Insulin resistance and muscle strength in older persons.
BACKGROUND
The functional consequences of an age-related insulin resistance (IR) state on muscle functioning are unknown. Because insulin is needed for adequate muscle function, an age-related insulin-resistant state may also be a determining factor. We evaluated the relationship between IR and handgrip muscle strength in men and women from a large population-based study (n = 968).


METHODS
The degree of IR was evaluated by the homeostasis model assessment (HOMA) and muscle strength was assessed using handgrip.


RESULTS
Simple sex-stratified correlations demonstrated that, in men, body mass index-adjusted handgrip strength correlated positively with physical activity (r = 0.321; p < .001), muscle area (r = 0.420; p < .001), muscle density (r = 0.263; p = .001), plasma albumin (r = 0.156; p = .001), insulin-like growth factor-1 (r = 0.258; p < .001), calcium (r = 0.140; p = .006), and testosterone (r = 0.325; p < .001) concentrations, whereas a negative association was found for age (r = -0.659; p < .001) and myoglobin plasma levels (r = -0.164; p =.001). In women, body mass index-adjusted handgrip strength correlated positively with physical activity (r = 0.280; p < .001), muscle area (r = 0.306; p < .001), muscle density (r = 0.341; p = .001), plasma albumin (r = 0.140; p =.001), and insulin-like growth factor-1 (r = 0.300; p < .001), whereas a negative association was found for age (r = -0.563; p < .001), myoglobin levels (r = -0.164; p = .001), and IR (r = -0.130; p = .04).


CONCLUSIONS
Sex-stratified analyses adjusted for multiple confounders showed that the relationship between IR and handgrip strength was found significant in women, whereas it was negligible and not significant in men.
Abbatecola
Angela M
AM
Department of Geriatric Medicine and Metabolic Diseases II, University of Naples, Italy.
Ferrucci
Luigi
L
Ceda
Gianpaolo
G
Russo
Cosimo R
CR
Lauretani
Fulvio
F
Bandinelli
Stefania
S
Barbieri
Michelangela
M
Valenti
Giorgio
G
Paolisso
Giuseppe
G
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000502:physiology*; D009211:Myoglobin / Q000097:blood; D012709:Serum Albumin / Q000032:analysis
D009211:Myoglobin; D012709:Serum Albumin; D007334:Insulin-Like Growth Factor I; D002118:Calcium