bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Preexercise Carbohydrate Status on Resistance Exercise Performance
Authors: Mitchell Joel B. , DiLauro Paul C. , Pizza Francis X. , Cavender Daniel L.
Published: August 2016

The purpose of this study was to determine the effect of a high vs. a low preexercise carbohydrate (CHO) diet on performance during multiple sets of resistance exercise. Eleven resistance-trained males performed cycle ergometry to deplete quadriceps muscle glycogen stores, followed by 48 hr of a high (HICHO) or a low (LOCHO) CHO diet. Subjects then performed five sets each of squats, leg presses, and knee extensions (resistance = 15 RM) to failure. Blood samples were taken before and during exercise for determination of glucose and lactate (LA). No differences in performance (repetitions X weight lifted) were observed (HICHO = 15,975±1,381 and LOCHO = 15,723±1,231 kg). Blood glucose was significantly higher after exercise for HICHO compared to LOCHO (HICHO = 4.8 ± 0.2 vs. LOCHO = 3.9 ± 0.2 mmol·L−1). No differences in LA accumulation were observed. The data indicated that preexercise CHO status did not affect resistance exercise performance. Further, the differences in blood glucose and the similarity in LA responses suggest that glycolysis was maintained in the LOCHO condition, and there may have been an increased reliance on blood glucose when preexercise CHO status was low.
Carbohydrate Intake and Recovery of Intermittent Running Capacity
Authors: Nicholas Ceri W. , Green Paul A. , Hawkins Richard D. , Williams Clyde
Published: August 2016

The purpose of the present study was to examine the influence of an increased carbohydrate intake on the recovery of endurance running capacity after exhaustive intermittent running. Six male subjects were randomly assigned to two dietary recovery conditions, each involving two running tests separated by 22 hr. The protocol comprised a prolonged, intermittent, high-intesity shuttle run test (I–HI). One week later subjects repeated the I–HI on consecutive days under different dietary conditions. During the 22-hr recovery, either the carbohydrate in take of the subjects was increased (CHO) or they ate an isocaloric diet by supplementing their normal diet with extra protein and fat (CON). Intermittent running capacity was improved when subjects increased their carbohydrate intake to 10 g · kg-1 bm during the 22-hr recovery between trials, but an isocaloric diet without additional carbohydrate did not bring about the same improvements.
Effect of Carbohydrate Substrate Availability on Ratings of Perceived Exertion Druting Prolonged Running
Authors: Utter Alan , Kang Jie , Nieman David , Warren Bev
Published: August 2016

The purpose of this study was to investigate the effects of carbohydrate substrate availability on ratings of perceived exertion (RPE) during prolonged submaximal running. Thirty marathon runners were recruited as subjects. A double-blind study design was used in which subjects performed an experimental trial that consisted of a 2.5-hr treadmill run at 75–80%

. During the experimenal trial, the subjects in the carbohydrate feeding group ingested a 6% glucose and fructose solution at a rate of approximately 60 g · hr-1, wheras subjects in the placebo group consumed an equal volume of artificially flavored placebo. Statistical analysis of RPE, respitory exchange ratio, fat at carbohydrate oxidation rate, and blood glucose concentrations indicated that increased carbohydrate substrate availability attenuated the intensity of exertional perceptions during the later stages of prolonged running at 75–80%

in marathon runners.
The Role of Social Physique Anxiety and Other Variables in Predicting Eating Behaviors in College Students
Authors: Cox Lori M. , Lantz Christopher D. , Mayhew Jerry L.
Published: August 2016

Early identification of potentially harmful eating patterns is critical in the effective remediation of such behaviors. The purpose of this investigation was to examine the degree lo which various factors including gender, family history, and athletic status predict disordered eating behavior; social physique anxiety and percent body fat were added as potential predictor variables. The eating behaviors of student-athletes and nonathlete students were also compared. One hundred eighty undergraduate students (males = 49, females =131) provided demographic information and completed the Eating Attitudes Test (EAT) and the Social Physique Anxiety Scale (SPAS). Stepwise multiple-regression analysis indicated that social physique anxiety, gender, and body fat (%Fat) combined to predict 34% of disordered eating behaviors: EAT = 0.921 SPA - 1.05 %Fat + 10.95 Gender (1 = M. 2 = F) - 17.82 (R2 = .34, SE = 4.68). A one-way ANOVA comparing ihe eating behaviors of athletes and nonathletes revealed no significant difference between these groups.
Examination of the Self-Selected Fluid Intake Practices by Junior Athletes During a Simulated Duathlon Event
Authors: luliano Sandra , Naughton Geraldine , Collier Greg , Carlson John
Published: August 2016

Thirty-two elite junior athletes in two age categories, older than or equal to IS years old (O15) (8 females and 9 males) and less than 15 years old (U15) (8 females and 7 males), performed a laboratory-based duathlon (run-ride-run). At the completion of the event, significant body mass losses were recorded for all groups. Compared with the other three groups, the O15 males lost body mass at a greater absolute rate (1.26 ±0.06 kg ⋅ hr−1 vs. a mean of 0.62 ±0.11 kg ⋅ hr−1 for the other three groups) and a greater relative rate (1.95 ± 0.10% BM ⋅ hr−1 vs. a mean of 1.23 ± 0.19 %BM ⋅ hr−1 for the other three groups) (p < .05). No differences were observed between groups for fluid consumption. Subjects consumed more fluid (p < .05) during the cycle phase and postevent than preevenl or during the run phases. Results indicated that the athletes' fluid intake practices were insufficient to maintain adequate hydration during the simulated event.
Nutritional and Fluid Intake in a 100-km Ultramarathon
Authors: Fallon Kieran E. , Broad Elizabeth , Thompson Martin W. , Reull Patricia A.
Published: August 2016

