Muscular adaptation to concentric and eccentric exercise at equal
power levels.
Mayhew TP, Rothstein JM, Finucane SD, Lamb RL
The effect of training with concentric and eccentric contractions on
fiber hypertrophy and isometric torque production was investigated in
20 healthy subjects. One group (eight female and two male subjects)
performed concentric contractions of their quadriceps femoris muscles
at an intensity of 90% of their maximal concentric power. The other
group (six female and four male subjects) performed eccentric
contractions at the same relative power level. Both groups exercised
three times per week for 4 wk at a constant speed of 60 degrees.s-1
on a Kin-Com dynamometer. Needle biopsies were obtained from the
vastus lateralis before and after the exercise program. Fiber-type
differentiation was performed using a myosin ATPase stain at a
preincubation of 10.5. Maximal isometric knee extension torque was
also measured before and after the exercise program. An analysis of
covariance was used to determine whether there were significant
differences between the exercise groups in: 1) the post-exercise
fiber areas and 2) maximal isometric torque (MIso), while controlling
for initial differences.
Results showed a significant difference
between the Type II fiber areas (P < 0.01) and the MIso (P = 0.01).
These data indicate that, when exercising at the same relative power
level, a subject performing concentric contractions will show greater
muscle hypertrophy and improve in MIso production more than a subject
training with eccentric contractions.
Isn’t it funny how the results almost always reflect the opinions of the researchers? Naturalman, do some research of your own.The next time you work hamstrings, try some stiff-legged-deadlifts, and REALLY CONCENTRATE
on doing slow and deliberate negatives. Then 3 days later ask yourself,“What do I believe-this nicely written paper or my friggen hamstrings
which are still killing me?”
Isn’t it funny how the results almost always reflect the opinions of the researchers? Naturalman, do some research of your own. The next time you work hamstrings, try some stiff-legged-deadlifts, and REALLY CONCENTRATE on doing slow and deliberate negatives. Then 3 days later ask yourself,
“What do I believe-this nicely written paper or my friggen hamstrings which are still killing me?”
Oh, and this isn’t just some little paper that was written up. It was an actual tested experiment. I’m just a little suspicious of the guru eccentric bandwagon. I’ve actually been reading ALOT of similar research.
Joey Z said, “Isn’t it funny how the results almost always reflect the opinions of the researchers?” Why do you assume that was their opinion before the experiment? I saw nothing that indicated any bias.
Okay, I am one of those people who put stock into what research shows. However, I think that there may be some problems concluding that eccentrics do no significantly aid hypertrophy or that concentrics result in greater hypertrophy. First, the exercises were performed at 90% of “maximun concentric power”. Well maximum concentric power is generated when moving a weight of approximately 50% of maximum as fast as possible (which equates to a weight which is moved approximately 67% as fast as maximum velocity without weight). Zatsiorsky, Science and Practice of Strength Training at p. 43. Now, does the 90% power mean that they are using a weight that is heavier than 50% of 1 rm? Lighter? Are the trainees using 50% but only moving the weight at 90% of the maximal velocity? The study examined power – but perhaps power is not the main determinant of hypertrophy. Seems to me that (from practical experience) greater loads than 50% of 1 rm elicit better hypertrophy gains. Also is 90% of concentric power generation also 90% of eccentric power generation? There are about a dozen additional questions I have about this study. Its not to say that the study isn’t interesting, its just that it raises more questions than it answers.
I might be wrong here but the way I see it is this. At the same power (weight?) level the eccentric is much stronger then the concentric. So therefore, there wasn’t enough overload applied ecentrically to induce as many changes.
Man such a bad study. Lets look at the control group, oh wait, where the heck is it? First off, why were there irregularities between gender in the groups— what ever happened to a control group? Since they measured type II fiber in the vastus lateralis, heres a nice little quote from Supertraining, “In human males, the Type II (FT) fibres of vastus lateralis are larger than the St fibres, but the opposite tends to occur in females” (61). ok so there was gender differences, what about the training level of the people, and their workouts that led up into here, (if they had been working out before, at more volume/intesisty these could be retaining loads for the group, so their growth then would be related to previous work, not to the study) Now for some some Supertraing, “However, it should be emphasized that this advantage of ecentric work is displayed only with slow movements and large loads” (125). Were these “large loads” performed slowly for eccentrics? I still i am not sure what 60degrees.s-1 means, but if it is what i think it means, it isnt that slow but then again maybe it’s ok. Also what exactly does 90% of maximal power mean. It sounded like a heavy weight but then again it isn’t maximal weight, its maximal power. Power is “the rate of doing work at any instant” (245). So it means that they took the peak power at the most advantageous angle, and the trainees did it at 90% over the full ROM? i don’t think so, as thats not even possible. (don’t even get into isokinetics). How did they measure the trainees peak power anyway?
This study maybe could have been interesting but was too small and seems flawed. Ok, on page 230 of supertraining, Siff says, “it is known that the eccentric exercise tends to produce greater and more rapid increases in muscle strengh and hypertrophy than concentric exercise,” (although later mentions that concentric training is still aplicable, and the combination of the two seems to be best [236]). He cites Hortobagyi et. al. “Changes in muscle strength, muscle fibre size and myofibrillar gene expression after immobiliztion and retraining in humans.” Interestingly enough, this study was also done on the vastus lateralis. Feel free to look it up.
