Journal of Mid-life Health

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 12  |  Issue : 4  |  Page : 299--303

Lean body mass, body fat percentage, and handgrip strength as predictors of bone mineral density in postmenopausal women


Khatri Om Prakash1, Raghuveer Choudhary1, Govind Singh2,  
1 Department of Physiology, Dr. Sampurnanand Medical College, Jodhpur, Rajasthan, India
2 Department of Physical Medicine and Rehabilitation, Dr. Sampurnanand Medical College, Jodhpur, Rajasthan, India

Correspondence Address:
Dr. Govind Singh
House No 481, Ganesh Nagar, Niwaru Road, Jaipur - 302 012, Rajasthan
India

Abstract

Objective: This study was conducted to assess lean body mass, body fat percentage, and handgrip strength in the prediction of bone mineral density (BMD) in postmenopausal women. Materials and Methods: This cross-sectional study included 102 postmenopausal women aged between 45 and 80 years (mean age 58) who were screened for osteoporosis using a dual-energy X-ray absorptiometry scan at the lumbar spine. The lean body mass, body fat percentage, and handgrip strength were calculated. Results: The lean body mass, body fat percentage, and handgrip strength were having a positive association (correlation coefficient: 0.48, 0.29, and 0.3, respectively) with BMD. Conclusion: Lean body mass, body fat percentage, and handgrip strength can detect early loss of BMD in postmenopausal women leading to early screening for osteoporosis resulting in early interventions minimizing BMD loss over a much longer period after menopause.



How to cite this article:
Prakash KO, Choudhary R, Singh G. Lean body mass, body fat percentage, and handgrip strength as predictors of bone mineral density in postmenopausal women.J Mid-life Health 2021;12:299-303


How to cite this URL:
Prakash KO, Choudhary R, Singh G. Lean body mass, body fat percentage, and handgrip strength as predictors of bone mineral density in postmenopausal women. J Mid-life Health [serial online] 2021 [cited 2022 Jul 5 ];12:299-303
Available from: https://www.jmidlifehealth.org/text.asp?2021/12/4/299/336149


Full Text



 Introduction



Osteoporosis was defined as “a generalized bone disease characterized by a decreased bone mass and a deterioration of bone microarchitecture resulting in an increased fracture risk.”[1] For epidemiological purposes, osteoporosis has been defined as a bone mineral density (BMD) lower than − 2.5 standard deviation below the mean peak BMD in young healthy adults of the same gender, also known and expressed as the T-score.[2] BMD is used as a measurement tool for the early identification of individuals at high risk of a fracture related to osteoporosis.[3]

Estrogen deficiency after menopause is associated with an increase in bone turnover, resulting in bone mineral loss with increased chances of osteoporotic fracture.[4] Rapid loss of BMD occurs after menopause which is believed to average approximately 2%–3% every year.[5] Postmenopausal osteoporosis is associated with significant morbidity and mortality as a result of increased fragility fractures.[6]

As a consequence of menopause and aging, peak bone mass is reduced in women. A higher percentage of lean body mass boosts our metabolism serving as a protective factor against bone fractures. Maintaining body fat percentage at a certain level is essential for optimum functioning of the body. In postmenopausal women, the strength of muscles decreased leading to the inability of bones to withstand the biomechanical forces increasing fracture risk.[7]

Most studies report that either lean mass or fat mass is associated with bone mass,[8],[9],[10],[11],[12] whereas Harris et al. indicated that both fat mass and lean mass can equally serve as a predicting factor for BMD.[13] Kim et al. made an observation that lean mass was associated with BMD in both pre- and postmenopausal women.[14] Cheung et al. reported a strong concomitant decline in both muscle strength and BMD with advancing age.[15]

Owing to the presence of conflicting findings in the association of lean mass, fat mass, and muscle strength to BMD, in this study, we try to find out lean body mass, body fat percentage, and muscle strength as predictors of BMD in postmenopausal women.

