HAND MUSCLE STRENGTH AND HAND DEXTERITY AFTER EXPOSURE TO HAND AND ARM FROM GRINDER VIBRATION AMONG GRINDING WORKERS

Abstract

This research was a quasi-experimental study designed for thirty female workers performing a grinding operation with another other thirty female workers as the control group. Hand muscle strength was measured by assessing hand grip strength (HGS) and pinch strength (PS) while hand dexterity was measured by the maximum tapping ability in 10 seconds (MTA). The study participants were asked to perform the tests at (1) initial time at 08.00 a.m., (2) before morning rest break at 10.00 a.m., (3) after morning rest break at 10.10 a.m., (4) before lunch at 12.00 a.m., (5) after lunch at 13.00 p.m., (6) before afternoon rest break at 15.00 p.m., (7) after afternoon rest break at 15.10 p.m. and (8) end of work at 17.00 p.m.. In contrast, the control group was measured only at before work (08.00 a.m.). The result showed that the HGS, PS and MTA of the dominant hand were generally stronger than those of the non-dominant hand (p-value <0.05). The MTA on the initial time of the study group was lower than that of the control group. The MTA was statistically significantly different (p-value <0.05). Both the study group and the control group did not show statistically significant difference of HGS and PS  of both right and left hands (p-value >0.05). Percent changes (%) from initial time in MTA, PS and HGS of right and left hands in all time intervals were lower than for the initial time except that MTA of the left hand in each time interval was not different from the initial time. These tests confirmed the changes of hand strength and dexterity. The result shows that after the workers were exposed to vibration from the grinding process, they were affected by decreased hand muscle strength and decreased hand maximal tapping ability. However, the strength and maximal tapping ability was able to recover after taking a break. Furthermore, in all tests there was reduced hand strength and maximal tapping ability at the end of work (17.00 p.m.), so there may be an accumulation of tissue damage and fatigue of hand muscles by hand and arm vibration from continuous work with grinding. The vibration could influence muscle strength and maximal tapping ability. This result can be used for considering appropriate work duration to the time to rest break for reducing possible accumulation of tissue damage and muscular fatigue of hand in grinding workers.

Journal of Sports Science and Technology 2012 ;12(1)11 - 32)