
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    eccentric only/ concentric only

    First, what is the benefit of concentric only training? Ive read that its good for recovery, but how/why? Mostly, I see sled dragging and medicine ball throws as recommended excercises for this, but would it also be possible to do something like... lift a weight with one limb, and then lower it with two (the opposite of what I see recommended for eccentric only training).

    Next, how would I go about adding eccentric and concentric only excercises into my workout routine? Should I add something like... 1 or 2 eccentric only movements per day? Or would it be better to do.. one week of eccentrics? I honestly have no idea, input would be greatly appreciated. Same for concentric only, would it be best done on my off day? Or just added movements to my normal routine. I couldnt imagine doing a week of concentric only, but would this perhaps be a better alternative to taking a full week off for recovery?

    Thanks for the help!

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  3. #2
    Gonnabebig Member JuniorMint6669's Avatar
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    bump

  4. #3
    "Tuna Boy" NateDogg's Avatar
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    I would think the benefit, in that it is good for recovery, would come from the idea that most damage is done to a muscle in during the eccentric phase of the lift. Therefore, you can get blood flowing without causing as much damage as complete reps would.

    Anyone else?
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  5. #4
    Rory Parker Behemoth's Avatar
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    I get them confused. Which is eccentric and which is concentric?

    I'm very interested in the answer to this also...
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  6. #5
    Baby Seal Clubber ElPietro's Avatar
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    Concentric training only I don't really see the point. Your muscle works much harder during the concentric phase of a movement, versus the eccentric phase, so really your muscle isn't being taxed very much eccentrically anyway, so impact-wise, I see relatively no difference.

    Now eccentric only training could work, as in you can add more weight and do heavy negatives, this in no way would be for recovery though. If you are working out just to aid in recovery just take a light weight, and do a ton of reps for a set or two and that's it. All you are trying to do is get that area warmed up again, aka blood flowing to the area, which should aid in recovery provided you are eating sufficiently.
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  7. #6
    Player Hater PowerManDL's Avatar
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    Originally posted by ElPietro
    Concentric training only I don't really see the point. Your muscle works much harder during the concentric phase of a movement, versus the eccentric phase, so really your muscle isn't being taxed very much eccentrically anyway, so impact-wise, I see relatively no difference.

    The workload is actually greater by a fair amount during the eccentric action. Additionally the increased stresses do cause a significant amount of cellular disruption (microtrauma) that is not found in concentric-only movements.

    Concentric-only training has the advantage of leaving out the damaging negative/eccentric component, which can be useful for recovery, as well as having useful neurological effects from starting a lift without the benefit of the stretch-shortening cycle.

    The latter is one reason why a max deadlift tends to be so much harder than a max squat. Starting a lift without a prior eccentric action/stretch is quite a bit more difficult; doing so can aid in the rate of force production and explosiveness.
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  8. #7
    Gym ratt/Part-time pimp LAM's Avatar
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    the majority of metabolic work is performed during the cocentric portion of a lift. so for fat loss it would be of some help but that's about it.

  9. #8
    Baby Seal Clubber ElPietro's Avatar
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    Originally posted by PowerManDL

    The workload is actually greater by a fair amount during the eccentric action. Additionally the increased stresses do cause a significant amount of cellular disruption (microtrauma) that is not found in concentric-only movements.

    Concentric-only training has the advantage of leaving out the damaging negative/eccentric component, which can be useful for recovery, as well as having useful neurological effects from starting a lift without the benefit of the stretch-shortening cycle.

    The latter is one reason why a max deadlift tends to be so much harder than a max squat. Starting a lift without a prior eccentric action/stretch is quite a bit more difficult; doing so can aid in the rate of force production and explosiveness.
    Perhaps the microtrauma is greater due to time under tension, but considering that you are applying less force to the weight during the eccentric versus concentric portion simply means you are not pushing yourself as hard at any one point in time.

    Considering that you could just let the weight drop without applying any force, I find it hard to believe you can actually quantify your claim. If you take the exact same weight, and the exact same time under tension for eccentric and concentric, you will be working harder during the concentric phase because you are lifting 100% of the weight, plus additional force output in order to move that weight against gravity, versus less than 100% in order to allow it to drop with gravitational assistance.

    I'm not even sure of the relevance of the deadlift/squat comparison. They are not the same lift, and everyone can perceive difficulty differently. But regardless, the squat actually mechanically benefits from stretch reflex in your hips which can be varied depending on stance, speed, flexibility, etc, etc, but even with all that, is entirely irrelevant to the discussion. They are different lifts mechanically.
    Deadlifts are like women, they'll hurt you everytime, but they'll also make you a man. - Me

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    I can picture in my mind a world without war, a world without hate. And I can picture us attacking that world, because they'd never expect it.

    Is there anything more beautiful than a beautiful, beautiful flamingo, flying across in front of a beautiful sunset? And he's carrying a beautiful rose in his beak, and also he's carrying a very beautiful painting with his feet. And also, you're drunk.

