Laboratory studies have suggested that the preferred cadence of walking is around 120 steps-per-minute, and the vertical acceleration of the head exhibits a dominant peak at this step frequency (2 Hz). These studies have been limited to short periods of walking along a predetermined path or on a treadmill, and whether such a highly-tuned frequency of movement can be generalized to all forms of locomotion in a natural setting is unknown. The aim of this study was to determine whether humans exhibit a preferred cadence during extended periods of uninhibited locomotor activity, and whether this step frequency is consistent with that observed in laboratory studies. Head linear acceleration was measured over a 10-hour period in 20 subjects during the course of a day, which encompassed a broad range of locomotor (walking, running, cycling) and nonlocomotor (working at a desk, driving a car, riding a bus or subway) activities. Here we show a highly-tuned resonant frequency of human locomotion at 2 ± 0.13 Hz with no evidence of correlation with gender, age, height, weight or body-mass-index. This frequency did not differ significantly from the preferred step frequency observed in the seminal laboratory study of Murray et al. (1.95 ± 0.19 Hz). Based on the frequency characteristics of otolith-spinal reflexes, which drive lower body movement via the lateral vestibulo-spinal tract, and otolith-mediated collic and ocular reflexes that maintain gaze when walking, we speculate that this spontaneous tempo of locomotion represents some form of central 'resonant frequency' of human movement.