SUMMARY: This is a possible therapy to reduce the unpleasant heavy limbs feeling of ME/CFS, also called "molasses limbs", using far infrared heat on the spine.
I have a theory that the ME/CFS heavy limbs sensation might be caused by inflammation in the dorsal root ganglia (DRG), which are situated along the length spine.
Dorsal root ganglia inflammation is known to exist in ME/CFS, as autopsies have found inflamed DRG in more than one patient. And Dr William Pridgen theorizes that fibromyalgia and ME/CFS may be caused by herpes simplex virus infection in the dorsal root ganglia. Varicella zoster virus also persists and can reactivate in the DRG.
The dorsal roots coming from the spine carry sensory information, rather than motor information (motor function — your ability to move limbs — is transmitted by the ventral roots of the spine).
This means that any disruption to the functioning of the dorsal root ganglia is likely to affect your sensations, rather than motor function. This is why I was theorizing that DRG inflammation might create the sensation of heavy limbs.
Since the dorsal root ganglia are located not very far beneath the surface of the skin on your back, I started experimenting with lots of far infrared radiation on my back, which is anti-inflammatory.
I have a ceramic far infrared heater which has three 800 watt porcelain ceramic elements (similar to the model shown below), and produces a lot of radiant heat. These type of far infrared heaters use the same ceramic heating elements as found in infrared saunas. (These ceramic elements simply consist of a ceramic material in which electrical heating wires are embedded).
The long wavelength of far infrared radiation penetrates deeper into the body tissues than the shorter wavelengths of near infrared, so is more likely to reach the DRG, where it will hopefully have an anti-inflammatory effect.
My impression is that daily exposure to this far infrared heat on my back for several hours a day does reduce the heavy limb feeling. I apply this heat to my back while sitting down and working on the computer.
Brands of far infrared ceramic heater include Master, Fireball, Sealey and Rhino. Note that these infrared ceramic heaters are not the same that the ceramic blow heaters you can buy (infrared ceramic heaters emit only IR radiant heat, they do not blow hot air).
Far infrared ceramic heaters are also different to the cheaper far infrared quartz halogen heaters. Ceramic heaters run at a lower temperature than quartz halogen, and Planck's law of black body radiation tells you that this lower temperature will produce a longer wavelength of infrared.
Quartz halogen infrared heaters (which have a glass halogen strip bulb) glow red, but ceramic infrared heaters produce no perceptible glow as they have a lower temperature (though you will see a very faint glow at night if you turn the lights off).
Because the wavelength emitted by the quartz halogen heaters is not as long as the ceramic heaters, I don't think it will penetrate the tissues as deeply.
Besides this possible therapeutic use, I find the far infrared heat from these ceramic heaters very nice. Because it penetrates tissue, it seems to "warm your bones". And unlike regular central heating, far infrared heat does not produce that grogginess and drowsiness that stale centrally heated indoor air results in, so it is a good way to keep warm in the winter without becoming groggy.