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  10. #9
    Baby Seal Clubber ElPietro's Avatar
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    Another thing about the microtrauma statement, I don't know this but maybe you can clarify. If there is significantly more microtrauma, perhaps this indicates there is greater recruitment eccentrically, but this wouldn't mean much as far as the concentric goes. I mean as why you would only do concentric. It would lend credence to doing eccentric only lifts, but not concentric only. Since you are already limited by the weight you can lift concentrically, it stand to reason you could accomplish more by increasing the weight and lifting eccentric only.
    Deadlifts are like women, they'll hurt you everytime, but they'll also make you a man. - Me

    Friends don't let friends do dumbell kickbacks. - Me

    ElP is the smartest man in the world. - Gyno Rhino

    A low voter turnout is an indication of fewer people going to the polls. -- Dan Quayle

    If do right, no can defense. -- Mr. Miyagi

    Deep Thoughts by Jack Handey:

    I can picture in my mind a world without war, a world without hate. And I can picture us attacking that world, because they'd never expect it.

    Is there anything more beautiful than a beautiful, beautiful flamingo, flying across in front of a beautiful sunset? And he's carrying a beautiful rose in his beak, and also he's carrying a very beautiful painting with his feet. And also, you're drunk.

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  11. #10
    Player Hater PowerManDL's Avatar
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    Originally posted by El Pietro
    Perhaps the microtrauma is greater due to time under tension, but considering that you are applying less force to the weight during the eccentric versus concentric portion simply means you are not pushing yourself as hard at any one point in time.

    Considering that you could just let the weight drop without applying any force, I find it hard to believe you can actually quantify your claim. If you take the exact same weight, and the exact same time under tension for eccentric and concentric, you will be working harder during the concentric phase because you are lifting 100% of the weight, plus additional force output in order to move that weight against gravity, versus less than 100% in order to allow it to drop with gravitational assistance.
    You asked for it.......


    Histochem Cell Biol 2003 Apr 24. The mode of myofibril remodelling in human skeletal muscle affected by DOMS induced by eccentric contractions. Yu JG.

    Myofibrillar Z-disc streaming and loss of the desmin cytoskeleton are considered the morphological hallmarks of eccentric contraction-induced injury. The latter is contradicted by recent studies where a focal increase of desmin was observed in biopsies taken from human muscles with DOMS. In order to determine the effects of eccentric contraction-induced alterations of the myofibrillar Z-disc, we examined the distribution of alpha-actinin, the Z-disc portion of titin and the nebulin NB2 region in relation to actin and desmin in DOMS biopsies. In biopsies taken 2-3 days and 7-8 days after exercise, we observed a significantly higher number of fibres showing focal areas lacking staining for alpha-actinin, titin and nebulin than in biopsies taken from control or 1 h after exercise. None of these proteins were part of Z-disc streamings but instead they were found in distinct patterns in areas characterised by altered staining for desmin and actin. These were preferentially seen in regions with increased numbers of sarcomeres in parallel myofibrils. We propose that these staining patterns represent different stages of sarcomere formation. These findings therefore support our previous suggestion that muscle fibres subjected to eccentric contractions adapt to unaccustomed activity by the addition of new sarcomeres.

    J Appl Physiol 2003 Jun;94(6):2475-2482. Intracellular sodium in mammalian muscle fibers after eccentric contractions. Yeung EW, et al.

    The effect of eccentric contractions on intracellular Na(+) concentration ([Na(+)](i)) and its distribution were examined in isolated rat and mouse muscle fiber bundles. [Na(+)](i) was measured with either Na(+)-binding benzofuran isophthalate or sodium green. Ten isometric contractions had no significant effect on force (measured after 5 min of recovery) and caused no significant change in the resting [Na(+)](i) (7.2 +/- 0.5 mM). In contrast 10 eccentric contractions (40% stretch at 4 muscle lengths/s) reduced developed force at 100 Hz to 45 +/- 3% of control and increased [Na(+)](i) to 16.3 +/- 1.6 mM (n = 6; P < 0.001). The rise of [Na(+)](i) occurred over 1-2 min and showed only minimal recovery after 30 min. Confocal images of the distribution of [Na(+)](i) showed a spatially uniform distribution both at rest and after eccentric contractions. Gd(3+) (20 &mgr;M) had no effect on resting [Na(+)](i) or control tetanic force but prevented the rise of [Na(+)](i) and reduced the force deficit after eccentric damage. These data suggest that Na(+) entry after eccentric contractions may occur principally through stretch-sensitive channels.

    Int J Sports Med 2002 Nov;23(8):567-74. Central versus peripheral adaptations following eccentric resistance training. Pensini M, et al.

