Aim: The aim of this study was to analyze the effects of aging on the viscoelastic properties of the upper trapezius (UT) and the sternocleidomastoid (SCM) muscle during transition from lying to sitting position. Materials and methods: The study included 39 older (mean age 67 +/- 5.9 years) and 36 younger (21.1 +/- 1.8 years) women. Tone, stiffness and elasticity of the UT and the SCM were measured by means of myotonometry (MyotonPRO) in lying and then, in sitting position. The results were compared using twoway analysis of variance. Results: Irrespective of the position, older women presented with significantly higher muscle tone, stiffness and elasticity than younger subjects (P < 0.05). In both groups, the transition from lying to sitting position resulted in a decrease (P0.05) of the SCM, and stimulated an increase in the tone, stiffness and elasticity of the UT (P < 0.05). The degree of changes in both study groups was similar, except from the absolute value of the UT elasticity, significantly higher increase in older women than in younger subjects (P < 0.05). Conclusion: Age contributes to an increase in the stiffness and tone of the UT and the SCM, as well as to a decrease in the elasticity of these muscles in female subjects. In contrast, age exerts only a slight effect on the mechanical properties of both muscles during transition from lying to sitting position. (C) 2016 Elsevier Ireland Ltd. All rights reserved.