Isometric exercise: Difference between revisions
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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. |
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. |
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==Definition== |
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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.<ref>[http://www.sport-fitness-advisor.com/isometric-exercises.html Article on static strength training]</ref> This is in contrast to ''[[isotonic (exercise physiology)|isotonic contractions]]'', in which the contraction strength does not change, though the muscle length and joint angle do. |
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==Isometric resistance== |
==Isometric resistance== |
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Revision as of 17:44, 31 October 2012
 | This article possibly contains original research. (February 2012) |
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.
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 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.
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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 equipment (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 holds in certain branches of yoga or oriental martial arts, for example 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.[1] Isometrics fell out of favor as it was discovered that many of the principal advocates were using anabolic steroids to enhance their gains.[2]
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 Dynamic Self-Resistance (that is: Pitting one muscle group against another) and Calisthenics.
Medical uses
Isometric exercises can also be used at the bedside to differentiate various heart murmurs; the murmur of mitral regurgitation gets louder[3] as compared to the quieter murmur of aortic stenosis.[4] They can also be used to prevent Disuse Syndrome in a limb that has been immobilized by a cast, following a fracture.
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 motion.[5]
NASA studies
NASA 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.[6]
See also
References
- ^ "Strength Training - Isometric Exercise". SPMESSENGER.com. Archived from the original on 2008-01-29. Retrieved 2008-11-10.
- ^ Mirkin, G (2006). "Isometric exercise background". Retrieved 2008-11-10.
- ^ Ching, W. "Evaluation of Cardiac Murmurs in the Clinic Setting" (PDF). University of Chicago. Retrieved 2008-01-10.
- ^ Cassidy J, Aronow WS, Prakash R (1975). "The effect of isometric exercise on the systolic murmur of patients with idiopathic hypertrophic subaortic stenosis". Chest. 67 (4): 395–397. doi:10.1378/chest.67.4.395. PMID 1168115.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Lindh M (1979). "Increase of muscle strength from isometric quadriceps exercises at different knee angles". Scand J Rehabil Med. 11 (1): 33–6. PMID 419396.
- ^ Barry, PL (2004-10-12). "Why do Workouts Work?". NASA. Retrieved 2008-01-10.
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