In all instances in which work is done, there is an object that supplies the force to do the work.
When work is done on the object, that object gains energy. The energy acquired by the objects upon which work is done is known as mechanical en-ergy . 15 Mechanical energy is the energy possessed by an object due to its motion or due to its position.
Mechanical energy can be either kinetic energy (energy of motion) or potential energy (stored energy of position). Objects have kinetic energy if they are in motion. Potential energy is stored by an object and has the potential to be created when that objected is stretched or bent or squeezed. The kinetic energy created by a clinician’s hands moves to apply a force that can stretch, bend, or com-press skin, muscles, ligaments, and the like. The stretched, bent, or compressed structure possesses potential energy that can be released when the force is removed.
Mechanical Energy Modalities
Intermittent compression, traction techniques, and massage each use mechanical energy involv-ing a force applied to some soft-tissue structure to create a therapeutic effect. These mechanical energy modalities are discussed in Chapters 11, 12, and 13.
Clinical Decision-Making Exercise 1–2 The athletic trainer is treating a patient with a chronic low back strain. At this point it has been decided that heating the area is the treatment of choice. Which of the modalities discussed briefly in this chapter may be used as heating modalities?
Which of these modalities would you choose to provide the greatest depth of penetration?
Clinical Decision-Making Exercise 1–3 With which of the modalities described briefly in this chapter are the cosine law and the inverse square law of greatest consideration?
mechanical energy Energy acquired by the objects upon which work is done.
kinetic energy Energy of motion.
potential energy Stored energy of position.
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1. The forms of energy that are relevant to the use of therapeutic modalities are electromag-netic energy, thermal energy, electrical energy, sound energy, and mechanical energy.
2. The various forms of energy may be reflected, refracted, absorbed, or transmitted in the tissues.
3. All forms of electromagnetic energy travel at the same velocity; thus, wavelength and fre-quency are inversely related.
4. The electromagnetic spectrum places all of the electromagnetic energy modalities including diathermy, laser, ultraviolet light, and lumi-nous infrared lamps in order based on wave-lengths and corresponding frequencies.
5. The Arndt-Schultz principle, the Law of Grot-thus-Draper, the cosine law, and the inverse square law can each be applied to the electro-magnetic energy modalities.
6. Thermotherapy and cryotherapy modalities transfer thermal energy from a heating or cool-ing source to the body through conduction.
7. Modalities that utilize electrical energy can (1) cause pain modulation through stimula-tion of cutaneous sensory nerves; (2) pro-duce muscle contraction and relaxation or tetany, depending on the type of current and frequency; (3) facilitate soft-tissue and bone healing through the use of subsensory micro-currents; and (4) produce a net movement of ions thus eliciting a chemical change in the tissues.
8. Acoustic energy and electromagnetic energy have very different physical characteristics.
9. Mechanical energy can be either kinetic energy (energy of motion) or potential energy (stored energy of position). The kinetic energy cre-ated by a clinician’s hands moves to apply a force that can stretch, bend, or compress skin, muscles, ligaments, and the like. The stretched, bent, or compressed structure possesses poten-tial energy that can be released when the force is removed.
Summary
Review Questions
1. What are the various forms of energy produced by therapeutic modalities?
2. What is radiant energy and how is it produced?
3. What is the relationship between wavelength and frequency?
4. What are the characteristics of electromag-netic energy?
5. Which of the therapeutic modalities produce electromagnetic energy?
6. What is the purpose of using a therapeutic modality?
7. According to the Law of Grotthus-Draper, what happens to electromagnetic energy when it comes in contact with and/or pen-etrates human biologic tissue?
8. Explain the cosine and inverse square laws relative to tissue penetration of electromag-netic energy.
9. How do the thermal energy modalities trans-fer energy?
10. What physiologic changes can the use of elec-trical energy produce in human tissue?
11. Which of the therapeutic modalities produce sound energy?
12. What are the differences between electromag-netic energy and sound energy?
13. What modalities utilize mechanical energy to produce a therapeutic effect?
CHAPTER 1 The Basic Science of Therapeutic Modalities 15
True or False
1. Wavelength is defined as the number of cycles per second.
2. To achieve deeper tissue penetration, the wavelength must be increased.
3. Continuous shortwave diathermy produces thermal effects.
Multiple Choice
4. Which of the following is NOT an electromag-netic energy modality?
a. Ultraviolet light b. Ultrasound c. Low-power laser d. Shortwave diathermy
5. Sound or radiation waves that change direc-tion when passing from one type of tissue to another are said to .
a. Transmit b. Absorb c. Reflect d. Refract
6. The states that if superfi-cial tissue does not absorb energy, it must be transmitted deeper.
a. Law of Grotthus-Draper b. Cosine law
c. Inverse square law d. Arndt-Schultz principle
7. According to the cosine law, to minimize re-flection and maximize absorption, the energy source must be at a angle to the surface.
