Get in a door frame and "Push" against the frame and then hold 2 dumbbells in db lateral fashion, same position, and note the differences
En fait je m'entraine moins que ca, 3 exos par séance, 30 secondes par exos, 2 min de pause peutêtre entre les exos
L'isométrique est tout à fait efficace (études à l'appui) mais il faut l'utiliser à bon escient.
Oui et les résultats sont là !
Niveau étude, pas de transfert de force sur toute l'amplitude du mvt, mais seulement sur une amplitude proche du point isométrique.
Vincent a écrit:Non, si tu t'entraines en isolation t'auras pas ce problème (ou du moins très très atténué, MC GUFF explique qu'au leg extension ca peut arriver car selon l'angle différents muscles de la cuisse interviennent + ou -), si tu progresses seulement en position haute au DC en faisant de l'iso en haut c'est que tu bosses que tes triceps, pas tellement les pecs, ni les épaules. Sur les exos de base c'est pas très pratique l'isométrique !
Lanvin a écrit:L'isometrie peut etre efficace dans certaine condition mais uniquement pour la force et non pour la masse.
c'est une idée préconcue complètement fausse
Vincent a écrit:
Absolument pas Lanvin, c'est une idée préconcue complètement fausse ! Fais une recherche sur internet avec isometric muscles hypertrophy un truc
Gilles Cometti du centre d'expertise de la performance de Dijon a écrit:Le muscle travaille contre une résistance fixe, les leviers et donc les insertions
musculaires ne se déplacent pas.
Ce sont Hettinger et Muller en 1953 qui ont exploré les premiers ce type de travail. Alors
qu'ils obtinrent des résultats très spectaculaires, l'isométrie a ensuite pratiquement disparu
des salles d'entrainement tellement cette méthode et son efficacité ont été contestées.
2.1.) Bases physiologiques:
Connue pour ne pas développer la masse, l'isométrie présente l'intérêt de permettre Ã
l'athlète de développer des tensions volontaires supérieures à son maximum concentrique
(Schmidbleicher parle de 10%) Duchateau sur l'adducteur du pouce a montré que le travail isométrique était plus favorable que le travail concentrique à charges légères pour
augmenter la force des fibres rapides. Zatsiorki mentionnait déjà (1966) que le gain de
force du à l'isométrie était spécifique de la position de travail (à plus de 20° de cette
position la force n'avait pas évolué.) Il existe donc d'après Sale une composante nerveuse
prépondérante dans le travail isométrique. Pour Monnot un effort isométrique soutenu
pendant quelques secondes entraîne une augmentation de la synchronisation des unités
motrices en cours d'exercice.
Relative changes in maximal force, EMG, and muscle cross-sectional area after isometric training.
Garfinkel S, Cafarelli E.
Department of Physical Education, Faculty of Pure and Applied Science, York University, Toronto, Ontario, Canada.
The purpose of this experiment was to determine whether training-induced increases in maximal voluntary contraction (MVC) can be completely accounted for by increases in muscle cross-sectional area. Fifteen female university students were randomly divided into a control (N = 7) and an experimental (N = group. The experimental group underwent 8 wk of isometric resistance training of the knee extensors of one leg; the other leg was the untrained control. Training consisted of 30 MVC.d-1 x 3 d.wk-1 x 8 wk. Extensor cross-sectional area (CSA), assessed by computerized tomographic (CT) scanning of a cross-sectional slice at mid-thigh, was used as a measure of muscle hypertrophy. After 8 wk of training, MVC increased by 28% (P < 0.05), CSA increased by 14.6% (P < 0.05), and the amplitude of the electromyogram at MVC (EMGmax) was unchanged in the trained leg of the experimental subjects. The same measures in the untrained legs of the experimental subjects and in both legs of the control subjects were not changed after training. Although there was an apparent discrepancy between the increase in MCV (28%) and CSA (14.6%), the ratio between the two, the specific tension (N.cm-2), was not significantly different after training. As a result of these findings, we conclude that in these subjects there is no evidence of nonhypertrophic adaptations to resistance training of this type and magnitude, and that the increase in force-generating capacity of the muscle is due to the synthesis of additional contractile proteins.
