The Effects of Sex, Women’s Body Composition and Monthly Cycle Phases on the Sensory Threshold of Upper Limb to Transcutaneous Electrical Nerve Stimulation in Healthy Subjects

Abstract

Neuromuscular excitability plays an essential role in electrotherapy treatment. The vast majority of these treatments are procedures that change the sensitivity to sensory stimuli, especially pain, with the use of an electric current. The aim of this study was to assess changes in the sensory threshold in response to transcutaneous electrical nerve stimulation (TENS), taking into account certain personal factors, such as sex, body composition, and phases of the menstrual cycle. The study involved 205 women and 49 men aged 19–33 years. Sensory threshold was examined by TENS stimulation (a biphasic current waveform, 100 Hz and 100 µs) and body composition using a TANITA analyzer. The mean sensitivity threshold in women was lower than in men (mean ± SD, F: 8.78 ± 2.11 mA vs. M: 11.20 ± 3.29 mA, p < 0.001). There were no significant differences in sensory threshold during the different phases of a woman’s monthly cycle. The taller the woman, the higher the sensory threshold (B ± SE, 0.15 ± 0.07, p = 0.036), while those with a higher percentage of body fat and a higher total water content had a lower sensory threshold (fat: B ± SE, −0.25 ± 0.07, p < 0.001; water: B ± SE, −0.20 ± 0.07, p = 0.003). In conclusion, the sensory threshold in women was lower than in men. In women aged 19–33 years, the phases of the monthly cycle did not affect the sensory threshold; however, being taller and having less body fat and a lower water content increased the sensory threshold.