Resistance training is all form of exercise wich uses resistance in any given manner to intensify the force of muscle contraction. The purpose is increased strength, mass, endurance and/or tone.
The external resistance can be dumbbells, rubber exercise tubing, your own body weight, weights, machines, or any other object that causes the muscles to contract.
Resistance training can be isometric, isokinetic and isotonic (the most common kind which includes concentric and eccentric contractions),
One of the great advantages of resistance training is that it can be done with none- to little expensive equipment like weights, and it does not require much amount of space. Doing squats and push-ups is one good example. You can do them almost anywhere.
Building muscle strength helps with body alignment, makes performing everyday actions easier, increases bone mineral density, raises the metabolism, and relieves stress.
Muscle contraction is a process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.
While under tension, the muscle may lengthen, shorten or remain the same. Although the term 'contraction' implies shortening, when referring to the muscular system, it means muscle fibers generating tension with the help of motor neurons (the terms twitch tension, twitch force and fiber contraction are also used).
- Concentric. A contraction is concentric when a muscle is stimulated to contract according to the sliding filament mechanism. This occurs throughout the length of the muscle, generating force at the musculo-tendinous junction, causing the muscle to shorten and changing the angle of the joint. An example of a concentric contraction in the raising of a weight during a bicep curl.
- Eccentric. A contraction is eccentric when the muscle elongates while under tension due to an opposing force being greater than the force generated by the muscle. An eccentric contraction is used as a means of decelerating a body part or object, or lowering a load gently rather than letting it drop.
Eccentric movements recruit most fast twitch fibres.
- Isotonic. A contraction is isotonic when the tension in the muscle remains constant despite a change in muscle length. This can occur only when a muscle's maximal force of contraction exceeds the total load on the muscle.
- Isometric. A contraction is isometric when the muscle is activated, but instead of being allowed to lengthen or shorten, it is held at a constant length. An example of an isometric contraction would be carrying an object in front of you. The weight of the object would be pulling downward, but your hands and arms would be opposing the motion with equal force going upwards. Since your arms are neither raising or lowering, your biceps will be isometrically contracting.
In reality, muscles rarely perform under any sort of constant force, velocity, or speed, but these contractions are useful for understanding overall muscle properties present in more complex contractions that occur in vivo.
When you lift weights at the gym to get stronger or bigger or more toned, you are performing resistance exercise. Occasionally you will hear the term "strength training" associated with lifting weights. Technically, it's incorrect to refer to resistance exercise as strength training. Instead, strength training would more accurately be described as resistance exercise that builds strength.
Bodyweight exercises are resistance training exercises that do not require free weights; the practitioner's own weight provides the resistance for the movement. Movements such as the push-up, the pull-up, and the sit-up are some of the most common bodyweight exercises.
Resistance training can challenge balance, endurance, strength and power. Resistance training not only impacts muscle but also the strength and health of bones, tendons, cartilage and ligaments. Resistance training includes exercises for core (spine and pelvis musculature), upper extremity (shoulder and elbow musculature) and lower extremity (hip, knee and ankle musculature).
Other articles in this series:
- Training with dumbbells
- Dynamic body-power training
- Resistance Training; E Medicine Health
- Types of muscle contractions; National Skeletal Muscle Research Center, University of California.
- Exercise Physiology: Human Bioenergetics and Its Applications; Brooks, G.A; Fahey, T.D. & White, T.P.
- Chest Workout Push-ups Variations; Train Body and Mind.
- How to Work Out if You Are Not a Body Builder; Originated by: Eric Maust, Andy Zhang.
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