Biomedical subjects

M E Cress

Publications and source records attributed to M E Cress.

5 recordsLinked to original sources

PubMed1995

From muscle properties to human performance, using magnetic resonance.

Our goal is to show how muscle properties can be used to understand the exercise performance limitations of the elderly. We show that magnetic resonance (MR) imaging and spectroscopy are useful for noninvasively characterizing the structural and energetic properties of muscle in vivo. Determination of muscle volume and cross-sectional area is easily and rapidly accomplished by applying quantitative morphometric methods to MR images. New MR spectroscopic techniques provide a noninvasive "biopsy" of the oxidative, glycolytic, and contractile capacities of muscle fibers. We show how the structural and energetic properties measured by MR can be used to define the functional capacity of muscle and the contribution of this capacity to the performance of the whole body (e.g., VO2max). Finally, we relate these laboratory measures of muscle properties and performance to activities meaningful to the functioning of the elderly in everyday life, such as sustained walking and stair climbing.

Activities of Daily Living↗

PubMed1995

Relationship between physical performance and self-perceived physical function.

OBJECTIVE: The objective of this study was to compare two methods of measuring physical function in subjects with a broad range of abilities and to evaluate the effects of cognitive, social, educational, and age factors on the relationship between the two methods. DESIGN: Multiple regression analysis was used to compare self-perceived (dependent variables) with performance measures (independent variables). Covariates included age, gender, Mini-Mental State Exam score, education, living status, and depression score. SETTING: Five community-dwelling and two nursing home sites. PARTICIPANTS: 417 community-dwelling subjects and 200 nursing home residents aged 62-98 years. MEASUREMENTS: Self-perceived physical function was assessed with the physical dimension summary score of the Sickness Impact Profile, which comprises three subscales: ambulation, mobility, and body care and movement. Physical performance was evaluated by self-selected gait speed, chair-stand time, maximal grip strength, and a balance score. RESULTS: Nursing home residents and community-dwellers were significantly different (P < .0001) in all variables except age and gender. Self-perceived and performance-based measures were moderately correlated, with a range from r = -.194 to r = -.625 (P < .05). Gait speed was the strongest independent predictor of self-perceived physical function in both groups. Symptoms of depression were also an independent predictor of self-perceived function in nursing home residents; subjects who had such symptoms report more self-perceived dysfunction than would be predicted based on performance tests. CONCLUSIONS: Self-selected gait speed is a global indicator of self-perceived physical function over a broad range of abilities. External determinants (depressive symptoms, cognitive function, marital status, etc.) affect self-perceived function in both groups, but gait speed is the greatest single predictor of self-perceived function. In nursing home residents depressive symptomatology is related to self-perceived.

Activities of Daily Living↗

PubMed1994

Isokinetic testing of ankle strength in older adults: assessment of inter-rater reliability and stability of strength over six months.

The study purposes were (1) to estimate the inter-rater reliability of isokinetic strength tests at the ankle in older adults (test-retest interval of three to 7 days), and to determine whether more experienced examiners were more reliable; and (2) to estimate 6 month stability of strength tests. Inter-rater reliability was high for plantar flexion and dorsiflexion tests where average strength was more than about 10 Newton-meters (Nm) (Pearson R = 0.87-0.95). When average strength was less than 10Nm, reliability was less (R = 0.42-0.75). Experienced examiners (physical therapists) and less experienced examiners (research assistants) were equally reliable. Variability in strength over 6 months was no greater than variability over a few days. We conclude that isokinetic tests of ankle strength in older adults are highly reliable and stable when examiners are adequately trained and subjects maintain usual physical activity levels.

Aged↗

PubMed1992

Changing affordances in stair climbing: the perception of maximum climbability in young and older adults.

This experiment extended Warren's leg-length model by investigating the relevance of leg strength and joint flexibility on perceptual judgments of climbability. From a set of 8 stairs (riser heights: 38-91 cm), 24 older and 24 young adults were asked to identify the highest stair they could climb without using their hands or knees. Ss then attempted to climb the selected stair. Tall and short young observers perceived similar action boundaries despite leg-length differences. Tall and short older adults had divergent action boundaries when a single-scale leg-length model was applied. A regression model that used flexibility and leg-strength measurements provided a better fit of the older adult data, indicating that models applying functional (kinematic and kinetic) criteria might be useful in describing lawful relationships between organisms and the environment.

Adult↗

PubMed1991

Effect of training on VO2max, thigh strength, and muscle morphology in septuagenarian women.

The purpose of this study was to determine the effects of a long-term (50 wk) combined aerobic-resistance training program on maximal oxygen consumption (VO2max, thigh strength, and vastus lateralis fiber morphology in healthy septuagenarian women (mean age = 72 +/- 6 yr). Subjects volunteered to be in either an exercise (Ex; N = 17) or control (Con; N = 10) group. Con subjects were 34% less active in winter than in summer, Ex subjects maintained their summer activity level on exercise days in winter. Initial, intermediate (20 wk), and final (50 wk) measurements were made for isokinetic knee extension/flexion strength; VO2max and morphological measurements from a muscle biopsy were made at the initial and final times only. Both groups gained in leg strength (Ex = +6.5%; Con = +7.8%; P less than or equal to 0.05) during the summer; in the winter the Ex group maintained leg strength and the Con group declined 12.2% (P less than or equal to 0.05). The fast-twitch muscle fiber area (Type IIb) increased 29% (P less than or equal to 0.001) in the Ex group and declined 26% (P = 0.014) in the Con group. VO2max increased only in the Ex group (16%; P less than 0.001). We conclude that healthy septuagenarian women can increase aerobic capacity, leg strength, and Type IIb muscle fiber area with a long-duration, combined aerobic-resistance exercise program.

Aged↗