The effect of handedness on upper extremity isometric strength symmetry

Background: Understanding upper extremity strength symmetry can have important implications for ergonomics assessment and design. Few studies have examined isometric joint strength symmetry of left-handed individuals, or examined how handedness can influence strength. As such, the purpose of this study was to investigate the influence of handedness on dominant/non-dominant (D/ND) strength ratio in several moment directions about the shoulder, elbow, wrist, and hand. It was hypothesized that the isometric strength symmetry of left-handed individuals would be significantly different from that of right-handed individuals. Methods: The study recruited 28 participants to perform a series of maximal voluntary isometric contractions (MVCs) with both arms for various efforts about the shoulder, elbow, and wrist, as well as handgrip for a total of 68 MVCs. Strength symmetry ratios were computed, and a two-way mixed-model ANOVA evaluated the effects of handedness and MVC test on strength symmetry. Interpretation: Significant differences in D/ND ratios between right and left-handed individuals were found for 11 of the 17 explored exertion directions. Left-handed individuals tended to possess greater strength in their nondominant limb, while right-handed individuals tended to have greater strength in their dominant limb. Left- and right-handed individuals often significantly differed in D/ND ratio, suggesting that separate normative values should be created to account for handedness when considering return-to-work or strength-based ergonomics design criterion.

Automated summary

This study investigated the differences in isometric strength symmetry between left-handed and right-handed individuals and found that left-handed individuals tend to have greater strength in their non-dominant limb, while right-handed individuals tend to have greater strength in their dominant limb. This suggests that separate norms should be created to account for handedness when considering ergonomic design and assessment criteria.