    Aim of the present investigation was to study the effects of an eccentric training on the neuromuscular properties of the plantar-flexor muscles. The experiment was carried out on 14 males divided into two groups (eccentric and control). Eccentric training consisted of six sets of six eccentric contractions at 120 % of one maximal concentric repetition and it was performed four times a week during four weeks. Before and after the 4-wk period, the plantar-flexor torque and the associated electromyographic activity were recorded during voluntary contractions (isometric, concentric and eccentric) and electrically induced contractions (twitch and tetanus), in order to distinguish central from peripheral adaptations. For the eccentric group, voluntary torque significantly increased after training independent of the action mode (relative gains 14 - 30 %, p < 0.05). This was associated with an increase in agonist EMG activity during isometric action and a decrease in antagonist coactivation in concentric (-27 %) and eccentric actions (-22 %) (p < 0.05). Voluntary activation level significantly increased from 80 +/- 5 % to 91 +/- 2 % (p < 0.05). Some of the twitch contractile properties (peak torque and maximal rate of twitch tension relaxation) were significantly modified (p < 0.05), but no changes were observed for the tetanus characteristics. These results allowed to conclude that the torque gains observed after the present training were more likely associated to central adaptations, affecting both agonist and antagonist muscles.

    Curr Opin Rheumatol 2002 Nov;14(6):648-52. Recent advances in the understanding of skeletal muscle fatigue. Westerblad H, et al.

    Prolonged or repeated contractions of skeletal muscles lead to impaired muscle function, fatigue develops. Fatigue may be caused by factors within the muscle cells (peripheral fatigue) and diminished activation from the central nervous system (central fatigue). The relative importance of peripheral central fatigue depends on the type of physical activity. Central fatigue may be more prominent in elderly subjects. Increased concentration of inorganic phosphate seems to be of major importance for acute peripheral fatigue. There is frequently a long-lasting depression of force production after fatiguing muscle activity, especially at low stimulation frequencies. This low-frequency fatigue seems to be due to "structural" changes in proteins involved in intracellular Ca handling. Contractions in which the muscle is stretched (eccentric contractions) cause muscle weakness and damage. The initial defect induced by eccentric contractions is overstretched sarcomeres, but these appear to cause localized membrane tears that subsequently contribute to muscle weakness and damage.

    Am J Phys Med Rehabil 2002 Nov;81(11 Suppl):S70-9. Mechanisms of muscle injury gleaned from animal models. Lieber RL, Friden J.

    Eccentric contractions of skeletal muscles produce injury and, ultimately, muscle strengthening. Current data suggest that the earliest events associated with injury are mechanical in nature and may be based primarily on the sarcomere strain experienced by the muscle. In this review, recent experimental data, primarily from rabbit dorsiflexor muscles, are used to provide general information regarding the factors that cause injury and means for preventing injury. Mechanical experiments reveal that excessive sarcomere strain is the primary cause of injury. We hypothesize that excessive strain permits extracellular or intracellular membrane disruption that may permit hydrolysis of structural proteins, leading to the myofibrillar disruption that is commonly observed. Inflammation that occurs after injury further degrades the tissue, but prevention of the inflammation leads to a long-term loss in muscle function. Simple preventative treatments such as increasing muscle oxidative capacity (getting into shape) or cyclic stress-relaxation of tissue (stretching out) have no measurable effect on the magnitude of muscle injury that occurs. Ultimately, an improved understanding of the damage mechanism may improve our ability to provide rehabilitative and strengthening prescriptions that have a rational scientific basis.

    Am J Phys Med Rehabil 2002 Nov;81(11 Suppl):S52-69. Exercise-induced muscle damage in humans. Clarkson PM, Hubal MJ.

    Exercise-induced muscle injury in humans frequently occurs after unaccustomed exercise, particularly if the exercise involves a large amount of eccentric (muscle lengthening) contractions. Direct measures of exercise-induced muscle damage include cellular and subcellular disturbances, particularly Z-line streaming. Several indirectly assessed markers of muscle damage after exercise include increases in T2 signal intensity via magnetic resonance imaging techniques, prolonged decreases in force production measured during both voluntary and electrically stimulated contractions (particularly at low stimulation frequencies), increases in inflammatory markers both within the injured muscle and in the blood, increased appearance of muscle proteins in the blood, and muscular soreness. Although the exact mechanisms to explain these changes have not been delineated, the initial injury is ascribed to mechanical disruption of the fiber, and subsequent damage is linked to inflammatory processes and to changes in excitation-contraction coupling within the muscle. Performance of one bout of eccentric exercise induces an adaptation such that the muscle is less vulnerable to a subsequent bout of eccentric exercise. Although several theories have been proposed to explain this "repeated bout effect," including altered motor unit recruitment, an increase in sarcomeres in series, a blunted inflammatory response, and a reduction in stress-susceptible fibers, there is no general agreement as to its cause. In addition, there is controversy concerning the presence of sex differences in the response of muscle to damage-inducing exercise. In contrast to the animal literature, which clearly shows that females experience less damage than males, research using human studies suggests that there is either no difference between men and women or that women are more prone to exercise-induced muscle damage than are men.

