RELATIONSHIP OF 25-HYDROXYVITAMIN D, REGIONAL MUSCLE MASS AND HANDGRIP STRENGTH IN ELDERLY PEOPLE Vaidile Strazdiene , Vidmantas Alekna , Marija Tamulaitiene , Asta Mastaviciute 1
1,2
2
2
1 State Research Institute Centre for Innovative Medicine, 2 Vilnius University Faculty of Medicine, Vilnius, Lithuania
OBJECTIVE
The aim of this study was to investigate the association of serum 25-hydroxyvitamin D (25(OH)D3) level with skeletal muscle mass and strength.
BACKGROUND The vitamin D deficiency is common in the elderly population [1]. It is known that vitamin D plays an important role in bone and mineral metabolism, but many others effects on health has been discovered over the past ten years. Vitamin D receptors have been identified on many other tissues including skeletal muscle [2]. Mechanisms underlying the effect of vitamin D on muscle strength are not fully understood but could be related to an independent effect on muscle mass, or alternatively, to enhancement of muscle function me-
diated through the effect of vitamin D. The vitamin D deficiency has been associated with muscle mass and strength, although evidence is conflicting. Some studies demonstrating an association [3-5], others finding no relationship between vitamin D levels and muscle function [6,7].
MATERIAL AND METHODS This was a cross-sectional study on elderly (60 years and older) people who had consecutively visited the National Osteoporosis Center (Vilnius, Lithuania) and agreed to participate. The local Ethics Committee approved the study protocol. Written informed consent was obtained from all participants. The data of medical history were obtained and physical examination was performed. All participants were community dwelling and ambulatory. Exclusion criteria were conditions and medications known to affect muscle metabolism or taking any vitamin D supplements. Subjects who have sustained bone fracture during the last 12 months were also excluded from study. Serum 25-hydroxyvitamin D (25(OH)D3) and parathyroid hormone (PTH) was measured by automated immunoassay (Cobas E411, Roche Diagnostic). Blood sampling was performed from 8 till 11 a.m., after fasting for at least 12 hours. DXA was used to measure skeletal muscle mass (iDXA,
GE Lunar). All subjects performed three maximum attempts for dominant handgrip strength measurements with handle dynamometer and the mean value of these trials was recorded in kilogram (kg). The statistical analysis was performed using SPSS software for Windows (version 18.0). Because of differences in muscle strength between men and women, we stratified analysis by gender. Quartiles of vitamin D were created based on men and women combined so that comparable vitamin D metabolite levels could be studied for each gender separately. After testing for normality and equality of variance of the distribution, the significance of difference between vitamin D levels was tested by one-way analysis of variance (ANOVA). Simple correlations were determined using Spearman’s correlation coefficient. All p-values less than 0.05 were considered as statistically significant.
RESULTS
A total of 354 participants were included in this study: 151 men (72.9±8.0 years; range 60-95 years) and 203 women (72.3±7.6 years; range 60-89 years). Table 1 lists the demographic, clinical and laboratorial data of study participants according to gender.
Table 4. Correlations between vitamin D, body composition characteristics, handgrip strength and parathormone in women Characteristics, units of measurement
Table 1. Demographics, clinical and laboratorial characteristics according to gender Characteristic, units of measurement
Men (n=151)
Women (n=203)
p value
Age, years
63.4±13.2
62.4±15.2
0.53
Handgrip strength, kg
37.8±12.3
18.2±7.8
<0.001
Appendicular mass, kg
25.9±4.1
18.6±3.7
<0.001
Lean mass, kg
56.4±7.2
41.7±6.3
<0.001
Arms muscle mass, kg
7.4±1.4
4.7±1.3
<0.001
Legs muscle mass, kg
18.5±2.9
13.9±2.6
<0.001
Vitamin D, ng/ml
14.0±7.6
12.9±8.5
0.22
PTH, pg/ml
50.3±24.7
50.5±20.4
0.94
Data are presented as mean ± SD; p values were calculated by using T test of equality.
Vitamin D r
p value
Handgrip strength, kg
0.23
0.001*
Appendicular mass, kg
0.04
0.57
Lean mass, kg
0.08
0.91
Arms muscle mass, kg
0.05
0.50
Legs muscle mass, kg
0.03
0.67
Parathormone
-0.24
0.001*
Table 5. Correlations between vitamin D, body composition characteristics, handgrip strength and parathormone in men Characteristics, units of measurement
Vitamin D r
p value
We haven‘t found significant differences of serum vitamin D values between men and women (14±7.6 ng/ ml and 12.9±8.5 ng/ml, respectively). Handgrip strength values were higher in men, comparing with women (37.8±12.3 kg and 18.2±7.8 kg respectively, p<0.001). Lean mass was also higher in men (56.4±7.2 kg and 41.7±6.3 kg respectively, p<0.001).
