Diathermy and radiation are noted to have which effect on muscle tissue?

• A. Muscle hypertrophy
• B. Relaxation of muscular tension
• C. Increased muscle spasm
• D. Decreased blood flow to muscle

Answer: (B)

Deep heating with diathermy and radiant energy increases muscle tissue temperature, which promotes relaxation of muscle by reducing reflexive muscle guarding and spindle activity. The warmer state also boosts blood flow and tissue elasticity, helping tensions ease and the muscle to relax. Hypertrophy requires mechanical overload and protein synthesis, not just heating, so heating alone won’t grow muscle. Decreased blood flow would contradict the effect of heating, which actually increases circulation through vasodilation, while increased muscle spasm would oppose the calming effect of warmth.