    Am J Physiol Regul Integr Comp Physiol 2002 Oct;283(4):R958-63
    Desmin cytoskeletal modifications after a bout of eccentric exercise in the rat. Barash IA, et al.

    Desmin content and immunohistochemical appearance were measured in tibialis anterior muscles of rats subjected to a single bout of 30 eccentric contractions (ECs). Ankle torque was measured before EC and at various recovery times, after which immunohistochemical and immunoblot analyses were performed. Torque decreased by approximately 50% immediately after EC and fully recovered 168 h later (P < 0.001). Loss of desmin staining was maximal 12 h after EC and recovered by 72 h. Immunoblots unexpectedly demonstrated a significant increase in the desmin-to-actin ratio by 72 h after EC (P < 0.01) and was still increasing after 168 h (P < 0.0001). These data demonstrate a relatively rapid qualitative loss of desmin immunostaining immediately after a single EC bout but a tremendous quantitative increase in desmin content 72-168 h later. This dynamic restructuring of the muscle's intermediate filament system may be involved in the mechanism of EC-induced muscle injury and may provide a structural explanation for the protective effects observed in muscle after a single EC bout.

    J Physiol 2002 Aug 15;543(Pt 1):297-306. Molecular adaptations of neuromuscular disease-associated proteins in response to eccentric exercise in human skeletal muscle. Feasson L, et al.

    The molecular events by which eccentric muscle contractions induce muscle damage and remodelling remain largely unknown. We assessed whether eccentric exercise modulates the expression of proteinases (calpains 1, 2 and 3, proteasome, cathepsin B+L), muscle structural proteins (alpha-sarcoglycan and desmin), and the expression of the heat shock proteins Hsp27 and alphaB-crystallin. Vastus lateralis muscle biopsies from twelve healthy male volunteers were obtained before, immediately after, and 1 and 14 days after a 30 min downhill treadmill running exercise. Eccentric exercise induced muscle damage as evidenced by the analysis of muscle pain and weakness, creatine kinase serum activity, myoglobinaemia and ultrastructural analysis of muscle biopsies. The calpain 3 mRNA level was decreased immediately after exercise whereas calpain 2 mRNA level was increased at day 1. Both mRNA levels returned to control values by day 14. By contrast, cathepsin B+L and proteasome enzyme activities were increased at day 14. The alpha-sarcoglycan protein level was decreased immediately after exercise and at day 1, whereas the desmin level peaked at day 14. alphaB-crystallin and Hsp27 protein levels were increased at days 1 and 14. Our results suggest that the differential expression of calpain 2 and 3 mRNA levels may be important in the process of exercise-induced muscle damage, whereas expression of alpha-sarcoglycan, desmin, alphaB-crystallin and Hsp27 may be essentially involved in the subsequent remodelling of myofibrillar structure. This remodelling response may limit the extent of muscle damage upon a subsequent mechanical stress.

    Histochem Cell Biol 2002 Jul;118(1):29-34. Eccentric contractions leading to DOMS do not cause loss of desmin nor fibre necrosis in human muscle. Yu JG, Malm C, Thornell LE.

    High force eccentric muscle contractions can result in delayed onset muscle soreness (DOMS), prolonged loss of muscle strength, decreased range of motion, muscle swelling and an increase of muscle proteins in the blood. At the ultrastructural level Z-line streaming and myofibrillar disruptions have been taken as evidence for muscle damage. In animal models of eccentric exercise-induced injury, disruption of the cytoskeleton and the sarcolemma of muscle fibres occurs within the first hour after the exercise, since a rapid loss of staining of desmin, a cytoskeletal protein, and the presence of fibronectin, a plasma and extracellular protein, are observed within the muscle fibres. In the present study, biopsies from subjects who had performed different eccentric exercises and had developed DOMS were examined. Our aim was to determine whether eccentric exercise leading to DOMS causes sarcolemmal disruption and loss of desmin in humans. Our study shows that even though the subjects had DOMS, muscle fibres had neither lost staining for desmin nor contained plasma fibronectin. This study therefore does not support previous conclusions that there is muscle fibre degeneration and necrosis in human skeletal muscle after eccentric exercise leading to DOMS. Our data are in agreement with the recent findings that there is no inflammatory response in skeletal muscle following eccentric exercise in humans. In combination, these findings should stimulate the search for other mechanisms explaining the functional and structural alterations in human skeletal muscle after eccentric exercise.

    Acta Physiol Scand 2002 Jan;174(1):47-56. The repeated bout effect and heat shock proteins: intramuscular HSP27 and HSP70 expression following two bouts of eccentric exercise in humans.
    Thompson HS, Clarkson PM, Scordilis SP.

