A direct physiologic outcome of applying diathermy and radiation is an increase in which parameter?

• A. Circulation
• B. Bone density
• C. Hair growth
• D. Muscle strength

Answer: (A)

The main concept is that heat from diathermy and radiant energy directly raises tissue temperature, which causes local vasodilation and increased blood flow. When tissue heats, the smooth muscle in the small arterioles relaxes, capillary perfusion rises, and more blood is delivered to the treated area. This increase in circulation is a direct, immediate effect of the heating.

Bone density changes require longer-term remodeling and loading, not an immediate heating response. Hair growth is not enhanced by heating and can even be affected negatively by radiation. Muscle strength doesn’t rise directly from heating; heating may improve tissue extensibility or comfort, but not the force-generating capacity of muscle.