Achieving Equity in Physical Activity Participation: ACSM Experience and Next Steps.

There is clear and consistent evidence that regular physical activity is an important component of healthy lifestyles and fundamental to promoting health and preventing disease. Despite the known benefits of physical activity participation, many people in the United States remain inactive. More specifically, physical activity behavior is socially patterned with lower participation rates among women; racial/ethnic minorities; sexual minority youth; individuals with less education; persons with physical, mental, and cognitive disabilities; individuals >65 yr of age; and those living in the southeast region of the United States.

Calcineurin localization in skeletal muscle offers insights into potential new targets.

The Ca(2+)/calmodulin-activated protein phosphatase, calcineurin, is believed to regulate the development and function of skeletal and cardiac muscle. Striated muscle contains many calcineurin substrates, a few of which have been colocalized or found in molecular complexes with calcineurin. We examined the subcellular distribution of calcineurin in developing rat skeletal muscle cells and adult mouse skeletal muscle fibers by immunofluorescence microscopy.

High efficiency transfection of primary skeletal muscle cells with lipid-based reagents.

Lipofection is a convenient method for gene transfer into muscle cells but reportedly is inefficient. We tested the efficacy of commercially available lipid-based and polyamine transfection reagents. Primary rat skeletal muscle cell cultures were transfected at three stages of development and assayed after fusion.

Studies of a targeted risk reduction intervention through defined exercise (STRRIDE).

Purpose: The Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) trial is a randomized controlled clinical trial designed to study the effects of exercise training regimens differing in dose (kcal.wk-1) and/or intensity (relative to peak VO2) on established cardiovascular risk factors and to investigate the peripheral biologic mechanisms through which chronic physical activity alters carbohydrate and lipid metabolism to result in improvements in these parameters of cardiovascular risk in humans.

Methods: We will recruit 384 subjects and randomly assign them to one of three exercise training regimens or to a sedentary control group.

Regulation of myosin heavy chain expression during rat skeletal muscle development in vitro.

Signals that determine fast- and slow-twitch phenotypes of skeletal muscle fibers are thought to stem from depolarization, with concomitant contraction and activation of calcium-dependent pathways. We examined the roles of contraction and activation of calcineurin (CN) in regulation of slow and fast myosin heavy chain (MHC) protein expression during muscle fiber formation in vitro. Myotubes formed from embryonic day 21 rat myoblasts contracted spontaneously, and approximately 10% expressed slow MHC after 12 d in culture, as seen by immunofluorescent staining.

Autocrine phosphorylation of p70(S6k) in response to acute stretch in myotubes.

Phosphorylation of 70-KDa S6 kinase (p70(S6k)) is correlated with in vivo skeletal muscle hypertrophy. Experiments tested whether mechanical stretch is sufficient to increase p70(S6k) phosphorylation in skeletal myotubes. Immediately following stretch, there was a small increase in p70(S6k) phosphorylation (63.

Orientation and length of mammalian skeletal myocytes in response to a unidirectional stretch.

Effects of mechanical forces exerted on mammalian skeletal muscle cells during development were studied using an in vitro model to unidirectionally stretch cultured C2C12 cells grown on silastic membrane. Previous models to date have not studied these responses of the mammalian system specifically. The silastic membrane upon which these cells were grown exhibited linear strain behavior over the range of 3.

Differentiation of mammalian skeletal muscle cells cultured on microcarrier beads in a rotating cell culture system.

The growth and repair of adult skeletal muscle are due in part to activation of muscle precursor cells, commonly known as satellite cells or myoblasts. These cells are responsive to a variety of environmental cues, including mechanical stimuli. The overall goal of the research is to examine the role of mechanical signalling mechanisms in muscle growth and plasticity through utilisation of cell culture systems where other potential signalling pathways (i.

Induction and maintenance of increased VEGF protein by chronic motor nerve stimulation in skeletal muscle.

Vascular endothelial growth factor (VEGF) causes endothelial cell proliferation in vitro and angiogenesis in vivo. Glycolytic skeletal muscles have a lower capillary density than oxidative muscles but can increase their capillary density and convert to a more oxidative phenotype when subject to chronic motor nerve stimulation (CMNS). We used Western analysis and immunohistochemical techniques to examine VEGF protein in a rabbit CMNS model of glycolytic skeletal muscle and in muscles with innate glycolytic versus oxidative phenotypes.

Regulation of type II adenylyl cyclase mRNA in rabbit skeletal muscle by chronic motor nerve pacing.

Skeletal muscle exhibits a wide range in functional phenotype in response to changes in physiological demands. We have observed that, in response to changes in work patterns, alterations in gene expression of some proteins coincide with changes in adenylyl cyclase (AC) activity [Kraus, W.E.

Fiber type-specific effects of clenbuterol and exercise training on insulin-resistant muscle.

