Body Mass Loss Research Articles

The Prevalence of Hypohydration in School-Sponsored Athletes Across and Within Practice Sessions

Hydration status monitoring through weight charts can help active individuals maintain optimal fluid balance and prevent health/performance impairments. This study aimed to determine the prevalence of athletes above an acute hypohydration threshold (within practices), a chronic hypohydration threshold (across practices), and the prevalence of athletes below the acute hypohydration threshold and above the chronic hypohydration threshold simultaneously (e.g., undetected chronic hypohydration). Second, involvement of baseline hydration verification (BV; with/without), sex, and competition level (high school, college/university) with acute hypohydration, chronic hypohydration, and undetected chronic hypohydration were also examined. Undetected chronic hypohydration was prevalent across sexes (6.4 ± 16.7% males; 1.4 ± 5.8% females) and competition levels (6.5 ± 16.4% high school; 5.4 ± 15.6% college/university). No significant differences existed across BV status for average acute hypohydration (with BV = 0.8; without BV = 0.8) or chronic hypohydation (with BV = 0.7; without BV = 0.8). All three calculations, absolute body mass loss, acute hypohydration, and chronic hypohydration, should be utilized to determine the prevalence of hypohydration, and they should also be used to assist athletic trainers while making clinical decisions regarding appropriate rehydration interventions.

Body Mass Management Practices of Olympic Weightlifting Athletes.

This study explored the body mass (BM) management practices among competitive male and female Olympic weightlifting athletes, hypothesizing that athletes compete in lighter weight categories than their habitual training weight (i.e.,making weight). Utilizing a validated, anonymous survey, data were collected from 149 Olympic weightlifting athletes (>18years; female = 94). The survey comprised five sections: demographics, training/competition history, weight history, source of influence, and BM management practices. The prevalence, magnitude, and methods employed for BM management were analyzed with subgroup analysis using one-way analysis of variance. Post hoc testing including Spearman's rho and chi-square analysis was completed when a significant effect was found. Three quarters (76%) of athletes acknowledged using chronic weight loss and/or acute weight loss strategies to make weight. Usual BM loss (2%-3%) in the week before competition was within recommended guidelines. Gradual dieting, fluid restriction, and low food weight, high-calorie options were the most commonly used BM management strategies. Female athletes were more likely to use gradual dieting (p = .043; r = .104) and were less likely to increase their exercise (p = .046; r = -.105) and utilize fasting (p = .038; r = .05) compared with their male counterparts. Women further identified dietitians/nutritionists (p = .006; r = .022) as a highly influential source of information. This research offers new insights into the BM management practices of Olympic weightlifting athletes, identifying that the majority of athletes compete at a BM lighter than their habitual training weight, achieved using a range of chronic weight loss and acute weight loss strategies.

Effects of resistance training on alleviating hypoxia-induced muscle atrophy: Focus on acetylation of FoxO1.

This study aims to explore the role of FoxO1 and its acetylation in the alleviation of hypoxia-induced muscle atrophy by resistance training. Forty male Sprague-Dawley rats were randomly divided into four groups: normoxic control group (C), normoxic resistance training group (R), hypoxic control group (H) and hypoxic resistance training group (HR). Rats in R and HR groups were trained on an incremental weight-bearing ladder every other day, while those in H and HR groups were kept in an environment containing 12.4% O2 . After 4 weeks, muscles were collected for analysis. Differentiated L6 myoblasts were analysed invitro after hypoxia exposure and plasmids transfection (alteration in FoxO1 acetylation). The lean body mass loss, wet weight and fibre cross-sectional area of extensor digitorum longus of rats were decreased after 4 weeks hypoxia, and the adverse reactions above was reversed by resistance training. At the same time, the increase in hypoxia-induced autophagy was suppressed, which was accompanied by a decrease in the expression of nuclear FoxO1 and cytoplasmic Ac-FoxO1 by resistance training. The L6 myotube diameter increased and the expression of autophagic proteins were inhibited under hypoxia via intervening by FoxO1 deacetylation. Overall, resistance training alleviates hypoxia-induced muscle atrophy by inhibiting nuclear FoxO1 and cytoplasmic Ac-FoxO1-mediated autophagy.

Effect of Preoperative Gastric Shape on Loss of Lean Body Mass After Distal Gastrectomy.