Effects of isometric strength training on quadriceps muscle properties in over 55 year olds
L. Welsh1 and O. M. Rutherford1
(1) Department of Physiology Biophysics, St. Mary''s Hospital Medical School, Imperial College of Science, Technology and Medicine, W2 1PG Norfolk Place, London, UK
Accepted: 17 April 1995
Abstract Changes in strength, speed and size of the quadriceps muscle have been investigated in elderly men and women after 6 months of isometric strength training. We have also indirectly investigated the role of metabolites as a stimulus for muscle hypertrophy by studying two training protocols. One thigh was trained using short, intermittent contractions (IC), while the other trained using long, continuous contractions (CC). This meant that there should be a greater metabolite change in the muscle performing CC, as the blood flow is occluded for longer. Nine subjects [eight women, mean (SE) age, 71.8 (2.9) years] were measured for contractile properties and strength before and after training, and compared to nine age-matched controls [71.5 (2.1) years]. The training group increased quadriceps strength by 48.7 (9.1)% (P < 0.005) and 53.1 (11.3) % (P < 0.005) following the IC and CC protocols, respectively. There was no change in muscle strength in the controls. Both muscles showed significant slowing after training as measured by the relaxation times and the force-frequency ratio. There were non-significant decreases in muscle fatigability after training. The control group also showed some significant decreases in fatigability and muscle speed. The training group showed significant increases in muscle (and bone) cross-sectional area of 4.0 (1.7)% and 4.9 (1.3)% following the CC and IC protocols, respectively. These increases were significantly different from the decrease observed in the control group. These findings suggest that people over the age of 55 still have the capacity to increase muscle strength and size, and that the training causes slowing of the muscle. Muscle hypertrophy does not seem to be strongly influenced by metabolite changes in this age group, as there were no differences in measurements observed between protocols.
The role of metabolites in strength training
II. Short versus long isometric contractions
J. Schott1, K. McCully1 and O. M. Rutherford2
(1) Department of Physiology, St. Mary's Hospital Medical School, W2 1PG Norfolk Place, London, UK
(2) Division of Geriatric Medicine, Medical College of Philadelphia, Philadelphia, Pennysylvania, USA
Accepted: 12 April 1995
Abstract The role of intramuscular metabolite changes in the adaptations following isometric strength training was examined by comparing the effect of short, intermittent contractions (IC) and longer, continuous (CC) contractions. In a parallel study, the changes in phosphate metabolites and pH were examined during the two protocols using whole-body nuclear magnetic resonance spectroscopy (NMRS). Seven subjects trained three time per week for 14 weeks. The right leg was trained using four sets of ten contractions, each lasting 3 s with a 2-s rest period between each contraction and 2 min between each set. The left leg was trained using four 30-s contractions with a 1-min rest period between each. Both protocols involved isometric contractions at 70% of a maximum voluntary isometric contraction (MVC). The MVC, length: tension and force: velocity relationships and cross-sectional area (CSA) of each leg were measured before and after training. The increase in isometric strength was significantly greater (P = 0.041) for the CC leg (median 54.7%; P = 0.022) than for IC (31.5%; P –0.022). There were no significant differences between the two protocols for changes in the length:tension or force:velocity relationships. There were significant increases in muscle CSA for the CC leg only. NMRS demonstrated that the changes in phosphate metabolites and pH were greater for the CC protocol. These findings suggest that factors related to the greater metabolite changes during CC training results in greater increases in isometric strength and muscle CSA.
keletal muscle hypertrophy in response to isometric, lengthening, and shortening training bouts of equivalent duration.
Adams GR, Cheng DC, Haddad F, Baldwin KM.
Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697-4560, USA. GRAdams@uci.edu
Movements generated by muscle contraction generally include periods of muscle shortening and lengthening as well as force development in the absence of external length changes (isometric). However, in the specific case of resistance exercise training, exercises are often intentionally designed to emphasize one of these modes. The purpose of the present study was to objectively evaluate the relative effectiveness of each training mode for inducing compensatory hypertrophy. With the use of a rat model with electrically stimulated (sciatic nerve) contractions, groups of rats completed 10 training sessions in 20 days. Within each training session, the duration of the stimulation was equal across the three modes. Although this protocol provided equivalent durations of duty cycle, the torque integral for the individual contractions varied markedly with training mode such that lengthening > isometric > shortening. The results indicate that the hypertrophy response did not track the torque integral with mass increases of isometric by 14%, shortening by 12%, and lengthening by 11%. All three modes of training resulted in similar increases in total muscle DNA and RNA. Isometric and shortening but not lengthening mode training resulted in increased muscle insulin-like growth factor I mRNA levels. These results indicate that relatively pure movement mode exercises result in similar levels of compensatory hypertrophy that do not necessarily track with the total amount of force generated during each contraction.
