Eccentrics: Maximize your Weight lifting outcomes – Isaac Corvo
Lifting weights can appear a straightforward action.
However, not all Lifts are created equal! In fact, depending on the focus the lift takes, there will be different adaptations.
The muscle contractions are split into 3 categories:
- Isometric (muscle contracts but there is no change in length )
- Concentric ( Muscle contracts and shortens )
- Eccentric ( Muscle contracts but lengthens )
During resistance training, it is noted that we can produce approximately 30% more force eccentrically (1). The manipulation of this can be used to create eccentric overload.
The principle of eccentric overload has been widely cited and researched extensively in the literature.
In summary, the principle is based on being able to produce higher peak forces during the eccentric phase of the exercise. This is achieved by manipulating the exercise so that there can be a greater load on the Eccentric phase. Therefore, greater mechanical stress is applied as a result when compared to a traditional 1:1 ratio of load across concentric to eccentric phases.
During traditional resistance training, eccentric overload may be difficult to apply: these contractions are non-frequent using standard free weight methods.
However, they usually appear in the stretch-shortening cycle ( a rapid muscle lengthening immediately followed by muscle shortening with our connective tissue aiding in passive force production like a spring mechanism) (1)
Several methods have been developed to offer Eccentric overload training; these include using a third party to for assistance / resistance, or even devices such as flywheel.
A simple and effective means is to combine the use of uni lateral ( one sided exercises ) and bi lateral ( 2 sided exercises ) in a singular lift to manipulate the load applied during each phase of the lift.
Or perform a concentric with a mechanical advantage and the concentric without (2)
This can lead to greater physical adaptations:
Higher solicitation of Type IIx Muscle fibres (the true powerhouse muscle fibres capable of producing the most force ). This allows a massive force production. It is also worth noting that due to this increased mechanical tension there is also an observed increase in cross-sectional muscle area ( muscle mass ) but also increased stress upon connective tissues which must be taken into account. This can be responsible for high levels of muscle damage and soreness after initial bouts. (1)
Eccentric overload has been seen to potentially be effective in rehab too, in fact, patients with chronic Achilles tendinopathy have used such a method during their recovery (3)
Current and high-quality literature supports the use of this training as there are greater improvements in, concentric and eccentric force production, Muscle hypertrophy, Vertical Jump height, and running speed in both healthy and well-trained individuals. (1)