bluuebunny/crossref_metadata_2025 huggingface dataset:
How to Help the Athlete with Bulimia: Practical Tips and a Case Study
Authors: Clark Nancy
Published: August 2016

Surveys suggest that 8 to 41% of athletes may struggle with binge/purge and bulimic eating behaviors. Many of these athletes with bulimia struggle alone, receiving no professional help for recovery. This article offers effective counseling strategies for nutrition professionals who want to help bulimic athletes. Through a case study of a triathlete who binges, and then purges through compulsive exercise, a nutrition care plan is discussed that addresses the food and weight concerns commonly expressed by athletes with bulimia. The priorities of the care plan are to reduce preoccupation with weight, establish a pattern of regular eating, and address the underlying causes of the binges. The case demonstrates that nutrition counseling is only one part of the treatment program, and emphasizes the importance of developing a team of health professionals to assist athletes with bulimia.
Influence of Postexercise Glucose Ingestion upon Serum Potassium Levels and ECG Function
Authors: Reynolds Hedy C. , Cordain Loren , Harris Mary A. , Linnell Sheri
Published: August 2016

Thirteen trained runners were studied to determine whether postexercise glucose ingestion contributes to electrocardiogram (ECG) alterations by enhancing decreases in serum potassium (K+) concentrations. For the two randomly ordered trials, subjects ingested a 100 g (25% w/v glucose polymer) drink, either alone or with the addition of 3 g of potassium chloride (KCI), within 15 min following a 90-min run. ECG parameters, serum , and glucose concentrations were measured preexercise (Time 0), 2-3 min postexercise (Time 1), and 25 (Time 2) and 60 (Time 3) min postexercise. The data suggest that postexercise glucose ingestion may cause ECG changes that are not directly related to the return of to muscle, and that these changes, although characteristic of hypokalemia, may be related to serum glucose excursions rather than to absolute levels of serum . The addition of KCl may have prevented these changes by delaying gastric emptying of glucose.
Vitamin B6 and Exercise
Authors: Manore Melinda M.
Published: August 2016

This paper presents an overview of vitamin and exercise, including the role that vitamin plays in gluconeogenesis and glycogenolysis and changes in vitamin metabolism during exercise. The dietary vitamin intakes of athletes are also reviewed. Most studies report that male athletes have adequate dietary intakes of vitamin , whereas some females, especially those with low energy intakes, appear to have low vitamin intakes. Few studies have assessed the vitamin status of nonsupplementing athletes using the recommended status criteria. The role that vitamin may play in attenuating the rise in plasma growth hormone observed during exercise is also reviewed. Finally, recomrnendations are given for further research in the area of vitamin and exercise.
The Effects of Aerobic and Anaerobic Exercise Conditioning on Resting Metabolic Rate and the Thermic Effect of a Meal
Authors: Schmidt W. Daniel , Hyner Gerald C. , Lyle Roseann M. , Corrigan Donald , Bottoms Gerald , Melby Christopher L.
Published: August 2016

This study examined resting metabolic rate (RMR) and thermic effect of a meal (TEM) among athletes who had participated in long-term anaerobic or aerobic exercise. Nine collegiate wrestlers were matched for age, weight, and fat-free weight with 9 collegiate swimmers. Preliminary testing included maximal oxygen consumption, maximal anaerobic capacity (MAnC) for both the arms and the legs, and percent body fat. On two separate occasions, RMR and TEM were measured using indirect calorimetry. was significantly higher in the swimmers while MAnC was significantly higher in the wrestlers for both the arms and the legs. RMR adjusted for fat-free weight was not significantly different between groups. The differences in total and percentage of TEM between the groups were not statistically significant, and there were no differences in baseline thyroid hormones. These data suggest that despite significant differences in and WAnT values following long-term aerobic and anaerobic exercise training, resting energy expenditure does not differ between these college athletes.
Dietary Supplementation and Improved Anaerobic Performance
Authors: Maresh Carl M. , Armstrong Lawrence E. , Hoffman Jay R. , Hannon Daniel R. , Gabaree Catherine L. V. , Bergeron Michael F. , Whittlesey Michael J. , Deschenes Michael R.
Published: August 2016

In the present study, the effects of an increased daily dose of a dietary supplement (ATP-E, 0.2 g · · ) on Wingate test performance were examined in 12 men (21 ± 1.6 years) prior to and following 14 days of supplement and placebo ingestion. A double-blind and counterbalanced design was used. Results revealed higher (p < .007) preexercise blood ATP (95.4 ± 10.5 μmol · ) for the entire group following 14 days of ATP-E ingestion compared to placebo measures (87.6 ± 10.9 μmol · ). Mean power (667 ± 73 W) was higher (p < .008) after 14 days of ATP-E ingestion versus placebo (619 ± 67 W). Peak plasma lactate was lower (p < .07) after 14 days of ATP-E ingestion (14.9 ± 2.8 mmol · ) compared to placebo (16.3 ± 1.6 mmol · ). These data suggested that the improvement in 30-s Wingate test performance in this group may be related to the increased dose of ATP-E.
Children's Perceptual Responses to Ingesting Drinks of Different Compositions during and Following Exercise in the Heat
Authors: Meyer Flavia , Bar-Or Oded , Wilk Boguslaw
Published: August 2016