 Materials and Methods



Study design

A total of 102 postmenopausal women aged between 45 and 80 years participated in this cross-sectional study conducted from September 2019 to August 2020. The inclusion criteria were women aged >45 years with a menopause duration of at least 1 year. Women with chronically debilitating conditions, having systemic disease affecting metabolism, having severely deformed or fractured spine, previous osteoporotic fracture, on long-term steroid therapy, and medications causing osteoporosis were excluded from the study. Enrollment in the study was done after taking written informed consent. The study was approved by the Institutional Ethics Committee. General demographic and relevant clinical history was taken.

Anthropometric and body composition measurement

Weight was measured in kilograms and height in centimeters using a standardized procedure. Body mass index (BMI) was calculated by standardized formula. The body fat % was calculated by using a formula that converts BMI into an estimate of body fat %:

Body fat % = (1.39 × BMI) + (0.16 × Age) − (10.34 × Gender) − 9

With gender equal to 1 for men and 0 for the woman (International Journal of Obesity and Related Metabolic Disorders in 2002). For calculating lean body mass, body fat percentage was subtracted from 100 to get the lean mass percentage and lean mass percentage was divided by 100 to calculate the decimal for lean mass percentage, and then lean mass decimal was multiplied with total body weight.

Bone mineral density measurement

BMD was measured using dual-energy X-ray absorptiometry at the lumbar spine as a mean of measured values from L1 to L4 spine and was analyzed using software, and the report was presented in the form of a T-score. Osteoporosis was defined as a T-score ≤2.5, low bone mass as T-score between −1.0 and −2.5, and normal as a T-score >−1.

Muscle strength measurement

The handgrip strength was measured with the help of the handgrip dynamometer to measure the maximum isometric strength of the hand and the muscle of the forearm. The subject was seated in a chair without armrests, with feet fully resting on the floor and the hips and knees positioned at approximately 90° with shoulder adducted with elbow flexed to 90° with the forearm in mid-prone position and wrist in 15° and 30° of extension and 0°–15° of ulnar deviation. Three successive measurements were taken, with a 15-s interval between them, selecting the best score out of the three measurements.[16]

Statistical analysis

The values of variables were calculated as a percentage, mean, and standard deviation. Correlation analysis of T-score with age, weight, height, body mass index, body fat percentage, lean body mass, and handgrip strength was done to obtain Pearson's correlation. Multiple linear regression analysis was used to obtain the predictors for the outcome variable. Associations were considered statistically significant at P < 0.05 level. All statistical analyses were performed using SPSS statistics version 26 (IBM Co., Armonk, NY, USA).

 Results



[Table 1] shows the baseline, anthropometric, and body composition characteristics of the 102 women studied. Among 102 postmenopausal women, 23.5% were normal, 46.1% had osteopenia, and 30.4% had osteoporosis, respectively, as per the WHO criteria. More than 75% of the study population was having low BMD (osteopenia and osteoporosis). In our study, low BMD was found in the early menopausal period up to 50 years and age >65 years. In our study, high BMI was associated with higher BMD values.{Table 1}

Women were categorized as par body fat percentage into underweight, healthy, overweight, and obese with prevalence of osteoporosis 6.5 % in underweight, 64.5 % in healthy, 22.6 % in overweight and 6.5 % in obese respectively. Body fat percentage was positively associated (correlation coefficient: 0.29) with BMD. As the body fat percentage is increased, T-score also increased suggesting a decreased prevalence of low mineral density, as shown in [Figure 1] plotted as a regression variable.{Figure 1}

The study population was divided into three categories as per lean body mass into <40, 40–45, and >45 with 35.5%, 45.2%, and 19.4% osteoporotic women, respectively, in each category with more than 80% values falling in below 45. The data suggest a positive correlation (correlation coefficient: 0.48) of lean body mass with BMD, as shown in [Table 2]. As shown in [Figure 2] plotted as regression variable, as the lean body mass is increased, T-score also increased so that the prevalence of low BMD is decreasing.{Figure 2}{Table 2}

The data on handgrip strength were divided into good, average, and poor, with 51.6% of women with poor handgrip. There was a positive correlation of BMD with handgrip strength (correlation coefficient: 0.30).