Based on gastric shape, patients with gastric cancer can be divided into storage (hook-shaped and ptotic stomach) and reverse outflow (steer-horn and cascade stomach) groups. In patients with gastric cancer, postoperative loss of lean body mass (LBM) is associated with a poor prognosis. This study investigated the influence of preoperative gastric shape on LBM loss 1 month after curative distal gastrectomy. Between May 2011 and May 2019, we enrolled 487 patients with pathological stage IA/IB/IIA gastric cancer who underwent curative distal gastrectomy and did not receive adjuvant chemotherapy. Patients were divided into storage (n=370) and outflow (n=117) groups according to whether barium was stored in the stomach during the preoperative fluoroscopic examination. Clinicopathological features, LBM 1 month after gastrectomy, and predictors of postoperative LBM loss were compared between the groups using multivariable logistic regression. The incidence of >5% LBM loss and >7.5% body weight loss 1 month postoperatively were significantly higher in the storage group than in the outflow group (p=0.003 and p=0.009, respectively). Multivariable analysis revealed that gastric shape [odds ratio (OR)=3.30, 95% confidence interval (CI)=1.95-5.59, p<0.001], male sex (OR=3.20, 95% CI=2.07-4.96, p<0.001), and Roux-en-Y reconstruction (OR=1.69, 95% CI=1.08-2.64, p=0.02) were independent predictors of LBM loss. Postoperative dietary problems, especially dumping syndrome, diarrhea, and reflux were more common in the storage group (p<0.001). Gastric shape may be a useful independent predictor of postoperative LBM loss in patients with gastric cancer undergoing distal gastrectomy.

Compositional Aspects of Beverages Designed to Promote Hydration Before, During, and After Exercise: Concepts Revisited.

Hypohydration can impair aerobic performance and deteriorate cognitive function during exercise. To minimize hypohydration, athletes are recommended to commence exercise at least euhydrated, ingest fluids containing sodium during long-duration and/or high-intensity exercise to prevent body mass loss over 2% and maintain elevated plasma osmolality, and rapidly restore and retain fluid and electrolyte homeostasis before a second exercise session. To achieve these goals, the compositions of the fluids consumed are key; however, it remains unclear what can be considered an optimal formulation for a hydration beverage in different settings. While carbohydrate-electrolyte solutions such as sports drinks have been extensively explored as a source of carbohydrates to meet fuel demands during intense and long-duration exercise, these formulas might not be ideal in situations where fluid and electrolyte balance is impaired, such as practicing exercise in the heat. Alternately, hypotonic compositions consisting of moderate to high levels of electrolytes (i.e., ≥45 mmol/L), mainly sodium, combined with low amounts of carbohydrates (i.e., <6%) might be useful to accelerate intestinal water absorption, maintain plasma volume and osmolality during exercise, and improve fluid retention during recovery. Future studies should compare hypotonic formulas and sports drinks in different exercise settings, evaluating different levels of sodium and/or other electrolytes, blends of carbohydrates, and novel ingredients for addressing hydration and rehydration before, during, and after exercise.

Fasting mimicking diet cycles versus a Mediterranean diet and cardiometabolic risk in overweight and obese hypertensive subjects: a randomized clinical trial

Abnormalities in the vascular endothelium such as impaired vasodilation can contribute to atherosclerosis and hypertension. Here we have performed a single-center randomized clinical trial to evaluate the efficacy of 4 months of a continuous Mediterranean diet (MD) regimen as compared to 4 cycles of fasting mimicking diet (FMD) administered for only 5 days/month on endothelial function, measured as reactive hyperemia index (RHI) and large/small-resistance artery compliance (AC1/AC2), and on other cardiometabolic risk factors, in hypertensive patients with obesity/excess weight [both sexes, body mass index (BMI) ≥ 28, RHI ≤ 2.0, and/or small-resistance artery compliance (AC2) ≤ 5.0]. At the end of the intervention period, FMD but not MD decreased RHI (p = 0.0023) compared to baseline with no increase in the portion of patients with abnormal RHI. Both FMD and MD improved PULS cardiac test score; evaluating the risk of cardiovascular events. FMD and MD did not show any significant change in either AC1 or AC2 compared to baseline. Both FMD and MD led to comparable decreases in weight, waist circumference, BMI, body fat mass and % body fat, total cholesterol, and leptin. FMD decreased HbA1c (p = 0.0059) and IGF-1 (p = 0.0427), while MD decreased glucose (p = 0.0488), HOMA-IR (p = 0.0476), and HDL-C (p = 0.0419). None of the parameters were significantly different between the FMD vs. MD group at the end of the intervention period. During the 3-month follow-up period, the FMD and MD groups continued to display weight and BMI reduction; however, the MD group also lost fat free mass (FMD vs. MD, p = 0.0498). In summary, both MD and FMD reduced a range of cardiometabolic risk factors, but FMD also decreased RHI, a change associated with either impaired functional integrity of vascular endothelial cells but also with vascular rejuvenation, with the latter being more likely considering the improved cardiometabolic profile, reduced PULS cardiac score and calculated heart age, and unaltered arterial compliance in the FMD group. MD but not FMD cycles caused loss of lean body mass.

