Associations between urine specific gravity and race/ethnicity at the population level: Implications for hydration status categorization.

OBJECTIVE: We aimed to evaluate how urine specific gravity (USG) and rates of supposed hypohydration vary by race/ethnicity, and to examine how adjustment for several important factors impacts estimated USG. METHODS: Using the National Health and Nutrition Examination Survey, this cross-sectional study evaluated a total of 4195 (2098 female, 2097 male) Americans and categorized them as supposedly hypohydrated (USG≥1.020) or not using spot urine samples. USG and prevalence of supposed hypohydration were compared across racial/ethnic groups, separately by gender. The analyses considered the impact of urine creatinine, body composition, age, dietary nutrients, and physical activity. RESULTS: Differences in supposed hypohydration prevalence were observed by race/ethnicity in men (p = .030) and women (p < .001). In unadjusted models, Black women's USG (1.0189) was higher (p < .05) than all the other race/ethnicity groups' USG (1.0142-1.0171). In men, Blacks' USG (1.0197) was higher (p < .05) than the USG of Whites (1.0177) and other/multi-racial (1.0176) but not Mexican Americans (1.0196) or other Hispanics (1.0192). Adjustments for age, arm circumference, nutrients (protein, sodium, potassium, and moisture), and physical activity minimally influenced USG estimates. Further adjustment for urine creatinine lowered USG for Black women and men by 0.003 and 0.0023, respectively, with no notable lowering of USG in the other races/ethnicities. Supplemental analyses matching Whites and Blacks on age, moisture intake, and poverty-to-income ratio confirmed racial differences in urine creatinine and USG, though the effects were most pronounced in women. CONCLUSIONS: Using a USG≥1.020 to identify hypohydration in all races/ethnicities may be inappropriate due to, among other factors, differences in urinary creatinine.

Effects of food bar chewing duration on the physiologic, metabolic, and perceptual responses to moderate-intensity running.

PURPOSE: Chewing duration can affect food particle size, gastric processing, and postprandial glycemia, but these effects have not been investigated with exercise. This study examined how the chewing duration of a food bar impacts glycemic and metabolic responses, gastrointestinal (GI) symptoms, psychological affect, and performance during endurance running. METHODS: This randomized, unblinded, crossover study had 15 males (35.2 ± 7.4 years, VO2peak: 56.1 ± 5.2 ml/kg/min) attend three laboratory visits. Visit 1 required a VO2peak test, 10 min familiarization run at 60% VO2peak, and familiarization time-to-exhaustion (TTE) test (10 min at 90% VO2peak, followed by TTE at 100% VO2peak). Visits 2 and 3 consisted of a 60 min run at 60% VO2peak, followed by TTE testing. Participants were fed 45 g of a bar (180 kcal, 4 g fat, 33 g carbohydrate, 3 g protein, 1 g fiber) in 9 g servings 30 min before running, and 27 g of bar in 9 g servings at three timepoints during the 60 min run. Participants consumed the servings in 20 (20CHEW) or 40 (40CHEW) masticatory cycles, at 1 chew/second. Outcomes included blood glucose, substrate use, GI symptoms, perceived exertion (RPE), overall feeling, and TTE. RESULTS: Post-prandial blood glucose, GI symptoms, and RPE increased over time, but there were no significant between-condition or condition-by-time effects. TTE showed no significant between-condition effect (20CHEW: 288 ± 133 s; 40CHEW: 335 ± 299 s; p = 0.240). Overall feeling demonstrated a time-by-condition effect (p = 0.006), suggesting possible better maintenance over time with 40CHEW. CONCLUSION: Cumulatively, the results suggest that extended chewing minimally impacts physiology, perceptions, and performance during 60 min moderate-intensity running.

Differences in urine creatinine and osmolality between black and white Americans after accounting for age, moisture intake, urine volume, and socioeconomic status.