Twelve 9- to 12-year-old children performed four exercise-in-the-heat trials (, 45% RH), which differed in the fluids consumed. In each trial, subjects were kept euhydrated while cycling one 20-min and two 15-min bouts at 50% peak followed by a 90% peak bout until exhaustion. Thereafter, they could drink ab libitum while resting. One drink was water, and the other three drinks had 6% CHO with different : 0, 8.8, and 18.5 mEq · . All drinks had the same grape flavor. The perceived thirst was similar among trials and it did not increase while subjects were exercising. On average, subjects felt their stomach “somewhat full” with no difference among drinks. Thermal sensations, RPE, and overall comfort were similar among trials. During a 30-min recovery, volume intake was similar among drinks (201 ± 27 ml). In conclusion, the drink composition did not affect perceptual responses to drinking while euhydrated children exercised in the heat, nor did it affect drinking behavior during recovery.
Chronic Oral Lactate Supplementation Does Not Affect Lactate Disappearance from Blood after Exercise
Authors: Brouns Fred , Fogelholm Mikael , Hall Gerrit van , Wagenmakers Anton , Saris Wim H.M.
Published: August 2016

This study tested the hypothesis that a 3-week oral lactate supplementation affects postexercise blood lactate disappearance in untrained male subjects. Fifteen men were randomly assigned to either a lactate supplementation (n = 8) or a placebo (n = 7) treatment. During the treatment period they drank an oral lactate or a maltodextrin (placebo) supplement twice a day. The lactate drink contained 10 g of lactate as calcium, sodium, and potassium salts. Blood lactate concentrations were studied before, during, and immediately after three exercise tests, both pre-and posttreatment. Peak lactate values for placebo (PL) or lactate (L) treatment groups during different tests were as follows: Test 1 PL, 13.49 ± 3.71; L, 13.70 ± 1.90; Test 2 PL, 12.64 ± 2.32; L, 12.00 ± 2.23; Test 3 PL, 12.29 ± 2.92; L, 11.35 ± 1.38 and were reached 3 min postexercise. The decrease in blood lactate during the long (30- to 45-min) recovery periods amounted to @ 10 mmol/L. Blood lactate changes were highly reproducible. However, a 3-week oral lactate supplementation did not result in differences in lactate disappearance. This study does not support the hypothesis that regular oral lactate intake at rest enhances the removal of lactate during and following exercise, that is, not with the given lactate load and supplementation period.
An Assessment of Carbohydrate Intake in Collegiate Distance Runners
Authors: Tanaka Jill A. , Tanaka Hirofumi , Landis William
Published: August 2016

To determine the extent to which well-trained endurance athletes practice the dietary recommendations for maximizing muscle glycogen resynthesis, collegiate cross-country runners (14 males and 10 females) kept 4-day dietary and activity records during a training period and a competitive period in the regular cross-country season. The mean running mileages for men and women were 16.0 ± 1.0 and 10.7 ± 0.6 km/day during the training period and 14.6 ± 0.8 and 8.7 ± 0.5 km/day during the competitive period, respectively. Males reported adequate energy intake in both phases, whereas females fell short of the RDA. However, the percentage of calories from carbohydrate was found to be inadequate (< 60%) for male runners. Although female runners derived 65-67% of calories from carbohydrate, the daily amount of carbohydrate taken was insufficient (< 10 g/kg body weight). Carbohydrate was ingested immediately postexercise approximately 50% of the time or less, with even far less taken in suggested quantities (−1 g carbohydrate/kg body weight). There were no significant differences in dietary trends between training and competitive phases. The results suggest that these endurance athletes were not practicing the recommended feeding regimen for optimal muscle glycogen restoration.
Effect of Carbohydrate Ingestion Subsequent to Carbohydrate Supercompensation on Endurance Performance
Authors: Kang Jie , Robertson Robert J. , Denys Bart G. , DaSilva Sergio G. , Visich Paul , Suminski Richard R. , Utter Alan C. , Goss Fredric L. , Metz Kenneth F.
Published: August 2016

This investigation determined whether carbohydrate ingestion during prolonged moderate-intensity exercise enhanced endurance performance when the exercise was preceded by carbohydrate supercompensation. Seven male trained cyclists performed two trials at an initial power output corresponding to 71 ± 1 % of their peak oxygen consumption. During the trials, subjects ingested either a 6% glucose/sucrose (C) solution or an equal volume of artificially flavored and sweetened placebo (P) every 20 min throughout exercise. Both C and P were preceded by a 6-day carbohydrate supercompensation procedure in which subjects undertook a depletion-taper exercise sequence in conjunction with a moderate- and high-carbohydrate diet regimen. Statistical analysis of time to exhaustion, plasma glucose concentration, carbohydrate oxidation rate, fat oxidation rate, and plasma glycerol concentration indicated that in spite of a carbohydrate supercompensation procedure administered prior to exercise, carbohydrate ingestion during exercise can exert an additional ergogenic effect by preventing a decline in blood glucose levels and maintaining carbohydrate oxidation during the later stages of moderate-intensity exercise.
Fluid Needs in Hot and Cold Environments
Authors: Murray Robert
Published: August 2016