The interrelationships among glucose uptake, GLUT-4 protein, and citrate synthase activity in insulin-resistant skeletal muscle were investigated. Female obese (fa/fa) Zucker rats were randomly assigned to treadmill training, ingestion of the selective beta 2-adrenergic agonist clenbuterol, or sedentary control groups. After 7-8 wk of treatment, hindlimbs were perfused to determine maximal insulin-stimulated (10 mU/ml) 2-[3H]deoxy-D-glucose (2-DG) uptake.

Interaction of aerobic exercise training and clenbuterol: effects on insulin-resistant muscle.

The effects of aerobic exercise training, chronic administration of the selective beta 2-adrenergic agonist clenbuterol, and the combination of these two treatments on muscle insulin resistance were compared in female obese (fa/fa) Zucker rats. Rats were randomly assigned to trained, clenbuterol, clenbuterol-trained, or control groups. Training consisted of treadmill running for 2 h/day at 18 m/min up an 8% grade.

Exercise training and clenbuterol reduce insulin resistance of obese Zucker rats.

This study compared the effects of aerobic exercise training and chronic administration of the selective beta 2-adrenergic agonist clenbuterol on whole body and skeletal muscle insulin resistance in obese (fa/fa) Zucker rats. Obese rats were randomly assigned to training, clenbuterol, or sedentary control groups. Lean littermates served as a second control group.

Insulin resistance of obese Zucker rats exercise trained at two different intensities.

The effect of exercise intensity on oral glucose tolerance and hindlimb glucose uptake and transport was studied in 26 female obese Zucker rats after a treadmill training program. The rats were randomly assigned to either a low-intensity (LI) or high-intensity (HI) exercise group, with equal work being performed by the two groups. A third group of rats served as sedentary controls (SED).

Effects of pyruvate and dihydroxyacetone consumption on the growth and metabolic state of obese Zucker rats.

Female obese Zucker rats (aged 6 wk) were randomly assigned to one of two control or one of three experimental-diet groups. Experimental diets contained 6% pyruvate (Pyr). 6% dihydroxyacetone (Dha), or 3% each pyruvate and dihydroxyacetone (Pyr-Dha).

Effects of acute, submaximal exercise on skeletal muscle vitamin E.

Vitamin E is the major lipid soluble anti-oxidant and may play an important protective role against free radicals produced during exercise. The purpose of this study was to determine the effect of a submaximal exercise bout on vitamin E levels in selected tissues. Five week- old lean, female Zucker rats were randomly divided into sedentary and run groups.

Muscle glucose uptake of obese Zucker rats trained at two different intensities.

Exercise training reduces the muscle insulin resistance of the obese Zucker rat. The purpose of the present study was to determine whether the magnitude of this training response is exercise intensity specific. Obese Zucker rats were randomly divided into sedentary (SED), low-intensity (LI), and high-intensity (HI) exercise groups.

Substrate utilization during acute exercise in obese Zucker rats.

The purpose of the present study was to compare the carbohydrate use of insulin-resistant obese Zucker rats with that of their lean littermates during steady-state exercise. Obese and lean rats were randomly assigned to a sedentary group or to a run group in which rats ran at 72-73% of their maximal O2 consumption, with the duration of exercise set to require an energy expenditure of 2.1-2.

Muscle morphological and biochemical adaptations to training in obese Zucker rats.

The purposes of the present study were to characterize the histochemical and enzymatic profiles of various hindlimb skeletal muscles, as well as to determine maximal O2 consumption (VO2max) and respiratory exchange ratios (R) during steady-state exercise in the obese Zucker rat. The changes that occurred in these parameters in response to a 6-wk training program were then assessed. Obese rats were randomly assigned to a sedentary or training group.

Skeletal muscle glucose transport in obese Zucker rats after exercise training.

Exercise training has been found to reduce the muscle insulin resistance of the obese Zucker rat (fa/fa). The purpose of the present study was to determine whether this reduction in muscle insulin resistance was associated with an improvement in the glucose transport process and if it was fiber-type specific. Rats were randomly assigned to a sedentary or training group.

Mechanical influences on long-lasting human muscle fatigue and delayed-onset pain.

1. The influence of three mechanical factors, force, muscle length and passive lengthening, on long-lasting changes in voluntary force generation, the force:frequency relationship and the development of tenderness has been studied in healthy human skeletal muscle. The elbow flexors were used in all studies.

Dismounts in gymnastics: should scoring be reevaluated?

Eleven high school and college gymnasts who sustained 12 major knee injuries were surveyed. Seven were injured as the result of dismounts from the beam of the uneven bar. Five of the seven used a twist in the maneuver.

The Bra Controversy: Are Sports Bras a Necessity?

In brief The authors questioned 85 intercollegiate athletes at the University of Washington about breast pain during sports and the kinds of bras they use. Only 20% reported occasional breast pain, usually associated with cold weather or the onset of their menstrual periods. One woman had received a traumatic breast injury during a basketball game, but the area of ecchymosis cleared within ten days.