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The following website analysed the effect of so-called isotonic exercise on strength: http://www-rohan.sdsu.edu/dept/coachsci/vol51/housh.htm << DCER (Isotonic) Training Improves Strength And Its Retention In Trained And Untrained Limbs Housh, T et al. (1995). Effects of eccentric only resistance training and detraining. International Journal of Sports Medicine, 17, 145-148. The effects on dynamic constant eccentric resistance (DCER - formerly called isotonic training) training on the extensor muscles of one leg were assessed for: eccentric DCER strength in both legs, concentric isokinetic leg extension peak torque-velocity curves in both legs, and retention of the previous two factors after detraining. Males were divided into a training group and a non-training control group . Training consisted of eight weeks of eccentric-only DCER exercise (3-5 sets of 6 repetitions at 80% of eccentric 1 RM) on the nondominant limb followed by an additional eight weeks of detraining. DCER strength improved in the trained (29%) and untrained (17%) limbs. No changes in isokinetic values were recorded in either limb. The training increases were retained after eight weeks of detraining. Implication: DCER (isotonic) training involves considerable neuromuscular skill development. It is known that initial strength training effects are neural (skill changes) and so it is not surprising that training "effects" are retained when development starts from an initially low level. This type of neural development also explains the "cross-training" effect to the untrained limb. Another explanation might be changes in everyday limb-use that stimulated development in the untrained limb. >> ------------------------------------ *** This article and its accompanying analysis warrant some careful dissection. REDEFINITION OF ISOTONICS The parenthetical definition of "DCER - dynamic constant eccentric resistance" training as the correct modern term for "isotonic" training is fraught with errors and inaccuracies. First of all, it is entirely tautological to use the adjective "dynamic", since eccentric exercise is always dynamic. There is no such entity as static eccentrics. Really! It sounds something like the tautology I heard on some TV weather report which referred to the "coastal seaboard" - are there any seaboards that are not coastal? Next, it is totally incorrect to equate any form of eccentric training with isotonic training, since the old concept of "isotonic" (constant muscle tension) training, however inaccurate it may have been, was applied to a full movement or series of movements and not just the eccentric phase of those movements. "Isotonic" training referred to allegedly constant muscle tension exercise in a movement comprising both concentric and eccentric phases, so it is mystifying how any scientists could deviate so from the original meaning of the concept of "isotonic" action. As a matter of historical interest, who actually decided to coin the term "DCER (Dynamic Constant Eccentric Resistance) as a substitute for "isotonic"? Why was concentric action left entirely out of the picture and why, for that matter, did the creators of that neologism not call "isotonic" training as DCCR (Dynamic Constant Concentric Resistance) training, or even DCCER (Dynamic Constant Concentric-Eccentric Resistance) training? Maybe they realised that, in all non-cyclical movement, there is also an isometric phase between each concentric and eccentric phase. Certainly, most of us are aware that it is virtually impossible to maintain constant muscle tension over any extended range of joint action and that the term "isotonic" should have been discarded or carefully qualified many years ago, but to replace it with DCER is equally inappropriate. After all, two quite acceptable and non-controversial terms have been widely used in Europe and Russia for many years, namely "auxotonic" and "allodynamic", which referred to exercise in which muscle length and tension were varying all the time. Even the rather more generic term "dynamic" would have been preferable to "DCER". Now let us address the concept of "constant eccentric resistance". "Isotonic" exercise did not refer to exercise against constant resistance, but to exercise which presumably implicated constant muscle tension. Constant muscle tension is very different from constant external resistance. Anyhow, even if constancy of resistance is the qualifying condition that the researchers intended to use, its application to the real world of exercise is highly questionable, because it requires special machines to ensure constancy of external resistance throughout the full range of any joint movement. This condition of constancy of eccentric resistance using conventional weights or pulley machines simply does not happen over any extended range of joint movement. Possibly this sounds unduly critical, but the reviewers of any article which unquestioningly accepted DCER as the appropriate synonym for "isotonic" surely must have carried out a very cursory evaluation of the original submission. Possibly they were far more interested in the statistical methods and laboratory procedure, rather than in the essential biomechanical and physiological issues under consideration. Maybe they really did not fully appreciate the field that they were called upon to analyse, in which case they should have recused themselves from the review process. Whatever the case may be, the exercise science community needs to appreciate that this latest attempt at renaming "isotonic" training is seriously inaccurate and should not be adopted as the standard definition in any publications or teaching situations. MAXIMAL ECCENTRICS? The experiment stated that "Training consisted of eight weeks of eccentric-only DCER exercise (3-5 sets of 6 repetitions at 80% of eccentric 1 RM)". How, may I ask was the eccentric 1RM (single repetition) maximum obtained for each test subject? One often reads that concentric action is the least 'strong' of all types of action, while eccentric action allows one to move something like 30-40 percent more than one's concentric maximum, but nobody has yet defined incontrovertibly what a true eccentric maximum is. We can estimate this by defining it to be the maximum load that we can lower against gravity over a period of not less than 3 or 5 seconds, but this actually implicates an element of local muscle endurance and not simply discrete 'strength'. Such measurements of maximum eccentric strength apparently prove that eccentric strength is greater than maximum isometric strength, which, in turn, is greater than maximum concentric strength. Now, maximum isometric strength is the utter limit strength that the muscles can produce to prevent a load from overcoming voluntary muscle effort, then maximum eccentric strength must be strength that one can exert to exceed one's voluntary maximal strength. This must then imply that maximum eccentric strength takes the muscles close to their mechanical limits. Of course, one presumes that the Golgi Tendon Organ Reflex fortunately reduces any potentially dangerous production of muscle tension before maximum tension and structural failure occur. This sounds fairly convincing until one notes that the muscle tension produced during a voluntary maximum eccentric phase of carefully controlled weight training movements very often is significantly less than rapidly amortised involuntary eccentric actions, such as those which occur when one drops from a height. So, as our eccentric tale unfolds, does this now suggest that a more realistic measurement of maximal eccentric strength has to be made under involuntary, very rapidly terminated eccentric movements? Despite all this further speculation, the measurement of a maximum maximorum (maximum of all maxima, as my colleague Dr Zatsiorsky aptly describes it in his "Science and Practice of Strength Training", 1995) under eccentric conditions still remains as elusive as ever. So, we have to ask if it is entirely realistic and even possible to meaningfully measure maximum eccentric strength in any given joint movement. Now, if we return to the publication that stimulated this discussion, how did the researchers manage to establish accurate 1 RM (Rep Max) measurements of eccentric knee extension-flexion so that their experiment would produce scientifically valid results? Dr Mel C Siff Denver, USA [log in to unmask] %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%