The fluid and food intakes of 7 male participants in a 100-km ultramarathon were recorded. The mean exercise time was 10 hr 29 min. Nutrient analysis revealed a mean inlrarace energy intake of 4.233 kJ. with 88.6% derived from carbohydrate. 6.7% from fat, and 4.7% from protein. Fluid intake varied widely. 3.3–1 1.1 L, with a mean of 5.7 L. The mean decrease in plasma volume at 100 km was 7.3%, accompanied by an estimated mean sweat rale of 0.86 L ⋅ hr−1. Blood glucose concentrations remained normal during the event, and free fatty acids and glycerol were elevated both during and at the conclusion of the event. No significant correlations were found between absolute amounts and rates of ingestion of carbohydrate and/or fluid and race performance.
Nutritional Practices of Elite Female Surfers during Training and Competition
Authors: Felder Jenni M. , Burke Louise M. , Lowdon Brian J. , Cameron-Smith David , Collier Gregory R.
Published: August 2016

The aim of this study was to assess the dietary practices of 10 elite female surfers. Four- and five-day food diaries completed over competition and training periods demonstrated energy intakes (mean ± SD) of 9,468 kJ (±2,007) and 8,397 kJ (±1,831), respectively. This level of energy intake was less than that estimated for the requirements of surfing. Female surfers' carbohydrate intakes failed to meet the recommendations, and suboptimal zinc intake was observed with 90% of subjects not meeting the Australian RDI. Comparisons between competition and training demonstrated that carbohydrate (g and g/kg body weight) and confectionary (g) intakes were significantly higher (p < .05) and protein intake was significantly lower (p < .05) during competition. These results show that although body fat stores were not compromised (mean 22%), self-reported energy, carbohydrate, and nutrient intakes were marginal in elite female surfers. Questionnaires revealed that 90% of surfers did not have good nutritional habits while traveling, which was compounded by a lack of knowledge of nutritional practices.
Blood Glucose and Glucoregulatory Hormone Responses to Solid and Liquid Carbohydrate Ingestion During Exercise
Authors: Robergs Robert A. , McMinn Susie B. , Mermier Cristine , Leadbetter Guy , Ruby Brent , Quinn Chris
Published: August 2016

This study was conducted to compare blood glucose and glucoregulatory hormone responses to the ingestion of solid and liquid carbohydrate (CHO) during prolonged cycling, followed by 30 min of isokinetic cycling. Eight male cyclists randomly completed three cycling trials (LC = liquid CHO, SCE = solid CHO with water equal to LC, SCA = solid CHO + ad libitum water). Each subject cycled for 120 min at 65% of VO2max with CHO ingestion (0.6 g CHO/kg/hr) at 0, 30, 60, 90, and 120 min. Subjects then completed a 30-min maximal isokinetic ride at 90 rpm. There was no significant (p < .05) difference between the trials for plasma glucose, insulin, glucagon, glycerol, lactate, RER, HR, VO2 RPE, and total work performed during the isokinetic ride. However, serum glucose was significantly lower in the SCE and SCA trials compared to LC at 80 min. The ingestion of a solid food containing CHO. protein, and fat with added water produced similar blood glucose, metabolic, glucoregulatory hormone, and exercise performance responses to those seen with the ingestion of liquid CHO.
Vitamin E Concentration in Rat Skeletal Muscle and Liver after Exercise
Authors: Swift Jon N. , Kehrer James P. , Seiler K. Stephen , Starnes Joseph W.
Published: August 2016

The purpose of this study was to determine whether submaximal exercise significantly changes the concentration of vitamin E (αToc) in rat liver and skeletal muscle and to establish a time course for the return to basal levels. Male Sprague-Dawley rats, age 8 to 10 weeks, were randomly divided into sedentary control (Con) (n = 7) and exercise n = 17) groups. Exercised animals ran 100 min on a motorized treadmill at approximately 70% VO2max for 3 consecutive days. They were then sacrificed immediately postexercise (0Post), 24 hr post (24Post), or 72 hr post (72Post). The gastrocnemius, red vastus lateralis (RV), white vastus lateralis (WV), and liver were excised and analyzed for αToc concentration by high-performance liquid chromolography utilizing electrochemical detection. We found that after 3 consecutive days of exercise, αToc was reduced in RV and WV at 0Post and 24Post but returned to control values by 72Post. Liver αToc content was not changed at OPost but was significantly reduced at 24 Post and 72 Post. No significant changes in αToc were observed in the gastrocnemius in response to exercise. The data indicate that following an exercise-related decrease, skeletal muscle vitamin E concentration requires more than 24 hr to return to the preexercise concentration, and that the replenishment process may involve redistribution of vitamin E from liver to muscle.
Resistance Training and Energy Balance
Authors: Poehlman Eric T. , Melby Christopher
Published: August 2016

