Types of muscle work overview :
Discussing What are the 2 Types of muscle work Isotonic and Isometric, A muscle is composed of actin and myosin fibers which are capable of generating tension by a cross-bridge cycle. When a muscle produces tension work is done by producing movements in the body segment. Contraction of muscle is done to produce a specific amount of tension or force to perform a work in the form of body movements. There are several types of muscle work defined on the basis of change in muscle length during contraction. Muscles may become shorten, lengthen and remain the same when they perform specific work on joints. Contraction means shortening and relaxation means lengthening of muscle fibers.
Key Terms:
Key terms we have to describe here are given below: to explain types of muscle work
- Work. A work is done when a specific distance is covered by the application of force or energy. In simple terms work is the product of force and distance.
- Isometric: it is a type of muscle work in which the length of the muscle remains the same.
- Isotonic: it is a type of muscle work in which the length of the muscle changes.
- Eccentric: when the muscle lengthens isotonically to produce movements.
- Concentric: when the muscle shortens isotonically to produce movement.
- Isokinetic: when the speed of muscle contraction remains constant regardless of force applied it is called isokinetic muscle work.
Detail description of Muscle Work:
Muscle work occurs with an increase in intramuscular tension; when there is a change in length of the muscle during a contraction it is said to be an isotonic contraction. The type of muscle contraction in which the length of the muscle does not change is called isometric contraction or isometric muscle work. Now there are the following types of muscle work.
1.Isometric or Static muscle work:
In this type of muscle work muscle generates tension to counteract opposing forces but there is no change in the length of muscle. Muscle does not shorten or lengthen so no work is done. No movements occur at the joint, still muscles produce force to maintain stability at the joint during activity.Iso means same and metric stands for length so length of the muscle remains same. Isometric contraction or isometric exercise are performed to maintain stability and overcome resistance.
Advantages isometric or static muscle work:
Advantages of isometric or static muscle work are following:
- Static muscle work is more economical than isotonic.
- Used for posture maintaining and strengthening
- Useful for activation of many muscle fibers at a time.
- Exercises by this type of muscle work are suitable for people having recent injury,bed bound and other medical conditions which restrict movement of the body.
- Isometric exercises may help to reduce pain according to some research.
- Beneficial to gain hypertrophy of muscle fibers.
Disadvantages isometric or static muscle work :
- If there is sustained muscle work so fatigue can occur due to hindrance in circulation.
- Isometric exercises when performed improperly can lead to injury.
Examples:
Examples of isometric muscle work are isometric exercises such as :
- Plank
- Wall sit
- Bridging
Isotonic muscle work:
Isotonic is a type of muscle work in which length of the muscle changes. Muscle becomes shorten and lengthen to develop intramuscular tension and produce movement. There are further two types of isotonic muscle work.
2.Concentric muscle work:
In this type of muscle work attachment of muscle fibers drawn close or towards the center of muscle and muscle become shorter and thicker to produce movement at a specific joint. Muscles work isotonically to overcome resistance. Some form of resistance are there:
- Mechanical resistance
- Manual pressure
- Force of gravity
- friction
Advantages Concentric muscle work:
- It seems to be natural.
- Less concentration is required to perform exercise through this type of muscle work.
- It is used to develop strength and power in muscles.
Disadvantages Concentric muscle work:
- Less economical.
- Physiological cost is high
- Some energy produced during contraction of muscle is used to overcome inertia;some energy is converted to heat and a little portion is available as mechanical work.
- Injury may result due to repeated concentric contractions.
Examples :
- Bicep curls
- Hamstring curls
Eccentric muscle work:
Muscles become longer and thicker and the muscle fibers are drawn apart away from the center when it works eccentrically. That means length of the muscle changes during eccentric contraction. There are further two types of eccentric contraction voluntary and involuntary. Voluntary contraction of muscle is done while controlling lowering the weight like dumbbells in bicep curls after concentric contraction and involuntary contraction occurs when weight is too heavy to bear.
Advantages :
- Physiological cost and metabolic cost of muscle work is four times lower than concentric muscle work.
- Forces generated by eccentric muscle work are greater than concentric contractions.
- Eccentric exercises require less oxygen and motor unit activation than other types of exercises.
Disadvantages :
- Muscle damage or microlesions in the muscle are greater during eccentric work due to stress by greater force and less motor unit activation.
- Greater concentration is required during exercise.
- Type II muscle fibers are more prone to damage during eccentric muscle contractions.
- Delayed onset of muscle soreness (DOMS) and other clinical symptoms like stiffness and swelling also results after eccentric contractions.
Examples :
- Lowering weight during shoulder press.
- Push-up (during downward movement).
- crunch(when lowering body).
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