Associations between Range of Motion and Tissue Stiffness in Young and Older People.

PURPOSE: The purpose of this study was to investigate differences in the associations between passive ankle dorsiflexion range of motion (ROM) and stiffness of the triceps surae, sciatic nerve, and deep fascia located in the posterior leg between young and older people. METHODS: Twenty young and twenty older males were recruited and were placed in a prone position with their hip and knee fully extended. Passive ankle dorsiflexion ROM was determined based on the onset of pain during passive dorsiflexion at 1°·s using an isokinetic dynamometer. Shear wave speeds (as a stiffness index) of the triceps surae, the sciatic nerve, and the deep fascia in the posterior leg were evaluated by ultrasound shear wave elastography. RESULTS: The shear wave speeds of the medial and lateral gastrocnemius measured at 15° dorsiflexion correlated negatively with passive ROM in young but not in older participants. The shear wave speed of the sciatic nerve measured at 15° dorsiflexion correlated negatively with passive ROM only in older participants. No association was observed between passive ROM and shear wave speed of the deep fascia in the posterior leg. For data measured at maximal dorsiflexion angle (as an index of stretch tolerance), shear wave speeds of the triceps surae and passive joint torque correlated positively with passive ROM in both groups. CONCLUSION: These results suggest that the tissues limiting passive ankle dorsiflexion ROM are muscle and nerve for young and older people, respectively, whereas stretch tolerance influences passive ROM for both groups. This implies that the relative contribution of nonmuscular tissues to joint flexibility become stronger than that of muscles with age.

Can Static Stretching Reduce Stiffness of the Triceps Surae in Older Men?

PURPOSE: The purpose of this study was to investigate reductions of muscle stiffness induced by static stretching in older and younger men. METHODS: Twenty older (62-83 yr) and 20 younger (21-24 yr) men were recruited. Ankle dorsiflexion static stretching was consisted of 90 s × 5 repetitions. Before and after the stretching, the dorsiflexion range of motion (RoM), passive plantar flexion torque, and shear modulus (an index of stiffness) of the medial (MG) and lateral gastrocnemius and the soleus were measured. RESULTS: RoM, passive torque, and shear modulus of the triceps surae measured at the maximal dorsiflexion angle before stretching were significantly lower for the older group than the younger group. This suggests a weak stretching intensity for older compared with younger people. The stretching significantly improved RoM for both groups. For the older group, a significant reduction in passive torque was only observed at a 15° dorsiflexion angle, and the shear modulus was significantly decreased only for the distal region of MG. For the younger group, passive torque was significantly reduced for the entire RoM, and a significant decrease in shear modulus was found for the central and distal regions of MG and lateral gastrocnemius. A significant correlation between the muscle shear modulus measured at the maximal dorsiflexion angle before stretching and a stretching-induced decrease in muscle shear modulus was observed for older and younger participants. This indicates that the higher stretching intensity can reduce more muscle stiffness. CONCLUSION: Static stretching can reduce muscle stiffness regardless of age, although the stretching effect on muscle stiffness was limited for older people. This might be due to a lower stretching intensity for older than younger people.