During the standard standing biceps curl exercise, after lifting the bar (known as the concentric phase), the bar is lowered during what is referred to as the eccentric or negative phase of the lift, whilst using eccentric muscle action. Now, there are a few differences between the properties of eccentric muscle contraction and a concentric contraction. These properties include an increased force production capability; lower motor unit recruitment, but higher stress placed upon each individual motor unit; increased micro-trauma; and delayed onset muscle soreness from training when using accentuated eccentric contractions. By manipulating the eccentric phase of the lift the trainees can experience superior results in both their athletic performance and their physique compared to more ‘traditional’ training methods.
Manipulating eccentric stress for strength and power
A study by Hortobagyi et al (1996) stated that the total maximal strength improvement from eccentric-only training showed improvement of eighty-five percent, while the concentric-only training led to seventy-eight percent improvement, where increase in the isometric, concentric and eccentric strength were combined. However, the researchers used sub-maximal eccentric actions and maximal concentric actions, which tells us that greater improvements in strength may be seen when performing eccentric actions that are closer to maximal eccentric strength levels. A more recent study concluded “an accentuated eccentric load evokes acute increases in vertical jump height, as well as in the kinetic and kinematic variables that are considered important to vertical jumping ability”.
Manipulating eccentric stress for enhanced hypertrophy
In one of the studies, it was concluded that the eccentric-only training program resulted in about 6% gain in lean muscle mass compared to the concentric-only group that had an average of approximately 5%. Although a difference of 1% (approx.) does not seem much, any experienced bodybuilder knows that a 1% difference would lead to a significant effect. Another study looked at upper arm thickness with eccentric-only compared to concentric-only training; subjects gained an average of 13% in upper arm size in the eccentric-only group, and 2.5% in the concentric-only group when performing repetitions at the same speed. It has been reviewed by Steroidio that eccentric training may result in a bigger set of biceps and triceps over traditional, uncontrolled eccentric training.
There are clear benefits to changing to eccentric training, so go out and apply some of these techniques to your current training to reach the next level of development.