Should I use ice or heat for my injury? How long should I leave it on? These are common questions I hear a lot around the office.
In short, it depends on your goal.
Ice provides very effective pain relief for acute pain including relief of muscle spasm and sprian/strains. It also may reduce swelling. Remove once the area is numb to prevent frost bite.
Heat helps to relax muscles and can be a soothing way to improve ranges of motion. The effect of heat are generally more temporary than ice.
A word of caution regarding heat: never fully immerse the area in heat (ie. hot tub) when experiencing acute back spasm as this may cause rebound spasm upon exiting a hot tub.
I am happy to discuss your unique condition with you to determine which application best suits your needs.