Of all the physiological perturbations that can cause early fatigue during exercise, dehydration is arguably the most important, if only because the consequences of dehydration are potentially life threatening. The rise in body temperature that normally accompanies exercise stimulates an increase in blood flow to the skin and the onset of sweating. Normal hydration is protective of these thermoregulatory responses, whereas even a slight amount of dehydration results in measurable declines in cardiovascular and thermoregulatory function. Mild to severe dehydration commonly occurs among athletes, even when fluid is readily available. This voluntary dehydration compromises physiological function, impairs exercise performance, and increases the risk of heat illness. Recent research illustrates that maintaining normal hydration (or close to it) during exercise maintains cardiovascular and thermoregulatory responses and improves exercise performance. Consequently, it is in the athlete’s best interest to adopt fluid-replacement practices that promote fluid intake in proportion to sweat loss.
Nutrient Intake and Psychological and Physiological Assessment in Eumenorrheic and Amenorrheic Female Athletes: A Preliminary Study
Authors: Perry Arlette C. , Crane Linda S. , Applegate Brooks , Marquez-Sterling Sylvia , Signorile Joseph F. , Miller Paul C.
Published: August 2016

The present study showed that amenorrheic athletes (AAs) scored higher on the Eating Attitudes Test (EAT) (p < .05) than eumenorrheic athletes (EAs), indicating more aberrant eating patterns in the first group. Scores on the EAT were inversely correlated with fat intake (p < .05), simple carbohydrate intake (p < .01), and percentage saturation of iron (p < .05) and were positively correlated with total iron binding capacity (p < .01) for the total sample. Physiological assessment of athletes revealed that there were no significant differences between groups in serum lipoproteins, with both EAs and AAs having serum lipid profiles indicative of low cardiovascular risk. Furthermore, low-density lipoprotein cholesterol was the only lipoprotein significantly and positively correlated with serum estradiol levels for the entire sample (p = .01). The present study was in agreement with previous work showing that scores on the EAT represent a primary difference between EAs and AAs; the present study was somewhat different than previous work in that serum lipoproteins were not significantly related to menstrual status.
Working with Young Athletes: Views of a Nutritionist on the Sports Medicine Team
Authors: Benardot Dan
Published: August 2016

Athletes are influenced by coaches, other athletes, media, parents, the national sport governing body, members of the sports medicine team, and the athlete's own desire for success. It is impossible, therefore, for one member of the sports medicine team to unilaterally determine workable solutions that enhance performance and diminish health problems in an athlete. A focus on ensuring that the athlete can perform to the best of her ability is a key to encouraging discussion between the nutritionist, athlete, and coach. Using the assumption that health and top athletic performance are compatible, this focus on performance provides a discussion point that all parties can agree to and, if approached properly, also fulfills the nutritionist's goal of achieving optimal nutritional status. Membership on the sports medicine team mandates that the nutritionist know the paradigms and health risks associated with the sport and develop assessment and feedback procedures specific to the athlete's needs.
Nutritional Aspects of Amenorrhea in the Female Athlete Triad
Authors: Benson Joan E. , Engelbert-Fenton Kathryn A. , Eisenman Patricia A.
Published: August 2016

Female athletes experience a high incidence of menstrual abnormalities. This has critical health consequences because amenorrhea athletes are at greater risk of developing osteopenia and bone injury compared to normally menstruating athletes or nonathletic normally cycling females. Female performers and athletes are also at risk for developing disordered eating behaviors. There appears to be a connection between menstrual dysfunction, athletic training, and disordered eating, but how they relate is not fully understood. In this paper we explore how low calorie intakes, nutritional inadequacies, vegetarianism, low body fat stores, and specific training behaviors may contribute to the abnormal menstrual patterns seen in this population. Recommendations for the detection and prevention of eating and training problems and consequent menstrual abnormalities are included.
Ergogenic Aids: Evaluating Sport Nutrition Products
Authors: Butterfield Gail
Published: August 2016

The desire to win leads physically active individuals to look for anything to improve performance. Many ergogenic aids are available; however, claims made about many of these products are not appropriate. To evaluate such products, one must consider the physiological sense of the claims, the supportive evidence provided, the research articles quoted, and the legal and health implications of use.
Short-Term Changes in Body Composition and Metabolism with Severe Dieting and Resistance Exercise
Authors: Gornall Jennifer , Villani Rudolph G.
Published: August 2016

The primary aim was to investigate whether the reduction in resting metabolic rate (RMR) and fat free mass (FFM) associated with a short-term very low kilojoule diet (VLKD) is altered by concurrent resistance exercise. Twenty overweight, premenopausal women were pair matched on body surface area and randomly assigned to either diet only (3,400 kJ/day) or diet combined with resistance training. Before and after 4 weeks of treatment, RMR was assessed by indirect calorimetry; total body mass (TBM), FFM, and fat mass (FM) by dual energy x-ray absorptiometry; total body water (TBW) by bioelectrical impedance; and strength by a weight-lifting test. Both groups had significantly lower TBM, FFM, FM, TBW, absolute RMR, and RMR, with FFM as the covariate, in the posttests than the pretests with no significant differences between groups. It was concluded that 4 weeks of resistance training did not prevent or reduce the decline in FFM and RMR observed with a VLKD.
Mixed Carbohydrate Supplementation Increases Carbohydrate Oxidation and Endurance Exercise Performance and Attenuates Potassium Accumulation
Authors: Tarnopolsky Mark A. , Dyson Kerry , Atkinson Stephanie A. , MacDougall Duncan , Cupido Cynthia
Published: August 2016

