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.

Contribution of Hip Abductors Muscles on Bone Mineral Density and Functionality in Older Women.

BACKGROUND: Despite the well-established role of muscle in maintaining bone mass and physical performance, there are still few studies that assess the relationship between muscle groups and specific bone sites and its contribution to physical function in older people. The aim of the study is to verify the association between hip and knee's muscle strength and bone mineral density of the femoral neck (BMD-FN) and investigated which muscle strength that are related with BMD-FN is associated with physical function in older women. METHODOLOGY: This is a cross-sectional study of 94 women over the age of 60 years, physically independent. Muscle strength of the hip and knee was evaluated using an isokinetic dynamometer (Biodex, USA) to obtain peak torque (PT). The BMD-FN was obtained using dual-energy x-ray absorption densitometry (DXA). Physical function was evaluated by the Timed Up and Go (TUG), gait speed (GS), five times stand to sit (5TSS) and single-leg stance (SS). To verify the association between muscle strength (independent variable) and the BMD-FN (dependent variable) and the relationship between muscle strength (independent variable) and clinical tests (dependent variable), the multiple linear regression was carried out, adjusted for age, time of menopause, height and level of physical activity. All of the analyses were carried out by the SPSS 17.0 software, with a level of p < 0.05 significance. RESULTS: We found an association between the hip abductors PT and the BMD-FN and between hip abductors PT and all clinical tests. CONCLUSION: We observe that hip abductor muscle strength contributes to BMD-FN and to performance in several clinical tests in older women. These findings reinforce the importance of this musculature not only for improving balance and gait, but also it can be a strategy to maintain/improve bone mass in the femoral neck in this population.

Rate of Torque Development and Torque Steadiness of the Lower Limb and Future Falls Among Community-Dwelling Older Adults Without Previous Falls: A Longitudinal 1-Year Study.

The objective was to investigate the association between rate of torque development (RTD) and torque steadiness (TS) of the lower limb and the occurrence of prospective falls in community-dwelling older adults without falls in the previous year. One hundred older adults performed the tests to obtain the RTD and TS of the hip, knee, and ankle. New episodes of falls were monitored through telephone contact for a prospective period of 12 months. The association of RTD and TS with the occurrence of prospective falls was verified by multiple logistic regression adjusted for confounding variables. There was no association between RTD of hip, knee, and ankle and prospective falls. Only the TS at 50% of the peak torque of the hip flexors was associated with the occurrence of future falls (p = .023). Identifying modifiable risk factors for the first fall in older adults is essential for the development of adequate prevention programs.

Hip muscle strength, dynamic balance and functional capacity of community-dwelling older adults aged 60 and older: A cross-sectional study.

The objective of the present study was to evaluate the association of hip muscle strength, dynamic balance and functional capacity in the older adults aged 60 to 79 years and older adults aged 80 years and older. A total of 191 community-dwelling older adults participated in this study. Isometric muscle strength was quantified as the peak torque (PT), measured using an isokinetic dynamometer. Functional capacity was determined by the forward step test (ST) and the dynamic balance by the tandem gait (TG) test. The hip flexor, extensor, abductor and adductor PT in the older adults aged 60 to 79 years had a positive influence on the execution of the step test (p < 0.05). The peak adductor torque did not show a significant association with tandem gait (p = 0.649). In older adults aged 80 years and older, the peak adductor torque was the only one that showed an association with the performance of the ST (p = 0.001) and TG (p = 0.024) tests. The hip adductors may have a higher contribution in adults aged 80 years and older during the execution of clinical tests. These findings are relevant to clinical practice as they can help in the development of appropriate physical exercise programs targeting older adults of different age groups.

Relationship Between Lower Limb Muscle Strength and Future Falls Among Community-Dwelling Older Adults With No History of Falls: A Prospective 1-Year Study.

Objective: To investigate whether lower limb muscle strength could be a risk factor for the first fall among nonfaller community-dwelling older adults. Method: Hip, knee, and ankle peak torque (PT) was measured with an isokinetic dynamometer in 101 older adults with no history of falls in the previous year. Next, the authors followed up the participants on a monthly basis by telephone contact to determine the occurrence of fall episodes over a period of 1 year. Multivariate logistic regression adjusted for confounding variables was applied to assess the relationship between falls and lower limb PT. Results: there was no association between lower limb PT and future falls (p > .05). Conclusion: Based on these results, it is important to identify other factors that predispose older adults with no history of falls to falling for the first time, so that early and effective preventive strategies may be elaborated.

The effect of unilateral muscle fatigue of hip abductor muscles on balance and functional capacity in community-dwelling older women.

BACKGROUND: Hip abductor muscles are important for the maintenance of postural stability, mainly on the mediolateral direction and unipodal support conditions. The objective of the present study was to evaluate the effect of unilateral induced fatigue of hip abductor muscles on balance and functional capacity of older women. METHODS: The study included physically independent women aged 60-75 years. We assessed static balance with the single limb stance test (SLS) and evaluated functional capacity with the maximum gait speed (MGS) and step test (ST). We ran the protocol of hip abductor muscle fatigue with a Biodex isokinetic dynamometer. Assessment of balance and functional capacity happened before and after the muscle fatigue protocol. We applied the t-test for repeated measures to determine whether unilateral hip abductor muscle fatigue influences the performance in the tests (SLS, MGS and ST). RESULTS: The protocol of hip abductor muscle fatigue negatively affected all three evaluated tasks: SLS (p = 0.000), ST (p = 0.000) and MGS (p = 0.000). However, the single limb stance test was the most task affected (effect size = 0.51, pre- and post-fatigue difference = 28.1 %). CONCLUSION: After the unilateral muscle fatigue of hip abductors, we observed the worst performance on clinical tests, mainly regarding the SLS test, which shows the involvement of hip abductors during usual motor tasks. However, the small magnitude of the limitation of functional tests (MGS and ST) suggests the presence of postural compensations.

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.