Summary
García-Alfaro et al [1] published the results of a cross-sectional study that aimed at determining the impact of age, age at menopause, body mass index (BMI), and lumbar and hip bone mineral density (BMD) on muscle strength of 392 young postmenopausal women (65 or less years), with no physical disabilities and normal serum 25-hydroxyvitamin D levels (≥30 ng/ml). They analyzed variables such as age, age at menopause onset, BMI, BMD (measured with DXA scanning and expressed as lumbar and hip T-scores), and dominant hand grip strength (measured with a digital dynamometer). Mean age of the whole sample was 57.30 ± 3.69 years with a mean age at menopause onset of 50.46 ± 2.16 years and a mean BMI of 24.93 ± 3.78 k/m2. Mean DXA results were lumbar T-score of -1.16 ± 1.18 and a mean hip T-score of -0.98 ± 0.93. Mean grip force of the dominant hand was 24.10 kg, with 12.2% (48/392) of women diagnosed as having dynapenia (cut-off value of <20 kg). There was a weak but significant inverse correlation between grip strength in the dominant hand and age (r = -0.131, p = 0.009). Multivariate logistic regression analysis determined that earlier age at menopause onset (50 or less years) was significantly associated with a higher risk of dynapenia (OR 2.741, 95% CI 1.23-6.11, p = 0.014). No other significant association was found with the other variables. The authors conclude that 12.2% of the studied young postmenopausal population with normal vitamin D status had dynapenia. Female age and age at menopause were significantly correlated with an increased dynapenia risk.
Commentary
During the menopausal transition and the early postmenopausal years, progressive estrogen depletion causes loss of bone mass due to an imbalance between bone resorption and bone formation. In addition, there is a reduction of muscle mass and strength and a redistribution of body fat from the periphery to the abdominal region [2,3]. There is a growing interest in recent years regarding the association of dynapenia, defined as the loss of muscle strength related to age, and BMI and nutrition. Indeed, a direct correlation has been observed between muscle strength and bone mass, that is, lower hand grip strength correlating with lower BMD, and hence higher rates of vertebral fractures [4]. Hand grip strength can be measured with a hand dynamometer, being an easy/simple and quick test to be performed in the clinical scenario, and most importantly is the fact that hand grip force correlates with leg strength. Although BMI has been used to assess nutritional status, this index is not as appropriate as DXA for the evaluation of body composition. As the authors state, although body weight is related to BMD, when body composition is analyzed with DXA, total body fat is the best predictor of bone status. Vitamin D status is another important factor correlating with muscle function, strength, balance, not to mention its role over bone status of elder women.
Despite all these facts, the association between age and age at menopause and muscle strength and the risk of dynapenia in postmenopausal women with normal vitamin D status is still not clear, reason why the authors aimed at determining the role of age and age at menopause onset over muscle strength. The authors [1] found that 12.2% of young postmenopausal women with normal vitamin D levels had dynapenia, in which their age and age at menopause onset were implicated risk factors. Studies related to sarcopenia (reduction of muscle mass), osteosarcopenia and frailty have increased during recent years and different papers, meta-analysis and consensus have been published including preventive and curative interventions [5-7]. Despite this, dynapenia, which may probably be the first step to muscle ageing and deterioration, has received less attention. Hence, the identification and treatment of this entity should be priority among apparently healthy postmenopausal women, and more important among those with a low quality diet and low physical activity, before sarcopenia or osteosarcopenia is instated. In this sense, among older adults, performing exercise has benefits on BMI, handgrip strength, gait speed, and quality of life [8,9].
The present study had two limitations, first, all participants had normal vitamin D levels, hence, no comparisons were made with a group of women with similar characteristics yet low vitamin D levels and second, information regarding individual degree of physical activity and exercise was not explored, which could have given data regarding its influence over muscle strength. Despite these limitations, it was found that 12.2% of this young postmenopausal series with normal vitamin D status had dynapenia. A weak inverse correlation between grip strength and female age was observed; and earlier age at menopause was associated with an increased risk of dynapenia. Hand grip force is a test that can be easily and quickly applied during routine clinical practice providing important information of muscle function. A future and urgent challenge would be to search find appropriate definitions, diets and supplements, in order to reduce the risk of dynapenia and thus reduce the prevalence of sarcopenia in the growing population of aged women.
Peter Chedraui, MD, PhD
Instituto de Investigación e Innovación en Salud Integral
Universidad Católica de Santiago de Guayaquil, Guayaquil, Ecuador
References
- Garcia-Alfaro P, Garcia S, Rodríguez I, Tresserra F, Pérez-López FR. Factors related to muscle strength in postmenopausal women aged younger than 65 years with normal vitamin D status. Climacteric. 2019;22(4):390-394.
https://pubmed.ncbi.nlm.nih.gov/30652954/ - Newman AB, Lee JS, Visser M, et al. Weight change and the conservation of lean mass in old age: the Health, Aging and Body Composition Study. Am J Clin Nutr. 2005;82(4):872-8.
https://pubmed.ncbi.nlm.nih.gov/16210719/ - van Geel TA, Geusens PP, Winkens B, Sels JP, Dinant GJ. Measures of bioavailable serum testosterone and estradiol and their relationships with muscle mass, muscle strength and bone mineral density in postmenopausal women: a cross-sectional study. Eur J Endocrinol. 2009;160(4):681-7.
https://pubmed.ncbi.nlm.nih.gov/19174532/ - Dixon WG, Lunt M, Pye SR, et al.; European Prospective Osteoporosis Study Group. Low grip strength is associated with bone mineral density and vertebral fracture in women. Rheumatology (Oxford). 2005;44(5):642-6.
https://pubmed.ncbi.nlm.nih.gov/15728415/ - Sanchez-Rodriguez D, Marco E, Cruz-Jentoft AJ. Defining sarcopenia: some caveats and challenges. Curr Opin Clin Nutr Metab Care. 2020;23(2):127-132.
https://pubmed.ncbi.nlm.nih.gov/31789867/ - Hita-Contreras F, Bueno-Notivol J, Martínez-Amat A, Cruz-Díaz D, Hernandez AV, Pérez-López FR. Effect of exercise alone or combined with dietary supplements on anthropometric and physical performance measures in community-dwelling elderly people with sarcopenic obesity: A meta-analysis of randomized controlled trials. Maturitas. 2018;116:24-35.
https://pubmed.ncbi.nlm.nih.gov/30244776/ - Stuck AK, Mäder NC, Bertschi D, Limacher A, Kressig RW. Performance of the EWGSOP2 Cut-Points of Low Grip Strength for Identifying Sarcopenia and Frailty Phenotype: A Cross-Sectional Study in Older Inpatients. Int J Environ Res Public Health. 2021;18(7):3498.
https://pubmed.ncbi.nlm.nih.gov/33800552/ - Jiménez-García JD, Martínez-Amat A, De la Torre-Cruz MJ, et al. Suspension Training HIIT Improves Gait Speed, Strength and Quality of Life in Older Adults. Int J Sports Med. 2019;40(2):116-124.
https://pubmed.ncbi.nlm.nih.gov/30605922/ - Schoufour JD, Tieland M, Barazzoni R, et al. The Relevance of Diet, Physical Activity, Exercise, and Persuasive Technology in the Prevention and Treatment of Sarcopenic Obesity in Older Adults. Front Nutr. 2021;8:661449.
https://pubmed.ncbi.nlm.nih.gov/34109204/
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