Many of my athletes aren’t too thrilled when I relay their new program includes squats, deadlifts, push-ups, pull-ups etc. with a 4 to 8 second negative. Following this statement, I usually receive an eye roll, a grumble, or a deep sigh. Little do they know how beneficial those 4 to 8 seconds will be to their overall strength, size, and performance gains. Negatives or Eccentrics (how we will refer to this style of training from here out) shouldn’t be the only focus in a training program but are important and often negated. So why is eccentric training so dang hard but so very beneficial?
In order to answer this question, we must first understand the 3 different actions a muscle can perform: concentric, eccentric, and isometric actions. In a concentric muscle action, the muscles apply force which results in those muscles shortening (i.e. the bicep on the “up” phase of a bicep curl). Just the opposite, an eccentric muscle action involves the lengthening of a muscle due to an external load (i.e. the bicep on the “down” phase of a bicep curl), and finally, an isometric contraction occurs when the joint angle and muscle length are held at a constant during a contraction (i.e. plank hold). While all 3 muscle actions are vital to health and performance, the focus of this article is the eccentric action.
Research suggests that eccentric muscle action allows for greater force production than is observed with concentric actions (1,2). Other than the mechanics of an eccentric muscle action (too complicated to explain here), neural activation during eccentric actions appears to differ as well and contribute to greater force production. These neural differences include: reduction in muscle activation during maximal eccentric contraction when compared to maximal concentric contraction, an altered pattern of muscle recruitment where fast twitch motor units (a motor neuron and it’s innervated muscle fibers) are recruited before slow twitch motor units, increased activation of agonist muscles (the muscle providing the majority of force production in an action) and reduction of antagonist (the major muscle opposing the muscle action) activation, and greater cross education effect (phenomena when training unilaterally, we observe bilateral strength gains) (1,2). Also, increased muscle fiber damage is observed with eccentric contraction, particularly more severe in the fast twitch muscle fibers. This translates to greater remodeling of muscle fibers and overall muscle size/hypertrophy and strength. However, research shows that the best stimulus for hypertrophy is training both eccentric and concentric action but favoring the eccentric (1).
So how does this practically translate to sports performance? First, with eccentric training we observe increased muscle hypertrophy, particularly in the fast twitch muscle fibers, translating to greater muscle force development and stronger, faster, and more powerful athletes. Eccentric training has also shown to improve tendon strength (1). Including it in programming, may help to prevent injury. Finally, every step an athlete takes when running, every jump, every drop step to change directions, includes an eccentric contraction. Training the muscle eccentrically translates to on field / court performance.
One final note…the muscle damage following eccentric training can be observed up to 8 days following a training session (2). Because of this, it is best to include eccentric training during an off season program rather than a pre season or in season program when athletes have additional practice and game demands.
By: Lauren Higgins, M.S., CSCS, FMS-level 1
SPARC Sports Performance Coordinator
References
- Bridgeman, L.A., McGuigan, M.R., Gill, N.D. (2015). Eccentric exercise as a training modality: a brief review. Journal of australian strength and conditioning, 23(5). 52-64.
- Gardiner, P.A. (2011). Motor unit recruitment during different types of movements. In, Advanced neuromuscular exercise physiology (25-44). Champaign, IL: Human Kinetics.