Date of Award
Master of Science
Dr. Greg Marsh
Leg muscle cross sectional area (CSA), isometric strength and contraction velocity were examined in a group of young (Y), old (O), and very old, (VO) women to investigate the effects of aging and sarcopenia among healthy women. Ten contiguous transverse MRI (3Telsa IMRIS Scanner) scans were done horizontal to the right leg and produced images of the upper 1/3 of the leg in seven Y (23±2y), five O (65±4y) and six VO (76±3y) women. Maximal voluntary isometric contraction (MVC) torque and maximal contraction velocity (at a fixed load of -IN m ) of the dorsiflexors and plantar flexors were determined using a Biodex dynamometer. To determine normalized strength, MVC torque was expressed relative to muscle cross sectional area (CSA).
Anterior compartment CSA was -27% and -19% less in the VO compared with the Y and O, respectively, but there was no significant difference between the Y and O women (-7% less in O). The VO had a -16% lower dorsiflexor MVC torque than the Y, but neither group differed significantly from the O women. No significant differences existed among groups for normalized dorsiflexor strength. Maximal voluntary contraction velocity was -15% less in the VO than the Y with no other significant group differences.
In the posterior compartment, CSA was -25% less in the VO compared with the Y, but the O did not significantly differ from either Y or VO (-16%, -10% less than O respectively). Similarly, plantar flexor MVC torque was -32% less in the VO compared with the Y women but not different between Y and O, or O and VO. Normalized plantar flexor strength was equivalent among the groups. The VO were 13% slower than the Y for plantar flexor maximal contraction velocity with no other significant differences between groups.
Lower maximal strength observed in the dorsiflexors and plantar flexors of the VO women was accounted for by an age-related decrease in muscle mass. Contraction velocity did not slow until the 8th decade of life and was similar for both the dorsiflexor and plantar flexor muscle groups which suggests that leg muscle strength is well preserved.
Barnett, Marcus R., "RELATIONSHIPS AMONG SARCOPENIA, STRENGTH AND AGEING IN HEALTHY ADULT WOMEN" (2011). Digitized Theses. 3753.