In this brief review we examine the effects of resistance training on energy expenditure. The components of daily energy expenditure are described, and methods of measuring daily energy expenditure are discussed. Cross-sectional and exercise intervention studies are examined with respect to their effects on resting metabolic rate, physical activity energy expenditure, postexercise oxygen consumption, and substrate oxidation in younger and older individuals. Evidence is presented to suggest that although resistance training may elevate resting metabolic rate, il does not substantially enhance daily energy expenditure in free-living individuals. Several studies indicate that intense resistance exercise increases postexercise oxygen consumption and shifts substrate oxidation toward a greater reliance on fat oxidation. Preliminary evidence suggests that although resistance training increases muscular strength and endurance, its effects on energy balance and regulation of body weight appear to be primarily mediated by its effects on body composition (e.g., increasing fat-free mass) rather than by the direct energy costs of the resistance exercise.
Energy Balance in Young Athletes
Authors: Thompson Janice L.
Published: August 2016

Very little is known about the energy needs of young athletes. Recent studies using the doubly labeled water method have shown that the recommended dietary allowances for energy may be too high for normally active children and adolescents living in affluent societies. No studies of energy balance in young athletes have been published. Self-report dietary records of young athletes indicate that energy, carbohydrate, and select micronutrient intakes of certain athletic groups and individual athletes may be marginal or inadequate. Potential consequences of inadequate energy and nutrient intakes in young athletes include poor bone health, fatigue, limited recovery from injuries, menstrual dysfunction in female athletes, and poor performance. Studies of energy balance and nutrient status in young athletes are needed to better understand the nutritional needs of this group.
The Effects of Caffeine on the Maximal Accumulated Oxygen Deficit and Short-Term Running Performance
Authors: Doherty Michael
Published: August 2016

The purpose of this study was to evaluate the effect of acute caffeine ingestion on the maximal accumulated oxygen deficit (MAOD) and short-term running performance. Nine well-trained males performed a preliminary assessment and. at least 4 days later, a supramaximal run to exhaustion. Their VO2max values were determined, and the MAOD test at an exercise intensity equivalent to 125% VO2max was performed. Caffeine (5 mg ⋅ kg−1) or placebo was administered 1 hr prior to the MAOD in a double-blind, randomized cross-over study. In comparison to the placebo condition, subjects in the caffeine condition developed a significantly greater MAOD and increased their run lime to exhaustion. However, posl-MAOD blood lactate concentration ([HLa]) was not different between trials for caffeine and placebo. Caffeine ingestion can be an effective ergogenic aid for short-term, supramaximal running performance and can increase MAOD. However, these results do not appear to be related to an increased [HLa).
Dietary and Performance Assessment of Elite Soccer Players during a Period of Intense Training
Authors: Rico-Sanz JesÚs , Frontera Walter R. , Molé Paul A. , Rivera Miguel A. , Rivera-Brown Anita , Meredith Carol N.
Published: August 2016

This study examined the nutritional and performance status of elite soccer players during intense training. Eight male players (age 17 ± 2 years) of the Puerto Rican Olympic Team recorded daily activities and food intake over 12 days. Daily energy expenditure was 3,833 ± 571 (SD) kcal, and energy intake was 3,952 ± 1,071 kcal, of which 53.2 ± 6.2% (8.3 g ⋅ kg BW−1) was from carbohydrates (CHO), 32.4 ± 4.0% from fat, and 14.4 ± 2.3% from protein. With the exception of calcium, all micronutrients examined were in accordance with dietary guidelines. Body fat was 7.6 ± 1.1% of body weight. Time to completion of three runs of the soccer-specific test was 37.65 ± 0.62 s, and peak torques of the knee flexors and extensors at 60° ⋅ s−1 were 139 ± 6 and 225 ± 9 N ⋅ m, respectively. Players' absolute amounts of CHO seemed to be above the minimum recommended intake to maximize glycogen storage, but calcium intakes were below recommended. Their body fat was unremarkable, and they had a comparatively good capacity to endure repeated bouts of intense soccer-specific exercise and to exert force with their knee extensors and flexors.
Nutrition, Physical Activity, and Bone Health in Women
Authors: Lewis Richard D. , Modlesky Christopher M.
Published: August 2016

Calcium and vitamin D can significantly impact bone mineral and fracture risk in women. Unfortunately, calcium intakes in women are low and many elderly have poor vitamin D status. Supplementation with calcium (~1000 mg) can reduce bone loss in premenopausal and late postmenopausal women, especially at sites that have a high cortical bone composition. Vitamin D supplementation slows bone loss and reduces fracture rates in late postmenopausal women. While an excess of nutrients such as sodium and protein potentially affect bone mineral through increased calcium excretion, phytoestrogens in soy foods may attenuate bone loss ihrough eslrogenlike activity. Weight-bearing physical activity may reduce the risk of osteoporosis in women by augmenting bone mineral during the early aduli years and reducing the loss of bone following menopause. High-load activities, such as resistance training, appear to provide the best stimulus for enhancing bone mineral; however, repetitive activities, such as walking, may have a positive impact on bone mineral when performed at higher intensities. Irrespective of changes in bone mineral, physical activities that improve muscular strength, endurance, and balance may reduce fracture risk by reducing the risk of falling. The combined effect of physical activity and calcium supplementation on bone mineral needs further investigation.
Practical Body Composition Assessment for Children, Adults, and Older Adults
Authors: Heyward Vivian H.
Published: August 2016

