Positive Versus Negative Strength: Implications And Training Recommendations
In the previous article I explained why muscles have different levels of positive and negative strength. Now I’m going to discuss the implications of this for exercise performance.
Over the years people have invented a variety of exercise protocols and machines meant to provide greater resistance during the negative portion of an exercise, under the assumption the heavier weight and more resistance means a more effective stimulus for strength and size increases. Nautilus inventor Arthur Jones developed and experimented heavily with these types of protocols and designed a line of Nautilus “Omni” machines specifically for negative-only training, which were used during the famous Colorado Experiment. Of these only the Omni Multi-Exercise was ever sold commercially; the rest were not for a variety of reasons including exorbitant friction.
Protocols and equipment providing greater resistance during the negative or emphasizing the negative portion of the exercise have generally produced an impressive rate of strength and size increases. There have been a few interesting studies and experiments and some anecdotes (not to be confused with evidence) showing greater results over short periods of time than with conventional repetition methods. I do not, however, think the reason is the heavier negative. Instead, I think the reason these protocols and equipment tend to be very effective is because they force you to work harder than you have learned to with conventional high intensity training repetition protocols.
Consider the following:
Stimulating strength and size increases has more to do with relative effort than absolute load. If the heavier loads used during protocols like negative-only and negative-accentuated were the important factor then we would see a positive correlation between load and effectiveness during other protocols, but we don’t. Instead, a variety of repetition ranges and loads can be equally effective as long as exercises are performed with a high level of intensity (which is relative effort, not percentage of 1RM as it is often mistakenly defined).
The ability to train with a high level of intensity is something that must be learned and practiced, particularly being able to maintain strict form through increasing fatigue and discomfort (the behavior most people associate with intensity – yelling, grimacing, bodily contortions, etc. – are attempts to reduce or distract oneself from it and should be avoided). Mastering it takes time. Most people stop short of a true maximum effort during conventional high intensity training protocols due to discomfort or lack of will. Many repetition protocols and machines which increase negative resistance force people to contract harder during the negative to control the speed of movement than they have learned to as they approach positive momentary muscular failure during normal reps. When someone else hands you a heavy weight at the end point of an exercise, or if you transfer a heavy weight from your legs to your arms at the top of chin ups or dips, you have to contract hard enough to slow negative movement to a safe speed or you risk injury.
I think with proper teaching and motivation almost anyone can eventually learn to learn to work this hard during conventional high intensity training repetition protocols. Once you have learned to work at this level of intensity you would probably see little difference in muscular strength and size increases between regular high intensity training protocols and those which hyperload or emphasize the negative.
While these protocols have proven to be highly effective, I have concerns over the safety and practicality of some of them.
Without specialized equipment performing negative-only repetitions on most exercises requires two strong spotters, since a single spotter would tire quickly of lifting the heavy weights required. It also makes communication during the hand-off trickier, especially when free weights are used, since both spotters need to gradually transfer the weight to the trainee at the same time and rate (Using spotters and conventional equipment is actually preferable to using motorized machines which hand-off additional weight to the user since the machines tend to do so in a very abrupt and jarring manner). If the weight is not handed off gradually or evenly there is a greater risk of injury. While this is less of a concern during exercises with intrapersonal transfer
Machines incorporating long assist-levers like Randy Rindfleisch’s Negative Attitude and Eccentric Edge machines provided a more practical way for a single trainer or spotter to either easily lift a weight which would provide a very high level of resistance for the user or to easily perform manual negative-only training, but because of the lever advantage they require extreme caution during resistance transfer.
Various repetition methods have been developed as a way to make the negative harder without spotters or specialized equipment, such as negative-accentuated repetitions (lifting a weight with both limbs and alternating between lowering with only the right or left), and negative-emphasized repetitions (taking twice as long or longer to lower the weight than lift it). These have their own problems, however.
While the unloading of alternate limbs which occurs during negative-accentuated training may not be detrimental as some suggest, there is a greater risk of injury during heavy unilateral loading due to uneven forces on the pelvis and/or shoulders and spine during certain exercises.
Rather than make the negative harder, the longer time spent performing the less metabolically-demanding negative during negative-emphasized repetitions makes the exercise easier over the same time under load. While this allows you to handle a heavier weight, keep in mind relative effort rather than absolute load appears to be what counts where muscular strength and size increases are concerned. The upside is, this can be beneficial if you want to minimize metabolic demand for some reason, such as when training someone with very poor conditioning.
While the transient, short-term effects may differ slightly in the long run I don’t believe all the variations in repetition method, rep range and TUL, etc. make much difference, and definitely not as much of a difference as the proponents of specific repetition methods often claim. Ultimately, how strong and muscular you can be come is dictated by your genetics, and any repetition method can get you there as long as you work hard, progressively, and consistently. However, repetition methods do differ in safety, efficiency, and practicality, and these factors should be considered when deciding what to use in your workouts or prescribe for others.
Considering the impracticality, inefficiency, and greater injury risk of negative-only and negative-accentuated repetitions and the higher cost of many machines designed specifically for hyperloading the negative, and that they probably make little difference in long-term results I don’t recommend them. Instead, learn to focus better and push yourself to work harder performing conventional high intensity training repetition protocols.