Effects of testosterone enanthate on aggression, risk-taking, competition, mood, and other cognitive domains during 28 days of severe energy deprivation

RationaleBehavioral effects of testosterone depend on dose, acute versus sustained formulation, duration of administration, personality, genetics, and endogenous levels of testosterone. There are also considerable differences between effects of endogenous and exogenous testosterone.ObjectivesThis study was the secondary behavioral arm of a registered clinical trial designed to determine if testosterone protects against loss of lean body mass and lower-body muscle function induced by a severe energy deficit typical of sustained military operations.MethodsBehavioral effects of repeated doses of testosterone on healthy young men whose testosterone was reduced by severe energy deficit were examined. This was a double-blind, placebo-controlled, between-group study. Effects of four weekly intramuscular injections of testosterone enanthate (200 mg/week, N = 24) or matching placebo (N = 26) were evaluated. Determination of sample size was based on changes in lean body mass. Tasks assessing aggression, risk-taking, competition, social cognition, vigilance, memory, executive function, and mood were repeatedly administered.ResultsDuring a period of artificially induced, low testosterone levels, consistent behavioral effects of administration of exogenous testosterone were not observed.ConclusionsExogeneous testosterone enanthate (200 mg/week) during severe energy restriction did not reliably alter the measures of cognition. Study limitations include the relatively small sample size compared to many studies of acute testosterone administration. The findings are specific to healthy males experiencing severe energy deficit and should not be generalized to effects of other doses, formulations, or acute administration of endogenous testosterone or studies conducted with larger samples using tests of cognitive function designed to detect specific effects of testosterone.

Browning of white adipose tissue may be an appropriate adaptive response to critical illness.

Both the baseline amount of brown adipose tissue (BAT) and the capacity to stimulate browning of white adipose tissue (WAT) may provide a protective effect to the patient in a critical care setting. Critical illness is associated with reduced mitochondrial volume and function resulting in the increased production of reactive oxygen species, greater demand for adenosine triphosphate, a switch to uncoupled fat metabolism, and hibernation of the organelle, which all contribute to multiple organ failure. Increasing insulin resistance, decreasing fatty acid oxidation, and dependence on carbohydrate metabolism result. Browning of WAT may oppose many of these adverse effects. The presence of BAT and the changes associated with browning may help dissipate oxidative stress, increase consumption and utilization of metabolites, and reduce pro-inflammatory actions. The number of mitochondria increases, and there is greater infiltration of macrophages into adipose tissue. A shift occurs in macrophage expression from the M1 to M2 phenotype, an effect which further dampens inflammation, increases insulin sensitivity, and improves tissue healing and remodeling. Any benefit from these responses may be lost in the disease states of chronic hypermetabolism (such as burns or cancer cachexia) in which the persistence of these physiologic effects may become detrimental, contributing to excessive weight loss, adipose wasting, and loss of lean body mass. This paper discusses the plasticity of adipose tissue and whether shifts in its physiology provide clinical advantages in the intensive care unit.

Effect of Excessive Environmental Heat Load on Digestibility, Energy Balance, and Urea Recycling in the Mediterranean (Member) Goat

This study investigates the energy and nitrogen economy of the Mediterranean goat across diverse environmental conditions, emphasizing the influence of heat stress and shelter on animal productivity. Environmental factors such as water availability, food quality, and heat stress affect the animal's capacity to convert indigestible plant components into digestible food and sustain energy balance. In particular, heat stress causes a significant decrease in the goat's food by 27.49% and by 34.85% in alfalfa hay and wheat straw respectively, leading to a loss of body mass, even when offered high-quality food such as alfalfa hay. However, when sheltered from direct sunlight, the goat can maintain an energy balance on any diet, a significant decrease in body mass was recorded, with a reduction of 10.59% for alfalfa hay and 17.79 ± 3.0% for wheat straw. Heat stress also impairs the goat's ability to maintain a balanced nitrogen economy, reducing nitrogen loss through excretion during heat load conditions and high-protein food digestion. The study found that the average urea recycling rate in goats kept in a shelter was 36%, which was significantly higher than the rate observed in goats exposed to heat stress, which was only 19.6%. Moreover, the amount of recycled urea was also higher in the shelter at 91% compared to 69.9% in the reflected heat stress recorded when the goats were maintained on a diet of wheat straw. As the goat cannot reduce its metabolic rate, a negative energy balance occurs, resulting in body mass loss. The quality of food and heat stress are critical determinants of the goat's food consumption, with high heat load reducing appetite. This study concludes that sheltered conditions, providing protection from direct sunlight, are necessary to sustain productivity and maintain a stable body mass on any diet. Furthermore, maintaining a balanced nitrogen balance can be challenging for animals consuming low-protein food, particularly under suboptimal feeding conditions. The study's findings have implications for the broader issue of global warming, as rising temperatures could increase heat stress and reduce food consumption and productivity in animals, with potentially negative consequences for agriculture and food security. Therefore, protecting animals from heat stress through adequate shelter and management practices is essential to mitigate the negative impacts of global warming on animal productivity, Animal husbandry, and human livelihoods.

