Resistance Training Is Associated With Higher Bone Mineral Density Among Young Adult Male Distance Runners Independent of Physiological Factors.

Duplanty, AA, Levitt, DE, Hill, DW, McFarlin, BK, DiMarco, NM, and Vingren, JL. Resistance training is associated with higher bone mineral density among young adult male distance runners independent of physiological factors. J Strength Cond Res 32(6): 1594-1600, 2018-Low bone mineral density (BMD) in male distance runners is common and could be modulated by a host of biomarkers involved in the dynamic balance of bone tissue. In contrast, resistance training can increase BMD; however, the efficacy of resistance training in protecting BMD in distance runners has not been elucidated. The aim of this study was to investigate the relationship between resistance training, testosterone and bone metabolism biomarker concentrations, and BMD in young adult male distance runners. Twenty-five apparently healthy men (23-32 years; mean ± SD: 25.9 ± 2.9 years; 1.77 ± 0.04 m; 75.4 ± 8.5 kg) were categorized into 1 of 3 groups: untrained control participants (CON; n = 8); nonresistance-trained runners (NRT; n = 8); or resistance-trained runners (RT; n = 9). Blood was collected and analyzed for concentrations of free and total testosterone and 14 bone metabolism biomarkers. Bone mineral density was assessed using dual-energy X-ray absorptiometry. At all measured sites, BMD was greater (p ≤ 0.05) for RT compared with NRT and CON. Vitamin D concentration was greater (p ≤ 0.05) in RT and NRT compared with CON. Concentrations of testosterone and remaining bone biomarkers did not differ between groups (p > 0.05). Resistance-trained runners had greater BMD than nonresistance-trained runners and untrained peers. This difference did not seem to be modulated by biomarkers that contribute to bone formation or resorption, indicating that differences in BMD are associated with habitual load-bearing exercise using external resistance. Runners should perform resistance exercise at least once per week because this is associated with greater BMD.

Impact of Menopause and Body Composition Status on Dyslipidemia in Women.

Objective: The aim of this study was to identify the effects of menopausal and body composition statuses on measures of total and regional body composition and dyslipidemia in women. Methods: Sedentary, non-smoking women (N = 212), not currently treated for dyslipidemia were grouped based on 2 categories: (1) menstrual status: premenopausal or postmenopausal and (2) body composition status: normal weight (NW; BMI < 25 kg/m² and body fat (BF) < 36%), normal weight obese (NWO; BMI < 25 kg/m² and BF > 36%), or obese (BMI > 25 kg/m² and BF > 36%), to determine differences in total and regional body composition and measures of lipid and lipoprotein-cholesterol concentrations. Results: Overall, a greater prevalence of NWO was observed in postmenopausal versus premenopausal women. Being postmenopausal was associated with higher TC, LDL-C, non-HDL-C, HDL-C, and HDL3-C. Premenopausal NWO women had elevated LDL-C and VLDL-C comparable to obese women. Postmenopausal NWO women had elevated Tg and VLDL-C and lower HDL-C similar to obese women. Conclusions: Menopausal status was not associated with differences in fat distribution, however, the age-related differences in lipids and lipoproteins appear to be due to a difference in menopausal status exacerbated in women who are NWO.

The effects of dietary taurine supplementation on bone mineral density in ovariectomized rats.

This study was performed to evaluate the effect of a diet rich in taurine (2.0 g/100 g) on bone metabolism in ovariectomized (OVX) rats. All rats were fed deionized water during the experimental period. Bone mineral density (BMD) and bone mineral content (BMC) of spine and femur were measured. Serum and urinary calcium and phosphorus content were determined. The levels serum osteocalcin and alkaline phosphatase (ALP) were used to assess bone formation. The rate of bone resorption was measured by the deoxypyridinoline (DPD) crosslink immunoassay and corrected for creatinine. Urinary Ca and P excretion, serum osteocalcin content, and the crosslink value were not significantly different between the Sham groups. The taurine supplemented, Sham group had higher spinal and femur BMC than those of the untreated control group, but the difference was not statistically significant. However, the taurine supplemented, Sham group had significantly higher spine and femur BMC per weight than those of the untreated control group. Within the OVX group, the taurine supplemented group had a lower crosslink value than the casein group. The taurine supplemented, OVX group had higher femur bone mineral content per weight than those of the control, OVX group, but the difference was not statistically significant. A study examining the long-term effect of taurine supplementation in humans is warranted.

