Is there any correlation between the strength of pronation and supination of the dominant hand and that of the non-dominant one in right-handed healthy adults: Preliminary results

We searched the existence of a link between the strength of pronation and supination of the dominant forearm and those of the non-dominant one. Ninety-seven volunteers were tested in pronation and supination with an analog dynamometer. Gender, age, dominance, height and weight were recorded. The measurement position was: 90 of elbow flexion, 0 of shoulder abduction, wrist slightly extended and neutral pronation-supination. We took four measurements per patient: strength in pronation and supination, in both the dominant and non-dominant sides. Fifteen subjects were evaluated twice. The left-handed (4) were removed from the statistical analysis. There were 38 men (37 years, 18-66) and 55 women (45 years, 21-71). Torques were higher (P < 0.05) in men than in women, higher in supination than in pronation and in the dominant side compared to the non-dominant one (average ratio ``non-dominant/dominant'': 0.85; sigma = 0.16). There was a strong correlation between non-dominant hand strength and dominant hand strength (Pearson > 0.6). Relating to the 15 subjects evaluated twice, the value of the forces varied during the day, but the ratio ``non-dominant/dominant'' was constant. The left-handed people were excluded, their values may be different from those of right-handers, as has been shown for grip strength. There was a strength variation during the day, but the ratio ``non-dominant/dominant'' was constant, making it more relevant intra-individual comparison (non-dominant side versus dominant side) rather inter-individual (based on charts of gender, age, weight and height). In the right-handed, the ratio ``strength non-dominant side/dominant'' is constant, defining easily in consultation the expected value of recovery of an injured forearm. (C) 2013 Elsevier Masson SAS. All rights reserved.