OBJECTIVE -To determine the efficacy of high-intensity progressive resistance training (PRT) on glycemic control in older adults with type 2 diabetes.RESEARCH DESIGN AND METHODS -We performed a 16-week randomized controlled trial in 62 Latino older adults (40 women and 22 men; mean Ϯ SE age 66 Ϯ 8 years) with type 2 diabetes randomly assigned to supervised PRT or a control group. Glycemic control, metabolic syndrome abnormalities, body composition, and muscle glycogen stores were determined before and after the intervention.RESULTS -Sixteen weeks of PRT (three times per week) resulted in reduced plasma glycosylated hemoglobin levels (from 8.7 Ϯ 0.3 to 7.6 Ϯ 0.2%), increased muscle glycogen stores (from 60.3 Ϯ 3.9 to 79.1 Ϯ 5.0 mmol glucose/kg muscle), and reduced the dose of prescribed diabetes medication in 72% of exercisers compared with the control group, P ϭ 0.004 -0.05. Control subjects showed no change in glycosylated hemoglobin, a reduction in muscle glycogen (from 61.4 Ϯ 7.7 to 47.2 Ϯ 6.7 mmol glucose/kg muscle), and a 42% increase in diabetes medications. PRT subjects versus control subjects also increased lean mass (ϩ1.2 Ϯ 0.2 vs. Ϫ0.1 Ϯ 0.1 kg), reduced systolic blood pressure (-9.7 Ϯ 1.6 vs. ϩ7.7 Ϯ 1.9 mmHg), and decreased trunk fat mass (Ϫ0.7 Ϯ 0.1 vs. ϩ0.8 Ϯ 0.1 kg; P ϭ 0.01-0.05).CONCLUSIONS -PRT as an adjunct to standard of care is feasible and effective in improving glycemic control and some of the abnormalities associated with the metabolic syndrome among high-risk older adults with type 2 diabetes.

Hispanics are at increased risk of morbidity and mortality due to their high prevalence of diabetes and poor glycemic control. Strength training is the most effective lifestyle intervention to increase muscle mass but limited data is available in older adults with diabetes. We determined the influence of strength training on muscle quality (strength per unit of muscle mass), skeletal muscle fiber hypertrophy, and metabolic control including insulin resistance (Homeostasis Model Assessment –HOMA-IR), C-Reactive Protein (CRP), adiponectin and Free Fatty Acid (FFA) levels in Hispanic older adults. Sixty-two community-dwelling Hispanics (>55 y) with type 2 diabetes were randomized to 16 weeks of strength training plus standard care (ST group) or standard care alone (CON group). Skeletal muscle biopsies and biochemical measures were taken at baseline and 16 weeks. The ST group show improved muscle quality (mean±SE: 28±3) vs CON (-4±2, p<0.001) and increased type I (860±252µm2) and type II fiber cross-sectional area (720±285µm2) compared to CON (type I: -164±290µm2, p=0.04; and type II: -130±336µm2, p=0.04). This was accompanied by reduced insulin resistance [ST: median (interquartile range) -0.7(3.6) vs CON: 0.8(3.8), p=0.05]; FFA (ST: -84±30µmol/L vs CON: 149±48µmol/L, p=0.02); and CRP [ST: -1.3(2.9)mg/L vs CON: 0.4(2.3)mg/L, p=0.05]. Serum adiponectin increased with ST [1.0(1.8)µg/mL] compared to CON [-1.2(2.2)µg/mL, p<0.001]. Strength training improved muscle quality and whole-body insulin sensitivity. Decreased inflammation and increased adiponectin levels were related with improved metabolic control. Further studies are needed to understand the mechanisms associated with these findings. However, these data show that strength training is an exercise modality to consider as an adjunct of standard of care in high risk populations with type 2 diabetes.

Minimally supervised exercise is safe and can improve functional performance in elderly individuals. The improvements in functional performance occurred along with improvements in balance but without a significant change in muscle strength or endurance.

Osteoporosis is a major public health problem that is characterized by low bone mass and increased susceptibility to fractures, primarily of the hip, spine, and wrist. It is estimated to cause 1.5 million fractures annually in the United States in people aged 50 yr and older. Physical activity, particularly weight-bearing exercise, is thought to provide the mechanical stimuli or "loading" important for the maintenance and improvement of bone health, whereas physical inactivity has been implicated in bone loss and its associated health costs. Both aerobic and resistance training exercise can provide weight-bearing stimulus to bone, yet research indicates that resistance training may have a more profound site specific effect than aerobic exercise. Over the past 10 years, nearly two dozen cross-sectional and longitudinal studies have shown a direct and positive relationship between the effects of resistance training and bone density. Conversely, a handful of other studies have reported little or no effect on bone density. However, these results may be partially attributable to the study design, intensity and duration of the exercise protocol, and the bone density measurement techniques used. High-intensity resistance training, in contrast to traditional pharmacological and nutritional approaches for improving bone health in older adults, has the added benefit of influencing multiple risk factors for osteoporosis including improved strength and balance and increased muscle mass.