A Review of Iodine Status of Women of Reproductive Age in the USA.

Iodine, an essential micronutrient, is required to produce thyroid hormones. Iodine deficiency disorders (IDD) comprise a range of adverse maternal and fetal outcomes, with the most significant irreversible effect resulting from neurodevelopmental deficits in fetal brain caused by deficient iodine status during early pregnancy. The objective of this scoping review was to summarize the studies that assessed iodine status of women of reproductive age in the USA. A systematic review of literature using the PRISMA Extension for Scoping Reviews (PRISMA-ScR) statement was conducted. PubMed, Medline, CINAHL, EMBASE, EBSCOHost, Cochrane, ERIC, Google Scholar, and Web of Science databases were searched, 1652 records were identified. One thousand six hundred forty-one records that did not satisfy the inclusion/exclusion criteria and quality review were excluded, and 11 peer-reviewed articles were determined to be eligible for this scoping review. Despite the USA being considered iodine sufficient for the general population, the US dietary iodine intakes have decreased drastically since the 1970s, with iodine deficiency reemerging in vulnerable groups such as women of reproductive age. Although data to conduct a scoping review of iodine status among women of reproductive age in the USA was scarce, majority of the articles reviewed demonstrate emergent iodine deficiency in this population of women of reproductive age, indicating alarm for a public health concern needing immediate attention.

Mothers of preschoolers report using less pressure in child feeding situations following a newsletter intervention.

OBJECTIVE: To determine the impact of written intervention materials on child feeding practices of mothers and on physical activity behaviors of preschoolers. DESIGN: Mothers were divided into 3 groups: newsletter (n = 30), booklet (n = 31), and control (n = 31). Questionnaires were completed before and after a 12-week intervention. SETTING: Mail correspondence. PARTICIPANTS: White (90%), full-time mothers (76%) in their thirties (68%). INTERVENTIONS: Nutrition and activity information was provided as twelve 4-page weekly newsletters or one 52-page booklet. MAIN OUTCOME MEASURES: Child feeding factors, physical activity practices. ANALYSIS: Child feeding factors were analyzed using Kruskal-Wallis and Wilcoxon. Physical activity practices were analyzed using 2-way chi-square and sign tests. The significance level was set at .0125. RESULTS: There was a significant decrease in the "pressure to eat" score for participants in the newsletter group (2.5 +/- 1.0 to 2.1 +/- 1.0, P < .01). No other differences in feeding practices were observed. At baseline, 43% of the mothers said their child spent at least 1 hour per day in active play, and 63% said their child watched television less than 2 hours per day. A significant increase in outdoor play was reported in the newsletter (P < .01) and control (P < .01) groups. CONCLUSIONS AND IMPLICATIONS: This study is one of the first to indicate that child feeding practices may be modifiable.

Daytime and nighttime casein supplements similarly increase muscle size and strength in response to resistance training earlier in the day: a preliminary investigation.

BACKGROUND: Casein protein consumed before sleep has been suggested to offer an overnight supply of exogenous amino acids for anabolic processes. The purpose of this study was to compare supplemental casein consumed earlier in the day (DayTime, DT) versus shortly before bed (NightTime, NT) on body composition, strength, and muscle hypertrophy in response to supervised resistance training. METHODS: Thirteen males participated in a 10-week exercise and dietary intervention while receiving 35 g casein daily. Isocaloric diets provided 1.8 g protein/kg body weight. RESULTS: Both groups increased (p < 0.05) in lean soft tissue (DT Pre: 58.3 ± 10.3 kg; DT Post: 61.1 ± 11.1 kg; NT Pre: 58.3 ± 8.6 kg; NT Post: 60.3 ± 8.2 kg), cross-sectional area (CSA, DT Pre: 3.4 ± 1.5 cm2; DT Post: 4.1 ± 1.7 cm2; NT Pre: 3.3 ± 1.6 cm2; NT Post: 3.7 ± 1.6 cm2) and strength in the leg press (DT Pre: 341 ± 87.3 kg; DT Post: 421.1 ± 94.0 kg; NT Pre: 450.0 ± 180.3 kg; NT Post: 533.9 ± 155.4 kg) and bench press (DT Pre: 89.0 ± 27.0 kg; DT Post: 101.0 ± 24.0 kg; NT Pre 100.8 ± 32.4 kg; NT Post: 109.1 ± 30.4 kg) with no difference between groups in any variable (p > 0.05). CONCLUSIONS: Both NT and DT protein consumption as part of a 24-h nutrition approach are effective for increasing strength and hypertrophy. The results support the strategy of achieving specific daily protein levels versus specific timing of protein ingestion for increasing muscle mass and performance. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03352583 .