Twitch contractile adaptations are not dependent on the intensity of isometric exercise in the human triceps surae.
Alway SE, Sale DG, MacDougall JD.
School of Health, Physical Education and Recreation, Ohio State University, Columbus 43210-1284.
Ultrastructural and twitch contractile characteristics of the human triceps surae were determined in six healthy but very sedentary subjects before and after 16 weeks of isometric training at 30% maximal voluntary contraction (MVC). Following training, twitch contraction time was approximately 16% shorter, although no differences were observed in one-half relaxation time or peak twitch torque. Percent fibre type was not changed by training. The mean area of type I and type II fibres in the soleus increased by approximately 30% but only type II fibres showed an increase in area in the lateral gastrocnemius (30%). Despite such changes in fibre area the volume density of the sarcoplasmic reticulum-transverse tubular network averaged 3.2 +/- 0.6% and 5.9 +/- 0.9% in type I and type II fibres respectively, before and after training in the two heads of the gastrocnemius. The results indicate that contractile adaptations to isometric training at 30% MVC were limited to twitch contraction time and were not directly related to changes in percent fibre distribution or the volume of sarcoplasmic reticulum and transverse tubules in either type I or type II fibres. The data further demonstrate that substantial fibre hypertrophy is achieved by training with low-intensity contractions.
** Isometrics do not 'turn your fibers to ST
Effects of isometric training on skeletal myosin heavy chain expression
Fadia Haddad, Anqi X. Qin, Ming Zeng, Sam A. McCue, and Kenneth M. Baldwin
Department of Physiology and Biophysics, University of California, Irvine, California 92697
This study tested the hypothesis that an isometric resistance-training program induces upregulation of slow myosin heavy chain (MHC) expression in a fast-twitch skeletal muscle. Thus we studied the effects of two resistance-training programs on rodent medial gastrocnemius (MG) muscle that were designed to elicit repetitive isometric contractions (10-12 per set; 4 sets per session) of different duration (8 vs. 5 s) and activation frequency (100 vs. 60 Hz) per contraction during each training session (total of 6 and 12 sessions). Results showed that both training paradigms produced significant increases in muscle weight (~11-13%) after completion of training (P < 0.05). Significant transformations in MHC expression occurred and involved specifically a decrease in the relative expression of the fast type IIb MHC and concomitant increased expression of the fast type IIx MHC. These adaptations were observed in both the "white" and "red" regions of the MG, and they occurred at both the mRNA and protein levels. These adaptations were detected after only six training sessions. Neither of the training programs produced any change in the relative expression of either the slow type I MHC or the moderately fast type IIa MHC, which can be upregulated in the red MG by chronic functional overload. These findings show that the isometric protocols used in this investigation were not sufficient to induce the hypothesized changes in the myosin heavy chain isoform expression in rodent skeletal muscle.
Vincent a écrit:Tout ce que tu peux trouver en francais date d'au moins 10 ans. Bein sympa les scientifiques francais mais c'est, je crois, leur seule "compétence"
Relative changes in maximal force, EMG, and muscle cross-sectional area after isometric training.
After 8 wk of training, MVC increased by 28% (P < 0.05), CSA increased by 14.6% (P < 0.05), and the amplitude of the electromyogram at MVC (EMGmax) was unchanged in the trained leg of the experimental subjects
Vincent a écrit:Elder je suis certains qu'il y a de très bons scientifiques FR, j'y suis allé fort, en fait, il aurait été plus juste de dire : tout ce que tu peux trouver en francais sur le net date d'au moins 10 ans.
Vincent a écrit:Relative changes in maximal force, EMG, and muscle cross-sectional area after isometric training.
Garfinkel S, Cafarelli E.
Department of Physical Education, Faculty of Pure and Applied Science, York University, Toronto, Ontario, Canada.