In [Figure 3] plotted as regression variable, as handgrip strength is increased, T-score also increased suggesting higher BMD in women with good handgrip strength.{Figure 3}

 Discussion



The results of this study show that there is a positive association between body fat percentage, lean body mass, and handgrip strength with BMD in postmenopausal women. Previous studies show an age-dependent decline in BMD, especially in elderly women due to cortical and trabecular bone loss.[17],[18],[19],[20] We also found a positive association between advanced age and the occurrence of osteoporosis. Previously, it was believed that women with low BMI are at increased risk of developing osteoporosis, but in our study, a higher body mass index was associated with high BMD which coincides well with recent studies showing overweight and obesity as protective factors against future osteoporotic fractures.[21],[22]

Epidemiological studies have suggested that body fat percentage may affect bone mass status, especially in the aged group. The effect of metabolically active adipose tissue on the bone or skeleton may be regulated by both weight-bearing and nonweight-bearing effects.[8],[9]

Previous studies have reported a positive association of obesity with bone mass, probably as a result of an increased level of hormones such as insulin, leptin, and estrogen that are known bone growth inducers and bone remodeling process inhibitors which coincides with our study findings showing strong positive association of body fat percentage with BMD.[23],[24],[25]

Lean mass is the strongest predictor of BMD in our study which coincides well with studies; higher lean body mass was associated with lower future fracture risk.[26],[27],[28] In this study, both lean mass and body fat percentage were predictors of BMD in comparison to studies showing either body fat percentage or lean mass as a predictor of BMD.

In this study, handgrip strength is associated with BMD which correlated well with a similar cross-sectional study confirming the association of poor handgrip strength as a predictor of future fracture risk.[15] These findings were supported by a cross-sectional study conducted among the Finnish postmenopausal women and documented a significant association between handgrip strength and hip fracture, a serious consequence of low BMD.[29]

The shortcomings of this study were its cross-sectional design and single-site BMD measurement. A long-duration follow-up study with a large number of subjects with three sites BMD measurement will further elaborate the findings of this study.

