Muscle hypertrophy in prediabetic men after 16 wk of resistance training.

Resistance training of healthy young men typically results in muscle hypertrophy and a shift in vastus lateralis composition away from type IIx fibers to an increase in IIa fiber content. Our previous studies of 8 wk of resistance training found that many metabolic syndrome men and women paradoxically increased IIx fibers with a decrease in IIa fibers. To confirm the hypothesis that obese subjects might have muscle remodeling after resistance training very different from healthy lean subjects, we subjected a group of nine obese male volunteers to progressive resistance training for a total of 16 wk. In these studies, weight loss was discouraged so that muscle changes would be attributed to the training alone. Detailed assessments included comparisons of histological examinations of needle biopsies of vastus lateralis muscle pretraining and at 8 and 16 wk. Prolonging the training from 8 to 16 wk resulted in increased strength, improved body composition, and more muscle fiber hypertrophy, but euglycemic clamp-quantified insulin responsiveness did not improve. Similar to prior studies, muscle fiber composition shifted toward more fast-twitch type IIx fibers (23 to 42%). Eight weeks of resistance training increased the muscle expression of phosphorylated Akt2 and mTOR. Muscle GLUT4 expression increased, although insulin receptor and IRS-1 expression did not change. We conclude that resistance training of prediabetic obese subjects is effective at changing muscle, resulting in fiber hypertrophy and increased type IIx fiber content, and these changes continue up to 16 wk of training.NEW & NOTEWORTHY Obese, insulin-resistant men responded to 16 wk of progressive resistance training with muscle hypertrophy and increased strength and a shift in muscle fiber composition toward fast-twitch, type IIx fibers. Activation of muscle mTOR was increased by 8 wk but did not increase further at 16 wk despite continued augmentation of peak power and rate of force generation.

Pre-Training Muscle Characteristics of Subjects Who Are Obese Determine How Well Exercise Training Will Improve Their Insulin Responsiveness.

Stuart, CA, Lee, ML, South, MA, Howell, MEA, Cartwright, BM, Ramsey, MW, and Stone, MH. Pre-training muscle characteristics of subjects who are obese determine how well exercise training will improve their insulin responsiveness. J Strength Cond Res 31(3): 798-808, 2017-Only half of prediabetic subjects who are obese who underwent exercise training without weight loss increased their insulin responsiveness. We hypothesized that those who improved their insulin responsiveness might have pretraining characteristics favoring a positive response to exercise training. Thirty nondiabetic subjects who were obese volunteered for 8 weeks of either strength training or endurance training. During training, subjects increased their caloric intake to prevent weight loss. Insulin responsiveness by euglycemic clamps and muscle fiber composition, and expression of muscle key biochemical pathways were quantified. Positive responders initially had 52% higher intermediate muscle fibers (fiber type IIa) with 27% lower slow-twitch fibers (type I) and 23% lower expression of muscle insulin receptors. Whether after weight training or stationary bike training, positive responders' fiber type shifted away from type I and type IIa fibers to an increased proportion of type IIx fibers (fast twitch). Muscle insulin receptor expression and glucose transporter type 4 (GLUT4) expression increased in all trained subjects, but these moderate changes did not consistently translate to improvement in whole-body insulin responsiveness. Exercise training of previously sedentary subjects who are obese can result in muscle remodeling and increased expression of key elements of the insulin pathway, but in the absence of weight loss, insulin sensitivity improvement was modest and limited to about half of the participants. Our data suggest rather than responders being more fit, they may have been less fit, only catching up to the other half of subjects who are obese whose insulin responsiveness did not increase beyond their pretraining baseline.

A meta-analysis of school-based obesity prevention programs demonstrates limited efficacy of decreasing childhood obesity.

Childhood obesity is a global concern. The objectives of this meta-analytical study were to evaluate the effectiveness of school-based childhood obesity prevention programs, and to examine program components (moderators). The methods included searching databases (PubMed, Google Scholar, and the university's EBSCOhost Web service) as well as handsearching reference lists of articles published in English. Selection criteria for studies to be included in the meta-analysis were limited to studies that reported body mass index (BMI) or skinfold thickness as outcome measures and were school-based obesity prevention interventions; cross-sectional design studies were excluded. We hypothesized the meta-analysis would yield a summary effect size of magnitude which would indicate that school-based interventions have been effective in improving children's BMI or skinfold thickness values. A total of 26 114 children from 27 school-based childhood obesity prevention programs provided 54 effect sizes. A random-effects model calculated a small summary effect size of 0.039 (95% confidence interval -0.013 to 0.092). Heterogeneity among studies was observed which disappeared after pooling studies that used a randomized controlled trial design with one program moderator (physical activity or nutrition). We failed to accept our hypothesis and concluded that overall, school-based interventions have not been effective for improving body mass index or skinfold thickness to curb childhood obesity; however, randomized controlled trials that focused on physical activity or nutrition appeared to produce promising results.