We studied the effects of different CHO supplements on exercise metabolism (1 hr at 75% ) and performance (fatigue time at 85% ) in 8 male endurance athletes Four treatments were administered in a randomized, double-blind fashion: Trial A = 3-day pretest, postexercise supplementation (177 kcal [81% carbohydrate, 19% protein] consumed < 10 min after exercise) + 600 ml 8% glucose polymers/ fructose 1 hr pretesting + 600 ml 8% glucose polymers/glucose during testing; Trial B = placebo during 3-day pretest + remainder same as Trial A; Trial C = placebo at all time points; and Trial D = same as Trial B with 8% glucose 1 hr before the test as well as during the test. Time to fatigue at 85% (Í24%) and total CHO oxidation were greater for A versus C (p < .05). Plasma glucose concentration was higher for A and B versus C, while increases in plasma potassium concentration were attenuated for A versus C (both p < .05). None of the supplements had differential effects upon hematocrit, plasma sodium [Na+] and lactate, , or rating of perceived exertion during exercise. Three-day preexercise protein + carbohydrate supplements followed by 1-hr pre- and during-exercise mixed carbohydrate supplements increased time to fatigue and carbohydrate oxidation and attenuated rises in plasma [K+] com pared to placebo.
The Effect of Oral Vanadyl Sulfate on Body Composition and Performance in Weight-Training Athletes
Authors: Fawcett J. Paul , Farquhar Stephen J. , Walker Robert J. , Thou Thearoth , Lowe Graham , Goulding Ailsa
Published: August 2016

The effects of oral vanadyl sulfáte (VOSO4) (0.5 mg/kg/day) on anthropometry, body composition, and Performance were investigated in a 12-week, double-blind, placebo-controlled trial involving weight-training volunteers. Performance was assessed in the treatment (VS) and placebo (P) groups using 1 and 10 repetitions maximum (RM) for the bench press and leg extension. Thirty-one subjects completed the trial, with 2 VS subjects withdrawing because of apparent side effects. There were no significant treatment effects for anthropo-metric parameters and body composition during the trial. Both groups had significant improvements in performance but the only significant effect of treatment was a Treatment × Time interaction in the 1 RM leg extension (p=.002), which could have arisen because the VS group had a lower performance at baseline in this test. It was concluded that oral vanadyl sulfáte was ineffective in changing body composition in weight-training athletes, and any modest performance-enhancing effect requires further investigation.
The Influence of a High Carbohydrate Intake during Recovery from Prolonged, Constant-Pace Running
Authors: Fallowfield Joanne L. , Williams Clyde
Published: August 2016

The present study examined the influence of ingesting 3.0 g CHO · body mass ⋅ 2  after prolonged exercise on recovery and running capacity 4 hr later. Nine men and 8 women completed two trials in a counterbalanced design. Each trial consisted of a 90-min run on a level treadmill at 70% () followed by 4 hr recovery (REC) and a further exhaustive run at 70% (R2). During REC, subjects ingested either two feedings of a 6.9% glucose-polymer (GP) solution (D trial) or two feedings of a 19.3% GP solution (C trial). There were no differences in mean (±SE) run times between the C and D trials or between the male and female subjects. More stable blood glucose concentrations were maintained during REC in the C trial, such that blood glucose was elevated in the C trial in comparison with the D trial after 210 min of REC. It was concluded that increasing postexercise carbohydrate intake from 1.0 to 3.0 g CHO ⋅ body mass 2  does not improve endurance capacity 1 hr later.
Oxidation of 13C-Glucose and 13C-Fructose Ingested as a Preexercise Meal: Effect of Carbohydrate Ingestion during Exercise
Authors: Burelle Yan , Péronnet François , Massicotte Denis , Brisson Guy R. , Hillaire-Marcel Claude
Published: August 2016

The oxidation of 13C-labeled glucose and fructose ingested as a preexercise meal between 180 and 90 min before exercise was measured on 6 subjects when either a placebo or sucrose was ingested during the exercise period. Labeled hexose oxidation, which occurred mainly during the first hour of exercise, was not significantly modified when sucrose was ingested, but exogenous glucose oxidation was significantly higher than exogenous fructose oxidation in both situations. The results suggest that the absorption rate of exogenous hexoses was high when exercise was initiated but diminished thereafter, and that glucose and fructose released from sucrose ingested during exercise did not compete with glucose or fructose ingested before exercise for intestinal absorption, for conversion into glucose in the liver (for fructose), or for uptake and oxidation of glucose in peripheral tissues. However, as already shown, in terms of availability for oxidation of carbohydrates provided by the preexercise meal, glucose should be favored over fructose.
The Effect of Creatine Supplementation on Two 700-m Maximal Running Bouts
Authors: Terrillion Kent A. , Kolkhorst Fred W. , Dolgener Forrest A. , Joslyn Sue J.
Published: August 2016

We investigated the effect of creatine supplementation on maximal running performance in a simulated track competition. Twelve competitive male runners were assigned to either a placebo or creatine supplementation group. Both groups completed two maximal 700-m running bouts 60 min apart on an outdoor track. A second identical trial was performed 7 days later, and for 5 days prior to the second trial, subjects ingested of either creatine monohydrate or a placebo. Subjects in the placebo group ran 110.2 ± 3.5 s and 110.4± 3.0 s for the first trial and 108.5 ± 2.9 s and 108.0 ± 1.7 s for the second trial, while the creatine group ran 109.9 ± 3.2 s and 110.4 ± 3.6 s for the first trial and 109.7 ± 3.3 s and 107.8 ± 2.2 s for the second trial. There were no significant differences between groups by trial or Trial × Time for running time, postexercise blood lactate concentration, or body weight (p > .05). We concluded that creatine supplementation does not enhance performance of single or twice-repeated maximal running bouts lasting 90-120 s.
Carbohydrate Drinks Delay Fatigue During Intermittent, High-Intensity Cycling in Active Men and Women
Authors: Davis J. Mark , Jackson David A. , Broadwell Melanie S. , Queary Joy L. , Lambert Charlie L.
Published: August 2016

