Association between vertebral fragility fractures, muscle strength and physical performance: A cross-sectional study.

BACKGROUND: Few studies have investigated the association between vertebral fragility fractures and lower limb muscle strength and physical performance in women with low bone mass. OBJECTIVES: To explore whether the presence of vertebral fracture is independently associated with poor physical performance and decreased lower limb muscle strength. To understand whether lower limb muscle strength is associated with physical performance in women with vertebral fracture. METHODS: Older women with low bone mass were divided into 2 groups: no vertebral fracture (NF) and presence of vertebral fragility fracture (VFF). Physical performance was evaluated using the Five Times Sit to Stand (5TSS) test, the Timed Up and Go (TUG) test and a 5m walk test (5MWT). Lower limb muscle strength was assessed using an isokinetic dynamometer. RESULTS: We included 94 women with low bone mass (mean age 71.6 [SD 5.7] years, time since menopause 24.4 [7.1] years, mean BMI 27.5 [5.1] kgm-2). VFF was only associated with low peak hip abductor torque (p = 0.001) after adjustments. In the VFF group (n= 47), each 1 Nmkg-1 increase: in knee extensor torque was associated with improved 5MWT (p = 0.005), TUG (p = 0.002) and 5TSS (p = 0.005) performances; in knee flexor torque was associated with improved 5MWT speed (p = 0.003) and TUG time (p = 0.006); in hip abductor torque was associated with improved 5MWT speed (p = 0.003); and in hip extensor torque with improved TUG time (p = 0.046). CONCLUSION: VFF was associated with reduced hip abductor strength in older women. However, the number of vertebral fractures influenced the association. Additionally, lower limb muscle strength was associated with physical performance, regardless of the clinical characteristics of the fractures. Therefore, strength and power training programs for the lower limbs could improve physical performance.

Association between the trunk muscle function performance and the presence of vertebral fracture in older women with low bone mass.

BACKGROUND: Despite the clinical importance, it has remained unclear which changes in the trunk muscle function parameters are more associated with the presence of vertebral fracture (VF). AIMS: The aim of this study was to verify the association between the trunk muscle function performance and the presence of VF in older women with low bone mass. The secondary aim was to evaluate the correlation between trunk muscle function and both fall history and muscle mass. METHODS: This cross-sectional study was composed by 94 women over 60 years within value of T-Score lumbar spine BMD <- 1.0 DP. Multidimensional evaluations were performed: appendicular skeletal muscle mass index (ASMI) was determined by the total body DEXA; the radiographic evaluations measured the degree of thoracic kyphosis and classification of VF. The trunk muscle function parameters, such as peak torque (PT), rate of torque development (RTD) and torque steadiness (TS) were evaluated by isokinetic dynamometer. The trunk muscle endurance was evaluated by the timed loaded standing test. The adjusted multivariate logistic regression model and multivariate linear regression were performed to verify the association between the variables studied. RESULTS: The results showed that the trunk muscle function parameter with greater association with the presence of VF is TS extensors (OR = 1.70; p < 0.001). The other two significant muscle parameters were: RTD30 flexors (OR = 0.31; p = 0.033) and PT extensors (OR = 0.13; p = 0.009). No statistical association was found between the presence of VF and the ASMI and trunk muscle endurance. No correlation between trunk muscle function and fall history was observed. There was a weak correlation between ASMI and extensor PT (R2 = 0.21; p = 0.027) and extensor RTD30 (R2 = 0.21; p = 0.026). CONCLUSIONS: This study demonstrated that deficit in trunk muscle function has shown a strong association with the presence of VF, highlighting issues heretofore unexplored regarding the association between VF with muscle power and motor control.