Muscle excitability testing: Age and sex dependency of normative data

Objective: To establish normative data for muscle excitability testing in the tibialis anterior muscle of a healthy
population, and to determine their dependence on age and sex.
Methods: Parameters of muscle velocity recovery cycle recordings with 1, 2 and 5 conditioning stimuli of 197
healthy subjects and frequency ramp recordings of 151 healthy subjects were retrospectively analysed for age
and sex differences.
Results: There were no differences by sex and only small age differences were found in healthy subjects older than
60 years for the muscle excitability parameters muscle relative refractory period, early supernormality and la tency to the first response in a train at 15 Hz and 30 Hz.
Conclusions: In this study, based on a large sample of muscle velocity recovery cycle and frequency ramp re cordings, we have provided normative data and shown that muscle excitability testing is not influenced by sex,
and that age only has an influence from the age of 60 years onwards on parameters reflecting muscle membrane
potential.
Significance: Our results suggest that future studies no longer need to control for sex when using a healthy control
group.