61 Life Stage Feeding: Is There Path Forward for Senior/Geriatric Nutrient recommendations?

Abstract Complete and balanced foods for “all life stages”, according to the Association of American Feed Control Officials (AAFCO), meet the needs for reproduction and growth. While these are recognized as the most nutritionally demanding stages, they are relatively short time periods in the life of a pet. Unique to companion animals, and humans, is the prolonged “senior” life stage. Although this stage is not well defined, it has become evident that energy, protein and other nutrient requirements may change with age in seniors. To establish guidelines for a lifestage, that lifestage must be defined (Table 1). Species and breed differences exist in terms of aging, in that small breed dogs have longer lifespans versus large breed dogs, and cats differ from dogs, with cats showing a definable fourth lifestage of “geriatric” that differs from a “senior” lifestage. A major challenge to defining senior or geriatric nutritional needs is the fact that animals “age” at different rates, causing senior/geriatric to be the most physiologically diverse lifestage. In nutritionally complete and balanced foods, nutrients are provided in proportion to the energy content of the diet and to the expected energy intake of the pet. Regardless of lifestage, energy requirements can differ significantly among dog breeds and among individuals. Added to this is evidence that energy requirements in dogs decrease with age, such that senior dogs need about 25% fewer calories, on average, than young adult dogs. Likewise, senior cats show a decrease in energy requirements, but geriatric cats display an increase in energy needs. Thus, even if the absolute requirement for nutrients did not change with age, the content needed on an energy basis will change. One of the challenges to establishing protein requirements for senior and geriatric pets is age-related loss of lean body mass (LBM), or sarcopenia. LBM serves as a protein reservoir and provides the amino acids used on a 24/7 basis for endogenous protein synthesis, while dietary protein maintains or restores this reservoir. It has become evident that nitrogen balance studies, long used to determine protein requirements for adults, are not sufficient in that they do not account for contributions from LBM. Maintenance of LBM may be a better assay for defining protein requirements. However, LBM is lost with age in all species studied, including humans, dogs and cats. Geriatric cats lose approximately one third of their LBM, while senior dogs lose about 10%. Loss of LBM is associated with greater morbidity and mortality, thus, preservation of LBM is an important goal. While increasing protein intake can slow the loss, and vice versa, increasing protein intake alone cannot prevent loss of LBM. Therefore, an important challenge is to determine how to measure protein requirements in aging pets.

Repeatability of Ad Libitum Water Intake during Repeated 1 h Walking/Jogging Exercise Sessions Conducted under Hot Ambient Conditions.

A drinking strategy aiming to replace a given percentage of the sweat losses incurred during exercise should result in reproducible fluid intake volume and, hence, fluid balance from one exercise session to the other performed under similar scenarios. Whether this may also be the case with ad libitum drinking during exercise is unclear. We characterized the repeatability of ad libitum water intake during repeated 1 h exercise sessions and examined its effect over time on fluid balance and selected physiological functions and perceptual sensations. Twelve (3 women) healthy individuals participated in this study. At weekly intervals, they completed four 2 × 30 min walking/jogging exercise bouts (55% V˙O2max, 40 °C, 20-30% relative humidity) interspersed by a 3 min recovery period. During exercise, participants consumed water (20 °C) ad libitum. There were no significant differences among the four exercise sessions for absolute water intake volume (~1000 mL·h-1), percent body mass loss (~0.4%), sweat rate (~1300 mL·h-1) and percent of sweat loss replaced by water intake (~80%). Heart rate, rectal temperature, and perceived thirst and heat stress did not differ significantly between the first and fourth exercise sessions. Perceived exertion was significantly lower during the fourth vs. the first exercise session, but the difference was trivial (<1 arbitrary unit). In conclusion, ad libitum water intake during four successive identical 1 h walking/jogging sessions conducted in the heat will result in similar water intake volumes and perturbations in fluid balance, heart rate, rectal temperature, and perceived thirst, heat stress and exertion.

