Using Thermotherapy to Treat Sports Injuries

By Terry Zeigler, EdD, ATC 

Thermotherapy can be an effective treatment in facilitating the healing process if it is used properly. However, the application of heat too early can exacerbate tissue damage in an acute injury and actually prolong the healing process. Understanding how and when to use heat is important in the care and treatment of athletic injuries.

When should heat be used to facilitate healing in an injury?

It is important to understand a little bit about how the body heals to understand how and when heat should be used to treat injuries. There are three recognized phases to the healing process.

The first phase is known as the inflammatory phase. The goal during this phase is to protect the injured area from further injury while the body debrieds and contains the damaged tissue. When an injury initially occurs, there is damage to the soft tissue structures (ligament, muscle, and tendon) but also damage to the blood vessels immediately in the area.

The damage to the blood vessels causes fluids to build up in the injured area causing the swelling that is typically seen in a new injury. To help reduce the flow of fluid into the area and thereby reduce swelling, cryotherapy (cold applications) is the best modality to use right after an injury. Cold modalities can help slow down and decrease the circulation to the area thereby reducing swelling.

Heat applied during this phase is contraindicated because heat increases blood flow into the injured area significantly increasing the amount of swelling. Increased swelling prolongs the rehabilitation process because it takes time to reverse the process and remove the extracellular fluid.

This first phase of the healing process can last for several days depending on the amount of tissue damage. For most injuries, two days is the most common time frame for phase one and is when ice should ONLY be applied to injuries.

The second phase of the healing process is known as the proliferation phase and is characterized by the laying down of new tissue and the formation of scar tissue. Again, depending on the amount of damage to the injured area, this phase can begin on post-injury day three and last for several weeks.

IT IS DURING THIS SECOND PHASE OF HEALING THAT HEAT CAN BE APPLIED TO THE INJURIED AREA TO FACILITATE THE HEALING PROCESS. The athlete can determine if he/she has entered phase two of healing when the initial swelling and pain of the injury starts to decrease.

Heat therapies can also be used during the third and final phase of the healing process known as the remodeling phase. During this phase the new tissue laid down during phase two matures. This phase can last up to one full year depending on the type of tissue that was injured.

What are the physiological effects of using heat?

When heat is applied during the second phase of healing, a number of physiological effects occur including:

• Increase in circulation to help remove debris and waste products
• Increase in cellular metabolism
• Increase in capillary permeability
• Provide an analgesic effect
• Reduce muscle spasms
• Increase in oxygen and nutrients into the area to promote healing
• Increase in extensibility of muscle and connective tissue to help facilitate stretch and elongate tissue

Many of these effects apply to modalities that create heat deep within soft tissue (ultrasound). Superficial heat therapies only heat tissue within several centimeters of the body and can be beneficial for superficial injuries. However, joint and muscle injuries (depending on their location) may not receive the same benefits if they are located deeper within the body.

To heat deep tissue (up to 1 ½ inches deep), the modality most commonly utilized in the therapeutic setting is ultrasound. Although ultrasound has different settings and can be used for different purposes, continuous ultrasound can effectively heat deep tissue.

Ultrasound works on the principle of sound waves. The sound waves enter the tissue and are transferred into heat energy under the surface. Ultrasound is a very effective modality for increasing the tissue temperature of localized injuries to facilitate the heating process (see above list).

Injuries that are commonly treated with ultrasound include rotator cuff strains, quadriceps strains, hamstring strains, and all types of sprains. The deep heat created by the ultrasound facilitates healing in tissues that cannot be reached by superficial heat modalities.

Unfortunately, although they are effective, ultrasound units are expensive and treatment needs to be administered by a trained sports medicine professional. Specific techniques must be utilized to ensure that the sound head continues to be in motion to protect the patient from possible burns.

What types of injuries can be treated by heat?

One of the most common injuries treated by heat is muscle spasms in the back area associated with muscular back strains. Because the back muscles have the unique ability to “splint” themselves to protect the injured area, initial treatment needs to focus on reducing the muscle spasms.

Heat has been found to be effective at reducing the pain associated with muscle spasms by providing an analgesic effect and relaxation effect for tight muscles. For small muscle spasms, moist or dry heat packs can be effective. Larger areas can be treated by full-body immersion in a hot whirlpool or Jacuzzi.

Heat therapy is also effective in increasing the range of motion of joints after injury. Once the swelling from the original injury begins to subside, the injured area can be heated using a warm whirlpool or hot pack for 10 -15 minutes.

Because tissue becomes more extensible after it has been warmed up, range of motion exercises can be performed after heating to improve joint motions. The goal is to gradually increase the range of motion of the joint and restore it to pre-injury levels. However, care must be taken to not push a joint through pain as this can actually reinjure the tissue.

Joint injuries that can benefit from superficial heating to increase joint movement after injury include sprained ankles, turf toe, knee sprains, elbow and wrist sprains, and thumb and finger sprains.

Superficial muscle strains can also benefit from superficial heating techniques based on the same principle as above. When muscle tissue is heated, it becomes more extensible and better able to stretch. Heat modalities should be used prior to stretching for 10 – 15 minutes. After heating, a gradual and progressive pain-free stretch can be applied to the area.

What types of superficial heat therapies are commonly used in therapy?

There are a number of thermotherapies currently available to treat injuries. They are divided into superficial and deep heat therapies. Superficial heat therapies are those in which heat is transferred directly from the heat source to the body but the temperature increase only penetrates to a depth of several centimeters.