The effects of ingesting carbohydrate drinks on fatigue druting intermittent, high-intensity cycling in men and women were determined. Physically active but untrained women (n = 7) and ment (n = 9) completed one practice trial and two experimental sessions separate by 1 week. Sessions consisted of repeated 1-min cycling bouts on a bicycle ergometer at 120–130%

exercise (18% CHO) and every 20 min during exercise (6% CHO). Plasma glucose and insulin were higher, RPE for the legs was lower, and time to fatigue was longer in CHO than P. Men's and women's responses were not different for any variable measured. These data suggest a beneficial role of CHO drinks on performance of intermittent, high-intensity exercise in men and women.
Sodium Bicarbonate Ingestion Does Not Attenuate the VO2 Slow Component during Constant-Load Exercise
Authors: Heck Kristen L. , Potteiger Jeffrey A. , Nau Karen L. , Schroeder Jan M.
Published: August 2016

We examined the effects of sodium bicarbonate ingestion on the VO2 slow component during constant-load exercise. Twelve physically active males performed two 30-min cycling trials at an intensity above the lactate threshold. Subjects ingested either sodium bicarbonate (BIC) or placebo (PLC) in a randomized. counterbalanced order. Arterialized capillary blood samples were analyzed for pH, bicarbonate concentration ([HCO3−), and lactate concentration ([La]). Expired gas samples were analyzed for oxygen consumption (VO2). The VO2 slow component was defined as the change in VO2 from Minutes 3 and 4 to Minutes 28 and 29. Values for pH and [HCO3−] were significantly higher for BIC compared to PLC. There was no significant difference in [La] between conditions. For both conditions there was a significant time effect for VO2 during exercise: however, no significant difference was observed between BIC and PLC. While extracellular acid-base measures were altered during the BIC trial, sodium bicarbonate ingestion did not attenuate the VO2 slow component during constant-load exercise.
Nutrition, Exercise, and Bone Status in Youth
Authors: Barr Susan I. , McKay Heather A.
Published: August 2016

The maximal amount of bone mass gained during growth (peak bone mass) is an important determinant of bone mass in later life and thereby an important determinant of fraeiure risk. Although genetic factors appear lo be primary determinants of peak bone mass, environmental factors such as physical activity and nutrition also contribute. In this article, bone growth and maintenance are reviewed, and mechanisms are described whereby physical activity can affect bone mass. Studies addressing the effects of physical activity on bone status in youth are reviewed: Although conclusive data are not yet available, considerable evidence supports the importance of activity, especially activity initiated before puberty. The critical role of energy in bone growth is outlined, and studies assessing the impact of calcium intake during childhood and adolescence are reviewed. Although results of intervention trials are equivocal, other evidence supports a role for calcium intake during growth. Recommendations for physical activity and nutrition, directed lochildren and adolescents, are presented.
Glycemic Index—A New Tool in Sport Nutrition?
Authors: Burke Louise M. , Collier Gregory R. , Hargreaves Mark
Published: August 2016

The glycemic index (GI) provides a way to rank foods rich in carbohydrate (CHO) according to the glucose response following their intake. Consumption of low-GI CHO-rich foods may attenuate the insulin-mediated metabolic disturbances associated with CHO intake in the hours prior to exercise, better maintaining CHO availability. However, there is insufficient evidence that athletes who consume a low-GI CHO-rich meal prior to a prolonged event will gain clear performance benefits. The ingestion of CHO during prolonged exercise promotes CHO availability and enhances endurance and performance, and athletes usually choose CHO-rich foods and drinks of moderate to high GI to achieve this goal. Moderate- and high-GI CHO choices appear to enhance glycogen storage after exercise compared with low-GI CHO-rich foods. However, the reason for this is not clear. A number of attributes of CHO-rich foods may be of value to the athlete including the nutritional value of the food or practical issues such as palatability, portability, cost, gastric comfort, or ease of preparation.
Effects of Exercise on Dietary Protein Requirements
Authors: Lemon Peter W.R.
Published: August 2016

This paper reviews the factors (exercise intensity, carbohydrate availability, exercise type, energy balance, gender, exercise training, age, and timing of nutrient intake or subsequent exercise sessions) thought to influence protein need. Although there remains some debate, recent evidence suggests that dietary protein need increases with rigorous physical exercise. Those involved in strength training might need to consume as much as 1.6 to 1.7 g protein ⋅ kg−1 day−1 (approximately twice the current RDA) while those undergoing endurance training might need about 1.2 to 1.4 g ⋅ kg−1 day−1 (approximately 1.5 times the current RDA). Future longitudinal studies are needed to confirm these recommendations and assess whether these protein intakes can enhance exercise performance. Despite the frequently expressed concern about adverse effects of high protein intake, there is no evidence that protein intakes in the range suggested will have adverse effects in healthy individuals.
Fluid-Electrolyte Balance during Labor and Exercise: Concepts and Misconceptions
Authors: Epstein Yoram , Armstrong Lawrence E.
Published: August 2016

