Resistance Training Effects on Arterial Compliance in Premenopausal Women

Endurance training has been shown to increase arterial compliance; however, the effect of resistance training is unclear. Purpose: The purpose of this study was to examine the effect lower body resistance training on arterial compliance in healthy premenopausal women. Methods: Thirty-two women were assigned to a resistance training group (n = 21) or a control group (n = 11). Large (C1) and small (C2) arterial compliance (Pulse Contour Analysis) were measured at baseline and after twelve weeks of training. Results: Two-way (group × time) repeated measured ANOVA did not detect significant group, time effects or group × time interactions for small arterial compliance (P > 0.05). There was a significant time effect for large arterial compliance (P < 0.05), which increased in both groups. Conclusions: In contrast to previous studies in men, which found decrease in arterial compliance with resistance training, no decrease in arterial compliance was observed.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

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

Age comparisons of bone density and geometry in men

Objectives: The purposes of this study were to examine tibia bone density and geometry in young and middle aged men, and to explore relationships between pQCT- and DXA-derived body composition variables. Methods: Healthy males (18-30 years old, n=31; 50-64 years old, n=37) had their total body areal bone mineral density (aBMD) and body composition measured with Dual Energy X-ray Absorptiometry (DXA). Volumetric bone characteristics, muscle cross-sectional area (MCSA) and fat crosssectional area (FCSA) of the leg were measured with peripheral Quantitative Computed Tomography (pQCT). Results:Young men were significantly (p Conclusions: Differences in tibial bone area and density existed between young and middle-aged men, and relationships between pQCT- and DXA-derived body composition variables were age-dependent

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

Muscle-Bone Interactions in Chinese Men and Women Aged 18–35 Years

To characterize bone mineral density (BMD), bone strength, muscle and fat mass, and muscle strength and power in Chinese women (n = 25) and men (n = 28) classified as in the bone accrual phase (18–25 years) or in the peak bone mass phase (26–35 years). Calcium intakes, physical activity levels, and serum vitamin D were measured. Dual-energy X-ray absorptiometry (DXA) assessed body composition, lumbar spine, and hip areal BMD (aBMD) variables and peripheral quantitative computed tomography (pQCT) assessed cortical and trabecular volumetric BMD (vBMD) and bone strength. Muscle strength and power were assessed by grip strength, leg press, and vertical jump tests. Calcium, serum vitamin D, and physical activity levels were similar across age and sex groups. Significant sex differences were found for most body composition variables, hip aBMD, tibia variables, and muscle strength and power. Adjusting for height and weight eliminated most of the significant sex differences. Women showed stronger positive correlations between body composition and bone variables (r = 0.44 to 0.78) than men. Also, correlations between muscle strength/power were stronger in women vs. men (r = 0.43 to 0.82). Bone traits were better related to body composition and muscle function in Chinese women compared to Chinese men aged 18 to 35 years, and peak bone mass seems to be achieved by 25 years of age in both Chinese men and women since there were no differences between the two age groups

Bone, Biomarker, Body Composition, and Performance Responses to 8 Weeks of ROTC Training

Context: Military personnel engage in vigorous exercise, often resulting in higher bone mineral density; however, lower leg bone injuries are common in this population. Predictors of change in tibial bone quality and strength need to be characterized in this high-risk population. Objective: This study aimed to examine the effects of an eight-week military training intervention on total body and site-specific bone density and tibial bone quality, serum biomarkers (parathyroid hormone and sclerostin), body composition, and physical performance. Additionally, we sought to investigate what outcome variables (biomarkers, body composition, physical performance) would be predictive of estimated tibial bone strength in college-aged Reserve Officers\u27 Training Corps (ROTC) members. Design: Prospective Cohort Study. Setting: XXX University. Patients of Other Participants: ROTC (n=14 male; n=4 female) were matched for sex, age, and body mass to physically active Controls (n=14 male; n=4 female). ROTC engaged in an eight-week training intervention, while physically active Controls made no changes to their exercise routines. Main outcome measures: Pre general health questionnaires and pre, mid, and post intervention bone scans (DXA, pQCT), serum blood draws (parathyroid hormone and sclerostin), and physical performance measures (muscle strength and aerobic capacity) were tested. Results: ROTC participants exhibited significantly increased hip bone density and content (all p≤0.03) after the eight-week intervention. Sclerostin, not PTH, was a significant positive correlate and predictor in all ROTC models for estimated bone strength at the fracture prone 38% tibial site. Both groups decreased total body and regional fat mass and ROTC increased aerobic capacity (all p≤0.05). Conclusions: All bone, body composition, and performance measures either improved or were maintained in response to ROTC training and sclerostin should be further investigated as a potential early indicator of changes in estimated tibial bone strength in military cohorts

