Beta-band oscillations accompanying fast, targeted ankle plantarflexions in older adults: the effects of resistance training.

This study evaluated short- and long-term resistance training on cortical movement-related beta-band oscillations, purportedly an indicator of somatosensory processing, in older adults. A cross-sectional comparison between long-term resistance-trained (n = 10) versus untrained individuals (n = 8) and a longitudinal 12-month intervention of short-term resistance training (n = 20) were employed in >70-year-old adults. Cortical activity was recorded by 306-channel whole-head magnetoencephalography (MEG) inside a magnetically shielded room. Participants underwent maximal unilateral plantarflexion force tests using a custom-built MEG-compatible dynamometer, from which 15% and 50% force levels were displayed on a screen. Thereafter, participants performed isometric contractions as fast and as accurately as possible to the target force line and relaxed as fast as possible. Thirty trials to each force level (15% and 50%) were performed sequentially. Average force, force and timing coefficient of variation, and rate of force development were analysed from both force levels. Only 15% trials were viable for MEG analysis, examining peak beta (10-30 Hz) suppression and rebound frequency, amplitude and timing, due to large magnitude artifacts from 50% trials. Long-term training was accompanied by lower relaxation time coefficient of variation (P = 0.021-0.027). After short-term training, beta rebound amplitude increased (∼107Δ%, P = 0.003) and time to peak rebound reduced (∼1.49 to ∼1.27 s, P = 0.039) with similar but non-significant differences between long-term trained and untrained individuals (∼1.27 vs. ∼1.57 s, P = 0.083). Both short- and long-term effects suggest more efficient sensorimotor processing and lower force variability accompanying resistance training in older age.