This paper provides an overview of practical methods for assessing body composition of children, adults, and older adults. Three methods commonly used in field and clinical settings are skinfolds, bioelectrical impedance analysis, and anthropometry. For each method, standardized testing procedures, sources of measurement error, recommendations for technicians, and selected prediction equations for each age category are presented. The skinfold method is appropriate for estimating body fat of children (6–17 years) and body density of adults (18–60 years) from diverse ethnic groups. Likewise, bioimpedance is well suited tor estimating the fat-free mass of children (10-19 years) as well as American Indian, black, Hispanic, and white adults. Anthropometric prediction equations that use a combination of circumferences and bony diameters are recommended for older adults (up to 79 years of age), as well as obese men and women.
Energy and Nutrient Intakes of the United States National Women's Artistic Gymnastics Team
Authors: Jonnalagadda Satya S. , Benardot Dan , Nelson Marian
Published: August 2016

The nutrient intakes and dietary practices of elite, U.S. national team, artistic female gymnasts (n = 33) were evaluated using 3-day food records. The gymnasts' reported energy intake was 34.4 kcal/kg (total 1,678 kcal/day), which was 20% below the estimated energy requirement. The contributions of protein, fat, and carbohydrate to total energy intake were 17%, 18%, and 66%, respectively. All reported vitamin intakes, except vitamin E, were above the RDA. The reported mineral intakes, especially calcium, zinc, and magnesium, were less than 100% of the RDA. The overall nutrient densities of the subjects' diets were higher than expected. Eighty-two percent of the gymnasts reported taking nonprescription vitamin and mineral supplements, and 10% reported taking prescription vitamin and mineral supplements. Forty-eight percent of the gymnasts reported being on a self-prescribed diet. Compared to NHANES III, the reported nutrient intake of these gymnasts was different from that of the average U.S. adolescent female. In summary, certain key nutrients such as calcium, iron, and zinc should be given more attention to prevent nutrient deficiencies and subsequent health consequences.
Nutrition Support Programs for Young Adult Athletes
Authors: Clark Nancy
Published: August 2016

After graduating from college and entering the work force, young adult athletes often struggle with the task of fueling themselves optimally for top performance and weight control. The stresses and time constraints of work, family, and social responsibilities often result in eating fast foods on the run. These young adults can benefit from nutrition education programs at the worksite, at health clubs, in the community, and via the media. Dietitians who specialize in sport nutrition have particular appeal to these athletes, who are struggling to eat well, exercise well, and stay lean yet put little time or effort into their food program. This article includes two case studies of young adults and the dietary recommendations that taught them how to make wise food choices, fuel themselves well for high energy, and control their weight.
Effects of Medium-Chain Triacylglycerol Ingested With Carbohydrate on Metabolism and Exercise Performance
Authors: Goedecke Julia H. , Elmer Richard , Dennis Steven C. , Schloss Ingrid , Noakes Timothy D. , Lambert Estelle V.
Published: August 2016

The effects of ingesting different amounts of medium-chain triacylglycerol (MCT) and carbohydrate (CHO) on gastric symptoms, fuel metabolism, and exercise performance were measured in 9 endurance-trained cyclists. Participants, 2 hr after a standardized lunch, cycled for 2 hr at 63% of peak oxygen consumption and then performed a simulated 40-km time trial (T trial). During the rides, participants ingested either 10% 14C-glucose (GLU), 10% 14C-GLU + 1.72%MCT(LO-MCT), or 10% l4C-GLU + 3.44%MCT(HI-MCT) solutions: 400 ml at the start of exercise and then 100 ml every lOmin.MCTingestiondid not affect gastrointestinal symptoms. It only raised serum free fatty acid (FFA) and ß-hydroxybutyrate concentrations. Higher FFA and ß-hydroxybutyrate concentrations with MCT ingestion did not affect fuel oxidation or T-trial performance. The high CHO content of the pretrial lunch increased starting plasma insulin levels, which may have promoted CHO oxidation despite elevated circulating FFA concentrations with MCT ingestion.
Pre- and Postgame Macronutrient Intake of a Group of Elite Australian Football Players
Authors: Schokman C. Peter , Rutishauser Ingrid H.E. , Wallace Roger J.
Published: August 2016

This study describes pre- and postcompetition mean energy and macronutrient intakes of 40 elite Australian Football players. Carbohydrate intake, expressed both as a percentage of total energy intake (En %) and as grams per kilogram of body mass (g/kg BM), was significantly less (51.7% En and 4.8 g/kg BM, p < . 001) than minimum recommendations for endurance athletes (60% En and 6 g/kg BM). Pregame carbohydrate intake (53.6% En) was significantly greater (p < .01) than postgame (49.7% En). However, expressed as g/kg BM, pre- and postgame macronutrient intakes did not differ significantly. Protein and fat intakes (as g/kg BM) fell within guidelines, whereas energy intake (13.2 MJ/ day or 153.8 kJ/kg BM) was lower than expected. Results suggest that for athletes engaging in endurance team sports where body mass and energy requirements vary considerably, carbohydrate recommendations are more appropriately expressed as g/kg BM rather than En %.
The Efficacy of Carbohydrate Supplementation and Chronic High-Carbohydrate Diets for Improving Endurance Performance
Authors: Jacobs Kevin Allen , Sherman W. Michael
Published: August 2016

