Determinants of lower-body muscle power in early postmenopausal women.
OBJECTIVE
To investigate the association between muscle size, density, and fiber composition; body composition; maximal isometric knee extension strength (KES); and lower-body muscle power in healthy postmenopausal women.


METHODS
Cross-sectional analysis of baseline data from a 1-year randomized controlled experiment.


METHODS
University-based research laboratory.


METHODS
Seventy-eight healthy postmenopausal women aged 50 to 57.


METHODS
Maximal lower-body muscle power was assessed using vertical jump height (VJH). Maximal isometric KES was measured on a dynamometer chair. Computed tomography scans were used to determine lean-tissue cross-sectional area and density of the thigh and lower leg muscles. Relative area occupied by type I, IIa, IIax, and IIx muscle fibers was assessed from the vastus lateralis muscle. lean body mass and total body fat mass were assessed using bioelectrical impedance.


RESULTS
High VJH was associated with low body fat mass, high KES, and high density of thigh and lower leg muscles. Multivariate linear regression modeling revealed that high thigh muscle density (beta=0.242; P=.019), relative area occupied by the fastest muscle fiber types (IIax+IIx; beta=0.246; P=.007), KES (beta=0.247; P=.007), and low body fat mass (beta=-0.455; P<.001) were independently associated with high VJH, accounting for 45% of the variability in VJH.


CONCLUSIONS
This study showed that thigh muscle composition, muscle strength, and body fat mass are important determinants of lower-body muscle power production during weight-bearing activity in healthy postmenopausal women.
Sipilä
Sarianna
S
Department of Health Sciences, Central Hospital, University of Jyväskylä, Jyväskylä, Finland. sarianna.sipila@sport.jyu.fi
Koskinen
Satu O A
SO
Taaffe
Dennis R
DR
Takala
Timo E S
TE
Cheng
Sulin
S
Rantanen
Taina
T
Toivanen
Jarmo
J
Suominen
Harri
H
D000368:Aged; D001707:Biopsy, Needle; D001823:Body Composition; D001827:Body Height; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D016189:Dystrophin / Q000032:analysis; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007537:Isometric Contraction; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008875:Middle Aged; D015999:Multivariate Analysis; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000166:cytology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D017698:Postmenopause / Q000502:physiology*; D014057:Tomography, X-Ray Computed
D016189:Dystrophin