Insulin resistance and muscle insulin receptor substrate-1 serine hyperphosphorylation.

Insulin resistance in metabolic syndrome subjects is profound in spite of muscle insulin receptor and insulin-responsive glucose transporter (GLUT4) expression being nearly normal. Insulin receptor tyrosine kinase phosphorylation of insulin receptor substrate-1 (IRS-1) at Tyr896 is a necessary step in insulin stimulation of translocation of GLUT4 to the cell surface. Serine phosphorylation of IRS-1 by some kinases diminishes insulin action in mice. We evaluated the phosphorylation status of muscle IRS-1 in 33 subjects with the metabolic syndrome and seventeen lean controls. Each underwent euglycemic insulin clamps and a thigh muscle biopsy before and after 8 weeks of either strength or endurance training. Muscle IRS-1 phosphorylation at six sites was quantified by immunoblots. Metabolic syndrome muscle IRS-1 had excess phosphorylation at Ser337 and Ser636 but not at Ser307, Ser789, or Ser1101. Ser337 is a target for phosphorylation by glycogen synthase kinase 3 (GSK3) and Ser636 is phosphorylated by c-Jun N-terminal kinase 1 (JNK1). Exercise training without weight loss did not change the IRS-1 serine phosphorylation. These data suggest that baseline hyperphosphorylation of at least two key serines within muscle IRS-1 diminishes the transmission of the insulin signal and thereby decreases the insulin-stimulated translocation of GLUT4. Excess fasting phosphorylation of muscle IRS-1 at Ser636 may be a major cause of the insulin resistance seen in obesity and might prevent improvement in insulin responsiveness when exercise training is not accompanied by weight loss.

Insulin responsiveness in metabolic syndrome after eight weeks of cycle training.

INTRODUCTION: Insulin resistance in obesity is decreased after successful diet and exercise. Aerobic exercise training alone was evaluated as an intervention in subjects with the metabolic syndrome. METHODS: Eighteen nondiabetic, sedentary subjects, 11 with the metabolic syndrome, participated in 8 wk of increasing intensity stationary cycle training. RESULTS: Cycle training without weight loss did not change insulin resistance in metabolic syndrome subjects or sedentary control subjects. Maximal oxygen consumption (V·O 2max), activated muscle AMP-dependent kinase, and muscle mitochondrial marker ATP synthase all increased. Strength, lean body mass, and fat mass did not change. The activated mammalian target of rapamycin was not different after training. Training induced a shift in muscle fiber composition in both groups but in opposite directions. The proportion of type 2× fibers decreased with a concomitant increase in type 2a mixed fibers in the control subjects, but in metabolic syndrome, type 2× fiber proportion increased and type 1 fibers decreased. Muscle fiber diameters increased in all three fiber types in metabolic syndrome subjects. Muscle insulin receptor expression increased in both groups, and GLUT4 expression increased in the metabolic syndrome subjects. The excess phosphorylation of insulin receptor substrate 1 (IRS-1) at Ser337 in metabolic syndrome muscle tended to increase further after training in spite of a decrease in total IRS-1. CONCLUSIONS: In the absence of weight loss, the cycle training of metabolic syndrome subjects resulted in enhanced mitochondrial biogenesis and increased the expression of insulin receptors and GLUT4 in muscle but did not decrease the insulin resistance. The failure for the insulin signal to proceed past IRS-1 tyrosine phosphorylation may be related to excess serine phosphorylation at IRS-1 Ser337, and this is not ameliorated by 8 wk of endurance exercise training.

Students delivering health care to a vulnerable Appalachian population through interprofessional service-learning.

Interprofessional student service-learning experiences are integrated into the preventive care of older adult residents of public housing in Appalachia. Receiving a Health Resources and Services Administration grant provided the College of Nursing at East Tennessee State University the opportunity to expand interprofessional clinical experiences for students by partnering with the College of Pharmacy, the College of Clinical & Rehabilitative Health Sciences, and the local public housing authority. Select faculty from each college met and developed a plan to form student teams from all three colleges to conduct in-home comprehensive medical and nutrition assessments and medication chart reviews of high-risk older adults. Following the in-home visit, students and faculty discuss the assessment findings at planned interprofessional meetings. Students present their findings from each discipline's perspective and collaboratively set health priorities and develop intervention strategies and an inclusive follow-up plan. Excerpts from students' reflective narratives discussing the impact of the interprofessional service-learning experiences are shared.