Modified activity-stress paradigm in an animal model of the female athlete triad.

The exercising woman with nutritional deficits and related menstrual irregularities is at risk of compromising long-term bone health, i.e., the female athlete triad. There is no animal model of the female athlete triad. The purpose of this study was to examine long-term energy restriction in voluntary wheel-running female rats on estrous cycling, bone mineral content, and leptin levels. Twelve female Sprague-Dawley rats (age 34 days) were fed ad libitum and given access to running wheels during an initial 14-wk period, providing baseline and age-related data. Daily collection included dietary intake, body weight, estrous cycling, and voluntary running distance. At 4 mo, rats were randomized into two groups, six restrict-fed rats (70% of ad libitum intake) and six rats continuing as ad libitum-fed controls. Energy intake, energy expenditure, and energy availability (energy intake - energy expenditure) were calculated for each animal. Serum estradiol and leptin concentrations were measured by RIA. Femoral and tibial bone mineral density and bone mineral content (BMC) were determined by dual-energy X-ray absorptiometry. Restrict-fed rats exhibited a decrease in energy availability during Weight Loss and Anestrous phases (P = 0.002). Compared with controls after 12 wk, restrict-fed rats showed reduced concentrations of serum estradiol (P = 0.002) and leptin (P = 0.002), lower ovarian weight (P = 0.002), and decreased femoral (P = 0.041) and tibial (P = 0.05) BMC. Decreased energy availability resulted in anestrus and significant decreases in BMC, estrogen and leptin levels, and body weight. Finally, there is a critical level of energy availability to maintain estrous cycling.

Original Research: Polyphenols extracted from grape powder induce lipogenesis and glucose uptake during differentiation of murine preadipocytes.

Assessing the effects of grapes and grape powder extracted polyphenols on lipogenesis and glucose uptake in adipocytes may clarify the risk/benefit of recommending them to individuals with obesity and insulin resistance. We investigated the effect of grape powder extracted polyphenols (GPEP) on intracellular fat accumulation and glucose uptake during differentiation of 3T3-F442A preadipocytes. Total polyphenols were extracted and measured based on gallic acid equivalents (GAE). There were 2167 mg of GAE polyphenols in 100 g of grape powder. 3T3-F442A cells were incubated with GPEP, extracted from 125-500 µg GP/mL of media, until day 8 of differentiation when the cells were collected for different assays. AdipoRed™ assay and Oil Red O staining showed that GPEP induced, in a dose-dependent manner, an increase in intracellular triacylglycerol (TAG) content of adipocytes. Concomitantly, grape powder extracted polyphenols increased, in a dose-dependent manner, glucose uptake by 3T3-F442A cells, and there was a strong positive correlation between glucose uptake and the amount of TAG accumulation (r = 0.826, n = 24, P ≤ 0.001). No changes in cell viability was measured by Trypan Blue staining, suggesting that these effects were independent of cytotoxicity. Western-blot showed that GPEP upregulated protein level of glucose transport protein 4 (GLUT4), p-PKB/Akt, and p-AMPK in 3T3-F442A adipocytes. LY294002 (10 µmol/L), a phosphatidyl-inositol 3 kinase inhibitor (PI3K), reversed the effects of grape powder extracted polyphenols on cellular lipid content and glucose uptake. Furthermore, quantitative real-time polymerase chain reaction showed that GPEP increased mRNA expression of GLUT4, fatty acid synthase, lipoprotein lipase, adiponectin, and peroxisome proliferator-activated receptor γ, while it decreased mRNA expression of leptin and Insig-1. Our results indicate that GPEP may induce adipocyte differentiation via upregulation of GLUT4, PI3K and adipogenic genes. Future research may be directed toward obese individuals with insulin resistance or individuals with diabetes.