Impact of Preparticipation Hypohydration on Cognitive Performance and Concussion-like Symptoms in Recreational Athletes.

Sports-related concussion is a relevant risk of contact sports, with several million cases per year worldwide. Prompt identification is crucial to prevent complications and late effects but may be impeded by an overlap with dehydration-associated impairment of cognitive function. Researchers have extensively studied the effects of pronounced dehydration in endurance sports, especially in the heat. However, little is known about the effects of isolated and mild dehydration. Healthy recreational athletes underwent a standardized fluid deprivation test. Hypohydration was assessed by bioelectrical impedance analysis (BIA) and laboratory testing of electrolytes and retention parameters. Participants underwent cardiopulmonary exercise testing (CPET) with a cycle ramp protocol. Each participant served as their own control undergoing CPET in a hypohydrated [HYH] and a euhydrated [EUH] state. Effects were assessed using a shortened version of Sport Concussion Assessment Tool 3 (SCAT3). Fluid deprivation caused a mild (2%) reduction in body water, resulting in a calculated body mass loss of 0.8% without alterations of electrolytes, serum-osmolality, or hematocrit. Athletes reported significantly more (1.8 ± 2.2 vs. 0.4 ± 0.7; p < 0.01) and more severe (4.4 ± 6.2 vs. 1.0 ± 1.9; p < 0.01) concussion-like symptoms in a hypohydrated state. Balance was worse in HYH by trend with a significant difference for tandem stance (1.1 ± 1.3 vs. 0.6 ± 1.1; p = 0.02). No relevant differences were presented for items of memory and concentration. Mild dehydration caused relevant alterations of concussion-like symptoms and balance in healthy recreational athletes in the absence of endurance exercise or heat. Further research is needed to clarify the real-life relevance of these findings and to strengthen the differential diagnosis of concussion.

Hypohydration induced by prolonged cycling in the heat increases biomarkers of renal injury in males

PurposeRecent studies have shown that hypohydration can increase renal injury. However, the contribution of hypohydration to the extent of renal injury is often confounded by exercise induced muscle damage. Therefore, the aim of the present study was to investigate the effect of manipulating hydration status during moderate-intensity cycling in the heat on biomarkers of renal injury.MethodsFollowing familiarisation, fourteen active males (age: 21 [20–22] y; BMI: 22.1 ± 1.9 kg/m2; V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\dot{V} $$\\end{document}O2peak: 55 ± 9 mL/kg/min) completed two experimental trials, in a randomised cross-over design. Experimental trials consisted of up to 120 min of intermittent cycling (~ 50% Wpeak) in the heat (~ 35 °C, ~ 50% relative humidity). During exercise, subjects consumed either a water volume equal to 100% body mass losses (EU) or minimal water (HYP; 75–100 mL) to induce ~ 3% body mass loss. Blood and urine samples were collected at baseline, 30 min post-exercise and 24 h post-baseline, with an additional urine sample collected immediately post-exercise.ResultsThirty minutes post-exercise, body mass and plasma volume were lower in HYP than EU (P < 0.001), whereas serum and urine osmolality (P < 0.001), osmolality-corrected urinary kidney injury molecule-1 concentrations (HYP: 2.74 [1.87–5.44] ng/mOsm, EU: 1.15 [0.84–2.37] ng/mOsm; P = 0.024), and percentage change in osmolality-corrected urinary neutrophil gelatinase-associated lipocalin concentrations (HYP: 61 [17–141] %, EU: 7.1 [– 4 to 24] %; P = 0.033) were greater in HYP than EU.ConclusionHypohydration produced by cycling in the heat increased renal tubular injury, compared to maintaining euhydration with water ingestion.

Isolate Whey Protein Promotes Fluid Balance and Endurance Capacity Better Than Isolate Casein and Carbohydrate-Electrolyte Solution in a Warm, Humid Environment.

