The purpose of this study was to test the hypothesis that the rate and extent of glycogen supercompensation in skeletal muscle are increased by endurance exercise training. Rats were trained by using a 5-wk-long swimming program in which the duration of swimming was gradually increased to 6 h/day over 3 wk and then maintained at 6 h/day for an additional 2 wk. Glycogen repletion was measured in trained and untrained rats after a glycogen-depleting bout of exercise. The rats were given a rodent chow diet plus 5% sucrose in their drinking water and libitum during the recovery period. There were remarkable differences in both the rates of glycogen accumulation and the glycogen concentrations attained in the two groups. The concentration of glycogen in epitrochlearis muscle averaged 13.1 +/- 0.9 mg/g wet wt in the untrained group and 31.7 +/- 2.7 mg/g in the trained group (P < 0.001) 24 h after the exercise. This difference could not be explained by a training effect on glycogen synthase. The training induced approximately 50% increases in muscle GLUT-4 glucose transporter protein and in hexokinase activity in epitrochlearis muscles. We conclude that endurance exercise training results in increases in both the rate and magnitude of muscle glycogen supercompensation in rats.
The purpose of this case report is to describe how taping designed to promote proximal scapular stability was used in conjunction with other physical therapy interventions to manage a patient with anterior shoulder impingement. The taping technique is described in detail. The evaluation and treatment of a patient with an 8-month history of shoulder pain are described as an example of when this type of taping procedure may be indicated. This case report demonstrates that a patient was able to return to all of his regular overhead sports activities without pain following scapular taping used in combination with a home exercise program. Presumably, the improved resting position of the scapula corrected faulty scapulothoracic joint movements.
Rats fed a high-fat diet develop skeletal muscle insulin resistance. There is disagreement regarding whether a decrease in the GLUT4 isoform of the glucose transporter is responsible. We found that feeding rats a high-fat diet that reduced the responsiveness of glucose transport to insulin in skeletal muscles by approximately 25-45% in 4 weeks, had no significant effect on muscle GLUT4 content. There is also controversy regarding whether the contraction/anoxia activated pathway of glucose transport stimulation is affected by fat feeding. We found that stimulation of muscle glucose transport by either swimming, in situ contractions, or anoxia was depressed to a similar extent as insulin responsiveness in high-fat-fed rats. It has been suggested that the muscle insulin resistance caused by a high-fat diet is due to increased fat oxidation and glucose-fatty acid cycle activity. However, we found that insulin-stimulated glucose transport was reduced by approximately 40% when muscles of fat-fed rats were incubated under anoxic conditions under which fatty acid oxidation should not occur. Rats maintained on the high-fat diet up to 32 weeks developed the characteristics of the abdominal obesity syndrome, including insulin resistance, hyperinsulinemia, hyperglycemia, elevated LDL cholesterol and VLDL triglycerides, and marked visceral obesity. We conclude that 1) in rats fed a high-fat diet the muscle insulin resistance is not due to a decrease in total GLUT4 content or to increased fat oxidation, 2) fat feeding also results in resistance of muscle glucose transport to stimulation via the contraction/anoxia pathway, and 3) rats fed a high-fat diet may be a useful model of the abdominal obesity syndrome.
Previous studies have shown that when exercise is stopped there is a rapid reversal of the training-induced adaptive increase in muscle glucose transport capacity. Endurance exercise training brings about an increase in GLUT-4 in skeletal muscle. The primary purpose of this study was to determine whether the rapid reversal of the increase in maximally insulin-stimulated glucose transport after cessation of training can be explained by a similarly rapid decrease in GLUT-4. A second purpose was to evaluate the possibility, suggested by previous studies, that the magnitude of the adaptive increase in muscle GLUT-4 decreases when exercise training is extended beyond a few days. We found that both GLUT-4 and maximally insulin-stimulated glucose transport were increased approximately twofold in epitrochlearis muscles of rats trained by swimming for 6 h/day for 5 days or 5 wk. GLUT-4 was 90% higher, citrate synthase activity was 23% higher, and hexokinase activity was 28% higher in triceps muscle of the 5-day trained animals compared with the controls. The increases in GLUT-4 protein and in insulin-stimulated glucose transport were completely reversed within 40 h after the last exercise bout, after both 5 days and 5 wk of training. In contrast, the increases in citrate synthase and hexokinase activities were unchanged 40 h after 5 days of exercise. These results support the conclusion that the rapid reversal of the increase in the insulin responsiveness of muscle glucose transport after cessation of training is explained by the short half-life of the GLUT-4 protein.
Attaining and demonstrating treatment fidelity is critical in the development and testing of evidence-based interventions. Treatment fidelity refers to the extent to which an intervention was implemented in clinical testing as it was conceptualized and is clearly differentiable from control or standard-of-care interventions. In clinical research treatment fidelity is typically attained by intensive training and supervision techniques and demonstrated by measuring therapist adherence and competence to the protocol using external raters. Yet, in occupational therapy (OT) and physical therapy (PT) outcomes research, treatment fidelity methods have not been utilized, which in our view is a serious gap that impedes novel treatment development and testing in these rehabilitation fields. In this article we describe the development of methods to train and supervise therapists to attain adequate treatment fidelity in a treatment development project involving a novel OT and PT-based intervention. We also present a data-driven model for demonstrating therapist adherence and competence in the new treatment and its differentiation from standard-of-care. In doing so, we provide an approach that rehabilitation researchers can use to address treatment fidelity in OT and PT-based interventions. We recommend that all treatment researchers in rehabilitation disciplines use these or similar methods as a vital step in development and testing of evidence-based rehabilitation interventions.
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