Physiological and biomechanical mechanisms underlying fine motor skills and their adjustments and adaptations to heightened sympathetic nerve activity, aging or inactivity, space flight or microgravity, neuromuscular fatigue, divided attention, and practice in humans. He uses state-of-the-art techniques in neuroscience, physiology, and biomechanics (e.g., TMS, EEG, fMRI, single motor unit recordings, microneurography, mechanomyography, ultrasound elastography, and exoskeleton robot) in identifying these mechanisms.