252 research outputs found
Acute and Chronic Bone Marker and Endocrine Responses to Resistance Exercise With and Without Blood Flow Restriction in Young Men
In this study, we compared acute and chronic bone marker and hormone responses to 6 weeks of low intensity (20% 1RM) blood flow restriction (BFR20) resistance training to high intensity (70% 1RM) traditional resistance training (TR70) and moderate intensity (45% 1RM) traditional resistance training (TR45) in young men (18–35 years). Participants were randomized to one of the training groups or to a control group (CON). The following training programs were performed 3 days per week for 6 weeks for knee extension and knee flexion exercises: BFR20, 20%1RM, 4 sets (30, 15, 15, 15 reps) wearing blood flow restriction cuffs around the proximal thighs; TR70, 70% 1RM 3 sets 10 reps; and TR45, 45% 1RM 3 sets 15 reps. Muscle strength and thigh cross-sectional area were assessed at baseline, between week 3 and 6 of training. Acute bone marker (Bone ALP, CTX-I) and hormone (testosterone, IGF-1, IGFBP-3, cortisol) responses were assessed at weeks 1 and 6, with blood collection done in the morning after an overnight fast. The main findings were that the acute bone formation marker (Bone ALP) showed significant changes for TR70 and BFR20 but there was no difference between weeks 1 and 6. TR70 had acute increases in testosterone, IGF-1, and IGFBP-3 (weeks 1 and 6). BFR20 had significant acute increases in testosterone (weeks 1 and 6) and in IGF-1 at week 6, while TR45 had significant acute increases in testosterone (week 1), IGF-1 (week 6), and IGFBP-3 (week 6). Strength and muscle size gains were similar for the training groups. In conclusion, low intensity BFR resistance training was effective for stimulating acute bone formation marker and hormone responses, although TR70 showed the more consistent hormone responses than the other training groups
Influence of Body Composition, Oral Contraceptive Use, and Physical Activity on Bone Mineral Density in Premenopausal Women
In premenopausal women, low bone density may reflect attainment of a lower peak bone mass which can increase risk of osteoporosis after menopause. The purpose of this study was to examine the relationship between total body, lumbar spine, and proximal femur bone mineral density (BMD) and body composition and oral contraceptive (OC) use in 18-30 year old women. Sixty-five healthy women, split into groups of oral contraceptive users (OC, n = 36) and non oral contraceptive users (Non-OC, n = 29), completed Baecke physical activity, calcium intake, and menstrual history questionnaires. Total body, AP lumbar spine, and dual proximal femur scans were performed using Dual Energy X-Ray Absorptiometry (DXA). Body composition measures were obtained from the total body scan analysis. No significant differences were found for BMD in OC users and non-users. Bone free lean body mass (BFLBM) and weight were positively correlated to all BMD sites, and fat mass was related to total body and L1-L4 spine BMD (p \u3c 0.05). Stepwise regression analyses determined that weight was a significant predictor for all BMD sites (p \u3c 0.05). When separating the two components of body weight, BFLBM was a significant predictor for all BMD sites, and fat mass only predicted total body BMD. In conclusion, this study indicates that weight and BFLBM are significant contributors to BMD in young healthy premenopausal women, and OC use did not influence the relationship between BMD and BFLBM
Effects of Short Term Low Intensity Resistance Training with Blood Flow Restriction on Bone Markers and Muscle Cross-Sectional Area in Young Men
Int J Exerc Sci 5(2) : 136-147, 2012. This study compared the effects of short term resistance training with and without blood flow restriction (BFR) on bone turnover markers and muscle cross-sectional area (MCSA) in young men (18-35 yrs). Subjects were randomly assigned to a BFR (20% 1RM) resistance training group (BFRT, n=10), a high intensity (80% 1RM) resistance training group (RT, n=10), or a BFR only group (BFR, n=10). Both BFRT and RT trained 3 days per week (2 sets, 10 repetitions) for 3 weeks for leg press, knee extension, and knee flexion isotonic exercises. BFR underwent the BFR procedure without the exercise protocol for 10 minutes 3 days per week. Body composition (DXA) and thigh MCSA (pQCT) were measured. Fasting bone formation (Bone ALP) and resorption (CTX) markers were assessed in the morning pre and post training. All groups significantly (p \u3c 0.05) improved MCSA, but RT (3.48 ± 0.68 %) had a greater increase compared to BFR (1.15 ± 0.54 %). RT also showed a significant increase (p \u3c 0.01) in Bone ALP after training (50.91 ± 12.77 %). In conclusion, low intensity resistance training with BFR was less effective than high intensity resistance training for eliciting bone formation and muscle hypertrophy responses
Associations between pQCT-based fat and muscle area and density and DXA-based total and leg soft tissue mass in healthy women and men
Peripheral Quantitative Computed Tomography (pQCT) can be used for muscle and fat area and density assessments. These may independently influence muscle and fat mass measurements from Dual Energy X-ray Absorptiometry (DXA).
Objective: To determine associations between pQCT-derived soft tissue density and area measures and DXA-derived soft tissue mass.
Methods: Linear regression models were developed based on BMI and calf fat and muscle cross-sectional area (FCSA and MCSA) and density measured by pQCT in healthy women (n=76) and men (n=82) aged 20-59 years. Independent variables for these models were leg and total bone-free lean mass (BFLM) and fat mass (FM) measured by DXA.
Results:Sex differences (p
Conclusion: Calf muscle and fat area and density independently predict lean and fat tissue mass
Acute and Chronic Bone Marker and Endocrine Responses to Resistance Exercise With and Without Blood Flow Restriction in Young Men
In this study, we compared acute and chronic bone marker and hormone responses to 6 weeks of low intensity (20% 1RM) blood flow restriction (BFR20) resistance training to high intensity (70% 1RM) traditional resistance training (TR70) and moderate intensity (45% 1RM) traditional resistance training (TR45) in young men (18–35 years). Participants were randomized to one of the training groups or to a control group (CON). The following training programs were performed 3 days per week for 6 weeks for knee extension and knee flexion exercises: BFR20, 20%1RM, 4 sets (30, 15, 15, 15 reps) wearing blood flow restriction cuffs around the proximal thighs; TR70, 70% 1RM 3 sets 10 reps; and TR45, 45% 1RM 3 sets 15 reps. Muscle strength and thigh cross-sectional area were assessed at baseline, between week 3 and 6 of training. Acute bone marker (Bone ALP, CTX-I) and hormone (testosterone, IGF-1, IGFBP-3, cortisol) responses were assessed at weeks 1 and 6, with blood collection done in the morning after an overnight fast. The main findings were that the acute bone formation marker (Bone ALP) showed significant changes for TR70 and BFR20 but there was no difference between weeks 1 and 6. TR70 had acute increases in testosterone, IGF-1, and IGFBP-3 (weeks 1 and 6). BFR20 had significant acute increases in testosterone (weeks 1 and 6) and in IGF-1 at week 6, while TR45 had significant acute increases in testosterone (week 1), IGF-1 (week 6), and IGFBP-3 (week 6). Strength and muscle size gains were similar for the training groups. In conclusion, low intensity BFR resistance training was effective for stimulating acute bone formation marker and hormone responses, although TR70 showed the more consistent hormone responses than the other training groups.This study was funded in part by a grant from the International Society for KAATSU Training Research awarded to MB (PI) and DB (Co-PI). Financial support was provided by the University of Oklahoma Libraries’ Open Access Fund.Ye
The Abelian Topological Mass Mechanism From Dimensional Reduction
We show that the abelian topological mass mechanism in four dimensions,
described by the Cremmer-Sherk action, can be obtained from dimensional
reduction in five dimensions. Starting from a gauge invariant action in five
dimensions, where the dual equivalence between a massless vector field and a
massless second-rank antisymmetric field in five dimensions is established, the
dimensional reduction is performed keeping only one massive mode. Furthermore,
the Kalb-Ramond action and the Stuckelberger formulation for massive spin-1 are
recovered.Comment: Three references added, 6 pages, late
Effective Action for High-Energy Scattering in Gravity
The multi-Regge effective action is derived directly from the linearized
gravity action. After excluding the redundant field components we separate the
fields into momentum modes and integrate over modes which correspond neither to
the kinematics of scattering nor to the one of exchanged particles. The
effective vertices of scattering and of particle production are obtained as
sums of the contributions from the triple and quartic interaction terms and the
fields in the effective action are defined in terms of the two physical
components of the metric fluctuation.Comment: 15 pages, LATE
InterMAHP: The International Model of Alcohol Harms and Policies: A comprehensive guide to the estimation of alcohol-attributable morbidity and mortality.
4D, N = 1 Supersymmetry Genomics (I)
Presented in this paper the nature of the supersymmetrical representation
theory behind 4D, N = 1 theories, as described by component fields, is
investigated using the tools of Adinkras and Garden Algebras. A survey of
familiar matter multiplets using these techniques reveals they are described by
two fundamental valise Adinkras that are given the names of the cis-Valise
(c-V) and the trans-Valise (t-V). A conjecture is made that all off-shell 4D, N
= 1 component descriptions of supermultiplets are associated with two integers
- the numbers of c-V and t-V Adinkras that occur in the representation.Comment: 53 pages, 19 figures, Report-II of SSTPRS 2008 Added another chapter
for clarificatio
Dark Matter Gravitational Interactions
We argue that the conjectured dark mater in the Universe may be endowed with
a new kind of gravitational charge that couples to a short range gravitational
interaction mediated by a massive vector field. A model is constructed that
assimilates this concept into ideas of current inflationary cosmology. The
model is also consistent with the observed behaviour of galactic rotation
curves according to Newtonian dynamics. The essential idea is that stars
composed of ordinary (as opposed to dark matter) experience Newtonian forces
due to the presence of an all pervading background of massive gravitationally
charged cold dark matter. The novel gravitational interactions are predicted to
have a significant influence on pre-inflationary cosmology. The precise details
depend on the nature of a gravitational Proca interaction and the description
of matter. A gravitational Proca field configuration that gives rise to
attractive forces between dark matter charges of like polarity exhibits
homogeneous isotropic eternal cosmologies that are free of cosmological
curvature singularities thus eliminating the horizon problem associated with
the standard big-bang scenario. Such solutions do however admit dense hot
pre-inflationary epochs each with a characteristic scale factor that may be
correlated with the dark matter density in the current era of expansion. The
model is based on a theory in which a modification of Einsteinian gravity at
very short distances can be expressed in terms of the gradient of the Einstein
metric and the torsion of a non-Riemannian connection on the bundle of linear
frames over spacetime. Indeed we demonstrate that the genesis of the model
resides in a remarkable simplification that occurs when one analyses the
variational equations associated with a broad class of non-Riemannian actions.Comment: 40 pages, 4 Postscript figure
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