    Exercise-induced damage significantly and predictably alters indirect indicators of muscle damage after one bout of damaging exercise but this response is dampened following a second bout of the same exercise performed 1-6 weeks later. Previously we have described a marked increase in the levels of heat shock proteins (HSPs) HSP27 and HSP70 in human biceps muscle following one bout of high-force eccentric exercise. The purpose of the present study was to examine the intramuscular HSP27 and HSP70 response following two identical bouts of exercise [bout 1 (B1) and bout 2 (B2), separated by 4 weeks] relative to indirect indices of muscle damage. Ten human subjects performed 50 high-force eccentric contractions with their non-dominant forearm flexors; muscle damage of the biceps brachii was evaluated 48 h post-exercise with indirect indices [serum creatine kinase (CK) activity, soreness, isometric maximal voluntary contraction (MVC) force and relaxed arm angle] and immunoblotting of high ionic strength muscle biopsy extracts for both HSPs. Not unexpectedly, the indirect indicators of damage changed dramatically and significantly (P < 0.01) after B1 but had a much smaller response after B2. The magnitude of the HSP response was the same after both bouts of exercise, though the control and exercised samples of B2 demonstrated a lower basal HSP expression. Thus, though both indirect and cellular indicators of exercise-induced muscle damage demonstrate an adaptation consequent to the first bout of exercise, these adaptations are quite different. It is possible that the lower basal HSP expression of the cellular response mediates the attenuation of damage associated with B2 as indicated by indirect indices.

    As for force production,

    J Sports Sci 2002 Feb;20(2):83-91. Differences in activation patterns between eccentric and concentric quadriceps contractions. McHugh MP, Tyler TF, Greenberg SC, Gleim GW.

    Previous studies analysing electromyograms (EMGs) from indwelling electrodes have indicated that fast-twitch motor units are selectively recruited for low-intensity eccentric contractions. The aim of this study was to compare the frequency content of surface EMGs from quadriceps muscles during eccentric and concentric contractions at various contraction intensities. Electromyograms were recorded from the rectus femoris, vastus lateralis and vastus medialis muscles of 10 men during isokinetic (1.05 rad x s(-1)) eccentric and concentric knee extension contractions at 25%, 50%, 75% and 100% of maximal voluntary contraction (MVC) for each contraction mode. Additionally, isometric contractions (70 degrees) were performed at each intensity. The mean frequency and root mean square (RMS) of the surface EMG were computed. Mean frequency was higher for eccentric than concentric contractions at 25% (P < 0.01), 50% (P < 0.01) and 75% (P < 0.05) but not at 100% MVC. It increased with increasing contraction intensity for isometric (P < 0.001) and concentric (P < 0.01) contractions but not for eccentric contractions (P = 0.27). The EMG amplitude (RMS) increased with increasing contraction intensity similarly in each contraction mode (P < 0.0001). Higher mean frequencies for eccentric than concentric contractions at submaximal contraction intensities is consistent with more fast-twitch motor units being active during eccentric contractions.

    J Physiol 2001 Aug 15;535(Pt 1):155-64. Effects of concentric and eccentric contractions on phosphorylation of MAPK(erk1/2) and MAPK(p38) in isolated rat skeletal muscle. Wretman C, et al.

    Exercise and contractions of isolated skeletal muscle induce phosphorylation of mitogen-activated protein kinases (MAPKs) by undefined mechanisms. The aim of the present study was to determine exercise-related triggering factors for the increased phosphorylation of MAPKs in isolated rat extensor digitorum longus (EDL) muscle. 2. Concentric or eccentric contractions, or mild or severe passive stretches were used to discriminate between effects of metabolic/ionic and mechanical alterations on phosphorylation of two MAPKs: extracellular signal-regulated kinase 1 and 2 (MAPK(erk1/2)) and stress-activated protein kinase p38 (MAPK(p38)). 3. Concentric contractions induced a 5-fold increase in MAPK(erk1/2) phosphorylation. Application of the antioxidants N-acetylcysteine (20 mM) or dithiothreitol (5 mM) suppressed concentric contraction-induced increase in MAPK(erk1/2) phosphorylation. Mild passive stretches of the muscle increased MAPK(erk1/2) phosphorylation by 1.8-fold, whereas the combination of acidosis and passive stretches resulted in a 2.8-fold increase. Neither concentric contractions, nor mild stretches nor acidosis significantly affected phosphorylation of MAPK(p38). 4. High force applied upon muscle by means of either eccentric contractions or severe passive stretches resulted in 5.7- and 9.5-fold increases of phosphorylated MAPK(erk1/2), respectively, whereas phosphorylation of MAPK(p38) increased by 7.6- and 1.9-fold (not significant), respectively. 5. We conclude that in isolated rat skeletal muscle an increase in phosphorylation of both MAPK(erk1/2) and MAPK(p38) is induced by mechanical alterations, whereas contraction-related metabolic/ionic changes (reactive oxygen species and acidosis) cause increased phosphorylation of MAPK(erk1/2) only. Thus, contraction-induced phosphorylation can be explained by the combined action of increased production of reactive oxygen species, acidification and mechanical perturbations for MAPK(erk1/2) and by high mechanical stress for MAPK(p38).

