(Timothy C. Fritz. Muscle & Fitness. Sept 2005 v66 i9 p108 )

MUSCLE CONTRACTIONS

Eccentric, or negative, movements harness the power of the "other half" of every repetition you perform. Muscle contractions are separated into two types: concentric and eccentric. Concentric contractions are those in which the muscle fibers shorten while contracting to lift the weight, demonstrated by the upward phase of a biceps curl.

Eccentric contractions are just the opposite--the muscle fibers lengthen to lower the weight. For example, the downward phase of the biceps curl is the eccentric contraction. While the fibers are lengthening, they're also contracting to return the weight to the start position in a controlled manner.

Most bodybuilders perform an exercise's eccentric phase simply as a means to repeat the concentric movement. However, negative training reverses that thinking: The lifting becomes a byproduct of the lowering and a means to return the weight to the start. By employing negatives in your program, you can elicit maximal muscle stimulation and growth. This advanced training technique requires experience and a commitment to building mass.

POWERFUL NEGATIVES

The results attainable from negative training are real, but like most things in life, what you get out of it depends on what you put in. If you pay your dues in the gym and follow some basic guidelines, eccentric training offers the following rewards:

* An Increase in Training Poundages

"Everyone can lift more weight eccentrically," says Michael B. Rodricks, MD, an amateur bodybuilder and anesthesiologist for JLR Medical in Orlando, Florida. "It's much easier to come down slowly with 315 pounds on the bench than it is to lift that same weight." Numbers vary, but the consensus seems to be that most lifters can handle about 30% more resistance eccentrically than they can concentrically.

Of course, lowering a bar with six plates isn't exactly the same as lifting it outright, but make no mistake: Training with 30% more resistance than you're used to will absolutely, positively shock your muscles into a state of growth.

In addition, some experts speculate that the strength gains you make from eccentric training may transfer, in part, to the concentric component of your movements. Regardless, negatives will make you stronger, allowing you to move more weight on all your exercises.

* Neural Adaptations Muscles get bigger and stronger due in part to the neural adaptations that take place following training. Your muscle fibers (and the nerves that deliver impulses that make them contract) adapt to specific repetitive movements. If you continually perform the same exercises at the same speeds, your muscles and nerves stop adapting because they have nothing new to learn. No wonder muscle gains eventually come to a halt.

Eccentric training presents a drastic change from its concentric counterpart. The sheer intensity of negatives causes some serious confusion at the neuromuscular level. Although eccentric and concentric movements work the same muscles, the shift from concentric to eccentric training forces your nerves to recruit different muscle fibers, resulting in continued neural adaptation and muscle growth.

* Muscle-Fiber Damage and Breakdown One theory concerning muscle hypertrophy, or growth, states that muscle cells rebuild themselves, becoming bigger and stronger, following the micro- trauma of intense contraction, such as that experienced through weight training. Compared to concentric contractions, eccentric contractions have been scientifically shown to generate more muscle trauma and neural adaptations, just as they've been shown to produce greater muscle force, speed and mass.

In fact, this style of training can cause muscle-fiber damage so intense that you'll likely experience more severe delayed-onset muscle soreness (DOMS) than you would after a nasty leg workout. Start slow and easy when you begin training eccentrically, and keep in mind that considerable muscle soreness is an unavoidable side effect of this technique.

* Type II Muscle-Fiber Activation A study published last year indicated that performing the eccentric phase of a movement with a resistance greater than that used in the concentric phase may recruit more type II muscle fibers. Those are the ones called upon for strength and speed, and they're highly desirable to bodybuilders and others striving for muscle mass.

* Longer-Lasting Strength Gains New research also suggests that strength training with maximal eccentric contractions may result in neural adaptations and strength gains that last longer than those typically achieved with concentric training. Although this study was performed with previously untrained individuals, the results could be significant for those who must often stop training for extended periods.

COMPONENTS OF NEGATIVE TRAINING

Negative training is not unlike traditional weight training, but to utilize it correctly, you need to modify some of the basic components of training to which you've become accustomed.

* Resistance As mentioned before, eccentric training lets you use significantly more weight than you normally do. The resistance you use depends on several factors, particularly the amount of time it takes you to execute the eccentric phase (see "Speed" below).

* Repetitions If you perform negatives with enough weight to make it effective, you probably won't be able to execute as many reps as you do concentrically. David Sandler, PhD, an assistant professor at Florida Atlantic University in Fort Lauderdale, says, "I set a target goal of doing eight reps, but if at four the individual can no longer control the descent rate reasonably well, [he or she has] had enough with that particular weight. That determines the number of reps to perform."

