eccentrische fase in oefening : echt negatief?

[Deejay_Spike]

lees eerst het effect van IL-6 in dit deel van het forum bij "Brain not body makes athletes feel tired"

Myofibers express IL-6 after eccentric exercise.

Tomiya A, Aizawa T, Nagatomi R, Sensui H, Kokubun S.

Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.

BACKGROUND: [b]Interleukin (IL)-6 is locally produced in skeletal muscles and shows a remarkable increase in plasma after eccentric exercises.[b] OBJECTIVE: To elucidate the cell types in the muscles responsible for IL-6 production after eccentric exercises. STUDY DESIGN: Controlled laboratory study. METHODS: An eccentric contraction model was made using electrical stimulation. The authors investigated the muscle damage and regeneration processes after eccentric exercises histologically, and the cell types expressing IL-6 and its subcellular compartimentalization with time immunohistochemically after eccentric exercises. RESULTS: Swollen myofibers were detected from 8 hours to 3 days after exercises. Disrupted myofibers were detected from 24 hours to 7 days, with a peak of 3 days. IL-6 was detected only in the cytoplasm of myofibers until 12 hours; thereafter, it was found in the inflammatory cells and proliferating satellite cells as well. The swollen myofibers were negatively stained for IL-6. The positive ratios of IL-6 in myofibers immediately increased after exercises, peaked in 12 hours, and then decreased. CONCLUSIONS: After eccentric exercises, IL-6 expression increased in myofibers preceding the disruption of myofibers. IL-6 might be closely related to muscle damage caused by strenuous exercises.

nu over kracht :

Eccentric muscle damage: mechanisms of early reduction of force.

Allen DG.

Department of Physiology and Institute for Biomedical Research, University of Sydney, Australia.

Pain and weakness are prominent symptoms which occur after a delay in muscles which have been stretched during contraction (eccentric contraction). These symptoms are particularly severe when the exercise is unaccustomed and when the stretch occurs in muscles on the descending limb of the force-length relation, i.e. at long muscle lengths. It is known that sarcomeres are potentially unstable on the descending limb and it has been proposed by Morgan that uncontrolled elongation of some sarcomeres occurs during eccentric contractions on the descending limb. In this article, the evidence that this mechanism leads to the reduced force is considered. If overextended sarcomeres persist after the eccentric exercise it will cause a shift in the peak of the force-length curve. There is also evidence that in some types of muscle, excitation-contraction coupling is impaired and contributes to the muscle weakness. Cytoskeletal proteins stabilize the sarcomeric structure and may be injured either by the overextended sarcomeres or by activation of proteases. The potential of these mechanisms to contribute to the effects of muscle training and to the symptoms of muscle disease, such as muscular dystrophy, is considered.

[Unregistered]

Echt interessant. Wat zou je vinden van een schema met puur positieven Spike?

[Unregistered]

O en nog een vraagje, bij het trainen van puur positieven, hoe gaat dan denk je het terugschakelen naar negatief-positief, of positief negatief in wedstrijdverband bijvoorbeeld?

[Deejay_Spike]

trainen van puur positieven is iets dat in powerlifting onmogelijk is. daar dat het deel uitmaakt van de oefening, en de eccentrische fase toch ook zorgt voor een opbouw van kracht (gekend als reversal strength).

enkel op positieven trainen is imo een beetje overdrijven. de eccentrische fase maakt gewoon deel uit van de beweging.


wat ik wil aanhalen is dat je de eccentrische fase zeker niet moet benadrukken zoals dat vaak in b wordt gedaan. de eccentrische fase dient als deel van de uitvoering en zorg voor een opbouw van reversal strength samen met de stretch reflex, maar daar blijft het bij. trainingen toewijden aan negatieven of bewust negatieven doen of het negatieve deel uitdrukkelijk benadrukken is imo helemaal niet productief.

[Deejay_Spike]

de enige oefeningen waarbij je enkel concentrisch zou kunnen werken is deadlifts, high pulls, powercleans etc.

maar ook daar wordt het niet erg praktisch want na elke rep zou je het gewicht moeten laten vallen om de eccentrische fase zoveel mogelijk te minimiseren.