Increased gait instability is common in older adults, even in the absence of overt disease. The goal of the present study was to quantitatively investigate the factors that contribute to gait instability and its potential reversibility in functionally impaired older adults. We studied 67 older men and women with functional impairment before and after they participated in a randomized placebo-controlled, 6-mo multimodal exercise trial. We found that 1) gait instability is multifactorial; 2) stride time variability is strongly associated with functional status and performance-based measures of function that have previously been shown to predict significant clinical outcomes such as morbidity and nursing home admission; 3) neuropsychological status and health-related quality of life play important, independent roles in gait instability; and 4) improvement in physiological capacity is associated with reduced gait instability. Although the etiology of gait instability in older persons with mild-moderate functional impairment is multifactorial, interventions designed to reduce gait instability may be effective in bringing about a more consistent and more stable walking pattern.

Spaceflight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (RT) and amino acid (AA) supplementation are potential countermeasures to minimize these losses. However, it is unknown if timing of supplementation with exercise can optimize benefits, particularly with energy deficit. We examined the effect of these countermeasures on body composition, strength, and insulin levels in 31 men (ages 31-55 yr) during BR (28 days) followed by active recovery (14 days). Subjects were randomly assigned to essential AA supplementation (AA group, n = 7); RT with AA given 3 h after training (RT group, n = 12); or RT with AA given 5 min before training (AART group, n = 12). Energy intake was reduced by 8 +/- 6%. Midthigh muscle area declined with BR for the AA > RT > AART groups: -11%, -3%, -4% (P = 0.05). Similarly, greatest losses in lower body muscle strength were seen in the AA group (-22%). These were attenuated in the exercising groups [RT (-8%) and AART (-6%; P < 0.05)]. Fat mass and midthigh intramuscular fat increased after BR in the AA group (+3% and +14%, respectively), and decreased in the RT (-5% and -4%) and AART groups (-1 and -5%; P = 0.05). Muscle mass and strength returned toward baseline after recovery, but the AA group showed the lowest regains. Combined resistance training with AA supplementation pre- or postexercise attenuated the losses in muscle mass and strength by approximately two-thirds compared with AA supplement alone during BR and energy deficit. These data support the efficacy of combined AA and RT as a countermeasure against muscle wasting due to low gravity.

The purpose of this study was to compare the ability of various body-composition assessment techniques to detect changes in soft tissue in older, weight-stable women (50-70 y of age) completing a 1-y randomized, controlled trial of progressive resistance training. The intervention group (n = 20) performed high-intensity strength-training 2 d/wk with five different exercises; the control group (n = 19) was untreated. Hydrostatic weighing, 24-h urinary creatinine, computed tomography of thigh sections, total body potassium, and tritium dilution techniques were used to measure increases in total fat-free mass (FFM) and the muscle and water components of FFM. A decrease in fat mass (by hydrostatic weighing) was seen in the strength-trained women compared with the control subjects (P - 0.01-0.0001). Anthropometry, bioelectric impedance, dual-energy X-ray absorptiometry, and total body nitrogen and carbon did not measure any significant change in soft tissue. The choice of a body-composition technique is important when designing a study expected to affect soft tissue, because not all techniques available are precise enough to detect small changes.

We examined the expression of the sodium-dependent glucose co-transporter system (hSGLT3) in skeletal muscle of Hispanic older adults with type 2 diabetes. Subjects (65±8 yr) were randomized to resistance training (3x/wk, n=13) or standard of care (controls, n=5) for 16 weeks. Skeletal muscle hSGLT3 and GLUT4 mRNA transcript levels were determined by real time RT-PCR. hSGLT3 transcripts increased by a factor of ten following resistance training compared to control subjects (0.10, P=0.03). There were no differences in GLUT4 mRNA expression levels between groups. Protein expression levels of these transporters were confirmed by immunohistochemistry and Western blotting. hSGLT3 after resistance exercise was found not to be co-localized with the nicotinic acetylcholine receptor. The change in hSGLT3 transcript levels in the vastus lateralis muscle was positively correlated with glucose uptake, as measured by the change in muscle glycogen stores (r=0.53, P=0.02); and with exercise intensity, as measured by the change in muscle strength (r=0.73, P=0.001). Group assignment was be the only independent predictor of hSGLT3 transcript levels, explaining 68% of its variability (P=0.01). Our data show that hSGLT3, but not GLTU4, expression was enhanced in skeletal muscle after 16 weeks of resistance training. This finding suggests that hSGLT3, an insulin-independent glucose transporter, is activated with exercise and it may play a significant role in glycemic control with muscle contraction. The hSGLT3 exact mechanism is not well understood and requires further investigation. However its functional significance regarding a reduction of glucose toxicity and improvement of insulin resistance is the subject of ongoing research.