    J Sports Sci 2001 Sep;19(9):687-91 Creatine kinase, myosin heavy chains and magnetic resonance imaging after eccentric
    exercise. Sorichter S, et al.

    The aim of this study was to examine the relationship between myosin heavy chain (MHC) release as a specific marker of slow-twitch muscle fibre breakdown and magnetic resonance imaging (MRI) of skeletal muscle injury after eccentric exercise. The effects of a single series of 70 high-intensity eccentric contractions of the quadriceps femoris muscle group (single leg) on plasma concentrations of creatine kinase and MHC fragments were assessed in 10 young male sport education trainees before and 1 and 4 days after exercise. To visualize muscle injury, MRI of the loaded thigh was performed before and 4 days after the eccentric exercise. All participants recorded an increase (P < 0.05) in creatine kinase after exercise. In five participants, T2 signal intensity was unchanged post-exercise compared with pre-exercise and MHC plasma concentration was normal; however, they showed an increase (P < 0.05) in creatine kinase after exercise. For the remaining five participants, there was an increase in T2 signal intensity of the loaded vastus intermedius and vastus lateralis. These changes in MRI were accompanied by an increase in MHC plasma concentration (P< 0.01) as well as an increase in creatine kinase (P < 0.01). We suggest that changes in MRI T, signal intensity after muscle damage induced by eccentric exercise are closely related to damage to structurally bound contractile filaments of some muscle fibres. Additionally, MHC plasma release indicates that this damage affects not only fast-twitch fibres but also some slow-twitch fibres.

    Eur J Appl Physiol 2001 Jun;84(6):569-74. Short-term changes in the series elastic component after an acute eccentric exercise of the elbow flexors. Michaut A, Pousson M, Ballay Y, Van Hoecke J.

    We have studied the effect of a unique eccentric exercise session on the series elastic component (SEC) properties of human elbow flexors. Ten active females performed five sets of ten maximal eccentric contractions on an isokinetic ergometer. Maximal isometric (MVC) torque, and the corresponding myoelectrical activity (RMS) of the biceps brachii and the triceps brachii muscles were recorded before, immediately after, 48 h after, and 1 week after the exercise session. SEC compliance was also measured, using the in situ quick-release technique. Maximal eccentric torque declined significantly among the five sets of the exercise session (P < 0.01). The exercise session induced a significant decrease of the MVC over the post-exercise 48-h period. MVC returned to its control value 1 week after the exercise session. The neuromuscular efficiency calculated from the MVC torque:RMS ratio did not change throughout the experimental period, suggesting an optimisation of the neural drive to muscle force production capacity. The compliance values increased when force values decreased, but the slope of the relationship between both compliance and force logarithmic values was not significantly modified by the experimental procedure, indicating that the intrinsic properties of the SEC were not affected by the eccentric exercise session. The contractility-elasticity coupling was also maintained at a constant level during the recovery period. In other words, after an acute eccentric exercise, the evolution of SEC compliance was closely linked to force changes.
    Last edited by PowerManDL; 08-13-2003 at 03:33 PM.
    Vin Diesel has a fever.. and the only prescription is more cowbell.

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    Budiak: macked
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    galileo: you're a fucking beast and I hate you
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  12. #11
    Player Hater PowerManDL's Avatar
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    Sorry to bust all that out at once, but eccentric exercise is probably the most studied thing in exercise science. There's more information you can shake a stick at regarding eccentric action, and it just happens that I have a lot of it sitting in a word file right now for reference purposes.

    The claims I made about the increased workload are pretty common knowledge in the field, as is the presence of microtrauma after an eccentric contraction and not after a concentric. There's different modes of work involved at the level of the myofibril, which causes the difference in work done and effect on the cell. Deceleration of a load is a different thing than accelerating it; the tissues have to absorb and account for the load as well as gravity, and the fact that the weight has to stop.

    So my point stands about concentric work being less taxing.

    I'm not even sure of the relevance of the deadlift/squat comparison. They are not the same lift, and everyone can perceive difficulty differently. But regardless, the squat actually mechanically benefits from stretch reflex in your hips which can be varied depending on stance, speed, flexibility, etc, etc, but even with all that, is entirely irrelevant to the discussion. They are different lifts mechanically.