[Unregistered]

Waarom niet praktisch? Wel als je ervan uit kunt gaan dat als het concentrische deel vooruitgaat, het essentrische deel dat ook doet. Maar dat weet ik niet zeker. In dat geval zou je sneller kracht kunnen opbouwen, omdat de druk op het CZS bij deze methode veel lager is, en je dus een hogere frequentie/intensiteit/volume etc kunt gebruiken.

[Deejay_Spike]

het probleem is dat veel oefeningen beginnen met een eccentrisch deel, of je zowieso een eccentrisch deel moet uitvoeren in een rep.


bvb squat : hoe wil je squatten zonder eccentrisch deel? bottom squats? ok, maar hoe kom je terug tot de beginpositie? je kan er bij veel oefeningen niet omheen. ze zijn er punt uit, maar imo niet om ze te benadrukken.

[MonsterStrength]

da's nu het voordeel van trainen met een sled

[Unregistered]

Idd... sled, tire filp, trainen met stenen in het zand, olympische lifts met bumper plates, conans wheel, kruiwagens, medicijballen, zandzakken, tonnen, de mogelijkheden zijn eindeloos om sterk te worden

Maar idd het is moeilijk om het op de squat toe te passen

[wazzup]

moeilijk ?

neem een squatrek/kooi met horizontale leggers als safeties, leg de BB daarop, hurk eronder, en duw....

persoonlijk zou ik eerder alleen negatieven doen dan alleen positief werken.

[Mugje]

Origineel gepost door wazzup

moeilijk ?

neem een squatrek/kooi met horizontale leggers als safeties, leg de BB daarop, hurk eronder, en duw....

persoonlijk zou ik eerder alleen negatieven doen dan alleen positief werken.

ja maar de barbell moet ook weer naar beneden

[wazzup]

misschien moeten unregistered en ik samen gaan trainen, hij alleen de positieven en ik de negatieven (of 2 spotters die dat ding steeds voor je naar beneden brengen !)

[Shy guy]

De meningen zijn iig goed verdeeld.

Zelf als vechtsporter train ik het allebij veel in verschillende methodes.
Soms om grenzen te verleggen nadruk eccentrisch, concentrisch weer voor explosieviteit. Van wat ik leerde was het zo dat eccentrisch het meeste kracht kon worden geleverd. want je kan bv meer dan 1 RM eccentrisch laten zakken naar je borst als dat je concentrisch kan duwen vanaf je borst. toch?

[MonsterStrength]

Origineel gepost door Shy guy

De meningen zijn iig goed verdeeld.

Zelf als vechtsporter train ik het allebij veel in verschillende methodes.
Soms om grenzen te verleggen nadruk eccentrisch, concentrisch weer voor explosieviteit. Van wat ik leerde was het zo dat eccentrisch het meeste kracht kon worden geleverd. want je kan bv meer dan 1 RM eccentrisch laten zakken naar je borst als dat je concentrisch kan duwen vanaf je borst. toch?

volgens mij kun je niet echt een 1RM op eccentrische delen, ik kan als ik wil ook 300 kg op mijn borst laten zakken (vallen ), maar omhoog gaan zal iets anders zijn

[Big T]

"trainingen toewijden aan negatieven of bewust negatieven doen of het negatieve deel uitdrukkelijk benadrukken is imo helemaal niet productief"

Als er meer schade optreed, die tot supercompensatie leidt is dat voor bb juist wel productief. Althans dat is mijn mening. Je moet in elk geval eccentrisch een bepaalde controle uitoefenen op het gewicht, zomaar neer zwaaien maakt de lift wel gemakkelijker, maar ook minder productief.

[Big T]

Spike lees deze studie ook eens:

The positive effects of negative work: increased muscle strength and decreased fall risk in a frail elderly population.

LaStayo PC, Ewy GA, Pierotti DD, Johns RK, Lindstedt S.