Body water and electrolyte balance are essential to optimal physiological function and health. During exercise, work, or high temperatures, a significant level of dehydration can develop, and the ratio of extracellular to intracellular fluid can change, despite an ample supply of water. Physical and cognitive performance are impaired at 1-2% dehydration, and the body can collapse when water loss approaches 7%. Because fluid needs and intakes vary, formulating one general guideline for fluid replacement is difficult. Knowing the amount of water lost in sweat may enable predicting fluid needs via mathematical models for industrial, athletic, and military scenarios. Sodium imbalance might result from excessive Na+ loss or from gross o verity dration. In most work or exercise lasting < 3-4 hr, the major concern is that fluid be available to prevent heat-related illnesses, which can be prevented if fluid and electrolyte losses are balanced with intake, using the recommendations presented.
The Effect of Encapsulated Soluble Fiber on Carbohydrate Metabolism during Exercise
Authors: Parcell Allen C. , Ray Melinda L. , Moss Kristine A. , Ruden Timothy M. , Sharp Rick L. , King Douglas S.
Published: August 2016

Previous investigations have reported that soluble fiber reduces the plasma glucose and insulin changes after an oral glucose load. To improve the payability of a soluble-fiber feeding, this study addressed how a combined, soluble fiber (delivered in capsule form) and a preexercise CHO feeding would affect metabolic responses during exercise. On 3 different days, participants ingested a placebo (CON), 75 g liquid CHO (GLU), or 75 g liquid CHO with 14.5 g encapsulated guar gum (FIB) 45 min before cycling for 60 min at 70% VO2peak. Peak concentrations of plasma glucose and insulin were similar and significantly greater than CON preexercise (p < .05). Similarities in carbohydrate reliance were observed in GLU and FIB. Muscle glycogen use did not differ significantly among trials. These results demonstrate that encapsulated soluble fiber delivered with a liquid CHO feeding does not affect plasma glucose, insulin, or muscle glycogen utilization during exercise.
Cross-Validation of Modified Fatness-Specific Bioelectrical Impedance Equations
Authors: Lockner Donna W. , Heyward Vivian H. , Griffin Sharon E. , Marques Martim B. , Stolarczyk Lisa M. , Wagner Dale R.
Published: August 2016

The Segal fatness-specific bioelectrical impedance (BIA) equations are useful for predicting fat-free mass (FFM). Stolarczyk et al, proposed a modified method of averaging the two equations for individuals who are neither lean nor obese, thus eliminating the need to know % BF a priori. To cross-validate this modification, we compared FFM determined using the averaging method versus hydrostatic weighing for 76 adults. Per the averaging method, accuracy for males was excellent (r = .91, SEE = 2.7kg, E = 2.7kg), with 78% of individuals within ± 3.5% BF predicted by hydrostatic weighing. Accuracy for females was lower (r = .88, SEE = 3.0kg, E = 3.1 kg), with %BF of 51% within ±3.5% of the reference method. The relative ease and practicality of the averaging method and the results of this study indicate this method may be useful with a diverse group.
Influence of Exercise Mode and Carbohydrate on the Immune Response to Prolonged Exercise
Authors: Henson Dru A. , Nieman David C. , Blodgett Andy D. , Butterworth Diane E. , Utter Alan , Davis J. Mark , Sonnenfeld Gerald , Morton Darla S. , Fagoaga Omar R. , Nehlsen-Cannarella Sandra L.
Published: August 2016

The influence of exercise mode and 6% carbohydrate (C) versus placebo (P) beverage ingestion on lymphocyte proliferation, natural killer cell cytotoxicily (NKCA), Interleukin (IL)-1ß production, and hormonal responses to 2.5 hr of intense running and cycling (~75% ) was measured in 10 triathletes serving as their own controls. The C versus P condition (but not exercise mode) resulted in higher plasma glucose concentrations, lower plasma cortisol concentrations, reduced poslexercise lymphocytosis and NKCA, and a lessened T-cell reduction during recovery. No condition or mode effects were observed for concanavalin A and phytohemagglutinin-induced lymphocyte proliferation. Significant mode (but not condition) effects were observed for lipopolysaccharide-induced IL-1ß production over time. However, when expressed per monocyte, the mode effect was abolished and a sustained suppression in IL-1 ß/monocyte was observed in all sessions throughout recovery. These data indicate that carbohydrate ingestion significantly affects plasma glucose and cortisol concentrations, blood lymphocyte counts, and NKCA, whereas exercise mode has no effect on these parameters.
The Effect of a Carbohydrate-Arginine Supplement on Postexercise Carbohydrate Metabolism
Authors: Yaspelkis Ben B. , lvy John L.
Published: August 2016

The effect of a carbohydrate-arginine supplement on postexercise muscle glycogen storage was investigated. Twelve well-trained cyclists rode for 2 hr on two separate occasions to deplete theirmuscle glycogen stores. At 0, l, 2, and 3 hr after each exercise bout, the subjects ingested either a carbohydrate (CHO) supplement (1 g carbohydrate/kg body weight) or a carbohydrate-arginine (CHO/AA) supplement (1 g carbohydrate/kg body mass and 0.08 g arginine-hydrochloride/kg body weight). No difference in rate of glycogen storage was found between the CHO/AA and CHO treatments, although significance was approached. There were also no differences in plasma glucose, insulin, or blood lactate responses between treatments. Postexercise carbohydrate oxidation during the CHO/AA treatment was significantly reduced compared to the CHO treatment. These results suggest that the addition of arginine to a CHO supplement reduces the rate of CHO oxidation postexercise and therefore may increase the availability of glucose for muscle glycogen storage during recovery.
Calcium Losses Resulting from an Acute Bout of Moderate-Intensity Exercise
Authors: Bullen Daryll B. , O'Toole Mary L. , Johnson Karen C.
Published: August 2016

