In using both hands, everyone dominantly use one hand and it is called left-handedness or right-handedness person. Measurements of grip and pinch strength provide objective indexes to represent functional integrity of the upper extremity. This study was conducted for thirty female college students(19 right-handedness and 11 lefthandedness). For assessment of the type of handedness, questionnaire was used; for grip strength, Jamar dynamometer was used; for pinch strength, Jamar pinch gauge was used. In right handedness, the grip and pinch strength of the dominant right hand was significantly higher than those of the non-dominant hand. In addition, regular exercises were shown to give influences on reduction of strength gaps between dominant and non-dominant hands. In both groups of left and right handedness, the grip and pinch strength of the dominant hand were significantly higher than those of the non-dominant hand, and regular exercises were shown to give influences on reduction of strength gaps between dominant and non-dominant hand.

Grip strength is an objective indicator for evaluating the functional movement of upper extremities. Therapists have been using it for a long time as an excellent barometer for evaluating the therapy process, therapeutic effects and prognosis of patients with injuries in upper extremities. This study investigated the effects of extensor pattern position and elastic taping of non-dominant hand on the grip strength of dominant hand among general adults. The subjects of this study were 23 males and 7 females from physical therapy departments of 3 Universities located in Busan who agreed to participate in the experiment and the resultant data were analyzed using SPSS version 12.0. The results of the study were as follows. First, there was a significant difference between the grip strength of dominant hand when the non-dominant hand was at the neutral position and that when the non-dominant hand was at the extensor pattern position and both hands were at the maximum strength simultaneously (Bonferroni-corrected p<.001). Second, there was a significant difference between the grip strength of dominant hand when the non-dominant hand was at the neutral position and that when the elastic taping of non-dominant hand was applied (Bonferroni-corrected p<.001). Third, there was no significant difference between the grip strength of dominant hand when the non-dominant hand was at the extensor pattern position and both hands were at the maximum strength simultaneously and that when the elastic taping of non-dominant hand was applied. The irradiation effects through the extensor pattern position of non-dominant hand and application of the elastic taping to non-dominant hand showed significant results in improving the maximum grip strength of dominant hand. This finding could be suggested as the probability for the indirect treatment of the upper extremities of hemiplegia and orthopedic patients due to the long-term fixing of upper extremities.

The purpose of this study was to investigate the effects of different objects and target location of dominant hand on the non-dominant hand movement kinematics in a bimanual reaching task. Fifteen right-handed volunteers were asked to reach from same starting point to the different target point of right and left hand with grasping the objects of different size. Independent variables were 1) three different object types (small mug cup, name pen, and PET bottle), and 2) three different target locations (shorter distance, same distance, and longer distance than the non-dominant hand) of the dominant hand. Dependent variables were movement time (MT), movement distance (MD), movement mean velocity (MVmean), and movement peak velocity (MVmean) of the non-dominant hand. Repeated measures two-way analysis of variance (ANOVA) was used to test for differences in the non-dominant hand movement kinematics during bimanual reaching. The results of this study were as follows: 1) MT of the non-dominant hand was increased significantly when traveling with grasping the mug cup and reaching the far target location, and was decreased significantly when traveling with grasping the PET bottle and reaching the near target location of the dominant hand. 2) MD of the non-dominant hand was significantly increased during reaching the far target location, and significantly decreased during reaching the near target location with dominant hand. 3) MVmean of the non-dominant hand was increased significantly when traveling with grasping the PET bottle, and was decreased significantly when traveling with grasping the mug cup of the dominant hand. Therefore, it can be concluded that the changes of the ipsilateral hand movement have influence on coupling of the contralateral hand movement in bimanual reaching.

In this study, 1,933 Korean male and female subjects ranging in age from 10 to 82 were selected to investigate the various statistics about hand dominance and employment characteristics of preferred hand in handling diverse products and facilities. The statistics show that 5.6% are left-handed and 7.6% are ambidextrous. The average left-hander has a strong tendency to use his or her left hand more often when taking a forceful action than one that requires accuracy. On the contrary, the average ambidextrous or right-handed person generally uses his or her right hand more with action that requires accuracy than force. Derived from such results, the conclusion is that depending on which hand is the dominant one, people seem to use their hands differently when they handle objects and is a point that should be considered in designing hand control devices.

Purpose: The purpose of this study was to investigate the effective learning method of non-dominant hand for the sequential timing performance. Methods: Twenty right-handed undergraduate and graduate students were randomly assigned to the non-dominant hand practice group that practiced with only non-dominant hand or the bimanual practice group that practiced with both hands simultaneously. The participant was asked to alternatively press two buttons six times with the index finger of the non-dominant hand or both hands in order to reproduce accurately the goal rhythm pattern (3,600ms in total duration). The goal rhythm pattern had three rhythm types and two perceptual structures, which the (in)congruent structure was that the structure of auditory signal was (or not) in accordance with that of visual signal. Results: Bimanual practice group was more effective for absolute-timing learning than non-dominant hand practice group. Although absolute timing performance improved in congruent structure during acquisition phase, the learning effect on absolute timing was occurred in incongruent structure. Relative timing performance of two groups improved in congruent structure during acquisition phase, but the learning effect on relative timing was occurred in both perceptual structures. Conclusion: We suggest that practice methods should be applied differently for absolute timing or relative timing, and the possibility of improving the learning effect of a non-dominant hand by utilizing an incongruent structure of visual-auditory information.