Urine osmolality is used throughout research to determine hydration levels. Prior studies have found black individuals to have elevated urine creatinine and osmolality, but it remains unclear which factors explain these findings. This cross-sectional, observational study sought to understand the relationship of self-reported race to urine creatinine and urine osmolality after accounting for age, socioeconomic status, and fluid intake. Data from 1,386 participants of the 2009-2012 National Health and Nutrition Examination Survey were utilized. Age, poverty-to-income ratio (PIR), urine flow rate (UFR), fluid intake, estimated lean body mass (LBM), urine creatinine, and urine osmolality were measured. In a sex-specific manner, black and white participants were matched on age, dietary moisture, UFR, and PIR. Urine creatinine was greater in black men (171 mg/dL) than white men (150 mg/dL) and greater in black women (147 mg/dL) than white women (108 mg/dL) (p < .001). Similarly, urine osmolality was greater in black women than white women (723 vs. 656 mOsm/kg, p = .001), but no difference was observed between white and black men (737 vs. 731 mOsm/kg, p = .417). Estimated LBM was greater in black men (61.8 kg) and women (45.5 kg) than in white men (58.9 kg) and women (42.2 kg) (p≤.001). The strongest correlate of urine osmolality in all race-sex groups was urine creatinine (Spearman ρ = .68-.75). These results affirm that individuals identifying as black produce higher urine creatinine concentrations and, in women, higher urine osmolality after matching for age, fluid intake, and socioeconomic status. The findings suggest caution when comparing urine hydration markers between racial groups.

Trunk-to-leg-volume ratio is not associated with bone density or fracture risk in middle-aged adults: results from the National Health and Nutrition Examination Survey.

Unlike a high body mass index or waist circumference, a high trunk-to-leg-volume ratio does not associate with a lower risk of osteopenia/osteoporosis at the femoral neck. While elevated TLVR showed a suggestive association with a history of wrist fracture in women, additional research is needed to confirm this suggestion. PURPOSE: Body mass index (BMI) and waist circumference (WC) are commonly used to predict bone health, which is typically assessed via bone mineral density (BMD). Trunk-to-leg-volume ratio (TLVR), a relatively novel measure, predicts cardiometabolic outcomes, but its relationships with BMD and fracture remain unstudied. This study evaluated these anthropometric measures' associations with BMD and fracture in Americans aged 40-60 years. METHODS: Analyses of middle-aged adults from the 2013-2014 to 2017-2018 National Health and Nutrition Examination Survey were conducted. Whole-body, dual-energy X-ray absorptiometry was used to quantify TLVR as well as BMD at the lumbar spine, while a femur-specific scan was used to quantify femoral neck BMD. Fracture history was self-reported. Linear and logistic regression models were constructed with age, diabetes, smoking, race/ethnicity, education, and physical activity as confounding variables. RESULTS: TLVR was generally not associated with BMD, while WC and BMI showed positive associations with femoral neck BMD. Odds of osteopenia/osteoporosis at the femoral neck were ~ 65-80% lower among participants in the highest tertile of BMI and WC versus the lowest (p < 0.001). There were no statistically significant associations between anthropometric predictors and fracture. Women in tertiles 2 or 3 of TLVR (p = 0.097 and 0.079, respectively) did have 2.66 times the odds of wrist fracture than women in tertile 1, but this was not significant. CONCLUSION: As shown in previous research, BMI and WC show positive associations with femoral BMD. In contrast, the more novel anthropometric marker TLVR shows no association with femoral BMD, and no clear association with fracture.

Anxiety and visceral sensitivity relate to gastrointestinal symptoms in runners but not pre- or during-event nutrition intake.

BACKGROUND: Previous research has shown anxiety to relate to gastrointestinal (GI) symptoms in endurance athletes, but it remains unclear whether competition-related fueling is impacted by anxiety. This study examined whether general anxiety, pre-race anxiety, and visceral sensitivity were associated with nutritional intake before and during endurance running races. METHODS: A total of 149 (86 female, 63 male) runners participated in this cross-sectional survey study. Assessments, which were carried out at a median of eight hours after races finished, included the State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA)-Trait, Visceral Sensitivity Index (VSI), perceived pre-race anxiety (0-10), during-race GI symptoms (total, upper, and lower), and intakes of energy, macronutrients, fluid, and caffeine for the pre-race period (4 h before) and during races. Spearman's correlations were used to examine associations between variables. A two-sided P value ≤0.01 was used as the threshold for significance. RESULTS: Median race durations were 139.5 and 126.9 min for women and men, respectively. VSI scores were positively correlated with total during-race GI symptoms, while STICSA-Trait scores were positively correlated with total and upper during-race GI symptoms (ρ=0.22-0.25; P<0.01). No significant correlations were observed between measures of anxiety/visceral sensitivity and nutrient intakes before or during races. CONCLUSIONS: In a sample of primarily recreational runners, greater anxiety and visceral sensitivity did not translate to lower intakes of energy, macronutrients, fluid, etc. around competition. Further work is needed in other settings, especially with high-level athletes, to understand the impact of competition anxiety on fueling choices.