Chronic exercise and the pro-inflammatory response to endotoxin in the serum and heart.

PURPOSE: To examine the effects of moderate intensity chronic exercise on tumor necrosis factor-alpha (TNFalpha) and inducible nitric oxide synthase (iNOS) responses to endotoxin in female Sprague-Dawley rats. METHODS: Rats were divided into two groups, exercise (n=17) and sedentary (n=24). Exercise (Ex) rats completed 12 weeks of motorized treadmill running 3 days/week for 15-25 min at 22-25 m/min, while sedentary (Sed) rats remained in their cages. Twenty-four hrs after the last exercise session, animals were subdivided into three groups. One subgroup served as baseline controls. These rats received an injection of saline (s) and were killed immediately (Sed-s and Ex-s), while the other groups received an injection of lipopolysaccharide (LPS). LPS animals were killed 2 h (Sed-L2 and Ex-L2) or 4 h after the LPS injection (Sed-L4 and Ex-L4). RESULTS: Serum TNFalpha was elevated 2 h after LPS injection in both Sed and Ex groups, but was significantly higher in the chronic exercise group (Ex-L2 versus. Sed-L2). Similarly, serum beta glucuronidase activity, an indicator of tissue damage, was elevated 2 and 4 h after LPS injection, and was significantly higher in the exercise groups. Post-treatment left ventricular TNFalpha and iNOS activity, as well as stable nitric oxide derivatives in the serum (NOx), were significantly higher in LPS-injected groups compared to saline groups, but no difference in LPS effect was observed between sedentary and exercise groups. CONCLUSIONS: Moderate intensity chronic exercise stress caused an exaggerated serum TNFalpha response to endotoxin and an elevation in a serum marker of LPS-induced tissue damage.

Transplantation of mesenchymal stem cells from young donors delays aging in mice.

Increasing evidence suggests that the loss of functional stem cells may be important in the aging process. Our experiments were originally aimed at testing the idea that, in the specific case of age-related osteoporosis, declining function of osteogenic precursor cells might be at least partially responsible. To test this, aging female mice were transplanted with mesenchymal stem cells from aged or young male donors. We find that transplantation of young mesenchymal stem cells significantly slows the loss of bone density and, surprisingly, prolongs the life span of old mice. These observations lend further support to the idea that age-related diminution of stem cell number or function may play a critical role in age-related loss of bone density in aging animals and may be one determinant of overall longevity.

Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance.

It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of foods and fluids, timing of intake, and supplement choices for optimal health and exercise performance. This updated position paper couples a rigorous, systematic, evidence-based analysis of nutrition and performance-specific literature with current scientific data related to energy needs, assessment of body composition, strategies for weight change, nutrient and fluid needs, special nutrient needs during training and competition, the use of supplements and ergogenic aids, nutrition recommendations for vegetarian athletes, and the roles and responsibilities of sports dietitians. Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. Fat intake should be sufficient to provide the essential fatty acids and fat-soluble vitamins, as well as contribute energy for weight maintenance. Although exercise performance can be affected by body weight and composition, these physical measures should not be a criterion for sports performance and daily weigh-ins are discouraged. Adequate food and fluid should be consumed before, during, and after exercise to help maintain blood glucose concentration during exercise, maximize exercise performance, and improve recovery time. Athletes should be well hydrated before exercise and drink enough fluid during and after exercise to balance fluid losses. Sports beverages containing carbohydrates and electrolytes may be consumed before, during, and after exercise to help maintain blood glucose concentration, provide fuel for muscles, and decrease risk of dehydration and hyponatremia. Vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods. However, athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume unbalanced diets with low micronutrient density, may require supplements. Because regulations specific to nutritional ergogenic aids are poorly enforced, they should be used with caution, and only after careful product evaluation for safety, efficacy, potency, and legality. A qualified sports dietitian and in particular in the United States, a Board Certified Specialist in Sports Dietetics, should provide individualized nutrition direction and advice subsequent to a comprehensive nutrition assessment.

