Over the past 15 to 20 years the various bodybuilding magazines have published a lot of information on the subject of positive and negative training. As you read the following,
you'll see that, perhaps, too much of it was written with too little to back it up. The best way to understand the difference between positive and negative actions is to
visualize yourself performing a dumbbell curl. As you curl the weight up toward your shoulder, you perform the positive, or concentric, portion, of the rep, and your biceps is
shortened. As you lower the weight back down to the starting position, you perform the negative, or eccentric, portion and your biceps is lengthened.
Note that while the biceps is lengthened during the negative part of the movement, that doesn't mean that it relaxes; it's working during both portions of the movement. The so-called bodybuilding experts have made much of the fact that you can handle more weight during negative training. As a result the gyms are filled with lifters and their training partners forcing reps and screaming at each other to lower the weight slowly after each forced rep, a scenario that goes on day after day workout after workout.
The problem with this approach is that eccentric, or negative, training is known to be a major cause of muscle injuries, especially delayed onset muscle soreness, or DOMS. To give you the facts about negative training, I cite the work of noted research scientist Prank G. Shellock, Ph.D. Shellock is associated with Tower Imaging in Los Angeles, the University of California at Los Angeles School of Medicine and St. John's Hospital in Santa Monica, California, and he has conducted several studies on concentric and eccentric muscle actions.
Bodybuilders often discount the findings of research scientists because so many scientists have no concept of weight training. That's not the case with Shellock, however, as he is a former 198-pound Class powerlifter who still trains regularly and looks it. One of Shellock's studies involved a comparison of the effects of positive and negative training. Each subject performed a positive dumbbell curl with one arm, and then an assistant passed the dumbbell to the subject's other arm, where he or she lowered it; and the pattern was repeated, with one arm performing the concentric action and the other performing the eccentric action, until the subject the muscle.
In another study, this one conducted by a different group of researchers, the subjects were divided into two groups: One group performed positive exercise only by walking uphill, and the other performed both positive and negative exercise by stepping up on and down from a box. The researchers found that while the muscles in the positive group recovered within two hours after the exercise, the muscles in the subjects who also performed negative exercise had still not recovered the next day.
Negative, or eccentric, contractions actually use fewer muscle fibers and need less oxygen to do work. Because there are fewer fibers performing the work however, there is a greater strain placed on the fibers, which is why negative exercise is more likely to lead to injury how does this data apply to your training? Simply stated, you should approach negative training with caution and respect, and in my opinion it has no place in a recreational trainee's workout.
The risk of injury is too great, and the enormous amount of time needed to recover from negative training makes it impractical for the average recreational bodybuilder. You can train and gain only as long as you are healthy enough to do so. Injuries will keep you out of the gym, which will cause to you to lose some of your hard-earned gains and possibly gain some unwanted weight. If and when you do get back into your training, you may have to eliminate some of the exercises that you enjoy most to accommodate the injury.
Consequently, the number-one priority of recreational trainees and world-class athletes alike should be to avoid injuries so they can continue to train. If you are using what are called "forced reps," that's exactly what you're doing-forcing the muscle beyond its limit, The forced movement is usually a concentric exercise, but it's combined with a slow, controlled negative rep performed by an already fatigued muscle. This makes it prime time for an injury to occur. Do you remember those tough workouts you did when you suddenly changed your routine and added negatives, forced reps and high volume and you were sore for a week?
That soreness indicated muscular injury If your muscles are in that state and you attempt to train again before they recover, you put yourself at risk for an even greater injury. It all boils down to a concept that I have emphasized in this column from the beginning-have a planned approach to your training. If you're having a bad day, either drop the poundage or go home. Don't risk an injury that could set you back weeks, months or even years.
Competitive bodybuilders as well as athletes in other sports may need to make judicious use of carefully planned negative training at some point in their training cycles. These sessions must be limited and infrequent because of the recovery time this type of training requires. Some sports include negative actions as part of their regular activities. For example, a sprinter may injure a hamstring when his or her lower leg is moving forward and the hamstrings perform a negative movement to slow the leg and absorb the shock when the foot hits the ground.
Therefore, a limited amount of negative training may help the sprinter's hamstrings adapt to the normal work load of sprinting. Despite what I've said here, it's unlikely that recreational trainees are going to stop doing forced reps and negative work. If you heed my words, however, you'll at least reduce your amount and frequency of this type of training and allow extra days for recovery when you do it. Just remember that it's the most likely scenario for an injury.
In the past few installments of our fitFLEX articles, we've presented information pertaining to training that was published in scientific journals, and these columns have been very well received. In my opinion, the weight-training and scientific communities have been at odds for too long. While the scientific community hasn't ignored training concepts and components in its research, the weight-training community has for the most part ignored what the scientific community has to offer. This column will continue to bridge that gap for fitFlex article readers.