Visceral sensitivity correlates with gastrointestinal symptoms in runners during training but does not negatively impact peri-exercise fueling.

OBJECTIVES: This study aimed to evaluate the associations between several psychological factors (stress, anxiety, body vigilance, and visceral sensitivity) and gastrointestinal (GI) symptoms in runners, as well as whether any of these factors impact pre-exercise and during-exercise fueling. METHODS: A virtual/online observational survey-based study with 82 (43 male and 39 female) runners was conducted. The Perceived Stress Scale (PSS)-14, State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA-Trait), Body Vigilance Scale (BVS), and Visceral Sensitivity Index (VSI) were assessed. GI symptoms during runs over 1 week, as well as nutrient intakes from food and fluid consumed 4 h before and during runs, were recorded. GI problems were quantified as the percentage of runs that a participant reported at least one symptom ≥ 3 out of 10. RESULTS: VSI scores significantly correlated with the occurrence of all, upper, and lower GI symptoms during runs (ρ = 0.32-0.38; p < 0.003), and these associations remained significant in partial correlation analyses. No significant associations were observed between GI symptom occurrence and scores on the BVS, PSS-14, or STICSA-Trait. In a subset of 72 runners with available nutrition data, intakes of energy, macronutrients, fluid, and caffeine before and during runs did not seem to be lower in those who had higher PSS-14, STICSA-Trait, BVS, or VSI scores, which was contrary to what was hypothesized. CONCLUSIONS: Runners' visceral sensitivity levels associate with GI symptoms during training over a week, but the impact of this and other psychological factors on nutritional intake is uncertain, particularly around competition.

A single bout of breast milk expression does not increase resting metabolic rate.

INTRODUCTION: Breastfeeding women have elevated resting metabolic rate (RMR); however, whether a single bout of lactation increases RMR is unknown. This study aimed to determine if a single bout of lactation acutely increased RMR. METHODS: Twenty-two lactating women (age: 31 ± 0.9 year, body mass index: 27.3 ± 1.2 kg/m2 ) were recruited. RMR was assessed at baseline and at 1- and 2-h following breast milk expression. RESULTS: RMR was unchanged in lactating women following a single bout of lactation (baseline: 1437 ± 39; 1 h: 1425 ± 37 2 h: 1440 ± 31 kcal/day) (p > .05). RMR was not correlated to daily milk produced (r = 0.05, p > .05), but was correlated to body mass (r = 0.74, p < .001), fat-free mass (kg) (r = 0.61, p < .01), and fat mass (kg) (r = 0.71, p < .01). CONCLUSION: RMR in lactating women appears to be more related to body mass or composition in the postpartum period rather than lactation.

The association of moderate-to-vigorous and light-intensity physical activity on static balance in middle-aged and older-aged adults.

BACKGROUND: Falls are the leading cause of injury among adults ≥ 65 years of age. Participation in physical activity (PA) is associated with improved balance, though it is impact in the middle-age population is not well understood. AIM: The purpose of the current study was to examine the influence of PA intensity on static balance in middle-aged and older aged individuals. METHODS: Included were middle-aged adults (40-64 years) and older adults (≥ 65 years) from the 2003-2004 years of the National Health and Nutrition Evaluation Survey. Light physical activity (LPA) and moderate-vigorous physical activity (MVPA) were collected via accelerometer and static balance via the Romberg Test of Standing Balance. RESULTS: No significant odds ratio relationship was found between MVPA or LPA and having good static balance in the middle-aged population; 1.04 (95% CI 0.95, 1.13) p = 0.427 and 1.05 (95% CI 0.97, 1.14) p = 0.182, respectively. Whereas, in older adults, every 60-min increase in LPA was significantly associated with 28% higher odds of good balance (95% CI 1.15, 1.41; p < 0.001), and every 10-min increase in MVPA with 25% higher odds of good balance (95% CI 1.08, 1.45; p = 0.006). DISCUSSION: LPA and MVPA were not associated with good static balance in middle-aged adults, but in older adults LPA was significantly associated with good static balance. CONCLUSION: A significant relationship is found between age and fall risk, which is a major concern in the aging population.