The purpose of this study was to compare daily calcium (Ca) losses in sweat (S) and urine (U) on an exercise day (E) with losses on the preceding day (i.e., a rest day) during which no exercise (NE) was performed. Ten healthy male volunteers (23.9 ± 3.2 years) performed a single bout of moderate exercise (running at 80% HRmax) for 45 min in a warm (32 °C, 58% relative humidity) environment on E. When E and NE were compared, neither Ca intake (1,232 ± 714 and 1,148 ±482 mg, respectively) nor urinary Ca excretion (206 ± 128 and 189 ± 130 mg, respectively) were different (p > .05). Sweat Ca losses during the exercise bout averaged 45 ± 12 mg. The results indicate that, although a small amount of Ca is lost in sweat during 45 min of moderate-intensity exercise, measured (sweat and urine losses combined) Ca losses (251 ±128 and 189 ± 130 mg) were not different (p > .05) between days (E and NE, respectively). These data suggest that moderate exercise for up to 45 min in a warm, humid environment does not markedly increase Ca intake requirements.
Nutritional and Physiological Status of U.S. National Figure Skaters
Authors: Ziegler Paula J. , Nelson Judith A. , Jonnalagadda Satya S.
Published: August 2016

This study assessed the nutrient intake, body composition and biochemical indices of National Figure Skating Championship competitors. Four-day diet records, fasting blood samples, and anthropometric measurements were obtained 2 months after the National Championships from 41 figure skaters 11-18 years of age. Energy, carbohydrate, fat, dietary fiber and cholesterol intake were significantly lower compared to the NHANES III averages for adolescents in the U.S. In general, the mean intakes for most vitamins except vitamin D and E were above the recommended intake. But the athletes had lower intakes of vitamin E and B12, and higher intakes of vitamin C, and thiamin (females only) compared with NHANES III. The mean intakes of magnesium, zinc, and iodine by the male skaters were below the recommended levels, as were the mean intakes of calcium, iron, phosphorus, magnesium, and zinc by the female skaters. Also, the number of servings from vegetable, fruit, dairy, and meat groups were below the recommended levels. Biochemical indices of nutritional status were within normal limits for all skaters. But plasma electrolyte concentrations were indicative of potential dehydration status. The results suggest there is a need to develop dietary intervention and educational programs targeted at promoting optimal nutrient and fluid intakes by these athletes to maintain performance and improve long-term health status.
Patterns of Vitamin/Mineral Supplement Usage by Adolescents Attending Athletic High Schools in Korea
Authors: Kim Sun H. , Keen Carl L.
Published: August 2016

An excessive use of vitamin/mineral supplements is considered by many to be a common health problem. We surveyed 1,355 adolescent boys and girls attending athletic high schools in Korea for their usage patterns of vitamin/mineral supplements. The usage rate of the vitamin/mineral supplements was 35.8%. The most favored supplements were vitamin C, multivitamins, and calcium. The reasons most cited for taking supplements were "to recover from fatigue," and "to maintain health." Vitamin and mineral intakes occurred over a wide range; mean intake values were typically higher than the Korean RDA. Vitamins B , B12 and C were consumed in very high amounts at 29.7,17.9 and 11.1 times the Korean RDA, respectively. When the intakes of nutrients from supplements and diet were combined, it was observed that the intakes of niacin, folic acid, vitamin C, and iron exceeded levels that have been proposed as upper safe limits. The above data underscore the need to provide sound nutritional education to athletic adolescents and their coaches with respect to the use of vitamin/ mineral supplements and the links between adequate diet, good health, and physical performance.
Iron Status of Highly Active Adolescents: Evidence of Depleted Iron Stores in Gymnasts
Authors: Constantini Naama W. , Eliakim Alon , Zigel Levana , Yaaron Michal , Falk Bareket
Published: August 2016

Much attention has focused on the nutrition and hematological profile of female athletes, especially gymnasts. The few studies on iron status of male adolescent athletes found a low incidence of iron deficiency. The present study investigated the iron status of male and female gymnasts (G) and compared it with athletes of other sports. Subjects were 68 elite athletes (43 M, 25 F) ages 12-18, of four sports: gymnasts (11 M, 12 F), swimmers (11 M, 6 F), tennis players (10 M, 4 F), and table tennis players (11 M, 3 F). All lived in the national center for gifted athletes, trained over 25 hr a week, ate in the same dining room, and shared a similar lifestyle. Mean levels of hemoglobin (Hb), red blood cell indexes, serum ferritin, serum iron, and transferrin were measured in venous blood. There was no difference in mean Rb among gymnasts (G) and nongymnasts (NG). However, Hb was less than 14 g/dL in 45% of M G vs. only 25% in NG, and less than 13 g/dL in 25% of premenarcheal FG vs. 15% in NG. Low transferrin saturation (< 20%) was detected in 18% of M G and 25% of FG vs. 6% and 8% in male and female NG, respectively (p < .05). The percentage of males suffering from low ferritin level (< 20 ng/ml) was twice as high in G (36%) vs. NG (19%), and about 30% in all females. In summary, iron stores were consistently lower in M G vs. NG. Adolescent athletes of both genders, G in particular, are prone to nonanemic iron deficiency, which might compromise their health and athletic performance.
The Effects of a 20-Week Exercise Training Program on Resting Metabolic Rate in Previously Sedentary, Moderately Obese Women
Authors: Byrne Heidi K. , Wilmore Jack H.
Published: August 2016