Carbohydrate (CHO) is the body's most limited fuel and the most heavily metabolized during moderate-intensity exercise. For this reason it is recommended that endurance athletes consume a high-CHO diet (8-10 g CHO ⋅ kg body weight−1 ⋅ day−1) to enhance training and performance. A review of the literature supports the benefits of CHO supplementation on endurance performance. The benefits of chronic high-CHO diets on endurance performance are not as clear. Recent evidence suggests that a high-CHO diet may be necessary for optimal adaptations to training. However, the paucity of data in this area precludes any concrete conclusions. The practicality of high-CHO diets is not well understood. The available evidence would indicate that a high-CHO diet is the best dietary recommendation for endurance athletes.
Creatine Supplementation Differentially Affects Maximal Isometric Strength and Time to Fatigue in Large and Small Muscle Groups
Authors: Urbanski Richard L. , Loy Steven F. , Vincent William J. , Yaspelkis Ben B.
Published: August 2016

Ten physically active, untrained, college-aged males (26.4 ± 5.8 years old) received creatine (CR. 5 g creatine monohydrate + 3 g dextrose) and placebo (PLA, 7 g dextrose) supplementation four times per day for 5 days in a double-blind, randomized, balanced, crossover design. Performance was assessed during maximal and three repeated submaximal bouts of isometric knee extension and handgrip exercise. CR supplementation significantly increased (p < .05) maximal isometric strength during knee extension but not during handgrip exercise. CR supplementation increased time to fatigue during each of the three bouts of submaximal knee extension and handgrip exercise when compared to the PLA trials. These findings suggest that CR supplementation can increase maximal strength and lime to fatigue during isometric exercise. However, the improvements in maximal isometric strength following CR supplementation appear to be restricted to movements performed with a large muscle mass.
Nutritional Intake of Elite Japanese Track-and-Field Athletes
Authors: Sugiura Katsumi , Suzuki Izumi , Kobayashi Kando
Published: August 2016

Mean daily intakes of energy and nutrients were surveyed from 3-day food records for 62 elite Japanese track-and-field athletes (28 males and 34 females) selected to participate in the 1994 Asian Championship games held in Hiroshima, Japan. Mean energy intakes of male and female athletes were 3,141 kcal (±592) and 2,508 kcal (±537), respectively. Based on the Japanese Recommended Dietary Allowances (JRDAs), long-distance and middle-distance runners had significantly higher energy and macronutrient intakes than did sprinters, jumpers, and throwers. There was no significant difference in micronutrient intake among the different types of athletes. However, of the sprinters, jumpers, and throwers. 15 males (54%) and 22 females (65%) consumed less than the JRDA for at least one micronutrient (i.e., vitamin or mineral). For some athletes, nutritional counseling that provides strategies for increasing food intake is recommended to optimize nutrient intake.
Effective Nutritional Ergogenic Aids
Authors: Applegate Elizabeth
Published: August 2016

Athletes use a variety of nutritional ergogenic aids to enhance performance. Most nutritional aids can be categorized as a potential energy source, an anabolic enhancer, a cellular component, or a recovery aid. Studies have consistently shown that carbohydrates consumed immediately before or after exercise enhance performance by increasing glycogen stores and delaying fatigue. Protein and amino acid supplementation may serve an anabolic role by optimizing body composition crucial in strength-related sports. Dietary antioxidants, such as vitamins C and E and carotenes, may prevent oxidative stress that occurs with intense exercise. Performance during high-intensity exercise, such as sprinting, may be improved with short-term creatine loading, and high-effort exercise lasting 1-7 min may be improved through bicarbonate loading immediately prior to activity. Caffeine dosing before exercise delays fatigue and may enhance performance of high-intensity exercise.
A Comparison of the Gastric Emptying Characteristics of Selected Sports Drinks
Authors: Murray Robert , Bartoli William , Stofan John , Horn Mary , Eddy Dennis
Published: August 2016

The purpose of this study was to determine the effects of repeated ingestion of drinks containing varying concentrations of carbohydrate on gastric emptying rate during steady-state exercise. On five separate occasions, 14 subjects cycled for 90 min at an average power output of 151 ± 2 W. At 15-min intervals, subjects ingested 227 ± 3 ml of either water, 4% carbohydrate (CHO), 6% CHO, or 8% CHO. Gastric volume was determined prior to each drink and at 90 min using the modified double-sampling technique. Gross gastric volumes were significantly greater and mean gastric emptying rates and the percentage of ingested beverage emptied from the stomach were significantly less for 8% CHO. These data indicate that repeated ingestion of an 8% CHO beverage during exercise significantly reduces gastric emptying rate, whereas lower concentrations of carbohydrate do not. In addition, beverage osmolality is not as important as beverage energy content in influencing gastric emptying rate at these carbohydrate concentrations.
Decreased Resting Metabolic Rate in Ballet Dancers with Menstrual Irregularity
Authors: Myburgh Kathryn H. , Berman Claire , Novick Illana , Noakes Timothy D. , Lambert Estelle V.
Published: August 2016