Occurrence and Impacts of Gastrointestinal Symptoms in Team-Sport Athletes: A Preliminary Survey.

OBJECTIVES: Although gastrointestinal (GI) symptoms are prevalent in endurance athletes, scant research has examined GI symptoms in team-sport athletes, their impacts, and explanatory factors. This study aimed to assess the prevalence and severity of GI symptoms in team-sport athletes and identify potential risk factors. DESIGN: An observational anonymous survey. SETTING: Online. PARTICIPANTS: Hundred forty-three athletes (79 men and 64 women) from team-based sports, with soccer, rugby, and American football athletes comprising approximately 75% of the sample. ASSESSMENTS OF RISK FACTORS: Age, gender, body mass index, competition experience, trait anxiety, and resting GI symptoms. MAIN OUTCOMES: Gastrointestinal symptoms during training and competition. RESULTS: Overall, past-month GI symptoms during training and competition were mild and relatively infrequent. However, 13.9% and 37.5% of men and women, respectively, reported that GI symptoms had ever impacted their performance. In comparison to men, women reported that nausea, bloating, and abdominal cramping were more likely to have affected performance ( P < 0.05). Women also had higher trait anxiety and higher scores for resting GI symptoms, during-training GI symptoms, and during-competition GI symptoms ( P < 0.001). Resting GI symptoms were the strongest predictor of training and competition GI symptoms (ρ = 0.46-0.67), although trait anxiety was also consistently correlated with competition GI symptoms (ρ = 0.29-0.38). CONCLUSIONS: This study suggests that female team-sport athletes experience a higher burden of GI symptoms than males, and that resting symptoms and anxiety predict competition symptoms. Interventions targeting anxiety could theoretically reduce GI symptoms in some team-sport athletes, but this should be confirmed through experimental designs.

Ordered Eating and Its Effects on Various Postprandial Health Markers: A Systematic Review.

OBJECTIVE: Aberrations in glucose, insulin, and other postprandial (PP) markers are common in obesity and cardiometabolic disorders. One potentially simple lifestyle/dietary modification to manage these issues is to change the order in which foods are consumed within meals. Carbohydrate exerts the largest effect on PP glucose, and there is some evidence that ingesting dietary fat or protein before carbohydrate delays gastric emptying of carbohydrate and reduces PP glucose. Additionally, certain dietary proteins may augment insulin release if ingested with carbohydrate, thereby improving blood glucose clearance. This review aimed to systematically evaluate evidence from acute experiments that modified the order in which foods were consumed in isocaloric meals. METHODS: Outcomes of interest were PP glucose and insulin (including area under the curve for both), C-peptide, gut hormones, and perceptual responses. Three databases were searched (PubMed, Cochrane CENTRAL, Web of Science) in February 2022. Additionally, reference lists of identified reports were searched, and an author of several studies was consulted to verify that relevant literature was included. The review included acute interventions that administered isocaloric meals of the same foods but with foods eaten in different orders. Studies were not excluded based on participant characteristics. RESULTS: Eleven reports were identified. All reports that assessed glucose and insulin showed a tendency toward lower levels, at least over parts of the PP period, by consuming carbohydrates last. GLP-1 tended to be higher in carbohydrate-last conditions, though this was only measured in a few studies. Perceptual responses (hunger, fullness, etc.) were not consistently different between conditions in two studies, but the certainty of evidence was very low. CONCLUSIONS: Findings indicate that, at least acutely, there may be benefits to eating carbohydrate after vegetable and/or protein-rich foods. The most consistent effect (judged as moderate certainty) is that carbohydrate-last meal orders tend to lower blood glucose and insulin excursions.

Thorn in Your Side or Thorn in Your Head? Anxiety and Stress as Correlates of Exercise-Related Transient Abdominal Pain.

