Relación entre la masa muscular, la densidad mineral ósea, la fuerza muscular, la aptitud funcional y la calidad muscular en personas mayores

Laburpena

Introduction: As part of the aging process, older people show a progressive decrease in bone mineral density (BMD), muscle mass, muscle strength and functional fitness. But when this decline exceeds normal levels, two well-known problems that affect the health of older people arise: sarcopenia and osteoporosis. Objective: The aim of this study was to determine the frequency of sarcopenia and osteoporosis in a group of older people from León, Spain. In addition, this study explored the association between muscle mass, BMD, muscle strength, functional fitness and muscle quality (MQ). Materials and Methods: A cross-sectional study was carried out on 83 men and 175 women (mean age 70.9 SD 5.5 years and 71.5 SD 5.2 years, respectively). Lean mass (LM) (total, arms, legs, thighs and appendicular), femur neck BMD (FNBMD) and lumbar spine BMD (LSBMD) were assessed by dual–energy X–ray absorptiometry. The isometric maximum strength of leg extension (IMSLE) and biceps curl were assessed by a load cell. The dynamic maximum strength of biceps curl (DMSBC) and leg extension were measured by one-repetition maximun (1-RM). The mean power measures of leg extension (MPLE) at 40%, 50%, 60%, 70% and 80% 1-RM were assessed with a linear motion transducer. The hand grip strength (HGS) was measured with a Jamar dynamometer. The functional fitness was assessed according to four tests taken from the Senior Fitness Test: Arm curl, Chair stand, Step–in–place, and 8 foot up–and–go (8f–UG). The MQ was defined by dividing each test of muscle strength by the specific muscle mass of upper and lower limbs. The osteoporosis of femur neck (OPFN) and the osteoporosis of lumbar spine XXIV (OPLS) were determined by the T-score of the FNBMD and LSBMD, respectively (<-2.5). The sarcopenia was determined according to the definition of the EWGSOP with the following criteria: appendicular lean mass index (ALMI), HGS and 8F-UG. 643316135 Results: The frequency of sarcopenia was 2.3%, while the OPFN was 11.6% and the OPLS was 22.5%; this last was higher in the women (p = 0.001). Most measurements of LM were correlated with muscle strength of arms and legs; however, in the linear regression analysis after adjustment for age and BMI, the ALMI did not behave as an explanatory variable of HGS in both sexes (important criteria used in the evaluation of sarcopenia). Moreover, the ALMI showed better associations with other tests of strength, especially with the MPLE evaluated up to 70% of 1-RM in women and up to 80% of 1-RM in men. Low performance on each test of SFT battery did not show major associations with the indicators of LM; while the tests of muscle strength and MQ showed higher significant differences in both sexes (p <0.05). The measurements of LM were positively correlated with LSBMD in women and FNBMD in both sexes (p <0.01); with respect to muscle strength, important positive correlations were presented in men between the FNBMD with DMSBC, the HGS and MPLE at 40%, 50% and 70% of 1-RM (p <0.05); while none of the variables of FF were correlated with BMD in both sexes. Men with OPFN showed lower LM in total body and arms, while women with OPFN showed lower values in the IMSLE and DMSBC; on the other hand, only women with OPLS showed lower significant values in most LM indicators, DMSBC and HGS; regarding to functional fitness and MQ, no associations with OPNF and OPLS were reported in both sexes. In assessing the risk of osteoporosis according to the diagnostic criteria for sarcopenia, only in women were the ALMI and HGS were associated with a lower risk of OPLS; however, when models were adjusted for age and BMI, only HGS remained associated with OPLS. Conclusions: Using the EWGSOP definition, the sarcopenia is overall lower than other published studies with similar populations. Only in women, XXV osteoporosis is influenced by anatomical area used for its diagnosis; it clearly is higher when determining BMD in lumbar spine that femoral neck. In general, there is an association between different indicators of muscle mass and strength of upper and lower limbs; however, more attention should be placed on the association between ALMI and HGS, considering that they are the most frequently used criteria in the evaluation of sarcopenia, but in our study their association was not important. Of relevance to clinical practice, it appears that maintenance of strength and MQ may be related to a suitable functional performance, rather than focusing solely on muscle mass. Moreover, our results suggest that improving muscle mass and muscle strength (mainly the latter) could contribute to improving bone health in women, rather than working on the functional fitness and MQ.