We studied 21 ballet dancers aged 19.4 ± 1.4 years, hypothesizing that undernu-trition was a major factor in menstrual irregularity in this population. Menstrual history was determined by questionnaire. Eight dancers had always been regular (R). Thirteen subjects had a history of menstrual irregularity (HI). Of these, 2 were currently regularly menstruating, 3 had short cycles, 6 were oligomenorrheic, and 2 were amenorrheic. Subjects completed a weighed dietary record and an Eating Attitudes Test (EAT). The following physiological parameters were measured: body composition by anthropometry, resting metabolic rate (RMR) by open-circuit indirect calorimetry, and serum thyroid hormone concentrations by radioimmunoassay. R subjects had significantly higher RMR than HI subjects. Also, HI subjects had lower RMR than predicted by fat-free mass, compared to the R subjects. Neitherreported energy intake nor serum thyroid hormone concentrations were different between R and HI subjects. EAT scores varied and were not different between groups. We concluded that in ballet dancers, low RMR is more strongly associated with menstrual irregularity than is currentreported energy intake or serum thyroid hormone concentrations.
Influence of Caffeine on Metabolic and Cardiovascular Functions during Sustained Light Intensity Cycling and at Rest
Authors: Engels Hermann-J. , Wirth John C. , Celik Sueda , Dorsey Jodee L.
Published: August 2016

This study assessed the influence of caffeine on metabolic and cardiovascular functions during sustained, light intensity cycling and at rest. Eight healthy, recreationally active adults participated in four randomly assigned, double-blind experimental trials of 60 min upright seated cycle exercise (30% VO2max) or equivalent rest with caffeine (5 mg ⋅ kg−1) or placebo consumed 60 min prior to data collection. Gas exchange was measured by open-circuit spirom-etry indirect calorimetry. Global blood flow was evaluated by thoracic impedance cardiography and arterial blood pressure by auscultation. A repeated measures ANOVA indicated that pretrial caffeine increased oxygen uptake and energy expenditure rate (p < 0.05) but did not change respiratory exchange ratio. Systolic, diastolic, and mean arterial blood pressure were elevated following caffeine intake (p < 0.05). Cardiac output, heart rate, stroke volume, and systemic vascular resistance were not significantly different between caffeine and placebo sessions. For each of the metabolic and hemodynamic variables examined, the effects of caffeine were similar during constant-load, light intensity cycling and at rest. These data illustrate that caffeine's mild thermogenic influence can be mediated without a major shift in substrate oxidation mixture. Caffeine at this dosage level alters cardiovascular dynamics by augmenting arterial blood pressure.
Glycogen Replenishment and Repeated Maximal Effort Exercise: Effect of Liquid Carbohydrate
Authors: Haub Mark D. , Potteiger Jeffrey A. , Jacobsen Dennis J. , Nau Karen L. , Magee Lawrence A. , Comeau Matthew J.
Published: August 2016

We investigated the effects of carbohydrate ingestion on glycogen replenishment and subsequent short duration, high intensity exercise performance. During Session 1, aerobic power was determined and each subject (N = 6) was familiarized with the 100-kJ cycling test (lOOKJ-Test). During the treatment sessions, the subjects performed a lOOKJ-Test (Ride-1), then consumed 0.7 g ⋅ kg body mass-1 of maltodextrin (CHO) or placebo (PLC), rested 60 min, and then performed a second lOOKJ-Test (Ride-2). Muscle tissue was collected before (Pre-1) and after Ride-1 (Post-1), and before (Pre-2) and after Ride-2 (Post-2), and analyzed for glycogen concentration. Both treatments yielded a significant increase in glycogen levels following the 60-min recovery, but there was no difference between treatments. Time to complete the lOOKJ-Test increased significantly for PLC, but not for CHO. These data indicate that the decrease in performance during Ride-2 in PLC was not the result of a difference in glycogen concentration.
Intestinal Permeability in Runners in the 1996 Chicago Marathon
Authors: Smetanka Rachel D. , Lambert C. Patrick , Murray Robert , Eddy Dennis , Horn Mary , Gisolfi Carl V.
Published: August 2016

Abdominal cramping, nausea, diarrhea, and GI bleeding are often reported in long-distance runners. This study set out to determine the effects of prolonged (2-4 hrs) exercise and NSAID ingestion on gastric and intestinal permeability during the first 5 hrs following the 1996 Chicago Marathon. Thirty-four healthy volunteers (20 M, 14 F; ages 30-50) completed the race and ingested the test solution (5 g sucrose, 5 g lactulose, 2 g rhamnose, in 40 ml water) within 10-15 min. The urinary excretion ratio of lactulose/rhamnose was used to assess small intestine permeability; sucrose excretion was used to evaluate gastric impairment. There were no significant differences for mean training mileage, postrace rectal temperature, and percent dehydration between runners who ingested NSAIDs and those who did not. In all, 75% of subjects reported aspirin or ibuprofen ingestion before or during the race. Runners who ingested ibuprofen had significant elevations in urinary lactulose excretion and lactulose/rhamnose ratio, whereas those who ingested aspirin or who did not ingest either NSAID had no significant differences in urinary excretion of lactulose, rhamnose, sucrose, or lactulose/rhamnose ratio compared to resting controls. Thirteen of the 26 NSAID users and 4 of the 8 non-users reported GI symptoms. It is concluded that (a) ibuprofen but not aspirin ingestion during prolonged exercise may increase gastrointestinal permeability and lead to GI symptoms, and (b) prolonged exercise alone can produce GI symptoms.
Effect of ENDUROX™ on Metabolic Responses to Submaximal Exercise
Authors: Cheuvront Samuel N. , Moffatt Robert J. , Biggerstaff Kyle D. , Bearden Shawn , McDonough Paul
Published: August 2016