Examples of superficial heat therapies that are commonly used include dry and moist hot packs, hot whirlpool, hot tub or jacuzzi, and paraffin bath. The benefit of these types of modalities is that most people have access to one or more of them from their home.

As noted above, superficial modalities only have the ability to heat superficial tissue in the body. However, superficial heat modalities also have the advantage of creating an analgesic effect which can also be beneficial to the athlete.

Dry hot packs are commonly used in the home setting. Dry hot packs sold on the market today are either electric (supply a steady source of heat) or may be placed in a microwave for quick heating. However, care must be taken that these hot packs are not overheated because this may cause a superficial burn to the skin.

Generally hot packs are applied to the injured area for 15 – 20 minutes. If the pack becomes uncomfortable to the skin, a towel can be placed between the skin and hot pack. Hot pack treatments can be given several times throughout the day.

Moist heat is another effective thermotherapy and is commonly used in the form of a warm whirlpool, jacuzzi tub, or warm bath. The benefit of these types of modalities is that they can be used for either single extremity treatment or full body.

Whirlpool therapy is a popular modality because it combines heat with the additional massage effect of the turbines. This type of modality can also help facilitate an increase in range of motion in an injured joint because the buoyancy of the water assists in the ease of movement.

For example, an athlete with an ankle injury who has limited range of motion in the ankle due to swelling and joint effusion can immerse the injured ankle into the warm water and then perform “alphabet” exercises. The athlete spells the alphabet with his/her toes from “A to Z” first spelling in small case letters and then moving to capital letters. The buoyancy of the water assists in the movement and makes the exercises a little easier to perform.

Caution must be taken when heating the water temperature especially in full-body immersion. For full-body immersion, the water should not exceed 102 degrees, but even this temperature may be uncomfortable for some people (especially youth or elderly).

Other special considerations for full-body immersion include:

• The length of time (should not exceed 20 minutes) of immersion
• Ensuring proper whirlpool hygiene and maintenance to avoid the transmission of bacteria.

Paraffin bath is another popular heat therapy and is used primarily for injured fingers, hands, toes, and feet. This type of heat is effective for heating bony extremities.

Paraffin wax and oil are heated in a containment unit and kept at a constant temperature ensuring that the paraffin and oil remain in a liquid state. After the injured area is washed with soap and water, the area is repeatedly dipped into the paraffin wax until a base of wax is obtained.

The extremity is then placed in a plastic bag and heated for 10 – 15 minutes. Once the heat starts to dissipate, the wax can be removed from the extremity. After the extremity has been treated with the paraffin wax, range of motion exercises can be performed.

This type of therapy is used to treat patients with rheumatoid arthritis for the purpose of relieving joint stiffness and increasing range of motion. It can also be used to treat athletes recovering from finger injuries (sprains and fractures).

What are the contraindications to using superficial heat modalities?

In general, superficial heat modalities are safe therapies for treating athletes. However, there are some precautions and contraindications for the use of heat including:

• Do not apply heat to an area when there is loss of sensation
• Do not apply heat immediately after an acute injury
• Do not apply heat when there is impaired or poor circulation
• Do not apply heat to the eyes or genitalia
• Do not apply heat to the abdomen during pregnancy
• Do not apply heat to an injured area that exhibits signs of acute inflammation (red, swollen, hot)

Are topical ointments effective in deep heating injured tissue?

A number of topical ointments are available on the market and advertised as products to help relieve pain. Oftentimes, the products are also advertised as effective methods of heating underlying tissue.

UNFORTUNATELY, THIS IS A MYTH as most of the products only contain skin irritants and are not capable of actually increasing the temperature of tissue. The ointment irritates the nerve endings under the skin and only masks the underlying pain.

The problem with products that “mask” pain is that pain is usually an indicator that something is wrong in the body and that the individual needs to stop the activity. Covering up the pain and continuing to exercise may actually put the athlete at risk for further injury.

The benefit that athletes may gain from topical ointments may actually come from the associated massage that accompanies the application of the ointment. The massage of the tissue may increase circulation to the area while the ointment overrides the sensation of pain.

When to See the Doctor

Hundreds of athletes sustain acute injuries everyday, which can be treated safely at home using the P.R.I.C.E. principle. But if there are signs or symptoms of a serious injury, emergency first aid should be provided while keeping the athlete calm and still until emergency service personnel arrive. Signs of an emergency situation when you should seek care and doctor treatment can include:

  • Bone or joint that is clearly deformed or broken
  • Severe swelling and/or pain,
  • Unsteady breathing or pulse
  • Disorientation or confusion
  • Paralysis, tingling, or numbness

In addition, an athlete should seek medical care if acute symptoms do not go away after rest and home treatment using the P.R.I.C.E principle.

Can Telemedicine Help?

Telemedicine is gaining popularity because it can help bring you and the doctor together quicker and more efficiently. It is particularly well suited for sports medicine, facilitating the diagnoses, treatment and prevention of sports related injuries both on and off the field. There are times when It can be very difficult to get an appointment with primary care doctors or specialists and Telemedicine can help to provide very quick treatment options. But if you prefer a more personal or face-to-face relationship, telemedicine might not be the option for you.

Though no service is perfect, telemedicine is a positive and growing medical treatment option. Studies continue to show that telemedicine saves time and money and seeing your primary care doctor after a telemedicine visit can always be set up to establish a second opinion.



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Arnheim, D.D. & Prentice, W. (2000). Principles of Athletic Training. (10th Ed.). McGraw Hill: Boston, MA.

Houglum, P. (2005). Therapeutic Exercise for Musculoskeletal Injuries. (2nd Ed.). Human Kinetics: Champaign, IL.