Therapeutic Effects of Infrared Heat

Therapeutic Effects of Infrared Heat

Infrared Heat

The following information has been summarized from Chapter 9 of Therapeutic Heat and Cold, Fourth Edition, Editors Justus F. Lehmann, M.D., Williams, and Wilkin, or concluded from data gathered there.

1. Infrared heat increases the extensibility of collagen tissues.

Tissues heated to 45 degrees Celsius and then stretched exhibit a non-elastic residual elongation of about 0.5 to 0.9 percent that persists after the stretch is removed. This does not occur in these same tissues when stretched at normal tissue temperatures.

Therefore 20 stretching sessions can produce a 10 to 18 percentage increase in length of tissues heated and stretched.
Stretching of tissue in the presence of heat would be especially valuable in working with ligaments, joint capsules, tendons, fasciae, and synoviurn that have become scarred, thickened, or contracted.

Such stretching at 45 degrees Celsius caused much less weakening in stretched tissues for a given elongation than a similar elongation produced at normal tissue temperatures.

Experiments cited clearly showed low-force stretching could produce significant residual elongation when heat is applied together with stretching or range-of-motion exercises. This is safer than stretching tissues at normal tissue temperatures.

Patella Tracking Disorder

2. Infrared heat decreases joint stiffness.

There was a 20 percent decrease in rheumatoid finger joint stiffness at 45 degrees Celsius (112 degrees Fahrenheit) as compared with 33 degrees Celsius (92 degrees Fahrenheit), which correlated perfectly to both subjective and objective observation of stiffness. Speculation has it that any stiffened joint and thickened connective tissues may respond in a similar fashion.

3. Infrared heat relieves muscle spasms.

Muscle spasms have long been observed to be reduced through the use of heat, be they secondary to underlying skeletal, joint, or neuropathological conditions.

This result is possibly produced by the combined effect of heat on both primary and secondary afferent nerves from spindle cells and from its effects on Golgi tendon organs. The results produced demonstrated their peak effect within the therapeutic temperature range obtainable with radiant heat.

Fireactiv Thermal Images 60 mins

4. Infrared heat treatment leads to pain relief.

Pain may be relieved via the reduction of attendant or secondary spasms. Pain is also at times related to ischemia (lack of blood supply) due to tension or spasm that can be improved by the hyperemia that heatinduced vasodilatation produces, thus breaking the feedback loop in which the ischemia leads to further spasm and then more pain.

Heat has been shown to reduce pain sensation by direct action on both free-nerve endings in tissues and on peripheral nerves. In one dental study, repeated heat applications led finally to abolishment of the whole nerve response responsible for pain arising from dental pulp.

Heat may lead to both increased endorphin production and a shutting down of the so called “spinal gate” of Melzack and Wall, each of which can reduce pain.
Localized infrared heat therapy using lamps tuned to the 2 to 25 micron waveband is used for the treatment and relief of pain by over 40 reputable Chinese medical institutes.

5. Infrared heat increases blood flow.

Heating one area of the body produces reflex-modulated vasodilators in distant-body areas, even in the absence of a change in core body temperature. Heat one extremity and the contra lateral extremity also dilates; heat a forearm and both lower extremities dilate; heat the front of the trunk and the hand dilates.

Heating muscles produces an increased blood flow level similar to that seen during exercise.

Temperature elevation also produces an increased blood flow and dilation directly in capillaries, arterioles, and venules, probably through direct action on their smooth muscles. The release of bradykinin, released as a consequence of sweat-gland activity, also produces increased blood flow and vasodilatation.

Whole-body hyperthermia, with a consequent core temperature elevation, further induces vasodilatation via a hypothalamic-induced decrease in sympathetic tone on the arteriovenous anastomoses. Vasodilatation is also produced by axonal reflexes that change vasomotor balance.

6. Infrared heat assists in resolution of inflammatory infiltrates, oedema, and exudates.

Increased peripheral circulation provides the transport needed to help evacuate oedema, which can help inflammation, decrease pain, and help speed healing.

7. Infrared heat affects soft tissue injury.

Infrared heat healing is now becoming a leading edge care for soft tissue injuries to promote both relief in chronic or intractable “permanent” cases, and accelerated healing in newer injuries.

Joint Instability

FAR Infrared heat increases blood flow in the knee by 203.6% and rate of blood flow by 89.6%

Measurements taken using Laser Blood Flow Instrument, Moor MBF 3D & MSR Signal Recorder MSR-5. Taiwan Textile Research Institute, November 2009


Pain induced by surgery is a dynamic symptom, which may be quite variable even in the same surgical procedures. The purpose of this study was to investigate the analgesic effect of far infrared rays on the patients during the postoperative period of total knee arthroplasty (TKA). The selection and application of analgesic methods after the orthopedic surgery are therefore valuable for advanced studies.


The quasi-experimental design with a total five consecutive days of far infrared ray (FIR) thermal therapy was employed in this study.
Subjects: The study involved 41 participants assigned by register code entry on computer to either the intervention or the control group.


The FIR pads were applied on the acupoints of ST37 (Shang Chu Hsu), ST38 (Tiao Kou), ST39 (Hsia Chu Hsu), and ST40 (Feng Lung) of the patients involved in the experimental group from the third day to the fifth day after the TKA.

Outcome measures:

The analgesic effect was evaluated via the pain intensity of the numeric rating scale (NRS) level and serum concentration of interleukin-6 (IL-6) and endothelin-1 (ET-1).


The FIR showed that the significant effects are on relieving pain and lowering the levels of IL-6 and ET-1. The results cannot only be the reference for the postoperative pain relief of TKA, but it can also be the database of another clinical application.


