Isometric exercise
Encyclopedia
Isometric exercise or isometrics are a type of strength training
in which the joint
angle and muscle
length do not change during contraction (compared to concentric or eccentric contractions, called dynamic/isotonic movements). Isometrics are done in static positions, rather than being dynamic through a range of motion
.
An example of this in the context of the bench press
would be that a yielding isometric would be holding the bar at a given place even though it could be pressed higher, and an overcoming would be pressing the bar up into the safety guards of a squat cage that prevent pushing the bar any higher.
The distinction is that in a yielding isometric, one is pressing roughly the exact amount of pressure needed to negate the resistance, neither dropping or lifting it. Whereas in an overcoming, one can be exerting more force and simply unable to move it. The yielding wavers slightly into concentric/eccentric actions due to inexact control, whereas the overcoming is more purely isometric and can involve more variation in the force used since one can press harder without the bar moving.
, in which the contraction strength does not change, though the muscle length and joint angle do.
Depending on the goal of the exercise, the exertion can be maximal, or sub-maximal.
in certain branches of yoga
or Chinese martial arts
(kung fu).
Isometrics were first brought to the modern public's attention in the early days of physical culture
, the precursor to bodybuilding
. Many of the great bodybuilders of the day incorporated isometric exercises into their training regimes. Isometrics fell out of favor as it was discovered that many of the principal advocates were using anabolic steroid
s to enhance their gains.
Today many new training protocols exist incorporating isometrics once again. Isometric exercises are often made into parts of normal, isotonic exercises. For example, during a set of rows, some people hold their position when the handles are closest to their chest in order to "squeeze" the muscle, in an effort to further strain the muscle.
Contrary to popular opinion, The Charles Atlas
"Dynamic Tension" Course did not use any true isometric exercises, but rather Self-Resistance (that is: Pitting one limb against the other) and Calisthenics
.
s; the murmur of mitral regurgitation
gets louder as compared to the quieter murmur of aortic stenosis.
. Generally speaking, people who train isometrically don't train through a full range of motion, as the strength gained at the training joint angle is where they require it. While dynamic exercises are slightly better than isometric exercises at enhancing the twitch force of a muscle, isometrics are significantly better than dynamic exercises at increasing maximal strength at the joint angle.
Flexibility may be increased when isometrics are performed at joint range of motion extremes. These isometric contractions recruit muscle fibers that are often neglected in some dynamic exercises. For example, gymnasts are extremely strong at great ranges of motion through the practice of isometric holds.
Danger in isometric exercise is primarily attributed to its immediate effects on the cardiovascular system. During an isometric hold, blood pressure
rises rapidly, and an overly long hold, or one performed with poor breath control, may result in fainting, stroke, or other injury. However, dynamic exercises present the same problem if heavy weight is used; additionally, dynamic exercises have the problem of changing, irregular demands on strength throughout the motion, and critical moments where the movement cannot stop without losing control over the weight. If control is lost, severe injuries may result; besides the possibility of crushing the body, joints and tissue can be torn. As well, the irregular strength demands can hide flaws(through shifts in balance or "cheating" motions) and can cause uneven development of muscle groups, which adds to the danger over time. Isometric holds, in contrast, do not place demands on form or balance, and will naturally apply the most stress to the weakest parts used in the hold, which leads to a well-rounded development of all joints and muscle groups used in the hold.
Because isometric exercise requires no special equipment or settings, and its techniques are simple and time-efficient, it presents a cheap and accessible alternative to dynamic exercise, (at the cost of being less effective for some fitness goals.)
has researched the use of isometrics in preventing muscle atrophy experienced by astronauts as a result of living in a zero gravity
environment. Isometrics, muscle lengthening and muscle shortening exercises were studied and compared. The outcome showed that while all three exercise types did indeed promote muscle growth, isometrics failed to prevent a decrease in the amount of contractile proteins
found in the muscle tissue. The result was muscle degradation at a molecular level. As contractile proteins are what cause muscles to contract and give them their physical strength
, NASA has concluded that isometrics may not be the best way for astronauts to maintain muscle tissue.
Strength training
Strength training is the use of resistance to muscular contraction to build the strength, anaerobic endurance, and size of skeletal muscles. There are many different methods of strength training, the most common being the use of gravity or elastic/hydraulic forces to oppose muscle contraction...
in which the joint
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...
angle and muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
length do not change during contraction (compared to concentric or eccentric contractions, called dynamic/isotonic movements). Isometrics are done in static positions, rather than being dynamic through a range of motion
Range of motion
Range of motion , is the distance that a movable object may normally travel while properly attached to another object. It is also called range of travel, particularly when talking about mechanical devices and in mechanical engineering fields...
