Exertion

Exertion is the physical or perceived use of energy.[1] Exertion traditionally connotes a strenuous or costly effort, resulting in generation of force, initiation of motion,[1] or in the performance of work.[2] It often relates to muscular activity and can be quantified, empirically and by measurable metabolic response.

## Contents

* 1 Physical
* 2 Physiological
* 3 Psychological
* 4 See also
* 5 References
* 6 External links

## Physical

In physics, exertion is the expenditure of energy against, or inductive of, inertia as described by Isaac Newton's third law of motion. In physics, force exerted equivocates work done.[3] The ability to do work can be either positive or negative depending on the direction of exertion relative to gravity. For example, a force exerted upwards, like lifting an object, creates positive work done on that object.[2]

Exertion often results in force generated, a contributing dynamic of general motion.[1] In mechanics it describes the use of force against a body in the direction of its motion (see vector).[citation needed]

## Physiological

Exertion, physiologically, can be described by the initiation of exercise, or, intensive and exhaustive physical activity that causes cardiovascular stress or a sympathetic nervous response. This can be continuous or intermittent exertion.[2]

Exertion requires, of the body, modified oxygen uptake, increased heart rate, and autonomic monitoring of blood lactate concentrations. Mediators of physical exertion include cardio-respiratory and musculoskeletal strength, as well as metabolic capability.[4] This often correlates to an output of force followed by a refractory period of recovery. Exertion is limited by cumulative load and repetitive motions.[2]

Muscular energy reserves, or stores for biomechanical exertion, stem from metabolic, immediate production of ATP and increased oxygen consumption.[4] Muscular exertion generated depends on force and velocity. Factors influencing these are muscle cross-section, muscle length, muscle fiber length, preloading of the muscle before contraction, neural activation of the muscle, muscle fiber type, and age of the muscle.[5]

Perceived exertion can be explained as subjective, perceived experience that mediates response to somatic sensations and mechanisms.[3] A rating of perceived exertion, as measured by the RPE-scale, or Borg scale, is a quantitative measure of physical exertion.[6]

Often in health, exertion of oneself resulting in cardiovascular stress showed reduced physiological responses, like cortisol levels and mood, to stressors. Therefore, biological exertion is effective in mediating psychological exertion, responsive to environmental stress.[7]

Overexertion causes more than 3.5 million injuries a year. An overexertion injury can include sprains or strains, the stretching and tear of ligaments, tendons, or muscles caused by a load that exceeds the human ability to perform the work.[8]

## Psychological

In sport psychology, the perceived exertion of an exercise is how hard it seems to the person doing it.[9] Perceived exertion is often rated on the Borg scale of 6 to 20, where 6 is complete rest and 20 is the maximum effort that an individual can sustain for any period of time. Although this is a psychological measure of effort, it tends to correspond fairly well to the actual physical exertion of an exercise as well.[10] Additionally, because a high perceived exertion can limit an athlete's ability to perform, some people try to decrease this number through strategies like breathing exercises and pranayamas[11] and listening to music.[12]

## See also

* Exercise
* Energy
* Cost
* Inertia
* Volition (psychology)
* Decision theory
* Ferdinand Tönnies [as in will (sociology)]
* Friedrich Nietzsche [as in strong-willed, drive and will]
* Isaac Newton
* Bionics
* Machine
* Muscular Energy
* Musculoskeletal Strength
* Physics
* Physiological stress
* Work

## References

1. ↑ 1.0 1.1 1.2 Newton's Third Law, Elert, Glenn. "Forces." Viscosity – The Physics Hypertextbook, physics.info/newton-first/.
2. ↑ 2.0 2.1 2.2 2.3 "Work and energy". http://physics.bu.edu/~duffy/py105/Energy.html.
3. ↑ 3.0 3.1 Barry, A. J. (1967). "Physical activity and psychic stress/strain". Canadian Medical Association Journal 96 (12): 848–53. PMID 6020888.
4. ↑ 4.0 4.1 Kumar, Shrawan (2007). "Theories of occupational musculoskeletal injury causation". Biomechanics in Ergonomics. pp. 21–58. doi:10.1201/9780849379093. ISBN 978-0-8493-7909-3. https://www.taylorfrancis.com/books/e/9780849379093/chapters/10.1201/9780849379093-6.
5. ↑ Biomechanical Basis of Human Movement. pp. 84.
6. ↑ Borg, Gunnar A.V. (1982). "Psychophysical bases of perceived exertion". Symposium 14 (5): 377–81. PMID 7154893. http://fcesoftware.com/images/15_Perceived_Exertion.pdf.
7. ↑ Gröpel, Peter; Urner, Maren; Pruessner, Jens C.; Quirin, Markus (2018). "Endurance- and Resistance-Trained Men Exhibit Lower Cardiovascular Responses to Psychosocial Stress Than Untrained Men". Frontiers in Psychology 9: 852. doi:10.3389/fpsyg.2018.00852. PMID 29910757.
8. ↑ "Indications of Physical Overexertion". JAMA: The Journal of the American Medical Association 71 (18): 1488. 1918. doi:10.1001/jama.1918.02600440040013.
9. ↑ "Perceived Exertion (Borg Rating of Perceived Exertion Scale) | Physical Activity | CDC" (in en-us). 2020-09-17. https://www.cdc.gov/physicalactivity/basics/measuring/exertion.htm.
10. ↑ "How to Use the RPE to Measure the Intensity of Your Workout" (in en). https://www.verywellfit.com/rating-of-perceived-exertion-scale-3119445.
11. ↑ Shukla, Mayank; Chauhan, Diksha; Raj, Ritu (November 2020). "Breathing exercises and pranayamas to decrease perceived exertion during breath-holding while locked-down due to COVID-19 online randomized study". Complementary Therapies in Clinical Practice 41. doi:10.1016/j.ctcp.2020.101248. ISSN 1873-6947. PMID 33074110.
12. ↑ "3 Tips to Reduce Perceived Exertion and Make Running Feel Easier" (in en-US). 2017-09-19. https://trailrunnermag.com/training/trail-tips/make-running-feel-easier.html.

## External links

* Measuring Physical Activity Intensity: Perceived Exertion (Borg Rating of Perceived Exertion Scale)
* RPE-scale (2nd)
* First principle of mechanics
* Exertion interfaces allowing exertion by proxy in sporting games

* v
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Physiology of muscles

Exertion|

* Exercise
* Movement
* Eye movement
* Gait
* Locomotion

Other|

* Hand strength
* Muscle tone

* Muscle contraction
* Isometric
* Isotonic
* Uterine contraction

* End-plate potential

* Myogenesis

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