Strength-training plateaus are frustrating but eventually, almost everyone reaches one. As you know, muscles grow stronger in response to progressive overload. You place a stimulus on the muscle that it’s not accustomed to and it adapts in a way that makes it stronger and more capable of generating force.
Gains in strength are often associated with an increase in muscle size although muscles can also become stronger due to neural adaptations. These are adaptations that improve the ability of your brain and muscles to communicate with each other. Your brain “talks” to your muscles via nerves called alpha motor neurons, nerves that connect with one or more muscle fibers. A motor neuron and the muscle fibers it innervates is called a motor unit. When a nerve impulse travels from the brain through a motor neuron, the motor neuron releases a chemical called acetylcholine that travels across the gap between the nerve and the muscle fibers. The timely release of acetylcholine tells the muscle fibers to contract. The force of the contraction depends on the:
. Number of motor units recruited
. Size of the muscle fibers recruited
. How frequently the impulse travels down the motor neuron
The reason muscles can become stronger without growing in size is that they improve their communication strategy. For example, in response to strength training, muscle fiber stimulation becomes more synchronized and more motor units can be activated at the same time. Motor units also increase their firing rate so more force can be generated. That’s why, early in training, you become stronger even though your muscles haven’t increased in size.
Now that you know how muscles become stronger – through an increase in size and through neural adaptations, what can you do to keep enhancing those strength gains? What if you’re using progressive overload and still aren’t making progress? According to a new study, accentuating the load you place on a muscle during the eccentric lifting phase of a contraction can help you break through a strength plateau.
Eccentric Lifting
You may have heard the terms “eccentric” and “concentric.” Resistance exercises have both an eccentric and concentric component. Concentric refers to the portion of an exercise where you shorten the muscle. For example, with biceps curls, the concentric phase is moving your hands up towards your shoulders. The eccentric phase is when you lengthen a muscle against resistance. With biceps curls, the eccentric is the “lowering” phase where your arms return to the starting position.
You may have heard the term “eccentric lifting.” With this type of training, you emphasize the eccentric phase of an exercise by slowing down the rate at which you lengthen the muscle. Doing this not only increases the time the muscle is under tension but leads to greater muscle fiber damage. The eccentric phase is actually the most damaging portion of the movement – and with damage comes growth. So, the idea behind eccentric training is to create more muscle fiber damage to promote bigger gains in strength and size.
Accentuated Eccentric Lifting
Yet there’s another way you can harness the power of eccentrics. A new study shows increasing the load used during the eccentric phase of an exercise can help lifters break through strength-training plateaus. Rather than slowing the tempo of the eccentric phase of an exercise, you increase the weight you’re working against eccentrically.
How well does this work? Researchers at the University of Jyvaskyla in Finland put the idea to the test. They divided 28 strength trained males into 3 groups. One group did accentuated eccentric load training – when they lifted, the load was higher during the eccentric phase than the concentric phase. The second group did traditional training, lifting the same load during the concentric and eccentric phases. A third group trained without supervision and were essentially on their own.
The results? After only five weeks of training, the accentuated eccentric lifting load training group was able to generate more force and showed a greater work capacity than the other two groups. This is consistent with other studies showing that eccentric training is better for building muscle strength.
In one study where participants performed concentric or eccentric training only, strength gains were superior in the eccentric only group. Eccentrics are also a strong stimulus for muscle growth. In one study of eccentric or concentric-only training, an eccentric lifting focus led to an average gain in muscle size of 6.6% while the concentric-only group experienced average gains of only 5%. Some studies suggest that eccentric training boosts the release of a compound called phosphatidic acid that stimulates muscle protein synthesis.
What you may not be aware of is you can eccentrically handle more weight, as much as 30 to 50% more, than you can concentrically. So, you’re capable of handling more weight during the lengthening phase of an exercise.
Incorporating Accentuated Eccentric Lifting into Your Workouts
So, how can you take advantage of accentuated eccentric training? One method is called the two to one method. You can do this by using two limbs during the concentric phase and one limb for the eccentric phase. Using this method, you double the load during the eccentric phase by using only one limb. For this technique, it’s best to use a resistance that’s around 70% of your one-rep max.
Another more common approach for accentuating the eccentric phase of an exercise is to slow the speed of the eccentric movement. Doing this keeps the muscles you’re working under tension longer. Start with 3 seconds for the eccentric phase and gradually slow it even more – to 5 seconds or longer.
If you have a weight-training partner, you can also use forced reps. For this, use a weight that’s around 70% of your one-rep max and do reps to the point that you’ve reached concentric failure. Then perform two forced reps as your partner applies extra resistance on the bar during the eccentric phase.
Another option is to use a weight that’s heavier than you can lift concentrically or about 110% of your one-rep max. Have your partner help you lift the weight concentrically and let you handle the entire load during the eccentric or lengthening phase. Remember, you can lift more eccentrically than you can concentrically.
Be Judicious
Eccentric training is more taxing on your muscles. Don’t do eccentric training every time you work out. At most, do it once a week. However, if you do it properly, it should help you break through a strength plateau and achieve more muscle growth as well. You can also use eccentric loading or negatives at the end of a workout as a “finisher.” The key is to be judicious about how frequently you do them and not overdo it. Eccentric training fatigues your muscles to a greater degree than traditional training.
References:
Aviat Space Environ Med 74(4):342-347. 2003.
Ergonomics 15:417-434. 1972
Front. Physiol., 27 April 2016 | http://dx.doi.org/10.3389/fphys.2016.00149
ACSM. “Eccentric Resistance Exercise for Health and Fitness”
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