Search

Background. Training cessation among older adults is associated with the loss of functional ability. However, exercise programs undertaken prior to activity cessation may offer functional protection. In the present study, the residual effects of muscle power or muscle strength training were investigated following extended detraining and subsequent retraining. Methods. Thirty-eight healthy independent older adults (65-84 years) entered a 24-week detraining period subsequent to 24 weeks of training. Following detraining, participants recommenced training using either the high-velocity muscle power (HV) or muscle strength (ST) protocol, as undertaken during the initial training period, twice weekly for 12 weeks. Isometric and dynamic muscle strength, muscle power, movement velocity, muscle endurance, electromyographic activity, and the results of a battery of functional performance tasks were assessed. Results. Muscle function and functional performance increased following initial training, however, no group differences were observed. Detraining resulted in similar declines in muscle power and muscle strength for both groups (p < .05) (power, HV 17.8 [+ or -] 1.8%, ST 15.5 [+ or -] 2.2%; and strength, HV 17.1 [+ or -] 2.2%, ST 16.5 [+ or -] 1.8%), with comparable accrual following retraining. No significant changes in functional ability were observed following detraining (average change; HV 3.1 [+ or -] 3.5% and ST 2.1 [+ or -] 3.5%) or retraining. No group differences emerged in this study. Conclusion. Cessation of training resulted in only a modest loss of muscle power and strength that was recouped following 12 weeks of retraining. Importantly, training-induced gains in functional performance were preserved during detraining. The residual effects of power or strength training appear comparable, and both may be suitable exercise modes prior to a period of activity cessation to promote physical independence. Key Words: Resistance training--Functional performance--Muscle function--Detraining--Retraining.

Background. Loss of muscle power due to normal aging has greater functional impact than loss of strength alone. The present study compared two resistance training programs, one aimed at enhancing muscle power and one at increasing muscle strength, on muscle function and functional performance in older adults. Methods. Sixty-seven healthy, independent older adults (65-84 years) were randomized to a high-velocity varied resistance (HV), constant resistance (ST), or nontraining control (CO) group. Participants trained twice weekly for 24 weeks using six exercises. Dynamic and isometric muscle strength, muscle power, movement velocity, muscle endurance, and a battery of functional performance tasks were assessed. Secondary outcomes included body composition, quality of life, and balance confidence. Results. Muscle strength increased significantly (p < .001) and similarly in the training groups compared to controls (HV, 51.0 [+ or -] 9.0%; ST, 48.3 [+ or -] 6.8%; CO, 1.2 [+ or -] 5.1%). Peak muscle power also increased with training (p < .05), with no difference between training groups. The change in peak power was 50.5 [+ or -] 4.1%, 33.8 [+ or -] 3.8%, and -2.5 [+ or -] 3.9% in the HV, ST, and CO groups, respectively. Training also improved selected functional performance tasks in the HV and ST groups compared to controls (p < .05), and the HV group reported improved quality of life (p = .018). Conclusion. 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. Key Words: Resistance training--Muscle power--Movement velocity--Functional performance--Muscle strength.

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. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]