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Background. Many older individuals decline functionally during hospitalization, and the deleterious consequences of bed rest may be one cause. This study reports on the effect of 10 days of bed rest on multiple functional parameters in healthy older adults. Methods. Healthy older men and women (n = 11, 67 [+ or -] 5 years old) remained on bed rest for 10 days continuously, and consumed a eucaloric diet providing the Recommended Dietary Allowance for protein. Measures of lower extremity strength and power, aerobic capacity and physical performance, as well as physical activity were performed before and after bed rest. Results. All measures of lower extremity strength were significantly lower after bed rest including isotonic knee extensor strength (-13.2 [+ or -] 4.1%, p = .004) and stair-climbing power (-14 [+ or -] 4.1%, p = .01). Maximal aerobic capacity was 12% lower after bed rest (p = .04), whereas measures of physical performance (Short Physical Performance Battery, and a five-item physical performance test) were not significantly different. Voluntary physical activity decreased after bed rest, and the percentage of time spent inactive increased (7.6 [+ or -] 1.8%, p = .004). There were no medical complications. Conclusions. In healthy older adults, 10 days of bed rest results in a substantial loss of lower extremity strength, power, and aerobic capacity, and a reduction in physical activity, but has no effect on physical performance. Identification of interventions to maintain muscle function during hospitalization or periods of bed rest in older adults should be a high priority. Key Words: Aging--Geriatric--Bed rest--Strength Power--Aerobic capacity--Function.

Background. The aim of the present study was to compare the changes in voluntary strength (isometric, concentric, and eccentric) and functional mobility in response to maximal isokinetic eccentric-only resistance training to those elicited by maximal isometric-only or maximal isokinetic concentric-only resistance training in older adults. Methods. Twelve women (73 [+ or -] 7 years) and 18 men (73 [+ or -] 5 years) completed a 12-week training program (three times per week) using a Biodex System 3 dynamometer. Primary outcome measures included peak isometric and isokinetic (concentric and eccentric) knee extensor strength, concentric work, concentric power, stair ascent and descent, and gait speed. Participants were randomly assigned to one of three training groups: isometric-only, isokinetic concentric-only, or isokinetic eccentric-only. Results. All three training groups demonstrated an increase in peak isometric and isokinetic concentric and eccentric strength following 12 weeks of training (p < .01). Step time was positively influenced (p < .03) by all three training modes; however, gait speed was unchanged following 12 weeks of training. All three training groups experienced a significant increase in peak concentric work and concentric power (p < .01) with the concentric training group demonstrating the largest increases in both peak concentric work and concentric power when compared to the isometric and eccentric training groups. Conclusions. It was clear that all three resistance training programs (isometric, concentric, and eccentric) in older adults were effective in increasing strength, concentric work, and concentric power over the 12-week training period. Furthermore, 12 weeks of resistance training resulted in improved stair ascent and descent performance.

Background. The purposes of the current study were (a) to determine the test--retest reliability of a single-session isokinetic and isometric strength testing protocol in older healthy men, and (b) to compare the outcomes of the reliability measures derived from averaged torque scores with those derived from a single peak torque score. Methods. In 19 men (mean age, 72 [+ or -] 5 years), both lower limbs were assessed independently on 2 separate test days using the Biodex System 3 dynamometer. After completing a 5-minute warm-up, each man performed three submaximal knee extensions followed by five maximal contractions at 90[degrees]/s (CON), 0[degrees]/s (ISO), and -90[degrees]/s (ECC). Average (best 3 of 5) and peak CON, ISO. and ECC torque, and CON work and CON power were determined. Peak CON work and CON power were recorded from the highest peak torque concentric contraction (HPTCC). Results. Intraclass correlation coefficients ranging from 0.84 to 0.94 were found to have good reliability. The typical error as a coefficient of variation ranged from 8% to 10% for averaged measures and from 8% to 17% for peak torque and HPTCC. The ratio limits of agreement for average and peak CON, ISO, and ECC torque ranged from 23% to 33% and from 40% to 54% for average CON and HPTCC work and power. Conclusions. The test-retest reliability of a single-session isokinetic and isometric strength testing protocol in this group of older healthy men displayed good relative reliability (intraclass correlation coefficient > 0.84); however, because the typical error as a coefficient of variation and ratio limits of agreement (absolute reliability) were large, single-session testing is not recommended.

The effects of increased muscle temperature via continuous ultrasound prior to a maximal bout of eccentric exercise were investigated on the symptoms of delayed onset muscle soreness (DOMS) of the elbow flexors. Perceived muscle soreness, upper arm circumferences, range of motion (ROM), and isometric and isokinetic strength were measured over 7 days on 14 college-aged men (n = 6) and women (n = 8). Ten minutes of continuous ultrasound (ULT) or sham-ultrasound (CON) were administered. Muscle temperature was measured in the biceps brachii of both arms. Muscle temperature increased by 1.79[degrees] [+ or -] 0.49[degrees]C (mean [+ or -] SD) in the experimental arm of the ULT group. Muscle soreness was induced by a single bout of 50 maximal eccentric contractions. The ULT group did not differ significantly (p < 0.05) from the CON group with respect to perceived muscle soreness, upper arm circumference, ROM, and isometric and isokinetic strength. In conclusion, increased muscle temperature failed to provide significant prophylactic effects on the symptoms of DOMS. KEY WORDS. muscle soreness, eccentric exercise, ultrasound, DOMS prevention

Because of the need for efficient, consistent strength measurements, the test-retest reliability of concentric, isometric, and eccentric strength; concentric work; and concentric power was determined in older women without a familiarization session. The reliability of measures derived from a single peak score were compared with those derived from an averaged score. On 2 occasions 25 older women with a mean age of 72 ± 6 years performed 3 submaximal knee extensions and 5 maximal contractions on an isokinetic dynamometer at 90°/s (CON), 0°/s, and -90°/s on both lower limbs. Statistical analyses for peak and averaged values (best 3 contractions of 5) exhibited good relative reliability (ICCs > .88), except for CON power. Typical error as a coefficient of variation and ratio limits of agreement for peak and averaged score values were larger than desired, with CON power scores demonstrating unacceptable error ranges. Although relative reliability of this 1-session assessment protocol was acceptable, further research is needed to determine whether additional practice trials could enhance absolute reliability. [ABSTRACT FROM AUTHOR]

The process of aging is associated with numerous changes in all bodily systems that ultimately manifest in a decline in peak physiologic function. Preservation of functional ability in advanced age is predicated on maintenance of the 4 components of fitness—cardiorespiratory endurance, muscular strength and endurance, flexibility, and body composition—each of which show changes with aging that adversely impact functional ability. A requisite awareness and understanding of the effects of aging on the components of fitness and understanding of the role of exercise as intervention is of paramount importance. This review presents underlying changes and adaptations within each component of fitness and the effects on overall physiologic capacity from the more overt changes underlying declining aerobic capacity, pulmonary function, and flexibility, to the more latent changes such as demineralization of bone leading to changes in body composition and the contraction-specific decline in the force generating capacity of skeletal muscle. Because exercise and physical activity have been shown to attenuate or delay many of the age-related changes in the components of fitness, recommendations and guidelines for exercise prescription are offered in the context of the these changes. [ABSTRACT FROM AUTHOR]