Exploring the relationship between somatosensory-evoked potentials, resting-state theta power, and acute balance performance.

Balance represents a fundamental motor ability whose considerable inter-individual variability and susceptibility to prior experience and task specificity complicate its assessment. Neurophysiological measures such as electroencephalography (EEG) and somatosensory-evoked potentials (SEPs) offer complementary windows into the sensorimotor mechanisms that underpin balance control and may be associated with individual differences in acute performance levels. In the present study, 25 healthy adults naïve to slacklining underwent tibial nerve SEP recordings using single-pulse and paired-pulse paradigms on both dominant and non-dominant legs to assess excitation and inhibition in the sensorimotor cortex. This was followed by five minutes of resting-state EEG. Participants then completed three balance tasks on a slackline: single leg stance with eyes open, single leg stance with eyes closed, and a successive steps task, on each leg. SEP amplitude and paired-pulse inhibition, as well as resting-state theta power were taken as neurophysiological measures. Analysis revealed a correlation between lower resting-state theta power and superior single leg stance performance with eyes-open on the non-dominant leg, while no significant relationships emerged for the eyes-closed or successive steps tasks. Furthermore, neither SEP amplitudes nor paired-pulse inhibition were significantly associated with any balance outcome. Collectively, the present findings indicate that resting-state theta power could be a non-invasive marker of acute balance performance. These results underscore the promise of spectral EEG measures for acute assessment of specific sensorimotor capacity and suggest that future research should explore their utility in clinical rehabilitation and performance monitoring.