Isokinetic Strength Profile of the Wrist Muscles: A Study of Healthy Women and Men

Background / Objective: In the isokinetic literature, relatively limited attention has been given to muscles of the wrist. Therefore, the objective of this study was to present an isokinetic profile of these muscles comprising the flexors (F), extensors (E), ulnar (U) and radial (R) deviators. Method: The dominant side F, E, U and R in 40 healthy participants (20 women and 20 men) were tested concentrically and eccentrically, using a single speed of 90°/s. Results: Men were significantly stronger than women in both the concentric and eccentric tests as indicated by both the absolute (Nm) or the bodyweight normalized (Nm/kgbw) representations. However, the bodyweight normalized women/men strength ratio (78.6±8.0%) was significantly higher than the absolute’s (64.1±6.6%). For both the concentric and eccentric effort and irrespective of the representation (absolute or normalized) the U was the strongest muscle group followed successively by F, R and E. This rank order was highly significant statistically. The eccentric/concentric strength ratios: E/CF and E/CU were significantly higher in men than in women with no remarkable inter-sex differences for E/CE and for E/CR. A correlational analysis which included all pairs of the basic isokinetic outcome parameters (e.g., the PM of Fcon) and performed with respect to ‘sex’ using Fisher’s r-to-z transformation, revealed that men had significantly higher overall correlation coefficients compared to women. Conclusions: The uniformity of main findings with respect to both the sex of the participants and the various strength ratios strongly support the validity of the findings. Specifically, the original rank ordering of the wrist muscle can potentially serve as an additional and preliminary guideline for return to normal strength pattern in rehabilitation of the wrist.