    That's the whole point. In a lot of lifters, the squat and deadlift stance are virtually identical. The squat makes use of the stretch reflex while the deadlift by its nature can't. Hence why a first deadlift rep is a lot harder than the first rep of a squat, if you factor out the other biomechanical differences.
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    Baby Seal Clubber ElPietro's Avatar
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    You whore, I can't believe you C/Ped all that crap. I just read through it all, and other than a few lines here and there, and the parts you put in bold, they are not good studies to go by. 99% of these studies do not compare force or recruitment of motor units/muscle fibres based upon the exact same TUT with the exact same weight. Also, they would have to be performed at seperate times of course with full recovery. Of course you can and probably do recruite more fibres/motor units eccentrically, it seems why this is, is still unknown, despite all you posted. But I guess that is not important for this conversation.

    But did any of your studies show what occured as a result of training eccentric versus concentric only long term? As in realized strength or muscle gains? Most of these studies it seemed would probably be using more weight eccentrically, than could possibly be used concentrically, as shown in I think it's the 4th study, where they were using 120% of potential concentric weight. I know for a fact you can lift more eccentrically, everyone knows this. But also, how from each of these studies can we compare eccentric without comparing tempo? I can unrack weight on the bench, and let it drop on my head and still call that eccentric, did I recruit any motor units? No.

    Also, I think much of the stress and microtrauma, specifically myofibrils is somewhat obvious. The eccentric phase is the stretch. One of your studies towards the end showed how eccentric lifting AND simple stretching both achieved high levels of microtrauma. Also, it goes on and you mentioned you are weaker after the eccentric phase, I guess we could say regardless of whether or not weight is the same or not. I haven't brushed up on my phsyiology lately, so please correct me if I'm wrong here, but since eccentric is the stretch, you will be seperating the actin and myosin much greater with this stretch, which probably wouldn't result in them instantaneously returning to a stronger position, along with the damage induced, which would result in you being weaker.

    So I think we agree AND perhaps disagree. It it obvious through regular training, that regardless of which method causes more trauma, or recruits more fibres, the concentric phase is more difficult yes? You cannot push as much on bench, as you can control downward toward you. This is true for everyone. This is why people like you and I do negatives, with 120%+ of our max weight, in order to stimulate type IIb fibre types, which aren't so easily recruited through concentric phases yes?

    Another, point for me, would the results from the eccentric repetitions be the same, if say you do not go to full ROM? I think it would be an entirely new ballgame. Because you aren't carry that weight all the way to your eccentric limit, in otherwords, you are not stretching your muscle to it's full limit under tension, which puts it in it's weakest position possible, and also is why most people, myself included, experience muscle tears at the furthers point of eccentric range, although I believe the tear occurs once you try to **** to concentric beyond the point where you are able to perform that rep at that given ROM of the muscle. There are simply not enough actin/myosin contacts to allow a contraction, and bye bye muscle. Of course, my terminology and physiology could be off, but I know this is true in perhaps laymans terms.

    So in the end, I would still maintain for the points I listed, which are also supported by your studies posted, that it is superior to train eccentric only if you are trying to recruit more fibres, either for growth (since type IIb are the best for that), of for strength (again since type IIb are the best for maximal strength as well). So because of all this, and to address the title of this thread, I don't see a point to doing concentric only training, but I do see a point to the occaisional eccentric only training, however in limited quantity, due to the increased stress, damage, and neurological recovery required.

    Originally posted by PowerManDL
    That's the whole point. In a lot of lifters, the squat and deadlift stance are virtually identical. The squat makes use of the stretch reflex while the deadlift by its nature can't. Hence why a first deadlift rep is a lot harder than the first rep of a squat, if you factor out the other biomechanical differences.
    Yeah the stance is the same, the point of resistance and muscles aren't being used in the same amounts. I understand what you mean about the stretch reflex, that is why I do full resets between heavy doubles or triples on deads. I was more speaking of the actuall elasticity of the hips in wide stance squats, so as you go down, tension builds in the hips, which make them want to spring back up, which aids in the lift, along with the leverage advantages that go along with wide stance. You don't have that exact same advantage on deadlifts at any point, since the source of resistance isn't coming from the same spot, and you aren't actually crouching down in the same manner. Well, at least I don't.

    Bleh, I can't believe I just typed all that sh!te out. No fair copy/paste boy. I want you to reword each line of each study into your own words!

    This is interesting though, so feel free to either correct my flawed logic, or carry on the discussion, but I still don't see the benefit of concentric only training, and I believe your studies back me up on this.
    Last edited by ElPietro; 08-13-2003 at 08:00 PM.
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  14. #13
    Player Hater PowerManDL's Avatar
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    Ok, you noted the exact points I was trying to make.

    Eccentric action = microtrauma

    Concentric action != microtrauma

    Hence, concentric-only muscle action would be "easier" on recovery.

    Additionally, again as you noted, the concentric contraction, when not coupled with an eccentric action, is more difficult than an auxotonic movement. Main reason is due to the lack of kinetic energy which is built up by the eccentric stretch and reversal. Have a look at the concept of "rate of force development" and you'll see why this would be useful as a training method.