.
Overcoming versus yielding
The joint and muscle are either worked against an immovable force (overcoming isometric) or are held in a static position while opposed by resistance (yielding isometric).An example of this in the context of the bench press
Bench press
The bench press is an exercise of the upper body. For bodybuilding purposes, it is used to stimulate the pectorals, deltoids, and triceps. While on his or her back, the person performing the bench press lowers a weight to the level of the chest, then pushes it back up until the arm is straight...
would be that a yielding isometric would be holding the bar at a given place even though it could be pressed higher, and an overcoming would be pressing the bar up into the safety guards of a squat cage that prevent pushing the bar any higher.
The distinction is that in a yielding isometric, one is pressing roughly the exact amount of pressure needed to negate the resistance, neither dropping or lifting it. Whereas in an overcoming, one can be exerting more force and simply unable to move it. The yielding wavers slightly into concentric/eccentric actions due to inexact control, whereas the overcoming is more purely isometric and can involve more variation in the force used since one can press harder without the bar moving.
Definition
Isometric exercise is a form of exercise involving the static contraction of a muscle without any visible movement in the angle of the joint. This is reflected in the name; the term "isometric" combines Greek the prefixes "iso" (same) with "metric" (distance), meaning that in these exercises the length of the muscle and the angle of the joint do not change, though contraction strength may be varied. This is in contrast to isotonic contractionsIsotonic (exercise physiology)
In an isotonic contraction, tension remains unchanged and the muscle's length changes. Lifting an object at a constant speed is an example of isotonic contractions. A near isotonic contraction is known as Auxotonic contraction....
, in which the contraction strength does not change, though the muscle length and joint angle do.
Isometric resistance
Resistance in isometric exercises typically involve contractions of the muscle using:- The body's own structure and ground
- Structural items (e.g., pushing against a fence)
- Free weights, weights machines or elastic equipmentResistance trainingResistance training has two different meanings. A broader meaning that refers to any training that uses a resistance to the force of muscular contraction , and elastic or hydraulic resistance, which refers to a specific type of strength training that uses elastic or hydraulic tension to provide...
(e.g. holding a weight in a fixed position) - Pressure plate type equipment that has a digital display of maximal force.
Depending on the goal of the exercise, the exertion can be maximal, or sub-maximal.
History
Isometric exercises are thousands of years old, with examples from the static holdsAsana
Asana is a body position, typically associated with the practice of Yoga, originally identified as a mastery of sitting still, with the spine as a conduit of biodynamic union...
in certain branches of yoga
Yoga
Yoga is a physical, mental, and spiritual discipline, originating in ancient India. The goal of yoga, or of the person practicing yoga, is the attainment of a state of perfect spiritual insight and tranquility while meditating on Supersoul...
or Chinese martial arts
Chinese martial arts
Chinese martial arts, also referred to by the Mandarin Chinese term wushu and popularly as kung fu , are a number of fighting styles that have developed over the centuries in China. These fighting styles are often classified according to common traits, identified as "families" , "sects" or...
(kung fu).
Isometrics were first brought to the modern public's attention in the early days of physical culture
Physical culture
Physical culture is a term applied to health and strength training regimens, particularly those that originated during the 19th century. During the mid-late 20th century, the term "physical culture" became largely outmoded in most English-speaking countries, being replaced by terms such as...
, the precursor to bodybuilding
Bodybuilding
Bodybuilding is a form of body modification involving intensive muscle hypertrophy. An individual who engages in this activity is referred to as a bodybuilder. In competitive and professional bodybuilding, bodybuilders display their physiques to a panel of judges, who assign points based on their...
. Many of the great bodybuilders of the day incorporated isometric exercises into their training regimes. Isometrics fell out of favor as it was discovered that many of the principal advocates were using anabolic steroid
Anabolic steroid
Anabolic steroids, technically known as anabolic-androgen steroids or colloquially simply as "steroids", are drugs that mimic the effects of testosterone and dihydrotestosterone in the body. They increase protein synthesis within cells, which results in the buildup of cellular tissue ,...
s to enhance their gains.
