Examples of eccentric contraction in the following topics:
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- Isotonic muscle contractions can be either concentric or eccentric.
- An eccentric contraction results in the elongation of a muscle while the muscle is still generating force; in effect, resistance is greater than force generated.
- For example, a voluntary eccentric contraction would be the controlled lowering of the heavy weight raised during the above concentric contraction.
- An involuntary eccentric contraction may occur when a weight is too great for a muscle to bear and so it is slowly lowered while under tension.
- An isotonic concentric contraction results in the muscle shortening, an isotonic eccentric contraction results in the muscle lengthening.
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- Exercise involves a series of sustained muscle contractions of either long or short duration depending on the nature of the physical activity.
- Muscle soreness, once thought to be due to lactic acid accumulation, has more recently been attributed to small tearing, or micro-trauma, of the muscles fibers caused by eccentric contraction.
- With repeated cycles of eccentric contraction this soreness will be reduced.
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- Exercise resulting in eccentric contractions at high loading can cause muscle soreness, indicative of muscle tearing, and reduced or impaired muscle function.
- This is specifically caused by eccentric exercise altering muscle ultrastructure and sarcoplasmic reticulum functioning.
- Creatine supplements, when used in the short-term, can increase performance during high intensity anaerobic exercise that requires short bursts of muscle contraction.
- Phosphocreatine is an important source of energy-rich phosphate groups that can be added to available ADP to resynthesize ATP for muscle contractions.
- Molecular structure of phosphocreatine donates the high energy phosphate group to ADP and acts as a short-term energy pool for muscle contractions.
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- Exercise damages muscles due to eccentric and concentric muscle loading and often results in delayed onset muscle soreness (DOMS).
- Exercise damages muscles due to eccentric and concentric muscle loading.
- Resistance training, and particularly high loading during eccentric contractions, results in delayed onset muscle soreness (DOMS).
- Acute inflammation of the muscle cells, as understood in exercise physiology, can result after induced eccentric and concentric muscle training.
- Participation in eccentric training and conditioning, including resistance training and activities that emphasize eccentric lengthening of the muscle such as downhill running on a moderate to high incline, can result in considerable soreness within 24 to 48 hours, even though blood lactate levels, previously thought to cause muscle soreness, were much higher with level running.
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- The eccentricity of a circle is zero.
- These are the distances used to find the eccentricity.
- Therefore, by definition, the eccentricity
of a parabola must be $1$.
- For an ellipse, the eccentricity is less than $1$.
- Conversely, the eccentricity of a hyperbola is greater than $1$.
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- One of the most useful definitions, in that it involves only the plane, is that a conic consists of those points whose distances to some point—called a focus—and some line—called a directrix—are in a fixed ratio, called the eccentricity.
- The type of a conic corresponds to its eccentricity, those with eccentricity less than 1 being ellipses, those with eccentricity equal to 1 being parabolas, and those with eccentricity greater than 1 being hyperbolas.
- In the focus-directrix definition of a conic, the circle is a limiting case with eccentricity 0.
- where e is the eccentricity and l is half the latus rectum.
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- There are a number of other geometric definitions possible, one of the most useful being that a conic consists of those points whose distances to some other point (called a focus) and some other line (called a directrix) are in a fixed ratio, called the eccentricity.
- The type of a conic corresponds to its eccentricity—those with eccentricity less than 1 being ellipses, those with eccentricity equal to 1 being parabolas, and those with eccentricity greater than 1 being hyperbolas.
- In the focus-directrix definition of a conic, the circle is a limiting case with eccentricity 0.
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- All conic sections have an eccentricity value, denoted $e$.
- All ellipses have eccentricities in the range $0 \leq e < 1$.
- An eccentricity of zero is the special case where the ellipse becomes a circle.
- An eccentricity of $1$ is a parabola, not an ellipse.
- The orbits of comets around the sun can be much more eccentric.
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- All parabolas possess an eccentricity value $e=1$.
- All circles have an eccentricity $e=0$.
- Ellipses can have a range of eccentricity values: $0 \leq e < 1$.
- Since there is a range of eccentricity values, not all ellipses are similar.
- This graph shows an ellipse in red, with an example eccentricity value of $0.5$, a parabola in green with the required eccentricity of $1$, and a hyperbola in blue with an example eccentricity of $2$.
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- With this definition, we may now define a conic in terms of the directrix: $x=±p$, the eccentricity $e$, and the angle $\theta$.
- For a conic with a focus at the origin, if the directrix is $x=±p$, where $p$ is a positive real number, and the eccentricity is a positive real number $e$, the conic has a polar equation:
- For a conic with a focus at the origin, if the directrix is $y=±p$, where $p$ is a positive real number, and the eccentricity is a positive real number $e$, the conic has a polar equation: