Browsing by Author "Gasier, HG"
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Item Open Access Comments on Point:Counterpoint: High altitude is/is not for the birds!(Journal of Applied Physiology, 2011-11) Gasier, HGItem Open Access Cumulative responses of muscle protein synthesis are augmented with chronic resistance exercise training(Acta Physiologica, 2011-03) Gasier, HG; Riechman, SE; Wiggs, MP; Buentello, A; Previs, SF; Fluckey, JDItem Open Access Increased training loads do not magnify cancellous bone gains with rodent jump resistance exercise(Journal of Applied Physiology, 2010-12) Swift, JM; Gasier, HG; Swift, SN; Wiggs, MP; Hogan, HA; Fluckey, JD; Bloomfield, SAThis study sought to elucidate the effects of a low- and high-load jump resistance exercise (RE) training protocol on cancellous bone of the proximal tibia metaphysis (PTM) and femoral neck (FN). Sprague-Dawley rats (male, 6 mo old) were randomly assigned to high-load RE (HRE; n = 16), low-load RE (LRE; n = 15), or sedentary cage control (CC; n = 11) groups. Animals in the HRE and LRE groups performed 15 sessions of jump RE during 5 wk of training. PTM cancellous volumetric bone mineral density (vBMD), assessed by in vivo peripheral quantitative computed tomography scans, significantly increased in both exercise groups (+9%; P < 0.001), resulting in part from 130% (HRE; P = 0.003) and 213% (LRE; P < 0.0001) greater bone formation (measured by standard histomorphometry) vs. CC. Additionally, mineralizing surface (%MS/BS) and mineral apposition rate were higher (50–90%) in HRE and LRE animals compared with controls. PTM bone microarchitecture was enhanced with LRE, resulting in greater trabecular thickness ( P = 0.03) and bone volume fraction (BV/TV; P = 0.04) vs. CC. Resorption surface was reduced by nearly 50% in both exercise paradigms. Increased PTM bone mass in the LRE group translated into a 161% greater elastic modulus ( P = 0.04) vs. CC. LRE and HRE increased FN vBMD (10%; P < 0.0001) and bone mineral content (∼20%; P < 0.0001) and resulted in significantly greater FN strength vs. CC. For the vast majority of variables, there was no difference in the cancellous bone response between the two exercise groups, although LRE resulted in significantly greater body mass accrual and bone formation response. These results suggest that jumping at minimal resistance provides a similar anabolic stimulus to cancellous bone as jumping at loads exceeding body mass.Item Open Access The application of 2H2O to measure skeletal muscle protein synthesis(Nutrition and Metabolism, 2010-04-22) Gasier, HG; Fluckey, JD; Previs, SFSkeletal muscle protein synthesis has generally been determined by the precursor:product labeling approach using labeled amino acids (e.g., [ 13C]leucine or [13C]-, [15N]-, or [ 2H]phenylalanine) as the tracers. Although reliable for determining rates of protein synthesis, this methodological approach requires experiments to be conducted in a controlled environment, and as a result, has limited our understanding of muscle protein renewal under free-living conditions over extended periods of time (i.e., integrative/cumulative assessments). An alternative tracer, 2H2O, has been successfully used to measure rates of muscle protein synthesis in mice, rats, fish and humans. Moreover, perturbations such as feeding and exercise have been included in these measurements without exclusion of common environmental and biological factors. In this review, we discuss the principle behind using 2H2O to measure muscle protein synthesis and highlight recent investigations that have examined the effects of feeding and exercise. The framework provided in this review should assist muscle biologists in designing experiments that advance our understanding of conditions in which anabolism is altered (e.g., exercise, feeding, growth, debilitating and metabolic pathologies). © 2010 Gasier et al; licensee BioMed Central Ltd.Item Open Access The assessment of bone mineral content and density of the lumbar spine and proximal femur in US submariners.(Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2014-09) Gasier, HG; Hughes, LM; Young, CR; Richardson, AMUnlabelled
The submarine environment is unique in that there is limited space and no sunlight, which may negatively affect skeletal health and lead to accelerated bone loss, osteoporosis, and fractures.Introduction
The primary purpose of this study was to determine whether there was an association with submarine service, specifically time spent at sea, and bone mineral content (BMC) and bone mineral density (BMD) of the lumbar spine and dual proximal femur (total hip and femoral neck) measured by DXA.Methods
This is a cross-sectional study of 462 submariners 20-91 years old. Variables included in the analysis were age, height, race, alcohol intake, tobacco use, fracture history, conditions, and medications known to cause bone loss and osteoporosis and submarine service.Results
Of the submarine service predictors, only serving onboard a diesel submarine was determined to be independently associated with a reduction in BMD of the total hip and femur neck, while no submarine service predictor increased the odds of having low BMD. In submariners 50+ years old, the age-adjusted prevalence of osteopenia was 15.7 % (lumbar spine) and 40.4 % (femur neck), while the prevalence of osteoporosis was 4.8 % (lumbar spine) and 4.2 % (femur neck), rates that did not differ from NHANES 2005-2008. In submariners <50 years old, 3.1 % was below the expected range for age. The proportion of submariners 50+ years old that met the FRAX criteria for pharmacological treatment was 12 %.Conclusions
Intermittent periods of submergence that can range from a few days to 3+ months do not appear to compromise skeletal health differently than the general population.