Today many new training protocols exist incorporating isometrics once again. Isometric exercises are often made into parts of normal, isotonic exercises. For example, during a set of rows, some people hold their position when the handles are closest to their chest in order to "squeeze" the muscle, in an effort to further strain the muscle.
Contrary to popular opinion, The Charles Atlas
Charles Atlas
Charles Atlas, born Angelo Siciliano , was the developer of a bodybuilding method and its associated exercise program that was best known for a landmark advertising campaign featuring Atlas's name and likeness; it has been described as one of the longest-lasting and most memorable ad campaigns of all...
"Dynamic Tension" Course did not use any true isometric exercises, but rather Self-Resistance (that is: Pitting one limb against the other) and Calisthenics
Calisthenics
Calisthenics are a form of aerobic exercise consisting of a variety of simple, often rhythmical, movements, generally using multiple equipment or apparatus. They are intended to increase body strength and flexibility with movements such as bending, jumping, swinging, twisting or kicking, using...
.
Medical uses
Isometric exercises can also be used at the bedside to differentiate various heart murmurHeart murmur
Murmurs are extra heart sounds that are produced as a result of turbulent blood flow that is sufficient to produce audible noise. Most murmurs can only be heard with the assistance of a stethoscope ....
s; the murmur of mitral regurgitation
Mitral regurgitation
Mitral regurgitation , mitral insufficiency or mitral incompetence is a disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood. It is the abnormal leaking of blood from the left ventricle, through the mitral valve, and into the left atrium, when...
gets louder as compared to the quieter murmur of aortic stenosis.
Comparison with dynamic exercises
Isometric exercises have some differences in training effect as compared to dynamic exercises. While isometric training increases strength at the specific joint angles of the exercises performed and additional joint angles to a lesser extent, dynamic exercises increase strength throughout the full range of motionRange of motion
Range of motion , is the distance that a movable object may normally travel while properly attached to another object. It is also called range of travel, particularly when talking about mechanical devices and in mechanical engineering fields...
. Generally speaking, people who train isometrically don't train through a full range of motion, as the strength gained at the training joint angle is where they require it. While dynamic exercises are slightly better than isometric exercises at enhancing the twitch force of a muscle, isometrics are significantly better than dynamic exercises at increasing maximal strength at the joint angle.
Flexibility may be increased when isometrics are performed at joint range of motion extremes. These isometric contractions recruit muscle fibers that are often neglected in some dynamic exercises. For example, gymnasts are extremely strong at great ranges of motion through the practice of isometric holds.
Danger in isometric exercise is primarily attributed to its immediate effects on the cardiovascular system. During an isometric hold, blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
rises rapidly, and an overly long hold, or one performed with poor breath control, may result in fainting, stroke, or other injury. However, dynamic exercises present the same problem if heavy weight is used; additionally, dynamic exercises have the problem of changing, irregular demands on strength throughout the motion, and critical moments where the movement cannot stop without losing control over the weight. If control is lost, severe injuries may result; besides the possibility of crushing the body, joints and tissue can be torn. As well, the irregular strength demands can hide flaws(through shifts in balance or "cheating" motions) and can cause uneven development of muscle groups, which adds to the danger over time. Isometric holds, in contrast, do not place demands on form or balance, and will naturally apply the most stress to the weakest parts used in the hold, which leads to a well-rounded development of all joints and muscle groups used in the hold.
Because isometric exercise requires no special equipment or settings, and its techniques are simple and time-efficient, it presents a cheap and accessible alternative to dynamic exercise, (at the cost of being less effective for some fitness goals.)
NASA studies
NASANASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
has researched the use of isometrics in preventing muscle atrophy experienced by astronauts as a result of living in a zero gravity
Weightlessness
Weightlessness is the condition that exists for an object or person when they experience little or no acceleration except the acceleration that defines their inertial trajectory, or the trajectory of pure free-fall...
environment. Isometrics, muscle lengthening and muscle shortening exercises were studied and compared. The outcome showed that while all three exercise types did indeed promote muscle growth, isometrics failed to prevent a decrease in the amount of contractile proteins
Muscle contraction
Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same...
found in the muscle tissue. The result was muscle degradation at a molecular level. As contractile proteins are what cause muscles to contract and give them their physical strength
Physical strength
Physical strength is the ability of a person or animal to exert force on physical objects using muscles. Increasing physical strength is the goal of strength training.-Overview:...
, NASA has concluded that isometrics may not be the best way for astronauts to maintain muscle tissue.