The purpose of this experiment was to determine whether training-induced increases in maximal voluntary contraction (MVC) can be completely accounted for by increases in muscle cross-sectional area. Fifteen female university students were randomly divided into a control (N = 7) and an experimental (N = group. The experimental group underwent 8 wk of isometric resistance training of the knee extensors of one leg; the other leg was the untrained control. Training consisted of 30 MVC.d-1 x 3 d.wk-1 x 8 wk. Extensor cross-sectional area (CSA), assessed by computerized tomographic (CT) scanning of a cross-sectional slice at mid-thigh, was used as a measure of muscle hypertrophy. After 8 wk of training, MVC increased by 28% (P < 0.05), CSA increased by 14.6% (P < 0.05), and the amplitude of the electromyogram at MVC (EMGmax) was unchanged in the trained leg of the experimental subjects. The same measures in the untrained legs of the experimental subjects and in both legs of the control subjects were not changed after training. Although there was an apparent discrepancy between the increase in MCV (28%) and CSA (14.6%), the ratio between the two, the specific tension (N.cm-2), was not significantly different after training. As a result of these findings, we conclude that in these subjects there is no evidence of nonhypertrophic adaptations to resistance training of this type and magnitude, and that the increase in force-generating capacity of the muscle is due to the synthesis of additional contractile proteins.
Effects of isometric strength training on quadriceps muscle properties in over 55 year olds
L. Welsh1 and O. M. Rutherford1
(1) Department of Physiology Biophysics, St. Mary''s Hospital Medical School, Imperial College of Science, Technology and Medicine, W2 1PG Norfolk Place, London, UK
Accepted: 17 April 1995
Abstract Changes in strength, speed and size of the quadriceps muscle have been investigated in elderly men and women after 6 months of isometric strength training. We have also indirectly investigated the role of metabolites as a stimulus for muscle hypertrophy by studying two training protocols. One thigh was trained using short, intermittent contractions (IC), while the other trained using long, continuous contractions (CC). This meant that there should be a greater metabolite change in the muscle performing CC, as the blood flow is occluded for longer. Nine subjects [eight women, mean (SE) age, 71.8 (2.9) years] were measured for contractile properties and strength before and after training, and compared to nine age-matched controls [71.5 (2.1) years]. The training group increased quadriceps strength by 48.7 (9.1)% (P < 0.005) and 53.1 (11.3) % (P < 0.005) following the IC and CC protocols, respectively. There was no change in muscle strength in the controls. Both muscles showed significant slowing after training as measured by the relaxation times and the force-frequency ratio. There were non-significant decreases in muscle fatigability after training. The control group also showed some significant decreases in fatigability and muscle speed. The training group showed significant increases in muscle (and bone) cross-sectional area of 4.0 (1.7)% and 4.9 (1.3)% following the CC and IC protocols, respectively. These increases were significantly different from the decrease observed in the control group. These findings suggest that people over the age of 55 still have the capacity to increase muscle strength and size, and that the training causes slowing of the muscle. Muscle hypertrophy does not seem to be strongly influenced by metabolite changes in this age group, as there were no differences in measurements observed between protocols.
The role of metabolites in strength training
II. Short versus long isometric contractions
J. Schott1, K. McCully1 and O. M. Rutherford2
(1) Department of Physiology, St. Mary's Hospital Medical School, W2 1PG Norfolk Place, London, UK
(2) Division of Geriatric Medicine, Medical College of Philadelphia, Philadelphia, Pennysylvania, USA
Accepted: 12 April 1995
Abstract The role of intramuscular metabolite changes in the adaptations following isometric strength training was examined by comparing the effect of short, intermittent contractions (IC) and longer, continuous (CC) contractions. In a parallel study, the changes in phosphate metabolites and pH were examined during the two protocols using whole-body nuclear magnetic resonance spectroscopy (NMRS). Seven subjects trained three time per week for 14 weeks. The right leg was trained using four sets of ten contractions, each lasting 3 s with a 2-s rest period between each contraction and 2 min between each set. The left leg was trained using four 30-s contractions with a 1-min rest period between each. Both protocols involved isometric contractions at 70% of a maximum voluntary isometric contraction (MVC). The MVC, length: tension and force: velocity relationships and cross-sectional area (CSA) of each leg were measured before and after training. The increase in isometric strength was significantly greater (P = 0.041) for the CC leg (median 54.7%; P = 0.022) than for IC (31.5%; P –0.022). There were no significant differences between the two protocols for changes in the length:tension or force:velocity relationships. There were significant increases in muscle CSA for the CC leg only. NMRS demonstrated that the changes in phosphate metabolites and pH were greater for the CC protocol. These findings suggest that factors related to the greater metabolite changes during CC training results in greater increases in isometric strength and muscle CSA.
keletal muscle hypertrophy in response to isometric, lengthening, and shortening training bouts of equivalent duration.
