The doctor for the US Tour de France teams and Lance Armstrong, Jeff Spencer, uses earthing sheets and blankets 'to help the team recover from injuries and for optimal rest during the grueling competition'. At least that's what earthing blankets sales-people say. [earthing.com] According to a study published in the Journal of Alternative and Complementary Medicine there may be some truth to the matter. But is the study reliable?
Earthing blankets or sheets are fitted with electrical cords which you can connect to the ground port or to the electrical earth circuit by plugging one in. An example of one of these systems is shown in the figure below, which we extracted from a 2004 patent. [US Patent 6,683,779]
According to the people who dreamt up earthing blankets, sheets and mattresses, our body functions better if it is 'earthed' or 'grounded'. They say that earthing blankets and sheets protect our bodies from the electrostress emitted from all the technology we surround ourselves with these days: TV, radios, mobile phones and Wi-Fi.
Physiologists at the University of Oregon tested the effects of these products on eight men, each of whom spent four days on or under an earthing sheet or blanket. In addition, the men wore earthing patches for the duration of the trial on their calves.
Unbeknown to them, the plugs for the patches and blankets of half of the men were not plugged into the socket [Placebo]; the other half were plugged in [Grounded].
The blankets and patches used were produced by Earth FX, a company based in Palm Springs in California. The company also paid for the research. One of the researchers also worked regularly for the company, and "owns a very small percentage of shares in the company".
On day two the researchers subjected the men to "an eccentric exercise that caused delayed-onset muscle soreness in gastrocnemius muscles". The researchers monitored their subjects' biomarkers for muscle damage, like muscle pain and the creatine kinase concentration in the blood, and saw that the earthing patches and sheets reduced the muscle damage caused by "eccentric exercise" and speed up muscle recovery.
It's a little strange that on the first day after the workout the creatine kinase level had gone down, and only started to rise a day later. Normally this starts to rise just a few hours after doing a workout.
What's also strange is the small rise in the creatine-kinase level. Even after a modest strength training session the level usually rises by several hundred percent, but in this case the level didn't rise more than a few tens of percent.
It's also strange that the researchers didn't actually use "eccentric exercise", but a more or less regular form of strength training.
After an eccentric strength training session you'd expect the creatine-kinase levels to keep on rising for days. After a regular strength training session you'd expect the level to rise for a day and then start to fall again slowly.
We leave you to draw your own conclusions. As we have done.
J Altern Complement Med. 2010 Mar;16(3):265-73.