Protein ingestion is known to enhance post-exercise hydration. Whether the type of protein (i.e., whey, casein) can alter this response is unknown. Accordingly, this study aimed to compare the effects of the addition of milk-derived whey isolate or casein protein to carbohydrate-electrolyte (CE) drinks on post-exercise rehydration and endurance capacity. Thirty male soldiers (age: 24 ± 2.1 y; VO2max: 49.3 ± 4.7 mL/kg/min) were recruited. Upon losing ~2.2% of body mass by running in warm and humid conditions (32.3 °C, 76% relative humidity [RH]), participants ingested either a CE solution (66 g/L carbohydrate [CHO]), or CE plus isolate whey protein (CEW, 44 g/L CHO, 22 g/L isolate whey), or CE plus isolate casein protein (CEC, 44 g/L CHO, 22 g/L isolate casein) beverage in a volume equal to 150% of body mass loss. At the end of the 3 h rehydration period, a positive fluid balance was higher with CEW (0.22 L) compared to CEC (0.19 L) and CE (0.12 L). Overall mean fluid retention was higher in CEW (80.35%) compared with the CE (76.67%) and CEC trials (78.65%). The time of the endurance capacity test [Cooper 2.4 km (1.5 miles) run test] was significantly higher in CEC (14.25 ± 1.58 min) and CE [(12.90 ± 1.01 min; (p = 0.035)] than in CEW [(11.40 ± 1.41 min); (p = 0.001)]. The findings of this study indicate that the inclusion of isolate whey protein in a CE solution yields superior outcomes in terms of rehydration and enhanced endurance capacity, as compared to consuming the CE solution alone or in conjunction with isolate casein protein.

Nutrition Considerations for Burn Patients: Optimizing Recovery and Healing

The hypermetabolic and hypercatabolic responses to severe burns put nutrition support at the forefront of treatments. When left untreated, severe weight loss, increased infection, and wound healing failure can occur. Enteral nutrition is the primary method of nutrition support in such patients. Meeting caloric needs and a positive nitrogen balance are short-term goals of nutrition support, with long-term goals of minimizing lean body mass loss and maximizing wound healing. High-carbohydrate and low-fat nutrition received evidence from randomized controlled trials of aiding in decreasing pneumonia rates and was found to promote positive nitrogen balance, which lipids do not do. We go through the macronutrient and micronutrient needs of the burn patient as well as techniques for meeting these needs in the modern intensive care unit, with some discussion of alterations in these techniques that are required in the austere environment.

Football Practices in Hot Environments Impact Subsequent Days' Hydration.

Ashley, CD, Lopez, RM, and Tritsch, AJ. Football practices in hot environments impact subsequent days' hydration. J Strength Cond Res XX(X): 000-000, 2023-The impact of proper hydration to prevent exertional heat illness in American football has not been evaluated during high school preseason football practices in a hot environment (wet-bulb globe temperature = 31.3 ± 1.8° C). The purposes of this study were to examine the accuracy of urinary hydration measures to assess body mass (BM) changes and to examine carryover effects of consecutive practices by comparing postpractice with the next prepractice values. Before and after each of 7 outdoor practices, 31 male high school football players (age = 16 ± 1 years, height = 181.2 ± 12.0 cm, BM = 85.7 ± 19.1 kg, body mass index = 20.8 ± 1.8) provided a urine sample and were weighed to assess hydration. Sensitivity and specificity of urine color (Ucol) and urine-specific gravity (USG) to determine BM changes were determined using receiver operating characteristic (ROC) analysis. Paired samples t-tests assessed carryover effects between practices. Repeated-measures analysis of variance assessed carryover effects across practices. Significance was set at p < 0.05. Sensitivity and specificity for using Ucol or USG to determine BM changes was not significant. For Ucol, there was a carryover effect from practice numbers 2 to 3, 6 to 7 am, 7 am to 7 pm (p < 0.001 for all), and 10 to 11 (p = 0.004); most with less than 24 hours between practices. The %BM loss (%BML) was significantly greater (p = 0.001 to 0.024) after 2-a-day practices. Effects of previous days' exercise in the heat, as evidenced by higher Ucol and %BL, are greater after 2-a-day practices, which occurred on later practice days. Athletes must replenish fluids during and between practices to remain euhydrated.

OR29-04 Vitamin D Signaling Prevents Glucocorticoid-Induced Musculoskeletal Tissue Loss And Cardiac Dysfunction By Targeting The Atrogene Pathway