Power and weight are not one in the same. Power is defined as force times velocity (or alternatively work divided by time). Using a heavier weight does not mean the same thing as increasing the force (weight) used. This is due to the inverse relationship between velocity and force. The greater the velocity the less force is generated… the greater the force generated the lower the velocity. Thus, the power generated by a maximum effort lift (wherein the velocity of the lift is relatively slow) is lower than a lift performed at 50% of 1 rm where the velocity is significantly higher. Power is the rate of force development or so-called speed-strength. A good example of maximal power development is the shotput or olympic weightlifting. A good example of maximal force production is powerlifting. The power generated in the shotput or in an olympic lift are far higher than the power generated in any of the "power"lifts (even tho the weight used by powerlifters exceeds the weight used by the other athletes). When examining studies like the one cited in the post it is important to understand the implication of the technical terms used. In science these terms have very specific meanings which may not coincide with the way we used them in common speach.
kelly said,“So therefore, there wasn’t enough overload applied ecentrically to induce as many changes.” Exactly, so why stress the negative portion of any exercise by slowing it down? Seems to me only pure negatives (120%+ of concentric) have been shown to have any more benifit than the concentric portion of the lift.
This is what I believe …“If the concentric phase of the lift was THE major determinant of hypertrophy, then why is it we have never heard of anyone who has built a championship physique using equipment such as Solo Flex, Nordi Flex or Bow Flex?” These are concentric dominant machines. Not even with heavy drug use has this been shown to happen.
Think how much money this would make for them!.. The study said the subjects were 20 healthy men and women, NOT seasoned bodybuilders or athletes.
This makes a huge difference!.. Finally, I strongly contend that both the ecentric and concentric are of near equal importance (for hypertrophy) giving a slight edge to the ecentric!"(PEACE!)
first the individuals were untrained and one geneticaly gifted person in either group of 10 could greatly change the results (either way)second they used the worst exercise for produceing muscle growth (leg extension). third P.R Staforth has already shown that although concentric-only will increase the tension-generating capacity of a muscle it is “unpredictabe” for muscle hypertrophy( The Journal of Applied Sports Science Research) not to mean it CAN’T do it. Its been shown that almost all of the subcellular damage which causes growth is caused dureing the negative portion of an exercise(R.B. Armstong in The Journal of Applied Physiology, J. Frieden in The International Journal of Sports Medicine, E.J. Newman in The Journal of Neurologic Science) I do believe concentric only CAN produce strength and some muscle growth it is just that it is NOT the most effective way. I would also like to know how anyone could realy train in a concentric only way (spotters lowering the wt. to your chest then you bench it?) so if you do not want to train in a concentric-only manor, than even if concentric-only produced the SAME results you are going to have to perform a negative rep, and then if only for safety you must perform it slowly ( you don’t have to its just if you like your joints you will) so whats the point, you see no value in negative-only training so you wont do it (I see it haveing great value) but you are still going to have to perform the negative portion of a rep and if your smart you will do it under control.
“Finally, I strongly contend that both the ecentric and concentric are of near equal importance (for hypertrophy) giving a slight edge to the ecentric!”
I have to agree with Joey Z. 300% on his statement. Sometimes these studies can “control” themselves so much that they don’t consider a myriad of more important variables.(As mentioned earlier by others).
Chris, you are correct, F=MA and A=dv/dt… Therefore, the greater the acceleration on a fixed mass, the greater the resultant force. With objects of the same weight greater force is generated when the weight is lifted more quickly. This is one of the reasons that many strength coach advocate always lifting the weight as quickly as possible (i.e., with maximal force) rather than in a slow and controlled manner (i.e., 2 sec up or super-slow, etc…). However, the inverse relationship between force and velocity using objects of different weight can be demonstrated as follows: Take a penny and throw it as hard as possible – a good deal of velocity is generated, but very little force. Now gradually increase the weight of the object, throwing each as hard as possible until you find an object that is the heaviest you can throw. The force generated will gradually increase with each heavier object and the velocity will gradually decrease. Power is of course the multiple of force and velocity. Therefore, assuming that a trainee is apply maximal force possible to the object the greatest power generated is when the object weighs such that only 50% of Fmm and roughly 2/3 of Vmm can be generated. In the study, p (actually 90% of Pmm) was the main factor that was determined to be relevant not Fmm or total work (force x distance) or some other factor. This one of the reasons that the study raises more questions than it answers since I have never thought that generating maximal power is the way to create maximal hypertrophy.
If you look at elite olympic lifters, like Victor Sots, David Rigert & Pyrros Dimas, for example, they all have pretty good builds, and everybody knows that the olympic lifts are almost all concentric, so it’s possible. I think the weight used for the eccentric contraction would be too light to be effective, unless the rep takes a long time, but the people doing the study didn’t specify TUT. However you look at it, you’d have to take their result with a grain of salt because it certainly doesn’t match up with what people actually experience in a gym.