OBJECTIVES: The etiology of exercise-related transient abdominal pain (ETAP) is not congruent among researchers notwithstanding numerous studies on the matter. No pursuit has sought to correlate ETAP with factors such as anxiety, stress, sleep dysfunction, and pain sensitivity that are linked to other gastrointestinal (GI) disturbances in athletes. DESIGN: Cross-sectional observational study involving an anonymous survey. SETTING: Online. PARTICIPANTS: One hundred sixty-eight male and female adults running at least 10 miles/wk. ASSESSMENTS OF RISK FACTORS: Age, body mass index, years of running experience, GI symptoms, the State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA), Perceived Stress Scale (PSS)-14, Sleep Problems Index-I, and Pain Sensitivity Questionnaire. MAIN OUTCOMES: Exercise-related transient abdominal pain prevalence over the past month as well as ETAP severity and frequency. RESULTS: Exercise-related transient abdominal pain occurred in 39.9% of participants at least once in the past month. Exercise-related transient abdominal pain-positive runners were significantly younger and less experienced than ETAP-negative runners. Exercise-related transient abdominal pain-positive runners demonstrated higher resting and running-related GI symptoms, PSS-14, and STICSA scores compared with ETAP-negative runners. After accounting for age and experience, the ETAP-positive group had STICSA and PSS-14 scores that were 3.4 [95% confidence interval (CI), 1.0-5.8] and 4.1 (95% CI, 1.2-6.0) points higher, respectively, than the ETAP-negative group. State-Trait Inventory for Cognitive and Somatic Anxiety scores were significantly, modestly correlated (ρ = 0.27, P = 0.03) with ETAP frequency but not severity in runners who were ETAP-positive. CONCLUSIONS: In runners, this is the first investigation to reveal that anxiety and stress are associated with the presence of ETAP.

Does pain sensitivity correlate with gastrointestinal symptoms in runners? An observational survey study.

Objective: Heightened pain sensitivity is common in functional gut disorders, but no research has examined whether it corresponds to exercise-associated gastrointestinal (GI) symptoms. We sought to explore whether scores on a questionnaire of pain sensitivity would correlate with GI symptoms during running. Design: This is a cross-sectional study. Subjects: The study involves 290 (137 male, 153 female) distance runners. Methods: Runners completed a survey inquiring about demographic, anthropometric and training information and rated GI symptoms at rest and during runs. In addition, the Pain Sensitivity Questionnaire (PSQ) was used to quantify pain sensitivity across all items (PSQ-Total) and on items typically rated as minor (PSQ-Minor). Spearman rho correlations were utilized to assess the associations between pain sensitivity and GI symptoms. Partial correlations were used to evaluate the associations after controlling for age, gender, running experience, body mass index and sleep problems. Results: PSQ scores weakly correlated with several GI symptoms at rest (rho = 0.13-0.20; p < 0.05), which remained largely intact in partial correlation analyses (partial rho = 0.12-0.18). PSQ scores weakly correlated with fullness, bloating and gas during runs (rho = 0.12-0.18; p < 0.05); fullness and bloating remained significant in the partial correlation analyses (partial rho = 0.12-0.15). These results were relatively consistent for both the PSQ-Total and PSQ-Minor. Conclusions: Although PSQ scores only weakly correlate with certain GI symptoms among runners, the effect sizes are similar to that of other predictors of GI distress. These results suggest a minor possible role of pain sensitivity in the development of certain GI symptoms in runners.

The association of physical activity on homocysteine in pregnant women.

