Powerline: Understanding eccentrics
The positive effects of negative training for advanced trainees
Most conventional strength training movements, regardless of the chosen modality, entail both concentric (raising) and eccentric (lowering) phases. Also known as positive (raising) and negative (lowering) contractions, performing both in a dedicated manner provides full-range, tension-generating overload for the target musculature.
A close examination of many strength training programs reveals a blatant disregard for the eccentric component of a repetition. This is especially true when the mandated rep duration is shorter for a host of protocol-driven reasons. If that is the case in certain movements you have your athletes perform, it is perfectly fine in the short term. However, if they receive a steady diet of that approach with little eccentric emphasis, you may be denying them some very important benefits.In no particular order, here is a short list of the physiological advantages that can be accrued by giving some attention to the eccentric phase of strength training exercises (Roig, M., O’Brien, K., Kirk, G., et al., 2009):
- Muscles are able capable of achieving higher absolute forces when contracting eccentrically as compared with concentrically. This capability could stimulate greater strength adaptations over a given training period.
- Eccentric contractions produce less fatigue and are more efficient — though possibly more demanding — at the metabolic level compared with concentric contractions.
- Eccentric training is more effective at increasing total strength (i.e., the combination of concentric and eccentric strength) than concentric training alone.
- Placing an emphasis on eccentric training appears to be more effective at increasing muscle mass than exclusive emphasis on concentric training.
- Placing an emphasis on eccentric contractions can aid in both the prevention and rehabilitation of tendinopathy (i.e., inflammation, injury or other similar anomalies to tendon tissue).
With this clearer understanding of the established benefits of paying more attention to the eccentric phase of a repetition, let’s examine some of the script protocols that will enable your athletes to achieve them.
It’s important to remember that all of the protocols and techniques to be described here are advanced in nature and very intense in terms proper execution. Athletes who have been strength training in earnest for at least a couple of years will do very well. However, these techniques are not designed for novice trainees or those who have not yet adapted to conventional strength training applications.
This specific protocol can be performed with any type of implement, though selectorized machines offer the most expedient and possibly safest modality for proper performance. Dumbbells offer an excellent free weight choice, as they can be neatly lined-up in a decremental order. Although it has a few different interpretations, we usually choose to begin the process upon completion of a normally executed set of eight to 10 reps. In other words, the scripted set is started and completed with its dictated technique and rep cadence for the desired number of reps.
At that point, the weight is reduced by approximately 20 to 25 percent, and the set resumes with one addendum; the eccentric phase will be executed with a strict six-second cadence. Once an additional concentric rep cannot be performed, the process is repeated with another 20 to 25 percent reduction in weight.
Less than 10 seconds for each breakdown transition is optimal. Two or three cycles of this technique is more than sufficient. You will find that the trainee will probably be able to achieve three to four additional reps with each successive breakdown, especially if the six-second cadence is strictly in effect.
With this protocol, the lifter chooses a weight that can normally be performed for 10 to 12 reps. However, rather that executing concentric reps under his or her own power, a spotter assists with that phase so that the lifter can conserve as much energy as possible for the eccentric reps.
The eccentric reps should be performed with a strict eight-second cadence. The set continues for at least six reps or until the lifter can no longer maintain the rep cadence. Obviously, caution and attention to detail are necessary for both the spotter and lifter when implementing this protocol, especially when using free weights. Communication throughout the set is vital.
Eccentric accentuated sets
Eccentric accentuated sets require the spotter to apply additional manual pressure to the lowering phase of each rep. This protocol can be performed with any modality that permits a comfortable spotting situation (i.e., hand placement on the modality) for the training partner. The rep cadence can be anywhere from four to six seconds with strict control, followed by an unassisted concentric rep.
Assistance can be provided to the concentric phase when it is eventually needed, and that point will come near the end of the set. Eight to 10 solid reps with this technique will suffice.
Troubleshooting and caveats
As mentioned earlier, placing an emphasis on the eccentric segment of any type of strength movement requires stringent adherence to correct technique and the assigned cadence. Known as “time under tension,” or “time under load,” the idea is to place as much working stress on the target musculature as safely as possible. As you may remember from last month’s discussion on the importance of strength training, this is a good stress — one that results in increased strength, power and resilience to injury.
Let’s examine some of the most frequently asked questions surrounding eccentric emphasized training and offer some further coaching points and suggestions based upon our experiences:
Q. How often should eccentric emphasized strength training be performed, and are there any times during the year when it should not be employed?
A. A good rule of thumb is to limit focused, eccentric training to once per week. This is a personal observation and one that’s based upon nearly 40 years of working with it as a coach, and another eight years or so as an athlete.
Eccentric emphasized training, at least in the initial phases, elicits muscle soreness above that of normally performed strength training activities, even with experienced trainees. I recommend that it be performed more during offseason periods than the in-season period, primarily for this reason. The exceptions for the in-season would be in rehab situations (e.g., tendinopathy) or as an occasional, low-volume change-up.
Q. How many sets of each exercise, and total sets within a workout, do you perform with any of the eccentric emphasized techniques?
A. Very seldom do we perform more than two to three consecutive sets of any given exercise in this fashion, regardless of the specific eccentric emphasized technique being employed. As far as total volume, that too is reduced to a degree.
Remember, you are dealing with a more efficient form of resistance training, one that activates and engages a high degree of muscle fibers within a given set. On average, trainees are able to handle between 30 to 40 percent more weight on an eccentric as opposed to concentric contraction. There is less need for high volume with this type of training, and high volume may, in fact, be counterproductive over time.
Six to eight total exercises for the upper body and four exercises for the lower body — 10 to 12 total exercises within the entire workout — attains excellent results.
Q. Are there any exercises/modalities that would be contraindicated for use with these protocols?
A. Avoid any movement or equipment choice that does not take into account the fact that the lifter may reach a point of fatigue and not be able to lift the weight under his or her own power or with assistance from a qualified spotter. In other words, do not perform a movement where there is a chance of not being able to get out from under the weight load. The barbell squat is a prime example; a leg press would be a much better choice for eccentric emphasized training. “Caution” should be the operative word in barbell bench pressing and overhead pressing.
We do not use any of these techniques with the barbell squat or the barbell overhead press. In the case of the barbell bench press, we make sure that the lifter can always contribute to the concentric phase as per the weight placed on the bar. And the spotter must be well-versed in his or her responsibilities.
Remember to make certain that your athletes maintain a consistent breathing rate throughout the entirety of any strength training set, especially with these protocols. As the time under tension tends to be a little longer with eccentric emphasized training, there is a tendency for disruption in this breathing rate. We constantly remind our athletes to breathe when strength training. Holding your breath while lifting can invoke the Valsalva Maneuver, which can lead to dizziness, and even fainting — both situations you certainly want to guard against.
Ken Mannie is the head strength and conditioning coach Michigan State University. His column, Powerline, appears regularly in Coach & Athletic Director magazine.References
Roig, M., O’Brien, K., Kirk, G., The Effects of Eccentric Versus Concentric Resistance Training on Muscle Strength and Mass in Healthy Adults: A Systematic Review with Meta-Analysis, British Journal of Sports Medicine, 43: 556-568, 2009.