Abstract Disclosure: A. Sato: None. M. Cregor: None. B. Adhikari: None. M. Boerma: None. T. Bellido: None. Glucocorticoid excess increases the risk of bone fractures and induces cardiovascular events. Earlier studies demonstrated that glucocorticoids upregulate the expression of E3 ubiquitin ligases (atrogenes) in bone and skeletal/cardiac muscles, suggesting a common targetable pathway to prevent harmful glucocorticoid actions. Atrogenes stimulate proteasomal degradation of proteins, which promotes musculoskeletal tissue loss and cardiac dysfunction, known hallmarks of glucocorticoid disease. Here, we investigated whether Vitamin D receptor activation, which has beneficial musculoskeletal effects and may prevent falls, blocks glucocorticoid-induced activation of the atrogene pathway. Skeletally mature female 4-month-old C57Bl6 mice (N=12) were implanted with placebo or 2.1mg/kg/d prednisolone pellets for 8wks and received vehicle or 50ng/kg/d of 1,25D3 (calcitriol), 5x/wk, starting 3d before pellet implantation. In bone, 1,25D3 fully prevented decreases in spinal bone mineral density (BMD) and cancellous bone microarchitectural deterioration (low BV/TV and Tb.Th) induced by glucocorticoids. 1,25D3 prevented glucocorticoid-induced resorption, as quantified by circulating CTX and osteoclast number/surface. In contrast, 1,25D3 did not prevent glucocorticoid-induced suppression of bone formation, as quantified by circulating markers (P1NP and osteocalcin) and histomorphometric indexes (MS/BS and BFR). In skeletal muscle, 1,25D3 fully prevented glucocorticoid-induced loss of lean body mass, a muscle mass index measured by DEXA, and decreases in muscle strength, as determined by in vivo plantarflexion torque testing of the posterior hindlimb muscular compartment. Consistent with clinical evidence, cardiac echocardiography detected glucocorticoid dysfunction as exhibited by left ventricular (LV) wall thinning (anterior and posterior LVs at diastole and systole) and inefficient heart contraction (increased LV systolic volume, reduced ejection fraction and fractional shortening). Remarkably, 1,25D3 prevented the cardiac LV thinning and dysfunction induced by glucocorticoids. Neither glucocorticoid nor 1,25D3 altered heart mass, LV mass, or heart rate. 1,25D3 also prevented glucocorticoid increases in atrogene MuRF1 expression in cardiac and skeletal tissues. Additionally, 1,25D3 prevented glucocorticoid-induced increases in atrogene expression in separate ex vivo organ cultures of bone, skeletal muscle, and left ventricles of the heart, demonstrating direct Vitamin D actions. In conclusion, 1) atrogene upregulation is a central mechanistic hub underlying the damaging actions of glucocorticoid excess in bone, skeletal muscle, and the heart and 2) activation of Vitamin D receptor signaling preserves tissue structure and function by interfering with the atrogene pathway in musculoskeletal and cardiac systems. Presentation: Sunday, June 18, 2023

FRI017 Precision-engineered Activin And GDF Ligand Trap HS235: A Novel Lean Mass-preserving Treatment for Obesity

Abstract Disclosure: G. Schang: Employee; Self; 35Pharma Inc. M. Poujol de Molliens: Employee; Self; 35Pharma Inc. E. Brûlé: Employee; Self; 35Pharma Inc. C. Chauvet: Employee; Self; 35Pharma Inc. J. Denis: Employee; Self; 35Pharma Inc. A. Sours: Employee; Self; 35Pharma Inc. V. Ganesh: Employee; Self; 35Pharma Inc. G. Tremblay: Employee; Self; 35Pharma Inc. J. Schoelermann: Employee; Self; 35Pharma Inc. M. O'Connor-McCourt: Employee; Self; 35Pharma Inc. Introduction: Novel anti-obesity medications including incretin mimetics have revolutionized the pharmacotherapy of obesity and type 2 diabetes, leading to unprecedented weight loss and clinically meaningful improvement of glucose metabolism and cardiometabolic health. However, this loss of fat mass is accompanied by undesirable loss of lean body mass (LBM) which can account for 15 - 40% of overall weight loss. Loss of LBM by incretin-based therapies negatively impacts resting metabolic rate, leading to a weight loss plateau and often unsustainable results. The preservation, or even increase, of LBM is therefore a desirable treatment goal for obesity pharmacotherapy and improvement of overall health. Activins and growth differentiation factors (GDFs), which are members of the TGF-beta superfamily, are validated targets controlling body composition and metabolism. Specifically, blockade of activins and GDFs has anabolic effects in metabolically active tissues such as skeletal muscle and brown adipose tissue, while reducing white adipose tissue mass. Therefore, specific and selective blockade of activins and GDFs represents a novel anti-obesity treatment strategy which can act orthogonally to current anti-obesity medications. Aims and objectives: HS235 is an activin receptor ectodomain-based (ActR) Fc-fusion protein that has been rationally designed to attain optimal inhibition of ligands controlling body composition in obesity. Methods: A structure-assisted rational molecular engineering approach coupled with cell-based potency screening was employed to design HS235. In vivo target engagement and pharmacodynamic response to HS235 were assessed in mice by quantifying metabolic biomarkers including muscle hypertrophy, muscle and fat gene expression, as well as plasma metabolites. To further validate the anti-obesogenic potential of HS235, diet-induced obese (DIO) mice were injected with HS235, an incretin mimetic, or a combination of both. Fat mass, LBM, glucose metabolism, exercise tolerance, and biomarker readouts were assessed at the end of study. Results: In cell-based assays, HS235 potently and selectively neutralized activins and GDFs implicated in body composition. This translated to complete in vivo target engagement and pharmacodynamic response. In a DIO mouse model, both HS235 and the incretin mimetic significantly improved metabolic parameters and decreased fat mass, but only HS235 increased LBM, while incretin-based treatment led to LBM loss. Importantly, the addition of HS235 to the incretin mimetic prevented this loss of LBM. Conclusion: Potent and selective inhibition of activins and GDFs by HS235 represents a novel LBM preserving weight loss strategy. Collectively, these data support the development of HS235 as a novel anti-obesity agent that may also complement currently approved incretin-based medications. Presentation: Friday, June 16, 2023