Adams GR, Cheng DC, Haddad F, Baldwin KM.
Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697-4560, USA. GRAdams@uci.edu
Movements generated by muscle contraction generally include periods of muscle shortening and lengthening as well as force development in the absence of external length changes (isometric). However, in the specific case of resistance exercise training, exercises are often intentionally designed to emphasize one of these modes. The purpose of the present study was to objectively evaluate the relative effectiveness of each training mode for inducing compensatory hypertrophy. With the use of a rat model with electrically stimulated (sciatic nerve) contractions, groups of rats completed 10 training sessions in 20 days. Within each training session, the duration of the stimulation was equal across the three modes. Although this protocol provided equivalent durations of duty cycle, the torque integral for the individual contractions varied markedly with training mode such that lengthening > isometric > shortening. The results indicate that the hypertrophy response did not track the torque integral with mass increases of isometric by 14%, shortening by 12%, and lengthening by 11%. All three modes of training resulted in similar increases in total muscle DNA and RNA. Isometric and shortening but not lengthening mode training resulted in increased muscle insulin-like growth factor I mRNA levels. These results indicate that relatively pure movement mode exercises result in similar levels of compensatory hypertrophy that do not necessarily track with the total amount of force generated during each contraction.
Twitch contractile adaptations are not dependent on the intensity of isometric exercise in the human triceps surae.
Alway SE, Sale DG, MacDougall JD.
School of Health, Physical Education and Recreation, Ohio State University, Columbus 43210-1284.
Ultrastructural and twitch contractile characteristics of the human triceps surae were determined in six healthy but very sedentary subjects before and after 16 weeks of isometric training at 30% maximal voluntary contraction (MVC). Following training, twitch contraction time was approximately 16% shorter, although no differences were observed in one-half relaxation time or peak twitch torque. Percent fibre type was not changed by training. The mean area of type I and type II fibres in the soleus increased by approximately 30% but only type II fibres showed an increase in area in the lateral gastrocnemius (30%). Despite such changes in fibre area the volume density of the sarcoplasmic reticulum-transverse tubular network averaged 3.2 +/- 0.6% and 5.9 +/- 0.9% in type I and type II fibres respectively, before and after training in the two heads of the gastrocnemius. The results indicate that contractile adaptations to isometric training at 30% MVC were limited to twitch contraction time and were not directly related to changes in percent fibre distribution or the volume of sarcoplasmic reticulum and transverse tubules in either type I or type II fibres. The data further demonstrate that substantial fibre hypertrophy is achieved by training with low-intensity contractions.
** Isometrics do not 'turn your fibers to ST
Effects of isometric training on skeletal myosin heavy chain expression
Fadia Haddad, Anqi X. Qin, Ming Zeng, Sam A. McCue, and Kenneth M. Baldwin
Department of Physiology and Biophysics, University of California, Irvine, California 92697
This study tested the hypothesis that an isometric resistance-training program induces upregulation of slow myosin heavy chain (MHC) expression in a fast-twitch skeletal muscle. Thus we studied the effects of two resistance-training programs on rodent medial gastrocnemius (MG) muscle that were designed to elicit repetitive isometric contractions (10-12 per set; 4 sets per session) of different duration (8 vs. 5 s) and activation frequency (100 vs. 60 Hz) per contraction during each training session (total of 6 and 12 sessions). Results showed that both training paradigms produced significant increases in muscle weight (~11-13%) after completion of training (P < 0.05). Significant transformations in MHC expression occurred and involved specifically a decrease in the relative expression of the fast type IIb MHC and concomitant increased expression of the fast type IIx MHC. These adaptations were observed in both the "white" and "red" regions of the MG, and they occurred at both the mRNA and protein levels. These adaptations were detected after only six training sessions. Neither of the training programs produced any change in the relative expression of either the slow type I MHC or the moderately fast type IIa MHC, which can be upregulated in the red MG by chronic functional overload. These findings show that the isometric protocols used in this investigation were not sufficient to induce the hypothesized changes in the myosin heavy chain isoform expression in rodent skeletal muscle.
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