Affiliations: [a] Winston Salem State University, School of Health
Sciences, Winston-Salem, NC 11111, USA | [b] Göteborg University, Institute of Clinical
Neurosciences, Rehabilitation Medicine, Göteborg, Sweden | [c] Uniformed Services University of the Health Sciences,
Graduate School of Nursing, Bethesda, MD 20814, USA | [d] Göteborg University, Department of Occupational
Therapy and Physiotherapy, Department of Orthopaedics, Göteborg,
Sweden
Note: [] Address for correspondence: Ulla Svantesson, RPT, PhD, Faculty
of Health Caring Sciences, Department of Occupational Therapy and
Physiotherapy, Göteborg University, Box 455, SE 40530 Göteborg,
Sweden. Tel.: +46 31 7735742; E-mail: ulla.svantesson@fhs.gu.se
Abstract: Passive stiffness (Nm/°) of the plantar flexors was measured
during a passive stretch into dorsiflexion (DF) in 18 healthy female subjects
(range 18–60 years old) using an isokinetic dynamometer. Passive
stiffness of the ankle joint was measured at a short range of motion (from
10° of plantar flexion (PF) to 10° of DF), and at a full range of
motion (from 10° PF to maximal DF for each individual) with a neutral EMG
from a subset of four legs. The purpose of the study was to assess the
variances in the measurements of passive stiffness of the calf muscle and to
correlate passive stiffness to age and jumping ability. There was a significant
correlation (r=0.76) between the FRS and FRS test-retest. The methodological
error for duplicate determinations was 7.7% for the SRS and 5.5% for the FRS.
There was a significant correlation between age and the (FRS) full-range
stiffness (r=0.83). There was a significant negative correlation between age
and jumping (r=−0.54). We conclude that the test model of passive
stiffness used in the present study is a useful method with good reliability.
The passive elastic properties of muscles and tendons might explain part of the
muscle performance in functional tests with ageing. However, other qualities
may influence performance as well.