    Accelerating a load from a dead stop is a lot harder than doing so with an eccentric action preceding it. But due to physiology, its not harder on the muscle. In other words, its harder to generate the force, but its comparatively easy on the muscle and the nervous system.

    As far as size gains, force alone takes a back seat when compared to total work done by the muscle. Rather, force wrt workload. And eccentric actions do perform more work than concentric at the same level of tension. This is a double-edged sword, as it means they will be responsible (almost totally in fact) for the growth effect, but they're also pretty taxing on the acute energy reserves.

    In terms of fiber recruitment, that's wholly dependent on force/tension produced in the muscle. As I've recently explained a lot, muscle fiber classification based on MHC (the I, IIa, IIx, etc) is pretty useless for figuring what a fiber "does." The MHC determines the speed of contraction, not the force produced. Metabolic character, similarly, is independent of MHC expression. So you're pretty much left with the generalized "fast twitch" and "slow twitch" categories, which are a function of motor-unit recruitment thresholds. Growth is directly related to fatigue; so a fiber that becomes fatigued is stimluated to grow. Since that is more directly a function of metabolic character than contractile velocity, it stands that the fibers w/ the highest recruitment threshold would fatigue the fastest, since they are going to be the hardest to activate. The MHC expression is more a case of form following function; IIa and IIx have little difference except the shortening velocity. MHC-IIx is more often found in cases where loads are handled rapidly.

    Its true that higher forces (or contraction velocities) will recruit more of the "stereotypical" IIx fibers. It simply follows that a more forceful contraction will do so, and a supramaximal eccentric would obviously fit that. But then again, so will a fast eccentric.

    The whole point wasn't necessarily about "force," though, as I mentioned. You still have to control the weight on the way down. And if you're resisting gravity as well as load, remember that a faster eccentric = more force. That's where the work performed comes into play.

    Anyways, my point was that concentric actions are useful for avoiding damage to muscle fibers, and that more force is generated during eccentric actions given an equal load. Perceived difficulty isn't a factor; impact on the body is.
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  15. #14
    Baby Seal Clubber ElPietro's Avatar
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    Originally posted by PowerManDL
    Its true that higher forces (or contraction velocities) will recruit more of the "stereotypical" IIx fibers. It simply follows that a more forceful contraction will do so, and a supramaximal eccentric would obviously fit that. But then again, so will a fast eccentric.

    The whole point wasn't necessarily about "force," though, as I mentioned. You still have to control the weight on the way down. And if you're resisting gravity as well as load, remember that a faster eccentric = more force. That's where the work performed comes into play.

    Anyways, my point was that concentric actions are useful for avoiding damage to muscle fibers, and that more force is generated during eccentric actions given an equal load. Perceived difficulty isn't a factor; impact on the body is.
    I am assuming you got mixed up and meant concentric where you said eccentric as I italicized.

    You still haven't given a good reason for concentric only training. It is less microtrauma, yes, it is less overall stress, sure, it doesn't require as long for recovery, ok. But why would you want this? You aren't not stimulating as much, aren't pushing as hard, and probably won't progress much with it. So why bother? Because something is more difficult at dead stop, is still no reason to do it. If you can stimulate more muscle mass, and cause more microtrauma with the same weight by including eccentric, then why wouldn't you. You'd also need somebody there lowering the weight to you every rep if you wanted concentric only ROM.

    I mean, even if you are doing an active recovery workout, there is no need to complicate it with uneccessary concentric only movements, since you are using such light weight that you are not going to be doing very much than warming the area up anyway.
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  16. #15
    Player Hater PowerManDL's Avatar
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    Originally posted by ElPietro
    I am assuming you got mixed up and meant concentric where you said eccentric as I italicized.

    No, I meant a fast eccentric.

    You still haven't given a good reason for concentric only training. It is less microtrauma, yes, it is less overall stress, sure, it doesn't require as long for recovery, ok. But why would you want this? You aren't not stimulating as much, aren't pushing as hard, and probably won't progress much with it. So why bother?

    One more time:

    1) Recovery

    2) Rate of force development

    Because something is more difficult at dead stop, is still no reason to do it. If you can stimulate more muscle mass, and cause more microtrauma with the same weight by including eccentric, then why wouldn't you. You'd also need somebody there lowering the weight to you every rep if you wanted concentric only ROM.

    Structural effects and neural effects of training are two different things. You're making this more = better generalization, when its a case of better = better. There's more than one mechanism at work here. The difference in neural recruitment for a concentric-only action is pretty considerable, and one that can lead to positive effects in terms of the speed of force generation.

    I mean, even if you are doing an active recovery workout, there is no need to complicate it with uneccessary concentric only movements, since you are using such light weight that you are not going to be doing very much than warming the area up anyway.

    Didn't necessarily say you had to do a concentric-only. But you should be minimizing the eccentric component.

    Its really no different than a paused movement. If you have no problem incorporating those, I don't see what your beef is with concentric-only, other than the potential difficulty in setting it up.
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