While writing the article on the force-velocity curve and it’s implications for training it occurred to me that it contradicted the claims of Nautilus inventor Arthur Jones of a specific ratio of positive to negative strength. I considered mentioning it in that post, then decided it I ought to save it for a separate article, then forgot about it since I did not add it to my “to write” list. Thankfully, Ryan Hall reminded me of this recently. In reference to the force-velocity curve graph below he wrote,
…as long as the eccentric component is relatively slow, ie. not dropping the weight, eccentric strength is more along the lines of 180% greater than static strength. What would have more of an impact would be the speed of the concentric component, as force drops off precipitously with even small increases in velocity. This looks like another Jones guess shown to be incorrect.
Take a look at the right side of the graph above showing the drop in muscle contraction force as contraction velocity increases. It is obvious the ratio of positive to negative strength is dependent on concentric contraction velocity. The slower the positive phase of a repetition is performed, the smaller the difference between positive and negative strength, the faster, the larger.
If you graph the ratio of eccentric to concentric strength at different muscle contraction velocities, you’ll see the difference between the two increases rapidly as speed increases. It is important to keep in mind that even relatively fast speeds during strength training are slow compared to how fast you can move when you are not working against significant external resistance. Most repetition speeds occur at contraction velocities towards the left of the graph. It is also important to keep in mind this ratio can vary between muscles based on fiber type, can vary with body temperature, and that the same contraction velocity can result in different joint angular velocity or exercise movement speed depending on muscle length, fiber arrangement, and musculoskeletal geometry. Realize the graph below is a rough estimate based on averages and was designed to show how much the ratio of eccentric to concentric strength varies with concentric contraction velocity, rather than an attempt to provide exact ratios.
If the ratio of eccentric to concentric strength increases with concentric contraction velocity, the greater your speed of positive movement the less resistance you can use and the more your muscles will be underloaded during the negative. Conversely, the slower your positive speed the less your muscles will be underloaded during the negative. However, because the positive is more metabolically costly than the negative, the longer the duration of the positive movement the more fatigued you will be between negatives. The optimum positive movement speed is probably somewhere in between; slow enough to minimize the difference in positive and negative strength without being of such long duration that the fatigue occurring during the positives significantly reduces the resistance that can be used.
Since most studies comparing the effects of eccentric and concentric contractions on muscular strength and size show the negative to be more effective, and of the few studies comparing positive-emphasized to negative-emphasized repetitions most show better results with negative-emphasized, I suspect the optimum positive movement speed is somewhat less slow than the negative, however more and better research is needed. I would be interested to conduct a study done somewhat along the lines of what I suggested in my recent post on Ellington Darden’s 30/30/30 protocol, comparing time and work matched protocols using varying ratios of positive to negative duration. I have discussed the possibility of this with James Steele and hope we are able to put something together eventually. I suspect either negative-emphasized or SuperSlow reps (equally slow positive and negative) may end up being the best way to train, however Ryan Hall recently mentioned a study in which positive-emphasized reps were more effective than negative-emphasized.
Another consequence of this is that for machines like the X-Force which hyperload the negative how well they balance the difficulty between the positive and negative depends on the cadence used. I think if the goal is to match the difficulty of positive and negative work, however, the only way to do this is with the accommodating resistance provided by motorized machines like those designed by Randy Rindfleisch.
Although it probably only applies to a very, very small number of readers, if anyone out there is still doing infimetric training (working contralateral muscles against each other instead of using external resistance) this would also suggest you should move as slowly as you can without segmentation.
Comments on this entry are closed.
Random thoughts: This seems to support the hypothesis of Darden with the very slow positive and negative reps. Thinking through 30 seconds each way, are you really moving throughout or is it really starts and stops along the way up (positive) and then down (negative)?
When you say negative strength is 180% more than static and Jones said negative is 40% more than concentric, you are both saying the same thing. And is it the same percentage difference during the entire set? You have added the velocity variable and even using charts it is hard to follow. I also think that each exercise is different because of the arc and the distance. It is a real chore to control heavy negatives on dips and chins but it is like resting on negatives for calf raises (for me!).
Hey Darren,
In theory, yes, but there are practical problems with going that slowly, including segmentation and sandbagging in the easier portions of the range of motion.
Saying negative strength is 180% higher than the static strength but only 40% higher than concentric strength is definitely not the same thing. First, the relationship between eccentric and static strength doesn’t vary considerably at different contraction velocities, while the relationship between eccentric and concentric strength is dependent on contraction velocity and would be even higher since concentric strength is at any velocity is lower than static strength.
A lot of other factors influence this, and it probably does vary a bit between exercises, however for practical reasons I would prefer to use a consistent cadence between most exercises.
Drew this is awesome food for thought, there’s one thing I don’t get: how increasing positive speed lower the amount of weight you can use? Doesn’t a faster positive make the rep easier and therefore allow the use of a leavier load?
