The current study investigated the differences in muscle stiffness between older and young adults at rest and during contraction. We also evaluated the differences in muscle stiffness assessments using a myotonometer (MyotonPRO) and shear wave elastography (SWE). Twenty-two older adults (mean age, 66.6 ± 1.6 years) and 23 young adults (mean age, 66.6 ± 1.6 years) participated in this study. Muscle stiffness of the tibialis anterior (TA) and medial gastrocnemius (MG) muscles at rest and during contraction were measured using SWE and the MyotonPRO. The stiffness increase rate (SIR) was also calculated to determine the absolute stiffness difference. The mean muscle stiffness of the TA and MG muscles was significantly lower in older adults than in young adults at rest and during contraction (p < 0.05). Similarly, the SIR values of the TA and MG were significantly lower in older adults than in young adults (p < 0.05). Our results indicate that both instruments could be used to quantify muscle stiffness changes and serve as a cornerstone for assessing aging-related losses in muscle function. Stiffness measures may help exercise professionals to develop an in-depth understanding of muscle impairment at the tissue level.

The present study aimed to evaluate forced expiration based on transverse abdominis (TrA) stiffness by identifying the relationship between TrA stiffness and peak expiratory flow (PEF) in both younger and older adults. We also assessed the relationship between diaphragm thickness and PEF. A total of 31 younger (21.24 ± 2.73 years) and 34 older (71.35 ± 5.26 years) adults were included in the present study. TrA muscle stiffness was measured at rest and during abdominal bracing using shear wave elastography. Diaphragm thickness was measured during deep inspiration and expiration using B‐mode ultrasound, and respiratory function was assessed by measuring PEF using a spirometer. We found that TrA stiffness during bracing was significantly lower in older than younger adults (p < 0.05). Similarly, the difference in absolute stiffness of the TrA when bracing versus at rest was significantly lower in older than younger adults (p < 0.05). Additionally, TrA stiffness during bracing was positively associated with PEF in the younger group (r = 0.483), while a very weak correlation was found in the older group (r = 0.172). Similarly, PEF was moderately correlated with diaphragm thickness during expiration as well as during changes between inspiration and expiration in the younger group (r = 0.405 and r = 0.403); however, no significant correlation was found in the older group. These findings of the present study indicate that the variations in PEF between younger and older adults may be due to age‐associated changes in the musculoskeletal structure and muscle fibre type.

Purpose This study primarily aimed to investigate the association between levator ani elasticity on shear-wave elastography and bladder base displacement using transabdominal ultrasonography for evaluating pelvic floor muscle function. Methods Forty-two nulliparous women were included in the study. Kegel exercises were used for educating how to contract pelvic floor muscles. The elasticity of the levator ani muscle at rest and during contraction using shear-wave elastography and bladder base displacement using transabdominal ultrasonography were obtained, simultaneously. Results The intraclass correlation coefficient for repeated measures of levator ani elasticity was 0.906 at rest and 0.687 during contraction. The mean levator ani elasticity was 24.7 ± 4.5 kPa at rest and 62.1 ± 10.4 kPa during contraction, mean bladder base displacement was 7.2 ± 2.5 mm, and normalized bladder base displacement was 0.3 ± 0.1 mm. Additionally, a moderate correlation coefficient was found between bladder base displacement and levator ani elasticity differences between contraction and rest (r = 0.486, p = 0.001). Conclusion Transperineal shear-wave elastography is reliable for assessing the elasticity of levator ani by providing a non-invasive evaluation of pelvic floor muscle function. Additionally, the study findings suggest shear-wave elastography as a promising technique for establishing appropriate treatment plans for pelvic floor disorders.