* Speed Whereas concentric movements are measured by the number of reps, eccentric movements are better gauged by time. "We typically look at a length of time in which we want to do the negative rep, whether it's five, six, three or 10 seconds," Sandler remarks. "If [trainees] start getting quicker and quicker doing the negative as the muscles fatigue, that's about the time to finish the set."

Eccentric movements should be done much more slowly than you typically lower a weight. Aim for a resistance that allows you to move the weight through the entire eccentric range of motion in 3-5 seconds. If you can resist for longer than five seconds, consider adding weight; if it takes you less than three seconds, the weight is either too heavy or you've adequately exhausted the muscle for the current set.

* Sets You must perform fewer sets eccentrically than you would concentrically to accommodate the increase in intensity. For larger muscle groups like legs, chest and back, 2-3 sets are sufficient. For smaller muscle groups like arms, shoulders and calves, 1-2 sets may be enough to completely fatigue the muscle.

* Rest You need more time to recover between sets due to the intensity of negative training. Rest 3-5 minutes, depending on the muscle group being trained and your conditioning level. You also have to rest longer between workouts for a particular bodypart. Allow about four days (96 hours) between eccentric training sessions of the same muscle group.

* Partner To fully incorporate the principles of eccentric training and elicit maximal results, you must train with a partner. A spotter will do in a bind, but effective negative training requires someone who knows you and your limits well and can push you to the very edge without going too far.

You can safely do some eccentric training without a partner on a Smith machine, on specialized equipment or by performing exercises unilaterally (see "Going Negative"). Otherwise, training solo with negatives can be dangerous. Who wants to be under a bench-press bar racked with 30% more weight than you can push up with no one in sight to help you? Not a good idea.

* Safety/Injury The only negative (pun intended) aspects of eccentric training are the ever-present risk of over-training due to the intensity of the movements and the chance of injury due to the technique's aggressive nature. Much of the risk associated with eccentric training can be avoided by knowing and listening to your body and training with a partner who knows you well.

EXPERIENCE IS KEY

To get the most out of eccentric training, you also need to train at the appropriate level.

* Level I -- Beginner "Beginner" refers to a novice to eccentric training, not weight training in general. If you don't have a solid weight-training background and at least three months of lifting behind you, you're not ready for eccentric training. Give it a try when you're physically prepared.

Beginners should strive to do at least one full set of negatives per training session. As your experience and conditioning advance, so too can your workout intensity.

* Level II -- Intermediate When you reach this level, dedicate one full exercise per training session to eccentric training. Aim for 1-3 sets of 4-6 reps.

* Level III -- Advanced Experienced negative trainees can lay it on the line, dedicating an entire training session to the use of eccentric movements. Keep these sessions short and sweet, as they quickly consume every ounce of your energy. Rest a muscle group for 4-7 days before working it again.

PUTTING IT ALL TOGETHER

By adjusting the components of your training and accounting for your lifting experience, you can safely integrate negatives into your workout. (See "Going Negative" for the five most common ways to use negatives.) The negative phase of any given exercise rep has as much potential to build strength and mass as the concentric phase, possibly more. Take your one-dimensional concentric movements and convert them into multipurpose exercises that focus on both phases, each receiving equal attention.

"You get the biggest bang for your workout buck," Sandler explains. "You get a double rep, so to speak. You get it on the concentric and you get it on the eccentric. You get more work done in a shorter period."

For those who want to get in the fast lane to accelerated muscle development, give negative training a shot. It's one more technique you can turn to when traditional training methods stop working. You'll be glad--and sore--you did.

REFERENCES

Andersen, L.L., Andersen, J.L., Magnusson, S.P., Aagaard, P. Neuromuscular adaptations to detraining following resistance training in previously untrained subjects. European Journal of Applied Physiology 93(5-6):511-518, 2005.

Byrne, C., Twist, C., Easton. Neuromuscular function after exercise-induced muscle damage: theoretical and applied implications. Sports Medicine 34(1):49-69, 2004.

Farthing, J.P., Chilibeck, P.D. The effects of eccentric and concentric training at different velocities on muscle hypertrophy. European Journal of Physiology 89(6):578-586, 2003.

Friedmann, B., Kinscherf, R., Vorwald, S., Muller, H., Kucera, K., Borisch, S., Richter, G., Bartsch, P., Billeter, R. Muscular adaptations to computer-guided strength training with eccentric overload. Acta Physiologica Scandinavica 182(1):77-88, 2004.

Proske, U., Allen, T.J. Damage to skeletal muscle from eccentric exercise. Exercise and Sport Sciences Reviews 33(2):98-104, 2005.

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