•Stiffness of skeletal muscle increases on contracted status.•Stiffness of skeletal muscle decreases with advancing age.•Stiffness increase rates remain similar between age subgroups. To evaluate the effects of aging on skeletal muscle stiffness in relaxed and contracted status using shear wave elastography (SWE). A total of 57 participants were enrolled to this institutional review board approved prospective study. Medial head of the gastrocnemius muscle (GM) of all participants were examined bilaterally by a single radiologist in prone position. Muscle thickness, stiffness values in both relaxed and contracted status were measured. Stiffness increase rate (SIR) was calculated for all muscles. The Spearman’s correlation test was used for correlation analyses. Mann-Whitney U test was used to compare subgroups. The mean age of the participants was 41.15 ± 16.19 (range, 18−74). The means of stiffness values of medial head of GM were 12.51 ± 2.56 kPa and 81.74 ± 15.77 kPa in relaxed and contracted status, respectively. The mean of SIR values was 5.62 ± 1.05 (range, 3.18–8.66). The stiffness values of relaxed and contracted medial head of GM had moderate to strong inverse correlations with age for both dominant and non-dominant extremities (r range: −0.703 to −0.590). Age subgroup analyses revealed significant differences in muscle thickness and stiffness values, whereas no significant difference was found in SIR values. In conclusion, despite the decrease in stiffness of skeletal muscle with advancing age, SIR remained similar. Any improvement in stiffness values of skeletal muscle in relaxed status may play pivotal role in the management of sarcopenia.