Background: Aging skeletal muscle is characterized not only by a reduction in size (sarcopenia) and strength but also by an increase in fatty infiltration (myosteatosis). An effective countermeasure to sarcopenia is resistance exercise; however, its effect on fatty infiltration is less clear. Objective: To examine in resistance-trained older persons whether muscle attenuation, a noninvasive measure of muscle density reflecting intramuscular lipid content, is altered with training status. Methods: Thirteen healthy community-dwelling men and women aged 65–83 years (body mass index 27.0 ± 1.2, mean ± SE) had computed-tomography scans of the mid-thigh performed following 24 weeks of training, 24 weeks of detraining, and 12 weeks of retraining. Training and retraining were undertaken twice weekly for several upper- and lower-body muscle groups. Skeletal muscle attenuation in Hounsfield units (HU) as well as mid-thigh muscle volume was obtained for the quadriceps and hamstrings. Muscle strength was assessed by 1-repetition maximum and physical function by a battery of tests. Results: The average change in muscle strength following training, detraining and retraining was 48.8 ± 2.9%, –17.6 ± 1.3%, and 19.8 ± 2.0%, respectively. Strength changes were accompanied by significant alterations in muscle density (p < 0.001), with the quadriceps HU decreasing by 7.7 ± 1.0% following detraining and increasing by 5.4 ± 0.5% with retraining. For the hamstrings HU measure, detraining and retraining resulted in an 11.9 ± 1.4% loss and a 5.5 ± 1.8% gain, respectively. There was no significant change in muscle volume. Conclusion: Cessation of resistance exercise in trained older persons increases the fatty infiltration of muscle, while resumption of exercise decreases it. Monitoring changes in both muscle size and fat infiltration may enable a more comprehensive assessment of exercise in combating age-related muscular changes.

Muscle power and muscle strength improved similarly using either resistance training protocol, and these changes were accompanied by improvements in several functional performance tasks. However, improvements in the HV group occurred with less total work performed per training session.

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Background: The age-related loss of muscle power in older adults is greater than that of muscle strength and is associated with a decline in physical performance. Objective: To investigate the effects of a short-term high-velocity varied resistance training programme on physical performance in healthy community-dwelling adults aged 60–80 years. Methods: Subjects undertook exercise (EX; n = 15) or maintained customary activity (controls, CON; n = 10) for 8 weeks. The EX group trained 2 days/week using machine weights for three sets of eight repetitions at 35, 55, and 75% of their one-repetition maximum (the maximal weight that an individual can lift once with acceptable form) for seven upper- and lower-body exercises using explosive concentric movements. Results: Fourteen EX and 10 CON subjects completed the study. Dynamic muscle strength significantly increased (p = 0.001) in the EX group for all exercises (from 21.4 ± 9.6 to 82.0 ± 59.2%, mean ± SD) following training, as did knee extension power (p < 0.01). Significant improvement occurred for the EX group in the floor rise to standing (10.4 ± 11.5%, p = 0.004), usual 6-metre walk (6.6 ± 8.2%, p = 0.010), repeated chair rise (10.4 ± 15.6%, p = 0.013), and lift and reach (25.6 ± 12.1%, p = 0.002) performance tasks but not in the CON group. Conclusions: Progressive resistance training that incorporates rapid rate-of-force development movements may be safely undertaken in healthy older adults and results in significant gains in muscle strength, muscle power, and physical performance. Such improvements could prolong functional independence and improve the quality of life.

The prevalence of sarcopenia among older residential aged care adults is very high. In addition, low BMI is a predictive of sarcopenia.