Purpose] The purpose of this study was to investigate the effects of relaxation postures by measuring airway occlusion pressure (P0.1) and heartbeat variability as indicators of respiratory motor output and autonomic nervous function, respectively. [Subjects] Eleven healthy university students (5 males, 6 females, aged 20.3  0.5 years) participated in this study. [Methods] The measurement postures were standing, sitting, forward-leaning sitting, and semi-Fowler's posture. Subjects maintained

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... ch posture for four minutes and their respiration and heartbeat variability were measured, following which P0.1 was measured five times in one minute. [Results] P0.1 and heart rate were significantly lower in the semi-Fowler's posture compared with sitting. Also, in terms of heartbeat variability, the activity level of the parasympathetic nervous system was high in the semi-Fowler's posture. [Conclusion] This result suggests that the semi-Fowler's posture is more effective than sitting at reducing heart rate and increasing parasympathetic nervous system activity as a relaxation posture.