PTA Physical Therapy Assistant

Answer: C - Effect on muscle spasm is not a differentiating feature between cold and heat application.

Both cold and heat reduces the muscle spasm.
Cold reduces the sensitivity of muscle spindle, thereby decreases spasm. Heat reduces the ischemia and pain by reducing the sensitivity of the gamma efferent. Heat increases the blood flow, thereby reduces the local metabolites resulting in further reduction of spasm.

The treatment depth, blood flow, and rate of metabolism are different for cold and heat.
The depth of cold treatment reaches up to 5 cm, whereas superficial heat reaches 1-2 cm and deep heat reaches 2-5cm.

When the cold is applied, there would be reduction in the blood flow, whereas while applying heat, there would be increase in the blood flow.

The rate of metabolism will be reduced while applying cold and increases while applying heat.