INTRODUCTION: Women with high levels of physical activity have improved pregnancy, labor, and delivery outcomes related to cardiovascular health. Hyperhomocysteinemia, which predicts cardiovascular disease risk, is associated with maternal vascular complications during pregnancy, such as placental abruption and preeclampsia. However, studies are lacking on whether physical activity impacts homocysteine in pregnant women, pointing to a potential mechanism behind the improved cardiovascular health in women who exercise during pregnancy. The purpose of this study was to examine if women with high levels of physical activity have lower levels of homocysteine compared to women with low levels of physical activity. METHODS: This study was a secondary analysis using data from the 2003 to 2006 National Health and Nutrition Examination Survey. A total of 257 pregnant women were included. Physical activity was assessed objectively over seven days with accelerometers. High and low groups based on moderate-to-vigorous physical activity (MVPA) and steps/day were defined. Homocysteine and related laboratory biomarkers (vitamin B12, folate, pyridoxal 5'-phosphate) were assessed through blood draws. Data assembly was performed using SAS and analysis via SPSS Complex Samples. RESULTS: Only an estimated 17.7 ± 4.7% of women met guidelines to achieve at least 150 min per week of MVPA. Plasma homocysteine was not different between pregnant women with high and low levels of moderate-to-vigorous physical activity (4.39 ± 0.21 and 4.44 ± 0.17 µmol/L; p > .05) or between those with high and low levels of steps (3.95 ± 0.26 and 4.62 ± 0.27 µmol/L; p > .05) when the data was split into two quantiles by the median. These results were similar when using log-transformed values for homocysteine to normalize the distribution of data. Pregnant women in the group of the high steps tended to have higher vitamin B12, folate, and pyridoxal 5'-phosphate than those in the group of the low steps. Sensitivity analyses revealed that homocysteine was not different between the upper 25% (4.04 ± 0.22 µmol/L) and lower 25% (4.17 ± 0.26 µmol/L) MVPA (p = .716) but that it was statistically higher in the low (<5000 steps/day) (4.99 ± 0.20 µmol/L) steps/day group compared to high (>7500 steps/day) steps/day (3.99 ± 0.23 µmol/L) (p = .003) after excluding individuals with hypertension and thyroid/kidney issues. CONCLUSION: Maternal steps/day, but not MVPA, appear to be associated with homocysteine (albeit weakly) in the present study after excluding potential factors which impact homocysteine. The volume of physical activity appears to be an important indicator as this difference was not revealed until the physical activity was more distinctly separated.

Associations of Urine Specific Gravity With Body Mass Index and Lean Body Mass at the Population Level: Implications for Hydration Monitoring.

Urine specific gravity (USG) thresholds are used in practice and research to determine hypohydration. However, some limited research has found that body size and body composition may impact USG, suggesting that fixed cutoffs may be insensitive. Cross-sectional data from 3,634 participants of the 2007-2008 National Health and Nutrition Examination Survey were analyzed. Along with USG, body mass index (BMI), estimated lean body mass (LBM), and dietary intake were quantified. Logistic regression models were used to evaluate whether higher quintiles of BMI and LBM were associated with elevated USG (USG ≥ 1.020 and ≥1.025) after accounting for dietary moisture and sodium. The USG (1.018 ± 0.0003 vs. 1.015 ± 0.0004); BMI (28.4 ± 0.2 vs. 28.0 ± 0.2 kg/m2); LBM (60.9 ± 0.3 vs. 42.2 ± 0.2 kg); dietary moisture (3,401 ± 92 vs. 2,759 ± 49 g/day); and dietary sodium (4,171 ± 85 vs. 2,959 ± 50) were greater in men than in women (p < .05). Men and women in the fifth quintiles of BMI or LBM (vs. Quintile 1) had greater odds (2.00-3.68, p < .05) of elevated USG. (The only exception was for the association between BMI and USG ≥ 1.025 in men.) Being in Quintile 4 of LBM or BMI (vs. Quintile 1) also tended to be associated with higher odds of elevated of USG, though this pattern was more consistent when using USG ≥ 1.020 than USG ≥ 1.025. In summary, BMI and LBM are associated with USG at the population level. These results affirm that USG depends on body size and composition and raise questions about using fixed USG thresholds for determining hypohydration, particularly for people in the upper quintiles of BMI and LBM.

Got Beer? A Systematic Review of Beer and Exercise.

Beer is used to socialize postexercise, celebrate sport victory, and commiserate postdefeat. Rich in polyphenols, beer has antioxidant effects when consumed in moderation, but its alcohol content may confer some negative effects. Despite beer's popularity, no review has explored its effects on exercise performance, recovery, and adaptation. Thus, a systematic literature search of three databases (PubMed, SPORTDiscus, and Web of Science) was conducted by two reviewers. The search resulted in 16 studies that were appraised and reviewed. The mean PEDro score was 5.1. When individuals are looking to rehydrate postexercise, a low-alcohol beer (<4%) may be more effective. If choosing a beer higher in alcoholic content (>4%), it is advised to pair this with a nonalcoholic option to limit diuresis, particularly when relatively large volumes of fluid (>700 ml) are consumed. Adding Na+ to alcoholic beer may improve rehydration by decreasing fluid losses, but palatability may decrease. These conclusions are largely based on studies that standardized beverage volume, and the results may not apply equally to situations where people ingest fluids and food ad libitum. Ingesting nonalcoholic, polyphenol-rich beer could be an effective strategy for preventing respiratory infections during heavy training. If consumed in moderation, body composition and strength qualities seem largely unaffected by beer. Mixed results that limit sweeping conclusions are owed to variations in study design (i.e., hydration and exercise protocols). Future research should incorporate exercise protocols with higher ecological validity, recruit more women, prioritize chronic study designs, and use ad libitum fluid replacement protocols for more robust conclusions.