Rapid Weight Loss Practices Within Olympic Weightlifters.

Gee, TI, Campbell, P, Bargh, MJ, and Martin, D. Rapid weight loss practices within Olympic weightlifters. J Strength Cond Res 37(10): 2046-2051, 2023-Rapid weight loss (RWL) practices are common among athletes to "make weight" for a chosen bodyweight class. This study's purpose was to investigate RWL prevalence, magnitude, and methods within Olympic weightlifters from Great Britain. Subjects (n = 39, male = 22, female = 17) were recruited from International Weightlifting Federation lifting populations (mandatory two-hour competition weigh-in). Subjects were categorized into competitive groups based on Sinclair coefficient total (high, mid, low) and also gender (male, female). The validated Rapid Weight Loss Questionnaire was used to establish RWL magnitude and practices. Of respondents, 33 of 39 (84.6%) had purposely acutely reduced body mass to compete, a higher proportion present within females (94.1%) than males (77.3%). The cohort's mean habitual precompetition acute body mass loss was 3.8 ± 1.7% and the "rapid weight loss score" (RWLS) was 23.6 ± 9.5. Across competitive groups there were no significant differences in habitual or highest precompetition body mass loss, postcompetition body mass gain or RWLS (p > 0.05). However, females attributed a significantly greater "highest" relative precompetition body mass loss compared with males (7.4 vs 4.9%, p = 0.045). For RWL methods used, frequencies of "always" and "sometimes" were reported highest for "restricting fluid ingestion" (81.8%), "gradual dieting" (81.8%), and "water loading" (54.5%). The prevalence of RWL is high among competitive Olympic weightlifters, and especially within the sampled female athletes. Magnitude of RWL was similar across different standards of athlete; however, female lifters demonstrated a higher maximum precompetition RWL.

Carbohydrate or Electrolyte Rehydration Recovers Plasma Volume but Not Post-immersion Performance Compared to Water After Immersion Diuresis.

We tested the hypothesis that a carbohydrate (CHO: 6.5%) or carbohydrate-electrolyte (CHO + E: 6.5% + 50 mmol/L NaCl) drink would better recover plasma volume (PV) and exercise performance compared to water (H2O) after immersion diuresis. Twelve men (24 ± 2 years; 82.4 ± 15.5 kg; and V̇O2max: 49.8 ± 5.1 mL · kg-1 · min-1) completed four experimental visits: a no-immersion control (CON) and three 4-h cold-water (18.0 °C) immersion trials (H2O, CHO, and CHO + E) followed by exercise in a warm environment (30 °C, 50% relative humidity). The exercise was a 60-minute loaded march (20.4 kg; 55% VO2max) followed by a 10-minute intermittent running protocol. After immersion, subjects were rehydrated with 100% of body mass loss from immersion diuresis during the ruck march. PV is reported as a percent change after immersion, after the ruck march, and after the intermittent running protocol. The intermittent running protocol distance provided an index of exercise performance. Data are reported as mean ± SD. After immersion, body mass loss was 2.3 ± 0.7%, 2.3 ± 0.5%, and 2.3 ± 0.6% for H2O, CHO, and CHO + E. PV loss after immersion was 19.8 ± 8.5% in H2O, 18.2 ± 7.0% in CHO, and 13.9 ± 9.3% in CHO + E, which was reduced after the ruck march to 14.7 ± 4.7% (P = .13) in H2O, 8.8 ± 8.3% (P < .01) in CHO, and 4.4 ± 10.9% (P = .02) in CHO + E. The intermittent running protocol distance was 1.4 ± 0.1 km in CON, 1.4 ± 0.2 km in H2O, 1.4 ± 0.1 km in CHO, and 1.4 ± 0.2 km in CHO + E (P = .28). Although CHO and CHO + E better restored PV after immersion, post-immersion exercise performance was not augmented compared to H2O, highlighting that fluid replacement following immersion diuresis should focus on restoring volume lost rather than fluid constituents.