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Community-based rehabilitative exercise programs might be an effective means to improve functional outcomes for hip-fracture patients. The purpose of this study was to evaluate the effectiveness of a community exercise program (CEP) for older adults recovering from hip fracture. Twenty-five older adults (mean age 80.0 +/- 6.0 years; 24 women; 71 +/- 23 days post-hip fracture) participated in this pilot study (17 exercise, 8 control). The CEP involved functional stepping and lower extremity-strengthening exercises. Control participants received only standard outpatient therapy. Measures of functional mobility, balance confidence, falls efficacy, lower extremity strength, and daily physical activity were evaluated at baseline and at 16 weeks. Improvements for self-reported physical activity, mobility, balance, and knee-extensor strength were observed for the CEP group. This study demonstrated that a CEP is beneficial for community-dwelling older adults post-hip fracture.

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 degrees/s (CON), 0 degrees/s, and -90 degrees/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.

The authors compared heart-rate and blood-pressure responses to typical isometric (ISO) and isokinetic (90 degrees /s) eccentric (ECC) resistance-training protocols in older adults. Twenty healthy older adults (74 +/- 5 years old) performed randomly ordered ISO and isokinetic ECC exercise (3 sets of 10 repetitions) at a target intensity of 100 % of their peak ISO torque value. Heart rate and systolic (SBP) and diastolic (DBP) blood pressures were recorded continuously, and mean arterial pressure (MAP) and rate-pressure product (RPP) were calculated. ECC peak torque (139 +/- 33 N. m) was significantly greater than ISO peak torque (115 +/- 26 N. m; p <.001). All variables increased significantly (p <.001) during both ISO and ECC exercise. Changes in SBP, DBP, MAP, and RPP were significantly greater during ISO exercise than during ECC exercise (p <.001). Clinically, an isokinetic ECC exercise program enables older adults to work at the same torque output with less cardiovascular stress than ISO exercise.

Maximum concentric (CONC) and eccentric (ECC) strength of the ankle plantar flexor muscles were compared between middle-aged adults who regularly participated in resistance exercise training versus those who participated in weight-bearing endurance exercise. A total of 40 men and women with a mean age of 48.9 years (SD = 5.3) were tested for CONC and ECC plantar flexor (PF) strength, using an isokinetic device at 3 velocities: 30, 90 and 180 degrees/s. Mean strength values for the groups of men and women involved in resistance exercise were consistently higher than those involved in the endurance training for the CONC tests, where values ranged from 35% to 46% (avg. 41%, p < .01), but less between-group difference was observed for the ECC loading condition: 4% to 30% (avg. 18%). Thus ECC/CONC ratios, which rose with increasing velocity, were consistently higher for the endurance group vs. resistance-trained. Finally, since concentric PF torque values were found to be quite low for the middle-aged women who did only endurance training, this movement may require preventive strengthening exercises.

Decrements in isometric and concentric (Conc) muscular strength with increased age are well documented. However, little information is available on the effects of aging on eccentric (Ecc) strength, even though Ecc or lengthening muscle actions are used in most physical activities. This study examined Conc and Ecc peak torques (PT) during knee extension at 90 degrees/sec in healthy older (62 to 89 yrs) and younger (20 to 29 yrs) men and women. Conc PT decreased more with age than did Ecc (p < 0.01), for both men and women. PT values for the older men and women as a percentage of those of the younger ones were 58.3 and 46.6% for Conc, and 75.1 and 61.7% for Ecc, respectively. These age differences need to be considered during isokinetic evaluations of Conc versus Ecc strength. Other muscle groups should be investigated, and mechanisms remain to be determined.

This review briefly summarizes the current state of knowledge regarding age related changes in skeletal muscle, followed by a more in-depth review of ageing effects on animal and human motor units (MUs). Ageing in humans is generally associated with reductions in muscle mass (atrophy), leading to reduced voluntary and electrically evoked contractile strength by the 7th decade for most muscle groups studied. As well, contraction and one-half relaxation times are typically prolonged in muscles of the elderly. Evidence from animal and human studies points toward age associated MU loss as the primary mechanism for muscle atrophy, and such losses may be greatest among the largest and fastest MUs. However, based on studies in animals and humans, it appears that at least some of the surviving MUs are able to partially compensate for MU losses, as indicated by an increase in the average MU size with age. The fact that muscles in the elderly have fewer, but on average larger and slower, MUs has important implications for motor control and function in this population.