Stimulant Use as a Fatigue Countermeasure in Aviation.

INTRODUCTION: Fatigue is a common problem in aviation. The identification of efficacious fatigue countermeasures is crucial for sustaining flight performance during fatigue-inducing operations. Stimulants are not recommended for consistent use, but are often implemented during flight operations with a high risk of fatigue. As such, it is important to evaluate the efficacy of approved stimulants for sustaining flight performance, alertness, and mood.METHODS: Four electronic databases (PubMed, PsycInfo, SPORTDiscus, Web of Science) were systematically searched to identify research on the effects of caffeine, dextroamphetamine, and modafinil during simulated or in-flight operations.RESULTS: There were 12 studies identified that assessed the effects of at least 1 stimulant. Overall, dextroamphetamine and modafinil were effective for sustaining flight performance and pilot mood during extended wakefulness. Results with caffeine were inconsistent.DISCUSSION: Dextroamphetamine and modafinil appear to sustain flight performance and mood during extended wakefulness. However, most studies have used flight simulators and short operation durations. Additional research is needed in realistic settings and during longer duration operations. Caffeines effects were inconsistent across studies, possibly due to differences in study methodology or individual caffeine responses. Despite fatigue being a common problem in civilian aviation as well, only one study in this review included civil aviators. More research should be conducted on the effects of caffeine during civil operations.CONCLUSION: Dextroamphetamine and modafinil appear to be effective fatigue countermeasures but should be further evaluated in more ecologically valid settings. The effects of caffeine are unclear at this time and should continue to be evaluated.Ehlert AM, Wilson PB. Stimulant use as a fatigue countermeasure in aviation. Aerosp Med Hum Perform. 2021; 92(3):190200.

Do Sex Differences in Physiology Confer a Female Advantage in Ultra-Endurance Sport?

Ultra-endurance has been defined as any exercise bout that exceeds 6 h. A number of exceptional, record-breaking performances by female athletes in ultra-endurance sport have roused speculation that they might be predisposed to success in such events. Indeed, while the male-to-female performance gap in traditional endurance sport (e.g., marathon) remains at ~ 10%, the disparity in ultra-endurance competition has been reported as low as 4% despite the markedly lower number of female participants. Moreover, females generally outperform males in extreme-distance swimming. The issue is complex, however, with many sports-specific considerations and caveats. This review summarizes the sex-based differences in physiological functions and draws attention to those which likely determine success in extreme exercise endeavors. The aim is to provide a balanced discussion of the female versus male predisposition to ultra-endurance sport. Herein, we discuss sex-based differences in muscle morphology and fatigability, respiratory-neuromechanical function, substrate utilization, oxygen utilization, gastrointestinal structure and function, and hormonal control. The literature indicates that while females exhibit numerous phenotypes that would be expected to confer an advantage in ultra-endurance competition (e.g., greater fatigue resistance, greater substrate efficiency, and lower energetic demands), they also exhibit several characteristics that unequivocally impinge on performance (e.g., lower O2-carrying capacity, increased prevalence of GI distress, and sex-hormone effects on cellular function/injury risk). Crucially, the advantageous traits may only manifest as ergogenic in the extreme endurance events which, paradoxically, are those that females less often contest. The title question should be revisited in the coming years, when/if the number of female participants increases.

Effects of high-carbohydrate versus mixed-macronutrient meals on female soccer physiology and performance.