Claims that ENDUROX™ enhances performance by altering metabolic responses to exercise were tested. In a double-blind crossover design, 10 male subjects were randomly assigned to consume 400 mg of placebo or 800 mg ENDUROX™ for 7 days. Cycle ergometry was performed for 30 minutes at 25%, followed by 10 min at 65% of peak oxygen consumption. After a 1-week washout period, subjects performed the identical exercise protocol following 7 days of reciprocal supplemental conditions. Expired gases were collected and analyzed continuously for oxygen consumption, minute ventilation, and respiratory exchange ratio. Heart rate, blood pressure, rating of perceived exertion, blood lactate, and serum glycerol data were also collected at regular intervals. A two-way ANOVA with repeated measures revealed no significant main or interaction effects involving group differences (p > 0.05) between trials for any variable during rest, 25% or 65% (VO2 peak), or recovery. Our findings do not support the ergogenic claims for ENDUROX™.
Weight Concern, Body Image, and Abnormal Eating in College Women Tennis Players and Their Coaches
Authors: Harris Mary B.
Published: August 2016

In order to study weight concerns and eating disorders in women tennis players, 107 women tennis players and 26 women’s tennis coaches from colleges across the U.S. responded to questionnaires relating to weight concern, body image, and abnormal eating. When evaluating drawings of female figures, players and coaches both considered the ideal body shape to be smaller than the healthiest one. Most players had normal weight, eating habits, and self-esteem; however, they also exhibited noticeable concern about their weight and appearance. Coaches revealed only moderate knowledge of weight related issues, believed such knowledge to be important, recognized that most of their players were of normal weight, and revealed somewhat negative feelings about overweight people. Players and coaches shared a healthy attitude toward tennis. The results of this study do not imply that college women tennis players are at greater risk of eating disorders than other young women, nor that college coaches are encouraging abnormal eating behaviors.
Effects of Training Status on the Metabolic Responses to High Carbohydrate and High Fat Meals
Authors: Bowden Victoria L. , McMurray Robert G.
Published: August 2016

The purpose of this study was to determine if there is a difference between the way in which aerobically trained and untrained women metabolize fats and carbohydrates at rest in response to either a high-fat or high-carbohydrate meal. Subjects, 6 per group, were fed a high CHO meal (2068 kJ, 76% CHO. 23% fat, 5% protein) and a high fat meal (2093 kJ, 21% CHO, 72% fat, 8% protein) in counterbalanced order. Resting metabolic rate (RMR) was measured every half-hour for 5 hours. RMR was similar between groups. Training status had no overall effect on postprandial metabolic rate or total energy expenditure. The high fat meal resulted in no significant differences in RMR or respiratory exchange ratio (RER) between groups. However, after ingesting a high CHO meal, trained subjects had a peak in metabolism at minute 60, not evident in the untrained subjects. In addition, postprandial RER from minutes 120-300 were lower and fat use was greater after the high CHO meal for the trained subjects. These results suggest that aerobically trained women have an accelerated CHO uptake and overall lower CHO oxidation following the ingestion of a high CHO meal.
Do Regular High Protein Diets Have Potential Health Risks on Kidney Function in Athletes?
Authors: Poortmans Jacques R. , Dellalieux Olivier
Published: August 2016

Excess protein and amino acid intake have been recognized as hazardous potential implications for kidney function, leading to progressive impairment of this organ. It has been suggested in the literature, without clear evidence, that high protein intake by athletes has no harmful consequences on renal function. This study investigated body-builders (BB) and other well-trained athletes (OA) with high and medium protein intake, respectively, in order to shed light on this issue. The athletes underwent a 7-day nutrition record analysis as well as blood sample and urine collection to determine the potential renal consequences of a high protein intake. The data revealed that despite higher plasma concentration of uric acid and calcium. Group BB had renal clearances of creatinine, urea, and albumin that were within the normal range. The nitrogen balance for both groups became positive when daily protein intake exceeded 1.26 g · kg−1 but there were no correlations between protein intake and creatinine clearance, albumin excretion rate, and calcium excretion rate. To conclude, it appears that protein intake under 2.8 g·kg−1 does not impair renal function in well-trained athletes as indicated by the measures of renal function used in this study.
Comparison of Dietary Intake and Eating Behavior of Professional Road Cyclists during Training and Competition
Authors: García-Rovés Pablo M. , Terrados Nicolàs , Fernández Serafina , Patterson Angeles M.
Published: August 2016

The dietary intake and eating behavior of a group of professional elite road cyclists during high intensity training and competition was compared. Their eating pattern consisted of several snacks throughout the race or training, a meal eaten no later than 1 hr postexercise, supper, and breakfast. Protein intake showed a significant difference between evaluation times expressed in three ways: per total amount intake, by kg body weight, and percentage of energy supplied. Due to the high energy intake of these cyclists during training and competition (22.9 ± 1.5, 22.4 ± 1.7 MJ, respectively), they presented a high consumption of each macronutrient both in competition and in training. The eating behavior of these athletes was similar during breakfast (possibility to choose from among approximately 25 foods) and supper (set menu), with variation in the energy intake and a similar relative contribution of the different macronutrients. In general, it is possible to consider the professional road cyclists as a homogeneous group with a similar nutrition intake, eating habits, and nutritional needs throughout the more demanding periods of the season. Furthermore, differences found in protein intake between periods could not be explained by differences in the food available in competition and training periods.
Towards Optimizing the Timing of the Pre-Exercise Meal
Authors: Maffucci Dawn M. , McMurray Robert G.
Published: August 2016