a. 45 degree b. 90 degree c. 180 degree d. 0 degree
8. Electrical stimulating currents may produce the following effects:
a. Muscle contraction b. Net ion movement c. Decrease in pain d. All of the above
9. Thermal energy modalities generally affect superficial tissue up to cm deep, a. 5 cm
b. 0.5 cm c. 1 cm d. 10 cm
10. Based on their different characteristics, which of the following travels at greater velocity through human tissue?
a. Sound energy
b. Electromagnetic energy
c. Both a and b travel at the same rate.
d. Neither a nor b travels through human tissue.
Self-Test Questions
Solutions to Clinical Decision-Making Exercises 1–1 Superficial heat and cold, electrical
stimulat-ing currents, and low-power laser may all be effective for modulating pain. However, ice is likely the best choice immediately following injury because it will not only modulate pain but will also cause vasoconstriction and thus help to control swelling.
1–2 The athletic trainer may choose to use infra-red heating modalities, shortwave diathermy,
or ultrasound—all of which have the ability to produce heat in the tissues. Ultrasound has a greater depth of penetration than any of the electromagnetic or thermal modalities since sound energy is more effectively trans-mitted through dense tissue than is electro-magnetic energy.
1–3 When setting up a patient for treatment using either microwave diathermy or ultraviolet
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therapy, it is critical that the athletic trainer consider the angle at which the electromag-netic energy is striking the body surface to ensure that most of the energy will be References
1. Blank, M, editor: Electromagnetic fields: biological interactions and mechanisms , Washington, DC, 1995, American Chemi-cal Society.
2. Gasos, J, and Stavroulakis, P: Biological effects of electromag-netic radiation , New York, 2003, Springer-Verlag.
3. Goats, GC: Appropriate use of the inverse square law, Phys-iotherapy 74(1):8, 1988.
4. Goldman, L: Introduction to modern phototherapy , Spring-field, IL, 1978, Charles C Thomas.
5. Griffin, J, and Karselis, T: Physical agents for physical athletic trainers , Springfield, IL, 1978, Charles C Thomas.
6. Hitchcock, RT, and Patterson, RM: Radio-frequency and ELF electromagnetic energies: a handbook for healthcare profession-als , New York, 1995, Van Nostrand Reinhold.
7. Lehmann, JF, and Guy, AW: Ultrasound therapy. Proc Workshop on Interaction of Ultrasound and Biological Tissues, Washington, DC, HEW Pub. (FDA 73:8008), Sept. 1972.
absorbed and not reflected. It is also essential to know the distance that these modalities will be placed from the surface to achieve the right amount of energy in the target tissue.
8. Lehmann, J, editor: Therapeutic heat and cold , ed. 4, Balti-more, 1990, Williams and Wilkins.
9. Nadler, SF: Complications from therapeutic modalities:
results of a national survey of athletic trainers, Arch Phys Med Rehab 84(6):849–853, 2003.
10. Schriber, W: A manual of electrotherapy , Philadelphia, 1975, Lea & Febiger.
11. Reitz, J, Milford, F, and Christy, R: Foundations of elec-tromagnetic theory, ed 2, Reading, MA, 1992, Addison Wesley.
12. Smith, G: Introduction to classical electromagnetic radiation, Boston, 1997, Cambridge University Press.
13. Stillwell, K: Therapeutic electricity and ultraviolet radiation , Baltimore, 1983, Williams & Wilkins.
14. Venes, D, and Thomas, CL: Taber’s cyclopedic medical dictionary, Philadelphia, 2005, F.A. Davis.
15. Young, H, and Freedman, R: Sears and Zemansky’s univer-sity physics , Reading, MA, 2007, Addison-Wesley.
Suggested Readings
Goodgold, J, and Eberstein, A: Electrodiagnosis of neuromuscular diseases , Baltimore, MD, 1972, Williams & Wilkins.
Jehle, H: Charge fluctuation forces in biological systems, Ann NY Acad Sci 158:240–255, 1969.
Koracs, R: Light therapy , Springfield, IL, 1950, Charles C Thomas.
Licht, S, editor: Electrodiagnosis and electromyography, ed 3, New Haven, CT, 1971, Elizabeth Licht.
Licht, S: Therapeutic electricity and ultraviolet radiation, New Haven, CT, 1959, Elizabeth Licht.
Scott, P, and Cooksey, F: Clayton’s electrotherapy and actinother-apy , London, 1962, Bailliere, Tindall and Cox.