PURPOSE: Athletes are often told to minimize intakes of fiber, fat, and protein in pre-competition meals to avoid gut distress, but this guidance is based on scant direct evidence. This study evaluated the physiological and perceptual effects of pre-competition mixed-macronutrient (MM) and high-carbohydrate (HCHO) meals in collegiate female soccer players. METHODS: Fifteen players participated in this randomized, investigator-blinded, crossover study involving two ~ 1000-kcal meals (HCHO and MM) consumed 4 h prior to 70-min scrimmages. Assessments included global positioning system (GPS) tracking, heart rate (HR), perceived exertion (RPE), ratings of fatigue (ROF), gut symptoms, and perceptions of satiety, hunger, and fullness. Differences between conditions for HR, RPE, ROF, and gut symptoms were evaluated with Wilcoxon signed-rank tests. GPS data and hunger, satiety, and fullness scores were compared using within-subjects repeated measures ANOVAs. RESULTS: No statistically significant differences were found between the conditions at any time point for HR, RPE, ROF, or gut symptoms. Significant time effects were found for two GPS variables (total distance covered and high-speed running), indicating that participants covered less distance during the second half of the scrimmages in comparison to the first half. However, there were no significant condition or condition × time interactions for GPS data. Finally, there were no condition or condition × time interactions for hunger, fullness, and satiety, though significant time effects were observed. CONCLUSION: A MM meal consumed 4 h prior to 70 min of soccer competition does not increase gut symptoms and can be similarly ergogenic as a HCHO meal.

Physical activity, nutrition, and psychological well-being among youth with visual impairments and their siblings.

PURPOSE: The primary purpose of this study was to examine physical activity, nutritional intake, and psychological well-being differences between youth with visual impairments and their siblings residing in the same household. A secondary purpose was to examine the relationship between physical activity behavior and psychological well-being among youth with visual impairments. MATERIALS AND METHODS: A sample of 22 dyads of youth with visual impairments and siblings completed this study. Data were collected through parent-reported demographic and psychological well-being questionnaires, nutritional intake questionnaires, and accelerometry. Data were analyzed descriptively and inferentially, examining proportion difference using McNemar's z-test, and mean differences using multivariate analyses of variance. RESULTS: Siblings without visual impairments had higher but not significantly higher daily average moderate-to-vigorous physical activity (d = 0.46), significantly higher prosocial score (d = 0.63), and lower but not significantly lower difficulty scores (d = 0.39), than youth with visual impairments. Small, not statistically significant, nutritional intake differences between siblings were found. CONCLUSIONS: Differences in physical activity and nutritional habits between those with visual impairments and their siblings were not significant, supporting the environmentally driven nature of these variables. Associations between physical activity and well-being were not apparent in this study but may be partially explained by low participant physical activity.Implications for RehabilitationYouth with visual impairments and the siblings may be influenced by the same familial factors and molded in a similar fashion by parenting behaviors regarding health-related behaviors.In this study, youth with visual impairments engaged in similar physical activity and nutritional behaviors to their siblings without visual impairments.Efforts to improve health-related behaviors among those with visual impairments may be most effective at the family level.Small subsets of youth with visual impairments gain mental health benefits from physical activity engagement.

Vitamin D Awareness and Intake in Collegiate Athletes.

ABSTRACT: Leitch, BA, Wilson, PB, Ufholz, KE, Roemmich, JN, Orysiak, J, Walch, TJ, Short, SE, and Fitzgerald, JS. Vitamin D awareness and intake in collegiate athletes. J Strength Cond Res 35(10): 2742-2748, 2021-Poor vitamin D status is a risk factor for negative health and performance outcomes in athletes, but little is known about how athletes' awareness and beliefs about vitamin D affect their consumption of vitamin D. This observational study investigated awareness of vitamin D for health and performance among collegiate athletes and evaluated the association of vitamin D awareness with its dietary intake. Fifty-two female and 29 male Division I collegiate athletes completed an online vitamin D awareness and dietary intake questionnaire between November 1, 2015, and January 30, 2016. Median intake of vitamin D was 330 International Units (IU), which is below the recommended daily allowance (RDA) of 600 IU, but was greater in male athletes (693 IU) than female athletes (263 IU, p < 0.01). The RDA for vitamin D was met by 62% of men and 30% of women. Athletes responded that vitamin D "probably" or "definitely" will play a role in their health (88.9%) and athletic performance (71.6%). However, only 23.4 and 28.4% of athletes reported concern for their vitamin D levels or believed that they were at risk for deficiency, respectively. Results showed small-to-moderate, positive correlations (r = 0.28-0.495, p < 0.05) between aspects of vitamin D awareness and vitamin D intake, particularly with supplemental forms of vitamin D. Given the lack of awareness concerning risk of vitamin D deficiency, and the links between aspects of vitamin D awareness and vitamin D intake, nutritional education programs designed to increase vitamin D awareness in athletes may be an effective strategy to reduce deficiency.