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Eccentric muscle action, also known as an eccentric contraction, is a type of muscle action where the muscle lengthens as the resistance becomes greater than the force the muscle is producing. This lengthening is a negative velocity, and the muscle absorbs energy during this process. Eccentric actions are an integral part of most movements during daily or sport activities, such as walking down a hill or lowering a heavy object. Eccentric training can be used to improve muscle strength and performance and reduce the risk of injury.
| Characteristics | Values |
|---|---|
| Definition | An eccentric muscle action occurs when a force applied to the muscle exceeds the force produced by the muscle itself, resulting in the lengthening of the muscle while contracting. |
| Muscle Action | Eccentric muscle actions are characterised by the proximal and distal muscle attachments moving away from one another. |
| Muscle Contraction | Eccentric contractions involve the lengthening of the muscle while it is under load. |
| Energy Absorption | Eccentric muscle actions absorb energy, which can be converted into elastic recoil energy and reused by the body. |
| Force Generation | Eccentric contractions generate greater force compared to other contraction types for a given angular velocity. |
| Neural Activation | Eccentric exercises stimulate neural activation and can improve motor control. |
| Rehabilitation | Eccentric training is used in rehabilitation to reduce pain and improve function in patients with microtrauma or overuse injuries. |
| Muscle Damage Protection | Eccentric training can induce adaptations that protect against subsequent muscle damage and soreness. |
| Metabolic Cost | Eccentric exercises require less motor unit activation and consume less energy and oxygen compared to concentric contractions. |
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What You'll Learn
Eccentric contractions produce greater force at lower costs
An eccentric muscle contraction occurs when a force applied to the muscle is greater than the force produced by the muscle itself, resulting in the forced lengthening of the muscle-tendon system while contracting. Eccentric contractions are commonly used in functional rehabilitation for their positive effect on collagen synthesis and resistance training to increase muscle strength and muscle mass in athletes.
The mechanism for this property is still not completely understood. Several explanations are currently being studied, including the role of the accessory protein titin. Titin is an elastic molecule found in sarcomeres that attaches to the actin filament and coils like a spring as the sarcomere shortens in the concentric phase. When the sarcomeres elongate in the eccentric phase, titin resists and opposes the stretch like a spring uncoiling.
Eccentric contractions are also relevant for clinicians wanting to include them in their Physical Medicine and Rehabilitation (PM&R) programs for patients who are often intolerant to intense cardiac and respiratory efforts, such as those with heart disorders or lung pathologies. Eccentric training allows for working at high levels of force with a lower metabolic cost and oxygen uptake, making it a suitable option for patients who may be unable to tolerate more intense exercises.
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Eccentric training can be used for rehabilitation
An eccentric muscle contraction occurs when a force applied to the muscle is greater than the force produced by the muscle itself, resulting in the lengthening of the muscle while it is contracting. Eccentric training has been used as a component of strength training for over seventy years. However, it has also been used in recent years for rehabilitation to manage a host of conditions.
Eccentric training is particularly useful for patients who are intolerant to intense cardiac and respiratory efforts, such as those with heart disorders or lung pathologies. This is because eccentric training allows for working at high levels of force with a lower metabolic cost and oxygen uptake. For example, eccentric exercise has been shown to be a safe and effective treatment for tendinopathies, as it requires less oxygen consumption than concentric work, which results in slow healing after tendon injuries.
Eccentric training is also useful for older adults with muscle atrophy and weakness, as it has been shown to improve muscle strength and muscle mass. This is because eccentric training stimulates muscle hypertrophy and increases the fascicle pennation angle, fascicle length, and neural activation. In addition, eccentric training may be effective for patients recovering from surgery and joint injuries, as it can be performed without damage and soreness. For example, Roos and colleagues designed a clinical trial to test the hypothesis that eccentric calf muscle exercises reduce pain and improve function in patients with Achilles tendinopathy. The results showed that at 12 weeks, members of the group who performed eccentric exercises reported significantly less pain, and more patients in that group returned to sports participation after 12 weeks.
Furthermore, eccentric training can be used for injury recovery and post-op, as it is relatively less fatiguing and works well for early intervention. Even clients with low exercise tolerance can benefit from gentle, low-weight eccentric exercises. Eccentric training has also been shown to be effective in the rehabilitation of muscle strains, particularly in hamstring injuries.
