Cryotherapy primarily achieves pain relief by what mechanism?

• A. Increasing blood flow.
• B. Analgesic effect and reduced swelling by decreasing blood flow.
• C. Blocking nerve signals permanently.
• D. Increasing metabolic rate throughout the body.

Answer: (B)

Cryotherapy relieves pain mainly through vasoconstriction of the local blood vessels, which reduces blood flow to the injured area. This limits swelling (edema) and the buildup of inflammatory mediators that contribute to pain. At the same time, cold lowers the rate at which nerves conduct pain signals and reduces the local tissue’s metabolic rate, both of which contribute to an analgesic effect. Together, less swelling and slowed nerve signaling lessen pain after injury and during rehabilitation. The other ideas don’t fit: increasing blood flow would worsen swelling, cryotherapy doesn’t permanently block nerve signals, and it doesn’t increase metabolic rate—the local metabolic rate is actually lowered.