Grounding (earthing)

What really holds up about walking barefoot

The mechanism that undisputedly works when walking barefoot is mechanical and sensory: the foot has to work without sole support, the intrinsic foot muscles are loaded, and the sole of the foot provides proprioception.

The systematic review on this follows PRISMA and PICOS, comprises 7 studies with 213 participants and rates quality using the PEDro and MINORS scales. Most interventions led to significant improvements in the volume of the intrinsic and extrinsic foot muscles, the function of the longitudinal arch, toe flexor strength and neuromuscular control — most clearly where strength, balance and agility were combined over several weeks. The authors cite heterogeneous protocols, small samples and a lack of follow-up as limitations.

The electron hypothesis

The grounding hypothesis is this: the ground carries a supply of free electrons at its surface; direct skin contact lets them pass into the body, where they are supposed to neutralize reactive oxygen species and reduce inflammation. This chain is not described in the physiological literature, and the transfer itself has never been measured. What was measured are end points further down the claimed chain: cortisol in saliva, pain on a visual analog scale, aggregation of red blood cells.

The only mechanistic paper outside humans tested isolated mitochondria: under grounded conditions they produced 5–11 % more ATP, 22–33 % fewer reactive oxygen species and had a 5–6 % lower membrane potential than under sham and naive conditions. That is an experiment on isolated organelles with direct wire contact, not evidence for walking barefoot on grass.

What the grounding studies look like

The source of the cortisol claim is a paper with twelve people who slept on a grounded conductive mattress pad for eight weeks; it reports lowered night-time values and a tendency toward normalization of the daily profile. There was no control group, no blinding, no randomization. The inflammation claim comes from a pilot study with eight people, four per group, in which differences of at least 10 % were considered notable — a descriptive criterion without a statistical test.

What the studies show

Barefoot training and foot function

Systematic review according to PRISMA and PICOS, preregistered in PROSPERO; 7 studies with 213 participants, quality assessment using the PEDro and MINORS scales. Most interventions led to significant improvements in muscle volume, arch function, toe flexor strength and neuromuscular control, most clearly in programs lasting several weeks that combined strength, balance and agility.

The cortisol pilot study

Twelve people with complaints of sleep disturbance, pain and stress slept on a grounded conductive mattress pad for eight weeks. Salivary cortisol was determined at four-hour intervals over 24 hours before the start and repeated in week 6. Lowered night-time values and a reduction in symptoms in almost all participants are reported — without a control group, blinding or randomization.

The pilot study on muscle soreness

Eight healthy people completed an eccentric exercise that triggered muscle soreness in both calves; four were grounded via electrode patches and conductive sheets, four were not. Blood count, enzymes, cortisol, MRI and pain scores were measured before the exercise and 24, 48 and 72 hours afterwards. Differences of at least 10 % were considered notable, without a statistical test.

The only double-blind randomized study

Six-week double-blind randomized stepped-wedge design with 16 massage therapists, mean age 42.8 years, at a single center: week 1 ungrounded, weeks 2 to 5 grounded during work and sleep, week 6 ungrounded again. More physical function and energy as well as less exhaustion, tiredness and pain are reported. All end points are based on self-report.

The largest human study and its problem

42 patients were grounded at night after spinal surgery; the control group of 42 patients had undergone surgery for lumbar spondylosis. A greater reduction in creatine kinase (45.0 versus 20.0 U/l), a smaller rise in CRP (0.05 versus 17.2 mg/dl) and more pain reduction (p < 0.01) are reported. The groups did not have the same procedure, and there was neither randomization nor blinding.

What the studies do not deliver

There is no human trial with more than 42 participants per group and no randomized study with more than 16 participants. The cortisol claim rests on an uncontrolled pilot study with 12 people, the inflammation claim on a pilot study with 8 people without statistical testing. No independent systematic review or meta-analysis exists: the available reviews are narrative summaries without a systematic search strategy and without an assessment of the risk of bias.

Added to this is a point that weighs heavily: the key authors are involved in the marketing. The standard reference states under Disclosure that three of the authors work as independent contractors for the company that funds the grounding research, and hold shares in it. Walking barefoot as a training stimulus is also only supported to a limited extent, with 7 studies and 213 participants.

How to do it

The 10 to 20 minutes barefoot on grass, soil, sand or stone mentioned in guides, and the exclusion of asphalt and wood, do not correspond to any study condition. They follow from the electron hypothesis, that is, from the assumption that the ground must be conductive, not from a dose investigation. None of the available papers compared surfaces or varied a duration. In the grounding studies, things were done differently: a grounded mattress pad over eight weeks, two hours of grounding via conductive patches with a stainless steel rod in the soil, or four weeks of grounding during work and sleep.

For the supported part, on the other hand, there is a guideline: the effects on foot musculature and neuromuscular control were clearest where strength, balance and agility exercises were combined over several weeks. That takes loading over weeks, not ten minutes of standing on grass.

Safety

The risk lies not in the grounding but in the bare feet and the electrical connection. Barefoot outdoors, there is a risk of cuts and puncture wounds, insect stings and ticks in the grass. For people with diabetes mellitus, this is the decisive point: with diabetic polyneuropathy, injuries to the feet go unnoticed and heal poorly, which leads to ulcers. The relevant guidelines and the recommendations of the German Diabetes Society explicitly advise people with neuropathy against walking barefoot; the same applies to peripheral arterial disease and any sensory disturbance in the feet. Grounding products are usually grounded via the protective earth conductor of the power socket, which requires a correct household installation — with a faulty protective conductor, a current path through the body is created, and the socket should then be checked by a qualified electrician. People with a pacemaker, implanted defibrillator or neurostimulator should discuss permanent grounding with a physician; there are no studies on this, which is a data gap and not an all-clear.

Sources

• Rodríguez-Longobardo et al., J Clin Med 2025
• Ghaly and Teplitz, J Altern Complement Med 2004
• Brown, Chevalier and Hill, J Altern Complement Med 2010
• Chevalier et al., J Environ Public Health 2012 (with disclosure)
• Chevalier et al., Explore 2019
• Sokal et al., J Clin Med 2025
• Giulivi and Kotz, FEBS Open Bio 2025
• German Diabetes Society (Deutsche Diabetes Gesellschaft), practice recommendations on diabetic foot syndrome