This study demonstrated that the FIR can lower the NRS of pain and thus reduce the discomfort experienced by the patient. Findings indicated that effective application of FIR decreased the serum level of IL-6 and ET- 1, which represent the subjective indicator of pain.

How the research was conducted


To evaluate the efficacy of combining continuous low-level heat wrap therapy with directional preference-based exercise on the functional ability of patients with acute low back pain.

Study design/setting

A randomized controlled trial was conducted at three outpatient medical facilities.

Patient sample

One hundred individuals (age 31.2±10.6 years) with low back pain of less than 3 months duration.

Outcome measures

The primary outcome measure was functional ability assessed by the Multidimensional Task Ability Profile questionnaire. Secondary outcomes were disability assessed by the Roland-Morris Disability Questionnaire and pain relief assessed by a 6-point verbal rating scale.


Participants were randomized to one of four groups: Heat wrap therapy alone (heat wrap, n=25); directional preference-based exercise alone (exercise, n=25); combination of heat wrap therapy and exercise (heat+exercise, n=24); or control (booklet, n=26). Treatment was administered for five consecutive days and included four visits to the study center over 1 week.


At 2 days after the conclusion of treatment (Day 7), functional improvement for heat+exercise was 84%, 95%, and 175% greater than heat wrap, exercise, and booklet, respectively (p<.05). Seventy-two percent of the subjects in the heat+exercise group demonstrated a return to pre-injury function compared with 20%, 20%, and 19% for heat wrap, exercise, and booklet, respectively (p<.05). Disability reduction for heat+exercise was 93%, 139%, and 400% greater than heat wrap, exercise, and booklet, respectively (p<.05). Pain relief for heat+exercise was 70% and 143% greater than exercise and booklet, respectively (p<.05).


Combining continuous low-level heat wrap therapy with directional preference-based exercise during the treatment of acute low back pain significantly improves functional outcomes compared with either intervention alone or control. Either intervention alone tends to be more effective than control.

‘Continuous Low-Level Heat Wrap Therapy Provides More Efficacy than Ibuprofen and Acetaminophen for Acute Low Back Pain’

Nadler, Scott F. DO*; Steiner, Deborah J. MD, MS†; Erasala, Geetha N. MS‡; Hengehold, David A. MS‡; Hinkle, Robert T. BS‡; Beth Goodale, Mary BS‡; Abeln, Susan B. BS‡; Weingand, Kurt W. DVM, PhD‡


Study Design.

A prospective, randomized, single (investigator) blind, comparative efficacy trial was conducted.


To compare the efficacy of continuous low-level heat wrap therapy (40 C, 8 hours/day) with that of ibuprofen (1200 mg/day) and acetaminophen (4000 mg/day) in subjects with acute nonspecific low back pain.

Summary of Background Data.

The efficacy of topical heat methods, as compared with oral analgesic treatment of low back pain, has not been established.


Subjects (n = 371) were randomly assigned to heat wrap (n = 113), acetaminophen (n = 113), or ibuprofen (n = 106) for efficacy evaluation, or to oral placebo (n = 20) or unheated back wrap (n = 19) for blinding. Outcome measures included pain relief, muscle stiffness, lateral trunk flexibility, and disability. Efficacy was measured over two treatment days and two follow-up days.


Day 1 pain relief for the heat wrap (mean, 2) was higher than for ibuprofen (mean, 1.51;P = 0.0007) or acetaminophen (mean, 1.32;P = 0.0001). Extended mean pain relief (Days 3 to 4) for the heat wrap (mean, 2.61) also was higher than for ibuprofen (mean, 1.68;P= 0.0001) or acetaminophen (mean, 1.95;P = 0.0009). Lateral trunk flexibility was improved with the heat wrap (mean change, 4.28 cm) during treatment (P ≤ 0.009 vs acetaminophen [mean change, 2.93 cm], P ≤ 0.001 vs ibuprofen [mean change, 2.51 cm]).

The results were similar on Day 4.

Day 1 reduction in muscle stiffness with the heat wrap (mean, 16.3) was greater than with acetaminophen (mean, 10.5;P = 0.001). Disability was reduced with the heat wrap (mean, 4.9), as compared with ibuprofen (mean, 2.7;P = 0.01) and acetaminophen (mean, 2.9;P = 0.0007), on Day 4.

None of the adverse events were serious. The highest rate (10.4%) was reported in the ibuprofen group.


Continuous low-level heat wrap therapy was superior to both acetaminophen and ibuprofen for treating low back pain.

FAR Infrared heat treatment leads to a 57% decrease in pain for patients with 6 year chronic low back pain.

Forty patients with chronic low back pain of over six years’ duration. Mean NRS scores in the FIR treatmentgroup fell from 6.9 of 10 to 3 of 10 at the end of the study.

The mean NRS in the placebo group fell from 7.4 of 10 to 6 of 10. The FIR therapy unit used was demonstrated to be effective in reducing chronic low back pain and no adverse effects were observed.

Gale GD, Rothbart PJ, Li Y. Infrared therapy for chronic low back pain: a randomized, controlled trial. Pain Research and Management 2006,11(3):193-196

Final Word

FAR infrared heat provides a safe, non-invasive, cost-effective therapeutic modality which is easy to administer.

I have witnessed and heard countless anecdotal public and clinical examples of how patients with a variety of chronic conditions have experienced pain relief over-and above what they have been able to receive from standard moist heat, cold therapy, electrotherapy or indeed pharmacological treatments.

That is not evidenced-based, however such a wealth of comments and observations begs many profound questions to clearly understand and explain the reported outcomes.

I have no doubt that the new FAR infrared technology will have wide reaching accepted applications in a variety of fields as awareness and scientific research into the benefits of FAR infrared expands.

One might go so far as to imagine the time when GPs will prescribe FAR infrared as a therapeutic modality in the place of medication, for certain conditions.

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