The Evolution of Blood Flow Restricted Exercise

The use of blood flow restricted (BFR) exercise has become an accepted alternative approach to improve skeletal muscle mass and function and improve cardiovascular function in individuals that are not able to or do not wish to use traditional exercise protocols that rely on heavy loads and high training volumes. BFR exercise involves the reduction of blood flow to working skeletal muscle by applying a flexible cuff to the most proximal portions of a person\u27s arms or legs that results in decreased arterial flow to the exercising muscle and occluded venous return back to the central circulation. Safety concerns, especially related to the cardiovascular system, have not been consistently reported with a few exceptions; however, most researchers agree that BFR exercise can be a relatively safe technique for most people that are free from serious cardiovascular disease, as well as those with coronary artery disease, and also for people suffering from chronic conditions, such as multiple sclerosis, Parkinson\u27s, and osteoarthritis. Potential mechanisms to explain the benefits of BFR exercise are still mostly speculative and may require more invasive studies or the use of animal models to fully explore mechanisms of adaptation. The setting of absolute resistive pressures has evolved, from being based on an individual\u27s systolic blood pressure to a relative measure that is based on various percentages of the pressures needed to totally occlude blood flow in the exercising limb. However, since several other issues remain unresolved, such as the actual external loads used in combination with BFR, the type of cuff used to induce the blood flow restriction, and whether the restriction is continuous or intermittent, this paper will attempt to address these additional concerns

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

Circulating microRNA responses to acute whole-body vibration and resistance exercise in postmenopausal women

Evaluating alterations in circulating microRNA (c-miRNA) expression may provide deeper insight into the role of exercise in the attenuation of the negative effects of aging on musculoskeletal health. Currently, there are sparse data on c-miRNA responses to acute exercise in postmenopausal women. The purpose of this study was to characterize the effects of acute bouts of resistance exercise and whole-body vibration on expression of selected c-miRNAs in postmenopausal women aged 65-76 years (n=10). We also examined relationships between c-miRNAs and muscle strength and bone characteristics. This randomized crossover design study compared c-miRNA responses to a bout of resistance exercise (RE) (3 sets 10 reps 70% 1 repetition maximum (1RM), 5 exercises) and a bout of whole-body vibration (WBV) (5 sets 1 min bouts 20Hz 3.38mm peak to peak displacement, Vibraflex vibration platform). DXA was used to measure body composition and areal bone mineral density (aBMD) of the total body, AP lumbar spine, and dual proximal femur. pQCT was used to measure tibia bone characteristics (4%, 38%, 66% sites). Blood samples were collected before exercise (Pre), immediately-post (IP), 60 minutes post (60P), 24 hours (24H), and 48 hours (48H) after exercise to measure serum miR-21-5p, -23a-3p, -133a-3p, -148a-3p (qPCR) and TRAP5b (ELISA). There was a significant modality × time interaction for c-miR-21-5p expression (p=0.019), which decreased from 60P to 24H after WBV only. TRAP5b serum concentrations significantly increased IP then decreased below Pre at 24H for both WBV and RE (p\u3c0.01). Absolute changes in TRAP5b were negatively correlated with c-miR-21-5p fold changes (r= -0.642 to -0.724, p\u3c0.05) for both exercise modalities. There were significant negative correlations between baseline c-miRNAs and bone status variables (r= -0.639 to -0.877, p\u3c0.05). Our findings suggest that whole-body vibration is a sufficient mechanical stimulus for altering c-miR-21-5p expression, whereas a high intensity resistance exercise protocol did not elicit any c-miRNA responses in postmenopausal women. Increases in the bone resorption marker, TRAP5b, were associated with greater downregulation of c-miR-21-5p expression

Comparison of Skeletal Muscle Tissue Oxygen Saturation Responses between Genders

Special attention should be given to subcutaneous thigh fat accrual and its impact on the amount of skeletal muscle blood flow and accumulation when using different initial restrictive pressure (IRP) during blood flow restriction (BFR) training. Due to different patterns of fat distribution and deposition in males and females, it is important to test the effects of subcutaneous fat on tissue oxygenation and lactate production during exercises with BFR. PURPOSE: The present study investigated the importance of thigh subcutaneous fat as a variable that may be associated with affecting the magnitude of initial pressure (tightness of cuffs before inflation with air) on skeletal muscle tissue oxygen saturation and lactate between males and females. METHODS: Twenty healthy volunteers, 10 males (25 ± 4.83 yr) and 10 females (20.7 ± 1.06 yr), performed exercises with an IRP of 40mmHg. The following procedures were performed in order: a) subcutaneous fat thickness, b) pre-maximal isometric force (MVC), c) 4 sets (1 × 30 reps and 3 × 15 reps) of dynamic knee extension exercises performed at 20% MVC, d) post-MVC. Skeletal muscle tissue oxygen saturation was continuously monitored before, during, and after exercises with near-infrared spectroscopy placed to a mark that was made at 50% on the line from the anterior superior iliac spine to the superior part of the patella. Plasma lactate levels were assessed prior to, in between the first and second set, immediately after post MVC, 5min-post, 10 min-post, and 20 min-post. RESULTS: Thigh subcutaneous fat thickness was significantly greater in females than males (p\u3c0.01). Tissue oxygenation significantly decreased (p\u3c0.03) throughout exercise in both genders with an observed significant time × gender interaction (p\u3c0.01). Both male and females responded to the BFR similarly with a significant decrease (p\u3c0.01) in peak force production from pre to post exercise, while plasma lactate levels significantly differed (p\u3c0.01) throughout the exercise with no time × gender interaction (p\u3c0.3). CONCLUSION: The observed gender difference in tissue oxygenation in response to BFR with an IRP of 40mmHg underline the necessity for future studies to consider subcutaneous fat as a variable to influence the magnitude of physiological adaptations between genders and adjust the IRP accordingly