LATERAL ASYMMETRY IN GRIP STRENGTH: UTILITY OF THE TEN PER CENT RULE

Abstract

Objective: To measure asymmetry in grip strength between hands in left, right and mixed
handers and to test utility of the ten per cent rule.
Design: A cross sectional study.
Setting: Queen Elizabeth Central Hospital, Blantyre, Mala1 vi.
Subjects: One hundred and seventy six healthy volunteers (I 02 males and 74 females) aged
15 to 66 years were selected from visitors to the patients ad! nitted at the hospital.
Main outcome measures: Bilateral measurements of maxim a1 grip strength, assessment of
handedness using a questionnaire incorporating questions on hand preferred for six habitual
activities.
Results: In about 70% of males and females, the right hand was stronger than the left hand
while frequency of left, mixed, and right handers was 5.7%, 4.5% and 89.2%, respectively.
Significant association (xZ = 6.43, n=2, pc0.05) was found be1 ween handedness and stronger
hand with preferred hand being stronger in most subjects. However, for about 40% of left
and mixed handers and 27% of right handers, the non-preferred hand was stronger. The
mean differences between grip strengths varied between 101 and 20% in different categories
of handers when stronger hand was taken into considefi~tion. Without considering the
stronger hand, the mean bilateral diierence in maximal gril strength in the three categories
of handedness was between three and six per cent.
Conclusion: Distinction between stronger hand and hand preferred for skilled activities
should be made and considered when assessing limitatio 1s in hand strength in clinical
practice.