Predictors of body size stigmatization in Hispanic preschool children.

OBJECTIVE: The purpose of the current study was to verify the occurrence of body size stigmatization in Hispanic preschoolers who are "at risk" for obesity and to examine potential predictors of body size stigmatization. METHODS AND PROCEDURES: At a local preschool, 70 lower-socioeconomic, Hispanic caregivers and their preschoolers participated. Preschoolers completed an attribution task including positive and negative adjectives to assess body size stigmatization. Child's perceived size and caregiver's body dissatisfaction were assessed using a line drawing ranging in size from very underweight figures to very overweight figures. Adult and child body indices were then assessed. RESULTS: Body size stigmatization in child participants was observed. Stepwise multiple regressions revealed that child BMI was the only significant predictor of the number of positive adjectives the child assigned to the overweight picture. As child BMI increased, the number of positive adjectives assigned to the overweight picture decreased. Two predictors, caregiver body dissatisfaction with self and caregiver BMI, significantly predicted the number of negative traits the child assigned to the overweight figure. Caregivers with higher BMIs and increased body dissatisfaction were most likely to have children who showed negative body size stigmatization. DISCUSSION: Increasing rates of obesity have not led to greater acceptance of the obese and even children who are at greater risk for obesity show body size stigmatization at early ages. Caregivers are influential in the development of body size stigmatization in children and must be considered in the development of programs aimed at reducing stigmatization and obesity.

Effects of increased dietary fat and exercise on skeletal muscle lipid peroxidation and antioxidant capacity in male rats.

BACKGROUND: Elevated dietary fat increases oxidative metabolism and has been linked to increased oxidative stress, while exercise training may augment antioxidant capacity. Most studies examining oxidative stress in skeletal muscle employ extremely high levels of dietary fat and/or intense exercise training that may not adequately model human diet and activity patterns. AIM: The purpose of this study was to examine the interaction between an elevated (40% of calories) monounsaturated fat diet and a moderate-intensity exercise program similar to recommended human exercise prescriptions, on skeletal muscle oxidative stress and antioxidant defenses. METHODS: Twenty-four male Sprague-Dawley rats (approximately 500 g) were randomly divided into 4 groups (n = 6/group): Standard Diet-Sedentary (SD-Sed), Standard Diet-Exercise (SD-Ex), Elevated Fat Diet-Sedentary (EFD-Sed), and Elevated Fat Diet-Exercise (EFD-Ex). The SD groups consumed 76% of calories from CHO, 14% from protein, and 10 % from fat, while the EFD groups received a diet of 46% of calories from CHO, 14% from protein, and 40 % from fat (high oleic sunflower oil). The exercise groups were progressively treadmill trained at 20 m/min, 4 days/week increasing from 15 min/day to 35 min/day by the end of 4 wks. RESULTS AND CONCLUSION: Antioxidant adaptations associated with exercise training or an elevated fat diet individually reduced basal lipid peroxidation levels in the plantaris muscle. However, the combination of exercise plus a monounsaturated fat diet increased lipid peroxidation levels above that with either treatment alone. This suggests an exhaustion of the antioxidant capacity in the plantaris muscle when both exercise and increased dietary fat diet are combined.

Perceptions of health status and play activities in parents of overweight Hispanic toddlers and preschoolers.

Childhood overweight among lower socioeconomic, Hispanic children has increased. Interviews regarding health status and play patterns were conducted with 76 predominantly Hispanic mothers of overweight toddlers and preschoolers served by Women, Infants, and Children (WIC). Most participants believed their child was healthy and half were unconcerned about their child's weight. Most parents reported having a safe place to play and access to a playground, although gender differences were found. Access to an outside play area was related to amount of active play activities. Children watched an average of 1.7 hours per day of television. Health professionals must partner with parents to address childhood obesity.