The effect of walnut rolling training on hand function and corticospinal tract

Background: We investigated the effect of the walnut rolling training for two weeks on the hand function and corticospinal tract (CST) in normal subjects. Methods: Seventeen right-handed normal subjects performed walnut rolling training with their non-dominant (left) hand, with the right hand defined as the control side. The walnut rolling training was performed three times daily, for 30 minutes at a time, over two weeks. The Purdue Pegboard Test (PPT), tip pinch and grip strength (GS) were used evaluate the change of hand function, and diffusion tensor tractography (DTT) evaluated change of the CST and transcallosal fibers for the hand motor somatotopy. Results: All of the clinical scores in terms of PPT, tip pinch and GS increased significantly in the post-training (PPT: 16.59 +/- 1.09, tip pinch: 5.03 +/- 2.18, GS: 40.61 +/- 10.99) in the left hand compared with pretraining (PPT: 14.94 +/- 1.36, tip pinch: 3.66 +/- 1.44, GS: 33.58 +/- 11.08) (P<0.05). By contrast, the clinical scores for the right hand did not differ significantly between pre- (PPT: 16.25 +/- 1.98, tip pinch: 5.75 +/- 2.26, GS: 37.58 +/- 14.61) and post-training (PPT: 16.97 +/- 1.67, tip pinch: 5.66 +/- 2.31, GS: 37.82 +/- 14.25). The fiber numbers (FN) of the right CST increased significantly in post-training DTT (2,123.05 +/- 529.07) compared with pre- training DTT (1,734.73 +/- 581.84) (P<0.05), whereas fractional anisotropy (FA) (pre- training: 0.50 +/- 0.02, post-training: 0.51 +/- 0.01) did not change significantly. Neither FA nor FN of the left CST and transcallosal fibers changed significantly from pre- (FA: 0.44 +/- 0.02, FN: 1,871.15 +/- 636.36) to post-training DTTs (FA: 0.45 +/- 0.03, FN: 1,823.84 +/- 701.14). Conclusions: We demonstrated improvement of hand function and facilitation of the contralateral CST by walnut rolling training in normal subjects. Our results suggest that walnut rolling training can be used for improvement of hand function and facilitation of the contralateral CST.