Division of Physical Therapy, University of Utah, 520 Wakara Way, Salt Lake City, UT 84108, USA. paul.lastayo@health.utah.edu

BACKGROUND: The objective of this study was to determine if a chronic eccentric training intervention, i.e., negative work, could limit or even reverse sarcopenia and its related impairments and functional limitations. Is high-force eccentric training tolerable by elderly people and will it result in improved muscle size, strength, balance, and fall risk? METHODS: 21 frail elderly subjects (mean age, 80 years) experienced 11 weeks of lower extremity resistance training. The experimental eccentric (ECC) group (n=11) performed negative work while exercising on a high-force eccentric ergometer. The active "controls" performed traditional (TRAD) (n=10) lower extremity resistance exercises (weight training). Muscle fiber cross-sectional area and strength, balance, stair descending abilities, and fall risk were assessed prior to and following this intervention. RESULTS: All ECC subjects who started the negative work intervention completed the study and reported the training to be relatively effortless; they experienced minimal and transient muscle soreness. Both groups experienced a significant increase in muscle fiber cross-sectional area (ECC=60%, TRAD=41%). Only the ECC group experienced significant improvements in strength (60%), balance (7%), and stair descent (21%) abilities. The timed up and go task improved in both groups, but only the ECC group went from a high to a low fall risk. CONCLUSIONS: These data demonstrate that lower extremity resistance exercise can improve muscle structure and function in those with limited exercise tolerance. The greater strength increase following negative work training resulted in improved balance, stair descent, and fall risk only in the ECC group. Because low energy cost is coupled to high force production with eccentric exercise, this intervention may be useful for a number of patients that are otherwise unable to achieve high muscle forces with traditional resistance exercise.

http://www.ncbi.nlm.nih.gov/entrez/q..._uids=12730250

[Unregistered]

Muscular adaptations to computer-guided strength training with eccentric overload.

Friedmann B, Kinscherf R, Vorwald S, Muller H, Kucera K, Borisch S, Richter G, Bartsch P, Billeter R.

Department of Sports Medicine, Medical Clinic and Policlinic, University of Heidelberg, Heidelberg, Germany.

AIMS: In order to investigate the muscular adaptations to a novel form of strength training, 18 male untrained subjects performed 4 weeks of low resistance-high repetition knee extension exercise. METHODS: Nine of them trained on a conventional weight resistance device (Leg curler, CON/ECC group), with loads equivalent to 30% of the concentric one-repetition maximum (1RM) for both the concentric and eccentric phase of movement. The other nine trained on a newly developed computer-driven device (CON/ECC-OVERLOAD group) with the concentric load equivalent to 30% of the concentric 1RM and the eccentric load equivalent to 30% of the eccentric 1RM. RESULTS: Training resulted in significantly (P < or = 0.05) increased peak torque and a tendency (P=0.092) to increased muscle cross-sectional area for the CON/ECC-OVERLOAD but not the CON/ECC group, while strength endurance capacity was significantly (P < or = 0.05) increased in the CON/ECC group only. RT-PCR revealed significantly increased myosin heavy chain (MHC) IIa and lactate dehydrogenase (LDH) A mRNAs, a tendency for increased MHC IIx mRNA (P = 0.056) and high correlations between the changes in MHC IIx and LDH A mRNAs (r=0.97, P=0.001) in the CON/ECC-OVERLOAD group. CONCLUSIONS: These results indicate a shift towards a more type II dominated gene expression pattern in the vasti laterales muscles of the CON/ECC-OVERLOAD group in response to training. We suggest that the increased eccentric load in the CON/ECC-OVERLOAD training leads to distinct adaptations towards a stronger, faster muscle.


Adaptation to chronic eccentric exercise in humans: the influence of contraction velocity.

Paddon-Jones D, Leveritt M, Lonergan A, Abernethy P.

Department of Surgery, University of Texas Medical Branch, Galveston 77550, USA. djpaddon@utmb.edu