 Conclusion



Lean mass, body fat percentage, and handgrip strength parameters can detect early loss of BMD in postmenopausal women leading to early detection of osteoporosis resulting in early interventions minimizing BMD loss over a much longer period after menopause. Hence, it is recommended that postmenopausal women with low lean body mass, low body fat percentage, and low handgrip strength go through early screening for BMD loss and take therapeutic intervention to reduce future fracture risk.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1WHO. Assessment of fracture risks and its application to screening for postmenopausal osteoporosis. Report of a WHO Study Group. World Health Organ Tech Rep Ser 1994;843:1-129.
2Genant HK, Cooper C, Poor G, Reid I, Ehrlich G, Kanis J, et al. Interim report and recommendations of the World Health Organization task-force for osteoporosis. Osteoporos Int 1999;10:259-64.
3Marshall D, Johnell O, Wedel H. Meta-analysis of how well measures of bone mineral density predict occurrence of osteoporotic fractures. BMJ 1996;312:1254-9.
4Rachner TD, Khosla S, Hofbauer LC. Osteoporosis: Now and the future. Lancet 2011;377:1276-87.
5Khatoon N. Management of osteoporosis among post-menopausal women in a selected hospital of Delhi. Nurs J India 2013;104:112-6.
6Murphy FT, Kivitz AJ, Sands EE. Management of postmenopausal osteoporosis. J Am Osteopath Assoc 2003;103:S6-11.
7Zhou Z, Zheng L, Wei D, Ye M, Li X. Muscular strength measurements indicate bone mineral density loss in postmenopausal women. Clin Interv Aging 2013;8:1451-9.
8Hsu YH, Venners SA, Terwedow HA, Feng Y, Niu T, Li Z, et al. Relation of body composition, fat mass, and serum lipids to osteoporotic fractures and bone mineral density in Chinese men and women. Am J Clin Nutr 2006;83:146-54.
9Ho-Pham LT, Nguyen UD, Nguyen TV. Association between lean mass, fat mass, and bone mineral density: A meta-analysis. J Clin Endocrinol Metab 2014;99:30-8.
10Gnudi S, Sitta E, Fiumi N. Relationship between body composition and bone mineral density in women with and without osteoporosis: Relative contribution of lean and fat mass. J Bone Miner Metab 2007;25:326-32.
11Khosla S, Atkinson EJ, Riggs BL, Melton LJ 3rd. Relationship between body composition and bone mass in women. J Bone Miner Res 1996;11:857-63.
12Durnin JV, Womersley J. Body fat assessed from total body density and its estimation from skinfold thickness: Measurements on 481 men and women aged from 16 to 72 years. Br J Nutr 1974;32:77-97.
13Harris SS, Dawson-Hughes B. Weight, body composition, and bone density in postmenopausal women. Calcif Tissue Int 1996;59:428-32.
14Kim JH, Choi HJ, Kim MJ, Shin CS, Cho NH. Fat mass is negatively associated with bone mineral content in Koreans. Osteoporos Int 2012;23:2009-16.
15Cheung CL, Tan KC, Bow CH, Soong CS, Loong CH, Kung AW. Low handgrip strength is a predictor of osteoporotic fractures: Cross-sectional and prospective evidence from the Hong Kong osteoporosis study. Age (Dordr) 2012;34:1239-48.
16Sousa-Santos AR, Amaral TF. Differences in handgrip strength protocols to identify sarcopenia and frailty – A systematic review. BMC Geriatr 2017;17:238.
17Pande KC, Veeraji E, Pande SK. Normative reference database for bone mineral density in Indian men and women using digital X-ray radiogrammetry. J Indian Med Assoc 2006;104:288-91.
18Rao H, Rao N, Sharma LR. A clinical study of bone mineral density using heel ultradensitometer in Southern Maharashtra. Indian J Orthop 2003;37:9.
19Aaron JE, Makins NB, Sagreiya K. The microanatomy of trabecular bone loss in normal aging men and women. Clin Orthop Relat Res 1987;(215):260-71.
20Riggs BL, Melton LJ, Robb RA, Camp JJ, Atkinson EJ, McDaniel L, et al. A population-based assessment of rates of bone loss at multiple skeletal sites: Evidence for substantial trabecular bone loss in young adult women and men. J Bone Miner Res 2008;23:205-14.
21Asomaning K, Bertone-Johnson ER, Nasca PC, Hooven F, Pekow PS. The association between body mass index and osteoporosis in patients referred for a bone mineral density examination. J Womens Health (Larchmt) 2006;15:1028-34.
22Greco EA, Fornari R, Rossi F, Santiemma V, Prossomariti G, Annoscia C, et al. Is obesity protective for osteoporosis? Evaluation of bone mineral density in individuals with high body mass index. Int J Clin Pract 2010;64:817-20.
23Zhao LJ, Jiang H, Papasian CJ, Maulik D, Drees B, Hamilton J, et al. Correlation of obesity and osteoporosis: Effect of fat mass on the determination of osteoporosis. J Bone Miner Res 2008;23:17-29.
24Kim KC, Shin DH, Lee SY, Im JA, Lee DC. Relation between obesity and bone mineral density and vertebral fractures in Korean postmenopausal women. Yonsei Med J 2010;51:857-63.
25Gower BA, Casazza K. Divergent effects of obesity on bone health. J Clin Densitom 2013;16:450-4.
26Sotunde OF, Kruger HS, Wright HH, Havemann-Nel L, Kruger IM, Wentzel-Viljoen E, et al. Lean mass appears to be more strongly associated with bone health than fat mass in urban black South African women. J Nutr Health Aging 2015;19:628-36.
27Casale M, von Hurst PR, Beck KL, Shultz S, Kruger MC, O'Brien W, et al. Lean mass and body fat percentage are contradictory predictors of bone mineral density in pre-menopausal Pacific Island women. Nutrients 2016;8:470.
28Liu JM, Zhao HY, Ning G, Zhao YJ, Zhang LZ, Sun LH, et al. Relationship between body composition and bone mineral density in healthy young and premenopausal Chinese women. Osteoporos Int 2004;15:238-42.
29Kärkkäinen M, Rikkonen T, Kröger H, Sirola J, Tuppurainen M, Salovaara K, et al. Association between functional capacity tests and fractures: An eight-year prospective population-based cohort study. Osteoporos Int 2008;19:1203-10.