Age-related changes in quadriceps stiffness and strength: a longitudinal observation in community-dwelling older adults
摘要
In aging muscles, altered elastin and collagen type III and extracellular matrix may be responsible for the age-related increase in muscle stiffness, which may compromise muscle force production. Indeed, cross-sectional studies have compared quadriceps stiffness between older and younger adults, yet their findings are contradictory. We aim to longitudinally observe quadriceps stiffness/strength changes, and to examine how those changes are associated in elders.
MethodsThis was a prospective longitudinal observation. Community-dwelling adults were recruited if they were aged 60–80 years and capable of walking 10 m independently. We excluded participants with knee injury/surgery, knee/hip joint replacement, cognitive impairment, or neurological conditions. Quadriceps stiffness and strength were assessed at baseline and the follow-up, using shear-wave ultrasound elastography and a Cybex dynamometer, respectively. Paired t-tests were used to examine changes in quadriceps stiffness and strength from baseline to the follow-up. Linear regression was performed to investigate the association between age-related changes in quadriceps stiffness and strength. Repeated measures ANOVA was used to assess differences in stiffness changes across rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM).
ResultsA total of 172 eligible participants (age: 65.7 ± 4.0 years; 64.0% females) completed the baseline and 18-month follow-up assessments. Quadriceps stiffness increased by 0.76 (95% CI: 0.56, 0.97) kPa, while quadriceps strength decreased by -0.15 (-0.18, -0.12) Nm/kg. Estimated annual changes in quadriceps stiffness and strength were 9.14% (7.02, 11.26) and − 7.95% (-9.78, -6.12), respectively. Greater increase in quadriceps stiffness was significantly associated with larger strength reduction in females (R²adjusted = 0.106; P = 0.021). RF stiffness underwent the most obvious increase, followed by VL and VM (1.41, 0.62, 0.26 kPa, P < 0.001). However, only increased quadriceps stiffness (0.76 > 0.71 kPa), particularly the RF stiffness (1.41 > 1.24 kPa), exceeded minimum detectable changes over this 18-month observation.
ConclusionsQuadriceps stiffness is increased with aging, and it is associated with strength decrements in female older adults. Age-related increases in quadriceps stiffness are most prominent in RF, followed by VL and VM. Alongside muscle strengthening, interventions for reducing age-related increases in quadriceps stiffness may be important in geriatric rehabilitation.