Advice from Sri Lanka and even further - part 2 - the evidence
In part one I talked about the Chinese custom of walking barefoot on special pebble paths, and I promised to take a look at the evidence in the scientific literature.
A study by Li et al (Improving physical function and blood pressure in older adults through cobblestone mat walking: a randomized trial) looked at this phenomenon. Second author Fisher says: “We visited China and noticed that adults of all ages spent about 30 minutes each day walking, standing, and sometimes dancing on these beautifully laid paths of river stones in the parks and gardens of large cities. They did this for their health every day of the week. We used manufactured mats that replicated these cobblestone paths and developed a special protocol so that participants gradually got used to walking on the uneven surface of the mats.”
There were two groups in the study: the cobblestone mat walkers and a control group. Both walked for one hour, three times a week for 16 weeks. They found that: “Cobblestone mat walking improved physical function and reduced blood pressure to a greater extent than conventional walking in older adults [age 60 to 92]. Additional benefits of this walking program included improved health-related quality of life. This new physical activity may provide a therapeutic and health-enhancing exercise alternative for older adults.” Very interesting!
Also very interesting are the following studies, where textured insoles are used to enhance somatosensory information:
Enhanced somatosensory information decreases postural sway in older people: “These findings suggest that textured insole surfaces can reduce postural sway in older people, particularly during more challenging balance tasks.”
Effects of textured insoles on balance in people with Parkinson’s disease: “To summarise, this study indicated that standing postural stability can be improved in people with PD, possibly by enhancing somatosensory information received from plantar mechanoreceptors of the feet. Textured insoles decreased both ML postural sway and ML SD under challenging conditions when standing on a foam surface with eyes closed. Such textured insoles may provide a low-cost means of improving postural stability in high-risk groups, such as people with PD, which may act as an important intervention to prevent falls.
Effect of textured insoles on balance and gait in people with multiple sclerosis: an exploratory trial: “After 2 weeks of wear, there were improvements in spatio-temporal parameters of gait. However, it is unclear whether this was a placebo effect or a learning effect.”
The effect of textured surfaces on postural stability and lower limb muscle activity: “Under the specific conditions of this study, texture did not affect either postural sway or lower limb muscle activity in static bipedal standing. The results of this study point to three areas of further work including the effect of textured surfaces on postural stability and lower limb muscle activity: (i) in young healthy adults under more vigorous dynamic balance tests, (ii) post-fatigue, and (iii) in older adults presenting age-related deterioration.”
The effect of textured insoles on postural control in double and single limb stance: “Increased afferent information from textured insoles improves postural control in bilateral stance.”
Do spike insoles enhance postural stability and plantar-surface cutaneous sensitivity in the elderly? “The results provided evidence that wearing sandals with spike insoles can contribute, at least temporarily, to the improvement of unperturbed stance in elderly people with relatively intact plantar cutaneous sensation. Further research is needed to assess the effects of longer and discontinuous stimulations with spike insoles on postural control.”
The lasting effects of spike insoles on postural control in the elderly: “Whatever the age, the enriched sensory context provided by this tactile sensitivity enhancement device led to a better postural control.”
Can tactile plantar stimulation improve postural control of persons with superficial plantar sensory deficit? “These results suggest that application of tactile plantar stimulation may compensate a loss of superficial plantar sensitivity.”
Here are some other studies, using vibrating insoles:
Vibrating insoles and balance control in elderly people: “Subsensory mechanical noise applied to the feet of quietly standing individuals with vibrating insoles leads to enhanced feedback and reduced postural sway. Differential effects noted between young and elderly indicate that elderly people gain more in motor control performance than do young people with the application of noise to the feet.”
Effects of vibrating insoles on standing balance in diabetic neuropathy: “Vibrating insoles improved standing balance in subjects with neuropathy only when attention was distracted.”
Subsensory Vibrations to the Feet Reduce Gait Variability in Elderly Fallers: “In summary, we have shown that subsensory vibratory noise applied to the soles of the feet during the gait cycle can reduce gait variability in elderly fallers.”
Although the results vary and are not miraculous, there seems to be an improvement in balance and gait, especially (but not only) in the elderly, and for some people with pathology. It’s not the purpose of this blog to dig any deeper, at least for now. And, as always, “further research is needed.”
(I’ve never published a peer reviewed article, but I think that “further research blablabla” is probably obligatory, especially near the end of the paper.)
Now if you look at all these data, what would be the logical conclusion: stimulation of the foot, more specifically the sole, has health benefits. That actually makes sense, especially where the benefits are seen in balance and posture. More, better and precise information for the sensory parts of the central nervous system, make the motor output part perform better.
It also makes sense from an evolutionary point of view. Our feet have always been stimulated a lot, due to barefootness and natural and varied surfaces. So these studies are talking about augmenting the sensory input, but this augmentation is relative. To me, it is an increase in information from below normal to normal, not from normal to supranormal.
Speaking about normal, do you need special insoles or beautifully but artificially made cobblestone paths? Isn’t there a more direct and cheaper way of getting these results? The old way? The normal way?
Yep! Naked feet!
That would be an interesting research hypothesis: Does barefoot walking on a natural and varied surface improve posture, balance, gait, overall physical functioning and wellbeing, on short and long term?
But you can also follow the advice from the studies: cobblestone mats and insoles. My preference would be the mats. This is also what Phillip Beach advises, maybe inspired by the same eastern tradition: standing on a ‘rock garden’ for a certain time to compensate for the sensory deprivation of the shoes people wear.
My advice would be:
Take of your shoes as much as you can, but do it carefully and gradually, depending on how your feet are and feel.
If you have to wear shoes, choose for minimalist options. This means: flat (zero drop), minimal cushioning, broad toe box, flexible soles. Many are commercially available
If more stimulating surfaces are not part of your daily life, try ‘supplementing’ with extra sensory input:
massage your own feet firmly
use your feet to roll a tennis ball on the ground (while sitting and again, firmly)
if your feet are a bit stronger, do the same with a stick
stand on a stick, or apply pressure on the stick while standing
stand on a rough mat (like the ones you have at the back door) or maybe you could try a cobblestone mat, e.g. while cooking or doing other standing work
stand or walk on the stones of your driveway (or the one of your neighbour)
The ‘supplementation’ can be more firm and even a bit painful while doing it, but you should feel fine afterwards, even ‘refreshed’ or ‘light’.
Thanks for reading,