Magnesium and muscle performance in older persons: the InCHIANTI study

Abstract

Background: The role of magnesium in maintaining muscle integrity and function in older adults is largely unknown.

Objective: We aimed to investigate the relation between serum magnesium concentrations and muscle performance in older subjects.

Design: Data are from the baseline examination conducted between September 1998 and March 2000 of the InCHIANTI (aging in the Chianti area) study, a prospective epidemiologic survey of risk factors for late-life disability. From among 1453 randomly selected community residents completing a home interview, 1138 men (46%) and women (aged 66.7 +/- 15.2 y; x +/- SD) with complete data on muscle performance and serum magnesium who were not severely cognitively compromised and had no evidence of kidney disease or hypercalcemia were included in the analysis. Muscle performance was evaluated by grip strength, lower-leg muscle power, knee extension torque, and ankle extension isometric strength and was normalized for age and body mass index (BMI) within each sex.

Results: After adjustment for age, sex, BMI, laboratory variables, presence of chronic diseases, muscle area, muscle density, and physical activity level, serum magnesium concentrations were significantly associated with indexes of muscle performance, including grip strength (beta = 2.0 +/- 0.5, P = 0.0002), lower-leg muscle power (beta = 8.8 +/- 2.7, P = 0.001), knee extension torque (beta = 31.2 +/- 7.9, P < 0.0001), and ankle extension strength (beta = 3.8 +/- 0.5, P < 0.0001).

Conclusions: The serum magnesium concentration is an independent correlate of muscle performance in older persons. Whether magnesium supplementation improves muscle function remains to be shown.

Figures

Figure 1

Scatterplots describing the relations of serum magnesium and maximum handgrip strength (r = 0.08, P < 0.05), lower-extremity (LE) muscle power (r = 0.06, p = NS), knee extension torque (r = 0.10, P = 0.01), and ankle extension isometric strength (r = 0.19, P < 0.0001) in men (; n = 523) and women (●; n = 615) who participated in the InCHIANTI study. To convert mg/dL to mmol/L, multiply by 0.411. Pearson’s correlation coefficients were used to analyze the linear correlations between muscle function and serum magnesium.

Figure 2

Mean (±SE) isometric muscle strength measurements [handgrip strength, lower-extremity (LE) muscle power, knee extension torque, and ankle extension isometric strength] according to serum magnesium concentrations. Tertile 1 is the lowest tertile, tertile 2 is the intermediate, and tertile 3 is the highest. To convert mg/dL to mmol/L, multiply by 0.411. Bars with different letters are significantly different, P < 0.05 (ANOVA followed by Tukey’s multiple-comparisons test). P values in the figure correspond to P for trend.