Exactly When to Use Heat Therapy vs Ice Therapy for Injuries

Application of ice and heat are two popular methods for pain relief on sore, tired muscles or injuries. However, there’s a time and a place for each, and misusing ice or heat can cause more harm than good. That's why it's important to truly understand the difference between ice therapy and heat therapy.

So to learn more about how and when to use heat and ice therapies, we reached out to two physical therapists, Dr. Amy Schultz and Dr. Joscelyn Shumate Bourne.  Keep reading for everything you need to know about heat therapy vs ice therapy, including how and when to use each.

How Does Heat Therapy Work?

“Heat therapy increases blood flow which will increase the circulation of nutrients to the desired site,” explains Shultz. For tight, stiff joints and muscles, this is helpful since the warmth relaxes the area.

When you exercise at high intensities, certain chemical byproducts are produced in the body, such as lactic acid. This buildup needs to be eliminated, but the body can become overwhelmed and take a while for this to happen. During this phase, the lactic acid build-up is thought to cause muscle soreness. Heat can encourage the elimination of these chemical byproducts and reduce soreness sooner.

“Heat therapy uses the power of convection to transfer heat from one surface to the next. Heat then penetrates the external surfaces of the skin layers, creating a relaxing effect,” says Shumate Bourne. The relaxation aspect of heat is also beneficial for muscle soreness, spasms, and stiffness.

When to Use Heat Therapy

For everyday muscle stiffness, soreness, and tightness, heat is your ally. “Heat is a good choice for stiff, tight, and sore muscles,” says Bourne. If you have muscle spasms, heat is a highly effective way of calming them down.

For injuries, more caution is necessary: “Heat therapy is appropriate to use for conditions that are not in the acute phases of injury, such as an ankle sprain sustained three to five days ago, in the absence of moderate swelling.

It is best to avoid heat therapy for the first 48 hours after an injury. For chronic conditions, Bourne advises only to use heat therapy if they have been around for approximately one month or longer. For best results, use heat therapy only after inflammation and swelling of the area have gone down. 

How to Treat Sore Muscles With Heat Therapy 

Use ice to reduce the swelling and numb the pain of any new soreness or mild injury. After this time, you can switch out heat and ice every 20 minutes or apply ice only or heat only for 20 minutes on and 20 minutes off.

Bourne and Shultz recommend the following methods for applying heat therapy:

• Hot shower, local heat packs, or the sauna increase body temperature, which can help with that post-exercise metabolite flush.
• Heating pads, moist heat packs, homemade heat packs with rice in a tube sock can serve as heating mediums. 
• Avoid using an electric heating pack at night when you may fall asleep. Use these heat packs from 10-20 minutes at a time.

Be sure to use warm—not scalding hot—towels, compresses, or heating pads. Protect your skin from hot surfaces by placing a cloth in between you and the compress or pad.  Other options include moist heat like a shower, whirlpool, or bath using warm water between 92 to 100 degrees.

How Does Ice Therapy Work?

Ice therapy works by reducing blood flow, preventing swelling and inflammation while blunting some of the nerve signals that cause pain. However, this is not always a desirable effect since that blood flow, and inflammation can help with the healing process.

“Controversial in the science world right now is the effectiveness of ice. More research is showing to stop 'RICE'—Rest, Ice, Compress, Elevate—and transition more to 'MEAT'— Movement, Exercise, Analgesia, Treatment,” explains Schultz. If you’re unsure how to treat your particular muscle soreness or pain, speak to your doctor.

When to Use Ice Therapy

It’s wise to weigh the pros and cons of using ice therapy. “Ice therapy can help decrease pain, but it will also slow the healthy movement of fluids after exercise and injury,” says Shultz. 

Shumate Bourne recommends ice therapy for a new injury: “Ice is appropriate to use for acute injury within the first 3-5 days, in the presence of swelling to provide pain relief.” 

How to Treat Sore Muscles with Ice Therapy

Ice is easy to apply using the following methods, according to Shumate Bourne:

• Ice pack, ice cup, frozen vegetables, in addition to compression therapy and regular ice cubes applied to the area.
• You can also try cooling sprays, cold whirlpools, ice massage, or ice baths for the whole body.
• Ice anywhere from 10-20 minutes at a time giving yourself an hour between the next scheduled icing break. 
• Avoid falling asleep with chemically frozen ice packs to avoid receiving an ice burn.

You can try a cold shower or alternate cold and hot water in your post-workout rinse off for a less intense effect.

The Takeaway

Ice and heat are both effective for treating muscle soreness and pain. The ideal method for using ice and heat depends on the age of your soreness or injury and what your exact issue is. In general, use ice immediately after your workout or injury and apply heat later, after inflammation has gone down. If you are unsure how to treat your issue or you have persistent pain, see a doctor.

It's also wise—if you're experiencing persistent pain—to seek out care from a physician. As well, if you have conditions such as diabetes, speak to your doctor before applying heat or ice.