January, 2020: The Effect of Walnut Rolling on Hand Function and Corticospinal Tract Facilitation
Happy New Year! What better time to consider one’s health and resolve to maintain and improve it? Along this line, Korean investigators have recently shown an easy way to enhance hand function and facilitate brain activity.
Rolling metal balls in the hand has been practiced in northeastern Asia for ages. The spheres are variably called meditation balls, baoding balls, medicine balls, chime balls. Elderly Koreans are known to roll walnuts to fend off dementia. And there may be something to it. Using functional MRI, several studies have demonstrated cortical activation by ball rolling, and one study found that walnut rolling was more effective compared to wooden ball rolling for brain stimulation.
With this information, the investigators of the present study wondered if walnut rolling would positively affect hand function and related neural pathways in the brain.
They studied 17 healthy right-handed subjects whose average age was 37 (range 25-55) years and who had no history or findings of psychiatric, neurological, or physical illness. Subjects performed walnut rolling with their non-dominant hand for 30 minutes three times daily for two weeks. Compliance was ensured with regular video phone supervision. The dominant hand served as an internal control and was not exercised.
Both before and immediately after the two-week study period, subjects took the Purdue Pegboard Test and had their tip pinch and grip strengths measured in a standardized manner. They also underwent MRI brain scanning using a special technique (diffusion tensor tractography) to visualize the corticospinal tract (CST), a major neural tract for human brain motor function.
RESULTS The investigators noted statistically significant improvements in the clinically measured parameters for the exercised hand. On average, pegboard scores increased 1.5 points, tip pinch increased 1.3 kg, and grip strength increased 7 kg. For the control hand, these clinical measures were unchanged. The researchers found salutary and significant changes on the MRI for the contralateral (right) CST (responsible for controlling the left hand). Conversely they noted no changes in the control (left) CST (controlling the right hand).
DISCUSSION The authors suggest that walnut rolling might be helpful for improving hand function and facilitating contralateral CST function in brain-injured individuals. They also offer that the study carries important implications for sport and skill training in normal individuals.
COMMENT The study was carefully done, including ensuring compliance by making video phone calls. (This may become the norm for compliance checks on studies involved with home exercises.) The study also combines an age-old practice (walnut rolling) with a modern, high-tech method of brain-activity analysis.
For clinical application, what could be easier? I ordered my walnuts from Amazon and have them on my desk to roll while reading. On further thought, I could call a relative in the Midwest and had them ship me a box of unshelled black walnuts or go to the grocery store and buy a bag of English walnuts.
Opportunities for further clinical studies on this topic abound. Investment in walnuts is negligible, and the pegboard and strength meters are readily available. Do English or black walnuts work as well as the gnarly ones from Amazon? Is counterclockwise or clockwise rotation better? What are the effects in the dominant hand? I’m hoping they stave off dementia, although that would be harder to study.