We compared changes in muscle fibre composition and muscle strength indices following a 10 week isokinetic resistance training programme consisting of fast (3.14 rad x s(-1)) or slow (0.52 rad x s(-1)) velocity eccentric muscle contractions. A group of 20 non-resistance trained subjects were assigned to a FAST (n = 7), SLOW (n = 6) or non-training CONTROL (n = 7) group. A unilateral training protocol targeted the elbow flexor muscle group and consisted of 24 maximal eccentric isokinetic contractions (four sets of six repetitions) performed three times a week for 10 weeks. Muscle biopsy samples were obtained from the belly of the biceps brachii. Isometric torque and concentric and eccentric torque at 0.52 and 3.14 rad x s(-1) were examined at 0, 5 and 10 weeks. After 10 weeks, the FAST group demonstrated significant [mean (SEM)] increases in eccentric [29.6 (6.4)%] and concentric torque [27.4 (7.3)%] at 3.14 rad x s(-1), isometric torque [21.3 (4.3)%] and eccentric torque [25.2 (7.2)%] at 0.52 rad x s(-1). The percentage of type I fibres in the FAST group decreased from [53.8 (6.6)% to 39.1 (4.4)%] while type IIb fibre percentage increased from [5.8 (1.9)% to 12.9 (3.3)%; P < 0.05]. In contrast, the SLOW group did not experience significant changes in muscle fibre type or muscle torque. We conclude that neuromuscular adaptations to eccentric training stimuli may be influenced by differences in the ability to cope with chronic exposure to relatively fast and slow eccentric contraction velocities. Possible mechanisms include greater cumulative damage to contractile tissues or stress induced by slow eccentric muscle contractions.

[Unregistered]

Acute adaptation to low volume eccentric exercise.

Paddon-Jones D, Abernethy PJ.

School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, 4072, Australia. djpaddon@utmb.edu

PURPOSE: Many symptoms of eccentric muscle damage can be substantially reduced if a similar eccentric bout is repeated within several weeks of the initial bout. The purpose of this study was to determine whether a nondamaging, low repetition, low volume eccentric exercise bout could also provide a protective/adaptive effect. METHODS: Subjects were assigned to a control (CON), eccentric exercise (ECC), or low volume familiarized eccentric exercise group (LV+ECC). Before the study, the LV+ECC group performed six maximal eccentric contractions during two familiarization sessions. The main eccentric bout targeted the elbow flexor muscle group and consisted of 36 maximal eccentric contractions. Muscle soreness, upper arm girth, elbow angle, creatine kinase activity, isometric torque, and concentric and eccentric torque at 0.52 and 3.14 rad.s-1 were assessed 0, 1, 2, 3, 4, 7, and 10 d postexercise. RESULTS: No evidence of muscle damage was observed as a result of the low volume eccentric bouts. Nevertheless, with the exception of muscle soreness and concentric torque, all variables recovered more rapidly in the LV+ECC group (P < 0.05). CONCLUSION: Adaptation to eccentric exercise can occur in the absence of significant muscle damage. Exposure to a small number of nondamaging eccentric contractions can significantly improve recovery after a subsequent damaging eccentric bout. Furthermore, this adaptation appears to be mode-specific and not applicable to concentric contractions.

[Unregistered]

The effects of eccentric and concentric training at different velocities on muscle hypertrophy.

Farthing JP, Chilibeck PD.

College of Kinesiology, University of Saskatchewan, 105 Gymnasium Place, Saskatoon, Saskatchewan, S7N 5C2, Canada.

The purpose of this study was to examine the effect of isokinetic eccentric (ECC) and concentric (CON) training at two velocities [fast, 180 degrees s(-1 )(3.14 rad s(-1)) and slow,30 degrees s(-1)(0.52 rad s(-1))] on muscle hypertrophy. Twenty-four untrained volunteers (age 18-36 years) participated in fast- ( n=13) or slow- ( n=11) velocity training, where they trained one arm eccentrically for 8 weeks followed by CON training of the opposite arm for 8 weeks. Ten subjects served as controls (CNT). Subjects were tested before and after training for elbow flexor muscle thickness by sonography and isokinetic strength (Biodex). Overall, ECC training resulted in greater hypertrophy than CON training (P<0.01). No significant strength or hypertrophy changes occurred in the CNT group. ECC (180 degrees s(-1)) training resulted in greater hypertrophy than CON (180 degrees s(-1)) training and CON (30 degrees s(-1)) training (P<0.01). ECC (30 degrees s(-1)) training resulted in greater hypertrophy than CON (180 degrees s(-1)) training (P<0.05), but not CON (30 degrees s(-1)) training. ECC (180 degrees s(-1)) training resulted in the greatest increases in strength (P<0.01). We conclude that ECC fast training is the most effective for muscle hypertrophy and strength gain.

[Unregistered]

Origineel gepost door Big_T

Spike lees deze studie ook eens:

De traditionele groep gebruikt waarschijnlijk een lagere intensiteit waaraan de conclusie te verklaren valt?