Concentric training is most easily thought of as the muscle contraction when a weight is lifted. The muscle fibers shorten while contracting to lift the load as in the upward movement of a bicep curl.
An eccentric muscle action is when the muscle fibers lengthen to lower a load, as in the downward movement of a bicep curl. While the fibers are lengthening, they’re also contracting to return the weight to the start position in a controlled manner. Eccentric muscle actions are common in strength training with free weights, body weight exercise, and non-hydraulic exercise machines.
Most activities of daily life contain both types of muscle actions. As an example, walking up the stairs works the quadriceps concentrically while walking down the stairs works the muscle eccentrically. Likewise, picking up a child or laundry basket are total-body concentric actions while lowering the child or laundry basket are eccentric movements.
Since we use the muscles in our bodies in both ways in every day life, we should also use both types of actions in strength-training programs.
According to the American College of Sports Medicine (ACSM) Position Stand On Resistance Training Progression published in 2002, muscle strength results from the proper activation of specific muscle fibers, which are recruited in response to the demands of the resistance-training program, and strength-training protocols should include both concentric and eccentric muscle actions.
What are the Benefits of Combined Concentric and Eccentric Training?
In 1990, Colliander and Tesch compared the effectiveness of training the quadriceps using either a concentric- only or concentric and eccentric program. Their results showed that the group that trained using both concentric and eccentric muscle actions achieved greater improvements in strength and strength-related tasks. The concentric and eccentric group outperformed the concentric-only group in vertical jump and three-repetition maximum half squat.
Concerned about the loss of muscle mass during space flight, a 2003 study by Hilliard-Robertson et.al. also compared combined action training to concentric-only training. Again, greater strength gains were found in the groups training with the combination of eccentric and concentric training.
A group of older adults were tested for their ability to perform activities of daily life (rising from a chair, stair climbing and descending, etc.). In the study, one group trained with concentric-only exercise while the other trained with eccentric and concentric exercise. The group that trained with the combined protocol showed greater improvements in function. Gur et al. (2002)
Bird et. al. (2005) recommend combined concentric and eccentric training using 1–3 sets and 15–20 repetitions to build muscular endurance. A study conducted by Marx JO et.al. (2001) compared the effects of different training volumes in women. They concluded that training programs with multiple sets and higher repetition produced greater gains in muscle endurance than lower volume programs.
What are the Benefits of Eccentric Training?
In addition to looking at the benefits of concentric and eccentric combined training programs, researchers have also studied the benefits of training eccentric muscle actions only compared to concentric muscle actions only. The results have shown that there are many benefits to training eccentric muscle actions.
These benefits include:
Greater increases in Strength
When eccentric only training has been compared to concentric only training, several researchers have discovered that eccentric training yields greater increases in strength than concentric.
One study looked at 6 weeks of eccentric vs. concentric training in women. Hortobagyi et.al. (1996). After the training, the concentric group improved strength 36% while the eccentric group had a 42% increase. This difference was significant (P<.05). The authors concluded that training eccentrically yielded greater strength adaptations faster than concentric training in women.
The superiority of eccentric training versus concentric training for developing strength has also been reported by Farthing and Chilibeck (2003), LaStayo et.al. (2003), Seger, et.al. (1998), and Hortobagyi et.al. (1997).
Greater muscle hypertrophy
It is well accepted that the stimulus for muscle growth is microtrauma to the muscle following exercise. The process of lengthening during a contraction increases the amount of microtrauma experienced by the muscle. In turn, this stimulates the muscle to rebuild and add and increase muscle fiber size in order to handle the load. While concentric training can induce some microtrauma, over the same period of time, eccentric training is more effective for promoting muscle growth.
Numerous studies have reported that eccentric training is superior to concentric training for inducing muscle hypertrophy. Farthing JP and Chilibeck PD (2003), Higbie (1996) and LaStayo et.al. (2003) References