Hey Mike,
Increasing concentric contraction speed reduces the force your muscles can produce because the faster the actin and myosin filaments slide past each other the fewer cross-bridge attachments can be formed. A faster, shorter repetition is less fatiguing than a slower, longer one with the same weight, however, which is one of the reasons more weight can be used. Another is that as people move faster they also tend to offload the work onto other muscle groups and cheat more.
Thanks Drew, I’ve never thought about it that way, but it does make sense.
Drew this probably goes back to the previous blog about very slow negatives vs. normal negative emphasized repetitions, but are you saying you get better results with a 2 sec positive and 8 second negative versus the 3-4 sec positive and 3-4 second negative? With free weights, how many repetitions do you get? I imagine all that additional tension with the negative has to fatigue you pretty quickly. I am trying to get strong again in a traditional commercial gym environment using free weights, some machines, like Hammer and body weight exercises like pull ups and dips. I was stuck doing traditional hit type reps on the bench and then came across Rippletoe’s Starting Strength protocol utilizing submaximal sets of 5, 3 straight sets across, so I can gradually increase weight. I am way down from where I was a year and a half ago when I stopped free weight training for superslow. It just doesn’t feel intense enough, yet 1 working HIT set doesn’t seem to be enough either. It’s different when training superslow style with MedX machines but with free weights and Hammer it doesn’t seem to be enough, but maybe the 2/8 is what I need to try? I am sure you have tried it all, what would you recommend for someone 50 plus?
Thanks
Jim
Hey Jim,
Negative-emphasized reps do appear to be more effective and I’ve been having good results with and recommend them, however more research is needed to say for sure.
If you’re training with a high enough intensity of effort you do not need more than one set per exercise regardless of the equipment used.
Great in depth article Drew. This is what I try and teach my students that there are so many variations to rep speed and negative/positive sequences that can stimulate muscle growth but the ‘how’ & the safety components are of so much more value.
I often get lauged at for referring back to Arthur Jones and while he did have a few guesses at things I think he intuitively knew alot about training and set the foundation for alot of what is being researched today.
Would love to see more about your dealings with Arthur and perhaps your thoughts on somenof his methods 50 years ago which have been proven to be worthy today.
Thanks again for the time to write this article.
Christian
Hey Christian,
You’re welcome, and I will be covering many of the training methods Arthur experimented with at Nautilus in the upcoming Advanced HIT Methods.
From “Evidence-Based Resistance Training Recommendations” by James Fisher, James Steele, and Dave Smith, a paper to which you have referred before:
“Neither the type of resistance, range of motion, nor muscle action (e.g. concentric, eccentric or isometric), seem to influence muscular growth…”
Given this, why do you say, “Negative-emphasized reps do appear to be more effective and I’ve been having good results with and recommend them, however more research is needed to say for sure.”
Hey Paul,
There are a few studies which do suggest a longer negative is more effective, however one recent study showed the opposite. I’d like to see more research, because I find much of the methodology and controls used in existing studies to be lacking. This is one of the things I’ve been discussing with Ryan Hall which we will cover in our interview.
Do we know for sure if it is absolute load/tension or relative load/ tension that matters most? Is it possible that a fast concentric done at 90% of the maximum force possible at a certain velocity might be more stimulative than a slow eccentric done at a higher absolute load that happens to represent say only 70% of the maximum force that could be exerted under those conditions?
It is claimed that high relative effort is what counts for provoking adaptation, so perhaps the relative degree of loading is also more important than absolute load? Olympic lifters typically train with fast explosive lifts, well out on the force velocity curve, and they don’t seem to lack for results.
Hey Craig,
Relative effort appears to be more important than load, however load does also affect results.
The fact that high level Olympic lifters are strong is because if you are not you won’t be successful at the sport (selection bias), and not because it is a relatively effective way to train for strength. If you were to take a hundred people and randomly assign them to either an Olympic lifting group or a group doing HIT with barbells using slow speeds, after a few months you would find the HIT group would have gained more muscular strength and size with a much lower amount of injuries, if any. The Olympic lifting group would be more skilled in performing the Olympic lifts, but that’s all.
I’ve done two motorized machine workouts so far with 4 exercises per workout. I don’t have the data right in front of me, but I do a positive 325 “nautilus pounds” on the leg press while on the motorized machine my negative was an astonishing 1300 pounds. (for reference I’m a 60 year old doc, 160 pounds wet.) If those are comparable, my ratio is more like 400%. The motorized machine sort of holds you to 10 second movements which is comparable to the SuperSlow/BBS things I’ve been doing for the past 16 months.
With weights, which don’t adapt or change, the BBS theory seems to be to wear out a population of fibers with each rep until you just can’t do it any more. Hard to injure yourself that way since when you get to maximum effort you just don’t have maximum strength.
