Can you explain to me what is meant by eccentric training and why this would be beneficial to my clients?
Traditionally speaking, the majority of most resistance training programs are focused upon the concentric aspect of muscle contraction in order to build muscle and rehabilitate musculoskeletal injuries. While all resistance training consists of both a concentric and eccentric phase, the majority of the general public focuses upon the concentric aspect of the muscle contraction when working out. In recent years, however, there has been much research carried out that has looked at the key differences between a concentric and eccentric based resistance training program. There are many benefits that can be attained with eccentric training.
There are three main methods by which one will contract a muscle during a workout, these being made up of a concentric, eccentric and isometric contraction. The concentric contraction involves shortening of the muscle (i.e., during a bicep curl, the weight is lifted from an extended arm position and the joint angle between the humerus and radius/ulnar decreases and the two bones approximate one another to shorten the bicep). The eccentric contraction involves lengthening of the muscle (i.e., as the weight is lowered down during the bicep curl). The isometric contraction involves contraction of the muscle without any shortening or lengthening.
Typically, when one has decided to focus on the eccentric phase of contraction in the program, this has been known as negative training. Weight lifters often include this type of training to add variety to their programs, help add size and stimulate muscle fibers that aren’t normally activated. An eccentric training program typically requires a training partner and can be controlled by altering the weight, speed, repetition and set variables.
For some time now, there has been an idea that concentric muscle training is best for muscle hypertrophy training, whereas eccentric muscle training has been used by physiotherapists and osteopaths alike for rehabilitative purposes.
Focusing on Eccentric Training
Our muscles are much stronger eccentrically than they are concentrically. Typically when lifting weights, our muscles will fail concentrically before eccentrically, and it is often this fatigue that limits our ability to keep lifting weight. Research has shown that our muscles are able to generate more force eccentrically because of the tension generating capacity of the connective tissue, rather than the contractile elements of the muscle. The force production for eccentric muscle activity is usually 120 to 160 percent greater than concentric. Therefore, when overloading in eccentric training, heavy resistance is often needed.
The relationship between eccentric training and muscle strength gains is still very much controversial. While there has been some research to show a benefit towards training eccentrically and strength gains, we are still very much limited in the fitness center environment to carry this out. Currently, there are very few weight machines accessible to the general public for this type of training, and we are still reliant upon a training partner.
One particular side effect common in those who carry out an eccentric training program is that individuals are more likely to develop delayed onset muscle soreness (DOMS) in the 24 to 48 hours following exercise. While there is a direct relationship between the occurrence of muscle damage and eccentric training, over a longer term training program, there has shown to be a massive ability of the body to adapt to this work. Those who train regularly or are training for competition need to be aware of DOMS and allow for this in their training programs. Eccentric training results in damage to the myofibrils and a reduction in dynamic strength in the days following the weights session. It is suggested to avoid high intensity exercises initially following this.
How and Why Muscular Injuries Occur
Research has found that most muscle strains and ruptures typically occur during the eccentric phase of the muscle contraction. Muscle strains are more likely to occur in the bi-articular muscles of the body (hamstrings, rectus femoris and gastrocnemius) and those muscles that have a complex architecture. Most injuries will also often occur at a stage of when the muscle is fatigued and has lost some of its ability to function effectively. In a sports situation, this is usually in the second half of the game. As it has been said many times before, it makes much more sense to train our clients under those specific conditions in which they perform to optimize performance and reduce the risk of injury. If we can incorporate functional and eccentric based exercises into the program, we will be better conditioning our clients for their chosen activities.
From a Rehabilitation Perspective
Eccentric based exercises have been used for some time now to rehabilitate musculoskeletal injuries (i.e., tendinopathy injuries). Only recently have they determined the physiological reasons as to why this type of training is effective. Eccentric training is thought to promote a much faster and better recovery by helping to increase the collagen synthesis and microcirculation. When eccentrically training an injury in the rehabilitative sense, it is important to progressively overload to help the connective tissue resist high impact forces associated with everyday activities such as running, jumping, etc.
In addition to this, eccentric training is also thought to allow for more efficient motor recruitment and improving one's proprioceptive abilities. When training eccentrically, it has been suggested that low intensity proprioceptive exercises (i.e., single leg balance) is good during the early stages, whereas high intensity exercises following the first 24 to 48 hours after eccentric training are avoided.
Tips for Eccentric Training
- Volume and intensity of eccentric training should be gradually progressed in order to achieve maximum physiological gains and to ensure minimal risk of injury.
- If looking to improve strength, eccentrically the weight should be overloaded from 20 to 80 percent beyond maximal isometric strength.
- Avoid high intensity eccentric exercise during the competitive phase of a training program to reduce the side effects of DOMS, as this may impair performance.
- Neuromuscular disturbances have been observed in the early phases of eccentric training. Therefore, avoid high intensity and difficult exercises during the competition phase.
- Incorporate eccentric work in the rehabilitation of muscle and tendon injuries. Seek advice from an osteopath or physiotherapist for exercise prescription guidance.
- Prior muscle injury and fatigue may predispose to muscular injury. Therefore, start simple and progress slowly.
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