A comparison of hand-held isometric strength measurement with isokinetic muscle strength measurement in the elderly.

OBJECTIVE: To compare hand-held isometric muscle strength measurement to an isokinetic muscle strength measurement in a healthy elderly population. DESIGN: Cross-sectional survey. SETTING: Retirement community in Southeastern Arizona. PARTICIPANTS: Thirty-two volunteers (16 men and 16 women) age 60 and over (mean age 70.3 years) who were free of musculoskeletal problems and did not have significant health problems. INTERVENTIONS: None. MEASUREMENTS: Isometric muscle strength was determined using a hand-held isometric strength device (Penny and Giles) for elbow flexion and extension and knee flexion and extension. Isokinetic muscle strength (average peak torque and average work per repetition) was measured on the same individuals using a Lido isokinetic dynamometer. RESULTS: Correlations between the strength measurement techniques were generally favorable with the lowest correlation being .72, (95 percent confidence interval .50-.86) and the highest being .85, (95 percent confidence interval .72-.93). However, there was substantial variability of hand-held strength reading at some levels of isokinetic strength. CONCLUSIONS: Hand-held dynamometry for strength measurement correlates strongly with measurement of strength using isokinetic dynamometry. Despite these high correlations, there is remaining variability of hand-held muscle strength readings when compared with isokinetic strength measurement at some levels of isokinetic muscle strength. Modification of the testing methodology or instrumentation used in this study is needed to improve the consistency of these measurements.

The relationship between muscle mass and muscle strength in the elderly.

To determine the extent that muscle mass is predictive of muscle strength in the elderly, anthropomorphic estimates of muscle area and impedance measurements of muscle mass and peak isometric muscle strength were obtained in a relatively healthy older population over 65 years of age (mean age = 71.7; n = 218). Midarm muscle area correlated strongly with upper arm strength (r = 0.68, P less than 0.0001) while midthigh muscle area had a much lower correlation with thigh muscle strength (r = 0.29, P less than 0.0001). These muscle area calculations also include bone area. Lean body mass calculated by bioelectric impedance correlated highly with cumulative muscle strength measured by summing all muscle groups (r = 0.79, P less than 0.0001). To determine whether aging alters muscle strength per unit of muscle mass, additional middle-aged subjects were included, and three groups, middle-aged (55-64) (n = 78), young-old (65-74) (n = 161), and old-old (75+) (n = 57), were compared. A significant age-related trend of decreasing muscle strength per unit of lean body mass was noted. It is concluded that although muscle mass correlates with muscle strength in a healthy older population, use of simple age-independent clinical measurements of body mass should not be used to predict muscle strength.

The interrelationship between physical exercise, muscle strength and body adiposity in a healthy elderly population.

OBJECTIVE: To determine the relationship between habitual physical exercise and body adiposity in a healthy elderly population. RESEARCH DESIGN AND METHODS: Physical exercise was measured by a questionnaire previously adapted for use with the healthy elderly. The level of exercise was converted into calories expended over the previous 14 days and was divided into tertiles. Body adiposity was measured at six sites by anthropometry, and overall percent body fat was measured by bioelectric impedence. PARTICIPANTS AND SETTING: Two hundred and thirteen healthy ambulatory subjects over the age of 60 (116 females and 97 males) were recruited from a large retirement community in Southern Arizona. The mean age of the subjects was 70.0 years. RESULTS: Percent body fat was similar in men with different levels of physical activity (27.9% for lowest tertile of activity, 28.1% for middle tertile of activity, and 28.5% for highest tertile of activity). The corresponding values of percent fat in women was 38.0%, 36.0%, and 37%, respectively. There was a statistically significant increase in muscle strength measured in five muscle groups with a hand-held dynamometer with increasing levels of activity. CONCLUSIONS: These data indicate that level of physical exercise, over the range of 0 to 1,528 Kcal/day, does not predict body adiposity in the healthy elderly population. To decrease body fat without a change in dietary habits would require a more intensive exercise regimen than currently being undertaken by most healthy elderly people.

Platform motorized wheelchairs in congregate care centers: a survey of usage and safety.

A survey of residents was done in three congregate care facilities to determine the prevalence and safety of platform motorized wheelchairs (PMWs) otherwise known as three-wheeled motorized wheelchairs or scooters. Thirty-one drivers of these vehicles were identified, 30 of whom consented to be interviewed. The mean age of the drivers was 80.7 years and 84% were women. Arthritis was the most frequent reason for use of the PMW (47%), followed by neurologic problems (23%) and orthopedic problems (23%). Of this group, 77% had their PMW prescribed by a physician, most commonly an orthopedic surgeon (40%) with only 14% being prescribed by a geriatrician or physiatrist. Thirty percent of the drivers felt other drivers in their facility drove unsafely. Most residents (57%) had no training in the use of the vehicle and two admitted they had a medical condition that made it difficult to drive. Five accidents were reported, two of which involved either a serious injury or property damage. Based on the results obtained from this survey, we conclude that driver safety evaluation should be done on all users of PMWs in congregate care facilities.