With the motorized machines it feels a bit different; the first rep is a real maximum negative rep. Is this risky? Also do I need to do more of a warmup since I’m going zero to sixty in just a few seconds?
Doc Jim
Hey Jim,
You can’t compare weights between different machines because the stroke of the weight stacks on selectorized machines or the vertical travel of the weights on plate-loaded machines and numerous factors like leverage and counterbalancing (or lack thereof) influence the resistance encountered. For example, the MedX machines have about a one foot stroke, so one hundred pounds on the weight stack equals one hundred foot pounds of work. Many Nautilus machines have strokes that are double this, so you would need to use about half as much weight for the resistance to be the same.
I do not recommend starting with a maximum effort when using motorized machines. Instead, if using an approximate 10/10 cadence, you should gradually increase your effort, starting with a fifty percent effort on the first rep, then a seventy five percent effort on the second, and only contracting with a maximum effort starting with the third rep. This reduces the risk of injury, since by the time you are using a maximum effort your remaining strength has already been reduced to the point where the difference between the force you are capable of producing and what is necessary to cause an injury has increased significantly.
I think that your comment on jones (another being wrong) is somewhat condescending.Jones used figures from actual experience with his trainees.
Des,
Arthur Jones has done more than any other person to advanced the field of exercise, and I admire and have a lot of respect for him, however he was not omniscient or infallible, and a few of the things he claimed and the theories he developed based on his observations have turned out to be wrong. If you use a relatively consistent cadence you will have a relatively consistent relationship between positive and negative strength, but the force-velocity curve makes it pretty clear the ratio of positive to negative strength varies with concentric contraction velocity.
I have to say I think that the 10/10 protocol will reign supreme. It doesn’t seem to make sense to emphasize the negative if the positive is slow enough already. and obviously being too slow causes segmentation in the repetitions and on each segment there is a respite, so 30/30 is not as efficient either.
When observing the force feedback monitor on the Renex machines in Ohio I noticed that the negative portion was only displaying a slightly lower force output than the positive, using the superslow repetitions. The best and one which gave the fastest inroading was the TSC. As a result I am feeling quite optimistic now, Drew that you think perhaps mechanical work is not as important as previously believed, because TSC will be back in business
Hey Bradley,
SuperSlow may very well turn out to be the most effective, but we need a well designed and conducted study to compare it to other work and time matched protocols. Timed static contraction training is also very effective, and the best option for many rehab situations, but it also has it’s limitations. RenEx equipment solves a lot of these, but unfortunately they are not widely available.
I suspect we will soon find out. I guess its hard to say when everyone responds so differently.
I do like the objective approach that renex employ. And I think a lot of their results with clients accross the board is testimony to their protocols’ effectivness.
Hey Bradley,
We may very well find out that none of them make any difference on average, but that some individuals respond better to one protocol than the others.
Hey Mr.Baye, so when attempting a new 1RM i should go for about a 3,3 tempo or could super slow be better? Arent you fatiguing the muscle fibers on the way down, so wouldn’t that mean you dont have as much force on the way up (besides not being as strong concentrically)? How slow should a 1RM attempt be? I understand you say same tempo as the way down, but if i did 3,3 surely i could push more weight for a 1rm attempt than i would for a 4,4-6,6-10,10.
Thank you
James C
St.Clair college Fitness and Health Promotion
Hey James,
Unless you are a competitive lifter or unless it is part of a research study I do not recommend attempting a 1RM. They are highly skill dependent and unnecessarily risky and there are better ways to test strength for progress evaluation or program design or for research (isometric tests using properly designed testing tools like those developed by MedX being the best option).
I will add this to my list of subjects to write about over the next few weeks.
Drew,
I have been working on updating my “Exercise and Genetic Variability” presentation, and correlating genes with some of the testing Jones performed on the pre-MedX Nautilus servo-powered isokinetic devices. Some of the information I ran across while perusing the earlier research reminded me of this conversation. Much of the testing that Jones observed concerning the ratio between concentric, isometric, and eccentric strength was performed on the pre MedX isokinetic machines. I had to look closely and study each graph, which revealed something to me. Almost all of the testing was performed using a leg extension machine, which was set to 110 degrees ROM, with the speed of movement set to 25 degrees per second, for both the concentric and eccentric phases of the movement.. Each repetition would be completed in a little over 4 seconds for each phase (8 seconds for the entire rep). This time interval doesn’t include the turnarounds, which were totally unloaded due to the nature of a servo-powered motor. However, having the concentric phase standardized to a predetermined speed would account for Jones’ observation of a consistent ratio between the different phases in a fresh muscle. Jones’ testing also demonstrated that this ratio doesn’t remain the same for a fatigued muscle, which is consistent with the research literature. I just thought you would find this interesting.
Ryan
Hey Ryan,
Thanks for sharing this. I would hate for people who don’t read through the comments to miss this observation so I will dedicate a separate post to this.