Efficacy of home-based exercise for improving quality of life among elderly women with symptomatic osteoporosis-related vertebral fractures.

This randomized controlled trial was designed to investigate the effect of a 6-month home-based exercise program versus control (usual activities) on quality of life for postmenopausal women with osteoporosis who had at least one vertebral fracture. Twelve-month assessments of outcomes were completed to determine if women would continue exercising with minimal supervision and if benefit could be sustained. The home exercise program followed a "lifestyle exercise" approach where participants completed exercises 60 min per day, 3 days a week and could complete exercises in small periods of time throughout the day. Exercise activities included stretching, strength training and aerobics (i.e. walking). Participants were assessed at baseline, 6 months, and 12 months using the Osteoporosis Quality of Life Questionnaire (OQLQ), the Sickness Impact Profile (SIP), a balance test, and the Timed Up And Go test. Bone mineral density was assessed at baseline and 12 months for both the lumbar spine and femoral neck. Quality of life (OQLQ) improved over 6 months in the exercise group compared to the control group in the domains of symptoms (P=0.003), emotion (P=0.01) and leisure (P=0.03). Results from the balance test indicated a greater effect in the exercise group over 12 months (P<0.05). There were no significant differences between groups in measures of Timed Up and Go, SIP at 6 and 12 months, and femoral neck and lumbar spine bone mineral density at 12 months. Home-based exercise with minimal supervision improves quality of life in elderly women with vertebral fractures. Future research is needed to determine if home exercise programs reduce falls and fall-related injuries in the elderly.

An evaluation of the length-tension relationship in elderly human plantarflexor muscles.

The purpose of this study was to determine the effect of aging on the muscle length-tension relationship in the plantarflexor muscles of 10 subjects aged 20-30 yr (Mean = 23; 5 males, 5 females), 10 subjects aged 60-80 yr (Mean = 72.3; 5 males, 5 females), and 10 subjects over 80 yr (Mean = 84.1, 5 males, 5 females). Isometric twitch properties, maximum voluntary strength, passive tension, and range of motion were measured at five different joint angles [20 degrees dorsiflexion (DF), 10 degrees DF, 0 degree, 10 degrees plantarflexion (PF), and 20 degrees PF]. Active (evoked and voluntary) and passive torque production were maximal when the ankle was rotated into the DF positions for all three age groups, whereas the lowest values were recorded when the ankle was rotated into 20 degrees PF. Males were stronger than females at all joint angles (p < .01). Also, young adults were stronger than both elderly adult groups (p < .01). These results illustrate that despite the considerable age-associated loss in both voluntary and evoked strength in the plantarflexors, the optimal angle for torque production remains the same for younger and older adults.

A 12-year follow-up study of ankle muscle function in older adults.

The purpose of this study was to examine changes in strength over time in a cohort of healthy elderly people who underwent assessments of ankle muscle function 12 years earlier. The isometric strength and contractile characteristics of the dorsiflexors and plantarflexors were studied in 11 male and 11 female subjects, ranging from 73-97 yrs (mean age 84 +/- 7.1 yrs). The same footplate apparatus was used as during the original testing. From 1982 to 1994, plantarflexor strength decreased 2.1% per year in females, and 2.5% per year in males (p < .01). The loss was relatively less in the dorsiflexor muscles; strength decreased 0.3% per year in females, and 0.8% per year in male (p > .05). There were no significant changes in evoked twitch torque in either muscle group, which may be due to the fact that passive tension of the connective tissue increased (p < .01) over the 12-year period. We conclude from this longitudinal assessment of ankle muscle function that the rate of loss of voluntary strength can vary considerably between antagonistic muscle groups. Factors influencing this variable loss warrant further investigation.

The effects of lithium on muscle contractile function in humans.

A side effect of lithium (Li+) treatment is fatigue. Li+ decreases inositol triphosphate (IP3) accumulation and IP3 may play a role in excitation-contraction (E-C) coupling in skeletal muscle. Li+ carbonate (600 mg b.i.d. x 6 days) was administered in a randomized, double-blind fashion to 12 males to measure the effect upon muscle contractile function: peak twitch torque (PTT), time to PTT, half-relaxation time, maximal voluntary contraction strength (MVC), percent motor unit activation, M-wave characteristics, and tetanic torque (3 min at 15 and 50 Hz). Li+ resulted in a significant decrease in 15- and 50Hz tetanic torque (P<0.00l), MVC, and resting PTT (P<0.05). There were no effects of Li+ upon any of the other measured variables. Li+ had a negative effect upon E-C coupling and did not affect central motor unit recruitment. Elucidation of the role of IP3 in E-C coupling may help to understand fatigue in some neuromuscular disorders.