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Eccentric contractions are linked to soreness
Eccentric muscle action, also known as "negative work", refers to a lengthening of the muscle-tendon system during contraction. This occurs when an external force applied to the muscle exceeds the force produced by the muscle itself, resulting in forced lengthening. Eccentric contractions are an integral part of most movements during daily or sports activities, such as downhill running or walking downstairs.
Eccentric contractions are associated with muscle soreness, particularly delayed-onset muscle soreness (DOMS). DOMS typically occurs a few hours after exercise and can last for several days. It is characterised by muscle weakness, sensitivity to contraction, and increased pain intensity 1-2 days after exercise. While any type of contraction can cause DOMS, eccentric contractions are particularly linked to this phenomenon due to the high forces and unique mechanical properties involved.
The soreness associated with eccentric contractions is a result of the muscle being worked harder while using less energy compared to other types of contractions. This means it is easier to over-exert the muscle, leading to delayed soreness. Additionally, eccentric contractions cause disruption to the muscle cell's cytoskeleton, which may contribute to muscle damage and soreness.
Research has shown that Type II muscle fibres are more susceptible to exercise-induced muscle damage (EIMD) after eccentric exercise. EIMD can manifest as delayed-onset muscle soreness, stiffness, swelling, and functional deficits. The protective effect of eccentric training against muscle damage has also been observed, suggesting that repeated submaximal eccentric contractions can induce adaptations that prevent further EIMD and DOMS.
In summary, eccentric contractions are linked to soreness due to the unique mechanical properties of the muscle during contraction, the higher forces generated, and the disruption to the muscle cell structure. While eccentric contractions can lead to muscle soreness, research also suggests that progressive eccentric training can help prevent and manage muscle damage and soreness.
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Eccentric contractions are a type of muscle action
Eccentric contractions are an important part of most movements during daily or sports activities, often occurring simultaneously with concentric contractions. For example, during a bicep curl, the action of lifting the weight involves a concentric contraction, while the action of lowering the weight back down involves an eccentric contraction. Eccentric contractions also occur during the downward phase of other exercises, such as the bench press or squat.
Eccentric contractions are unique because they can create more force than concentric contractions while requiring less energy. This is because, during eccentric contractions, the muscle is lengthening and working to resist an external force, whereas during concentric contractions, the muscle is shortening and working to produce a force that overcomes the load. The greater force generated during eccentric contractions can be explained by the involvement of more cross-bridge attachments between myosin and actin filaments, which results in greater force production.
Eccentric training involves repetitively performing eccentric contractions to build muscle, improve athletic performance, and reduce the risk of injury. It can also be used in rehabilitation settings to help patients recover from injuries and improve muscle function. For example, eccentric calf muscle exercises have been shown to reduce pain and improve function in patients with Achilles tendinopathy. Additionally, research suggests that performing repeated sessions with submaximal eccentric contractions may help prevent further muscle damage and soreness.
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Eccentric contractions are the opposite of concentric contractions
An eccentric muscle contraction occurs when a force applied to the muscle is greater than the force produced by the muscle itself, resulting in the lengthening of the muscle while it is contracting. Eccentric contractions are the opposite of concentric contractions.
Concentric contractions involve a shortening of the muscle, with muscle tension rising to meet resistance and remaining stable as the muscle shortens. This is also referred to as a positive contraction. An example of a concentric contraction is the upward thrust in a bench press or squat.
In contrast, eccentric contractions involve a lengthening of the muscle while it is contracting. This is referred to as a negative contraction. An example of an eccentric contraction is the downward phase of a bench press or squat.
Eccentric contractions are unique because they can generate more force than concentric contractions, even though they require less motor unit activation and consume less oxygen and energy. This is because the muscle absorbs energy during eccentric contractions, which can then be converted into elastic recoil energy and reused by the body, increasing efficiency.
Eccentric training involves repetitively performing eccentric contractions, which can help to build muscle, improve athletic performance, and reduce the risk of injury. It is particularly useful for rehabilitation as it can be performed at a low metabolic cost, making it suitable for patients who are intolerant of intense cardiac and respiratory efforts.
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Frequently asked questions
Eccentric muscle action is when the muscle lengthens as the resistance becomes greater than the force the muscle is producing.
An example of eccentric muscle action is the lowering of a dumbbell during a bicep curl.
Eccentric muscle action can be used to build muscle, improve athletic performance, and reduce the risk of injury.
Eccentric muscle action strengthens muscles by increasing the fascicle pennation angle, fascicle length, and neural activation.
