Effects of sex and age on strength-duration properties

PubMedID: 16875875Objective: To evaluate the possible effects of sex and age on strength-duration time constant (SDTC). Methods: The SDTC of 126 healthy volunteers was measured following stimulation of right median nerve at the wrist. Variations in values were evaluated according to sex and age. Results: The SDTC was 438.6 ± 114.5 µs in women and 396.2 ± 90.3 in men (P = .023). In men, as age increased, so did SDTC. However, this was not true in women. Comparing the values of women and men, aged below 40, demonstrated a difference in excitability, confined to younger patients. Conclusions: As SDTC depends on the biophysical properties of the axonal membrane and can provide some information about Na+ channel function, these data raise the possibility of a difference in Na+ channel function between men and women and a difference in the conductance with age. Significance: The age- and sex-related differences shown in this study suggest a possible biochemical or hormonal influence on axonal excitability. © 2006 International Federation of Clinical Neurophysiology