The purpose of this study was to compare the effect a 6-hr versus 3-hr prefeeding regimen on exercise performance. The subjects were 8 active women (21.4 ± 0.9 years, 60.4±2.4 kg, 19.9 ± 1.3% body fat. and 165.6±2.1 cm). All women completed 2 exercise trials (separated by 3—6d) on a treadmill where they ran at moderate intensity for 30 min with 30-s sprints at 5-min intervals, followed directly by increasing incrementally the grade until volitional fatigue was achieved. The exercise trials were performed 3 hr and 6 hr after consuming 40 ± 3 kJ/kg meal. Time to exhaustion was 0.75 min shorter (p = .0001) for the 6-H trials compared to the 3-H trials. There were no significant differences in submaximal or peak oxygen uptake, heart rate, or rating of perceived exertion (p > .05). The 6-H trials compared to the 3-H trials resulted in .05 lower RERs (p = .0002), and a 2 mmol lower blood lactate at exhaustion (p = .012). Blood glucose levels and cortisol responses to exercise were similar between trials (p > .05). However, both resting and post exercise insulin levels were lower during 6-H trials. It was concluded that performance of moderate- to high-intensity exercise lasting 35—40 min is improved by consuming a moderately-high carbohydrate. low fat, low protein meal 3-hr before exercise compared to a similar meal consumed 6 hr prior to exercise. Thus, athletes should not skip meals before competition or training sessions.
Diet and Short Term Plasma Lipoprotein-Lipid Changes after Exercise in Trained Men
Authors: Bounds Roger G. , Martin Steven E. , Grandjean Peter W. , O’Brien Barbara C. , Inman Cindi , Crouse Stephen F.
Published: August 2016

To test the effect of diet on the short-term lipid response to exercise, fourteen moderately trained (VO2max: 50.2 ± 6.7 ml/kg/min), healthy men (mean age: 28 ± 4 years) were alternately fed a high fat (60±6.7% fat) and a high carbohydrate (63 ± 3.2% carbohydrate) isoenergetic diet for 2 weeks in a randomized crossover design. During the last 4 days of the treatments, fasting total cholesterol, triglyceride. HDL-cholesterol, and -cholesterol were measured the day before, and again immediately, 24 hr. and 48 hr after exercise (4190 kJ, 70% ). LDL-cholesterol and -cholesterol were calculated. Lipid concentrations were adjusted for plasma volume changes after exercise. A 2 (diet) × 4 (time) ANOVA with repeated measures revealed no significant interaction between the diet and exercise treatments. Furthermore, diet alone did not influence lipid concentrations in these trained men. Exercise resulted in an increase in HDL-C (10.7%) and -C (8.5%) concentrations and a concomitant fall in triglyceride (-25%) and total cholesterol (-3.5%). Thus, we conclude that diet composition does not affect the short-term changes in blood lipids and lipoproteins that accompany a single session of aerobic exercise in moderately trained men.
Behavioral, Psychological, and Physical Characteristics of Female Athletes with Subclinical Eating Disorders
Authors: Beals Katherine A. , Manore Melinda M.
Published: August 2016

The purpose of this study was to delineate and further define the behavioral, psychological, and physical characteristics of female athletes with subclinical eating disorders. Subjects consisted of 24 athletes with subclinical eating disorders (SCED) and 24 control athletes. Group classification was determined by scores on the Eating Disorder Inventory (EDI), the Body Shape Questionnaire (BSQ), and a symptom checklist for eating disorders (EDI-SC). Characteristics representative of the female athletes with subclinical eating disorders were derived from an extensive health and dieting history questionnaire and an in-depth interview (the Eating Disorder Examination). Energy intake and expenditure (kcal/d) were estimated using 7-day weighed food records and activity logs. The characteristics most common in the female athletes with subclinical eating disorders included: (a) preoccupation with food, energy intake, and body weight; (b) distorted body image and body weight dissatisfaction; (c) undue influence of body weight on self-evaluation; (d) intense fear of gaining weight even though at or slightly below (-5%) normal weight; (e) attempts to lose weight using one or more pathogenic weight control methods; (g) food intake governed by strict dietary rules, accompanied by extreme feelings of guilt and self-hatred upon breaking a rule; (h) absence of medical disorder to explain energy restriction, weight loss, or maintenance of low body weight; and (i) menstrual dysfunction. Awareness of these characteristics may aid in more timely identification and treatment of female athletes with disordered eating patterns and, perhaps, prevent the development of more serious, clinical eating disorders.
Sub-Regional Tissue Morphometry in Male Athletes and Controls Using Dual X-Ray Absorptiometry (DXA)
Authors: Stewart Arthur D. , Hannan James
Published: August 2016

Athletes have traditionally been evaluated for body composition by percent fat, percent muscle, and somatotype. Since the late 1980s, dual X-ray absorptiometry (DXA) has offered total and regional body composition of bone mineral content (BMC), lean tissue and fat, but studies involving athletes are rare (11) and have not included regional tissue distribution. In the present study, DXA was used to compare a total of 121 male subjects belonging to 9 different athletic groups and controls. ANOVA showed total tissue percent BMC, lean tissue, and fat were significantly different between the various athletic groups (p < .001). Regional differences in tissue distribution between different athletic groups affect BMC and lean tissue (p < .001), but not fat (p > .05). However, athletes of the leanest groups had different fat distribution to that of nonexercising controls (p < .01). It appears that fat distribution is nonspecific in its response to exercise, while lean and BMC distributions show highly specific adaptations to specific sports.