  A novel experimental paradigm and a novel modelling approach are presented to
investigate oscillatory human motor performance by means of a key concept from
condensed matter physics, namely, thermodynamic state variables. To this end,
in the novel experimental paradigm participants performed pendulum swinging
movements at self-selected oscillation frequencies in contrast to earlier
studies in which pacing signals were used. Moreover, in the novel modelling
approach, a canonical-dissipative limit cycle oscillator model was used with a
conservative part that accounts for nonharmonic oscillator components in
contrast to earlier studies in which only harmonic components were considered.
Consistent with the Landau theory of magnetic phase transitions, we found that
the oscillator model free energy decayed when participants performed
oscillations further and further away from the Hopf bifurcation point of the
canonical-dissipative limit cycle oscillator.