Handgrip strength, kg
0.14
0.84
Appendicular mass, kg
0.22
0.007*
Lean mass, kg
0.16
0.04*
Arms muscle mass, kg
0.17
0.03*
Table 2. Demographics, clinical and laboratorial characteristics by vitamin D level in men
Legs muscle mass, kg
0.25
0.002*
Parathormone
-0.29
<0.001*
Characteristics, units of measurement
Vitamin D quartiles
p value
1 (n=42)
2 (n=34)
3 (n=37)
4 (n=38)
Age, years
76.1±8.7
73.0±6.9
71.6±8.0
70.4±7.1
0.09
Handgrip strength, kg
27.2±11.2
33.2±9.1
33.0±10.3
32.2±10.8
0.04
Appendicular mass, kg
22.8±3.5
25.3±3.4
24.7±3.8
25.0±3.7
0.01
Lean mass, kg
51.5±6.5
56.1±6.3
54.3±6.7
54.5±6.5
0.02
Arms muscle mass, kg
6.3±1.1
7.1±1.0
6.8±1.2
6.9±1.1
0.02
Legs muscle mass, kg
16.5±2.5
18.1±2.4
17.9±2.7
18.2±2.8
0.01
PTH, pg/ml
64.4±24.1
54.1±22.6
46.8±17.8
44.2±14.5
0.001
Data are presented as mean ± SD; p values were calculated by using ANOVA test.
The analysis of data revealed the correlation of 25-hydroxyvitamin D level with total lean mass (r=0.2, p=0.04), legs muscle mass (r=0.3, p=0.002), and arms muscle mass (r=0.2, p=0.03) in men. There was no such correlation in women. We have found association between 25-hydroxyvitamin D and handgrip strength in women only (r=0.2, p=0.01).
CONCLUSION
This study showed that 25-hydroxyvitamin D is positively associated with regional muscle mass in men and muscle strength in women.
Data are presented as mean ± SD; p values were calculated by using ANOVA test.
Table 3. Demographics, clinical and laboratorial characteristics by vitamin D level in women Characteristics, units of measurement
Vitamin D quartiles
p value
1 (n=42)
2 (n=34)
3 (n=37)
4 (n=38)
Age, years
76.7±7.4
73.4±7.9
70.2±6.2
69.0±6.5
<0.001
Handgrip strength, kg
12.5±6.5
13.8±7.9
15.9±5.5
15.9±5.5
0.02
Appendicular mass, kg
18.2±3.8
18.0±3.1
18.3±3.3
18.0±2.5
0.98
Lean mass, kg
40.5±5.6
40.7±5.2
40.2±5.8
40.3±4.7
0.97
Arms muscle mass, kg
4.7±1.6
4.4±0.8
4.7±1.4
4.6±0.7
0.72
Legs muscle mass, kg
13.5±2.5
13.6±2.4
13.6±2.2
13.5±2.0
0.99
PTH, pg/ml
59.6±25.8
54.8±23.4
50.2±17.8
48.0±16.2
0.01
Data are presented as mean ± SD; p values were calculated by using ANOVA test.
ACKNOWLEDGMENTS We are grateful to the staff of National Osteoporosis Center and especially to Elvyra Stapcinskiene, Edita Merkeliuniene and Audrone Misiunaite for their contribution to the survey.
REFERENCES 1. Holick MF. Vitamin D status: measurement, interpretation, and clinical application. Ann Epidemiol 2009; 19:73–78. 2. Bischoff HA, Borchers M, Gudat F, Duermueller U, Theiler R, Stahelin HB, Dick W. In situ detection of 1, 25 dihydroxyvitamin D3 receptor in human skeletal muscle tissue. Histochem J 2001;33:19–24. 3. Visser M et al. Low vitamin D and high parathyroid hormone levels as determinants of loss of muscle strength and muscle mass (sarcopenia): the Longitudinal Aging Study Amsterdam. J Clin Endocrinol Metab. 2003; 88: 5766-5772. 4. Pfeifer M, Begerow B, Minne HW, et al. Vitamin D status, trunk muscle strength, body sway, falls, and fractures among 237 postmenopausal women with osteoporosis. Exp Clin Endocrinol Diabetes. 2001; 109: 87-92. 5. Gerdhem P, Ringsberg KA, Obrant KJ, et al. Association between 25-hydroxyvitamin D levels, physical activity, muscle strength and fractures in the prospective population-based OPRA Study of Elderly Women. Osteoporos Int. 2005; 16:1425-1431. 6. Houston DK, Cesari M, Ferrucci L, et al. Association between vitamin D status and physical performance: the InCHIANTI study. J Gerontol A Biol Sci Med Sci. 2007; 62(4): 440-446. 7. Verreault R, Semba RD, Volpato S, et al. Low serum vitamin D does not predict new disability or loss of muscle strength in older women. J Am Geriatr Soc 2002; 50: 912-917.
*Contact address: vaidile.strazdiene@osteo.lt