Acute effects of static stretching on the shear elastic moduli of the medial and lateral gastrocnemius muscles in young and elderly women

Purpose: Generally, static stretching (SS) is the recommended intervention for a decline in the range of motion among elderly adults. However, no study has investigated the acute effects of SS on the shear elastic modulus in elderly people. The aims of the present study were to investigate the acute effects of SS on the shear elastic moduli of the medial and lateral gastrocnemius muscles and to examine the differences in these acute effects between young and elderly women. Methods: This study included 15 healthy young women (age: 23.1 +/- 3.4 years) and 15 healthy elderly women (age: 75.9 +/- 2.8 years) with no history of neuromuscular disease or musculoskeletal injury involving the lower limbs. The shear elastic moduli of the medial and lateral gastrocnemius muscles (MG and LG, respectively) were measured using ultrasound shear wave elastography at 30 degrees plantar flexion, 0 degrees, and 20 degrees dorsiflexion before and immediately after 5 min of SS with the knee extended. Results: The shear elastic moduli of the MG and LG in all ankle position decreased after SS in both the young and elderly women, and there were no significant differences in the percent changes in the shear elastic moduli of the MG and LG at all ankle positions between the young and elderly women. Conclusions: These results suggested that 5 min of SS might be effective for decreasing shear elastic modulus in both young and elderly women and that the effects on shear elastic modulus are similar between young and elderly women.