The present study was designed to investigate the effects of exercise training on resting metabolic rate (RMR) in moderately obese women. It was hypothesized that exercise training would increase resting metabolic rate. Nineteen previously sedentary, moderately obese women (age = 38.0 ± 0.9 years, percent body fat = 37.5 ± 0.8) trained for 20 weeks using either resistance training (RT) or a combination of resistance training arid walking (RT/W). The high intensity resistance training program was designed to increase strength and fat-free mass and the walking program to increase aerobic capacity. There was also a non-exercising control group (C) of 9 subjects in this study. Fat-free mass was significantly increased in both the RT (+1.90 kg) and RT/W (+1.90 kg) groups as a result of the training program. No group showed significant changes in fat mass or relative body fat from pre- to post-training. Aerobic capacity was slightly, though significantly, increased in the RT/W group only. The RT group showed a significant increase (+44 kcal · day−1), while the RT/W group showed a significant decrease (-53 kcal · day−1) in resting metabolic rate post-training. RT can potentiate an increase in RMR through an increase in fat-free mass, and the decrease in RMR in the RT/W group may have been a result of heat acclimation from the walk training.
Body Composition Profiles of Elite American Heptathletes
Authors: Houtkooper Linda B. , Mullins Veronica A. , Going Scott B. , Brown C. Harmon , Lohman Timothy G.
Published: August 2016

This study characterized body composition profiles of elite American heptathletes and cross-validated skinfold (SKF) and bioelectrical impedance analysis (BIA) field method equations for estimation of percent body fat (%Fat) using dual energy x-ray absorptiometry (DXA) as the criterion. Weight, height, fat mass (FM), fat-free mass (FFM), bone mineral density (BMD), and %Fat were measured in 19 heptathletes using standard measurement protocols for DXA, SKFs and BIA. The ages, heights, and weights were respectively 25.5 ± 3.5 years, 175.0 ± 6.6 cm, 67.3 ± 7.1 kg. DXA estimates of mean ± SD values for body composition variables were 57.2 ± 6.1 kg FFM, 10.1 ± 2.6 kg FM, 114 ± 7% BMD for age/racial reference group, and 15 ± 3.0 %Fat. Ranges of bias values for %Fat (DXA minus SKF or BIA) were, respectively, −0.5 to 1.6% and −5.5 to −1.2%. Ranges for standard errors of estimate and total errors were, respectively, SKF 2.4–2.5%, 2.4–2.8% and BIA 3.0%, 5.0–6.5%. Regression analyses of the field methods on DXA were significant (p < .05) for all SKF equations but not BIA equations. This study demonstrates that elite American heptathletes are lean, have high levels of BMD, and that SKF equations provide more accurate estimates of %Fat relative to DXA than estimates from BIA equations.
The Effect of Low-Carbohydrate Diet on the Pattern of Hormonal Changes during Incremental, Graded Exercise in Young Men
Authors: Langfort Jozef , Zarzeczny Ryszard , Nazar Krystyna , Kaciuba-Uscilko Hanna
Published: August 2016

The purpose of this study was to discover whether severe dietary carbohydrate (CHO) restriction modifies the relationship between exercise intensity and hormonal responses to exercise. Changes in the plasma adrenaline (A), noradrenaline (NA), growth hormone (hGH), testosterone (T), and blood lactate (LA) during an incremental exercise performed until volitional exhaustion were determined in 8 physically active volunteers after 3 days on low CHO (<5% of energy content; L-CHO) and isocaloric mixed (M) diets. Following L-CHO diet, the basal plasma A, NA, and hGH concentrations were increased, whilst T and LA levels were decreased. During exercise all the hormones increased exponentially, with thresholds close to that of LA. Neither the magnitude nor the pattern of the hormonal changes were affected by L-CHO diet except the NA threshold, which was lowered. Blood LA response to exercise was diminished and LA threshold was shifted towards higher loads by L-CHO diet. It is concluded that restriction of CHO intake (a) does not affect the pattern of changes in plasma A, hGH, and T concentrations during graded exercise but lowers NA threshold, indicating increased sensitivity of the sympathetic nervous system to exercise stimulus; (b) alters the basal and exercise levels of circulating hormones, which may have an impact on the balance between anabolic and catabolic processes and subsequently influence the effectiveness of training.
Effect of Glycerol-Induced Hyperhydration on Thermoregulation and Metabolism during Exercise in the Heat
Authors: Anderson M.J. , Cotter J.D. , Garnham A.P. , Casley D.J. , Febbraio M.A.
Published: August 2016

This study examined the effect of glycerol ingestion on fluid homeostasis, thermoregulation, and metabolism during rest and exercise. Six endurance-trained men ingested either 1 g glycerol in 20 ml H2O · kg−1 body weight (bw) (GLY) or 20 ml H2O · kg−1 bw (CON) in a randomized double-blind fashion, 120 min prior to undertaking 90 min of steady state cycle exercise (SS) at 98% of lactate threshold in dry heat (35 °C, 30% RH), with ingestion of CHO-electrolyte beverage (6% CHO) at 15-min intervals. A 15-min cycle, where performance was quantified in kJ, followed (PC). Pre-exercise urine volume was lower in GLY than CON (1119 ± 97 vs. 1503 ± 146 ml · 120 min−1; p < .05). Heart rate was lower (p < .05) throughout SS in GLY, while forearm blood flow was higher (17.1 ± 1.5 vs. 13.7 ± 3.0 ml · 100 g tissue · min−1; < .05) and rectal temperature lower (38.7 ± 0.1 vs. 39.1 ± 0.1 °C; p < .05) in GLY late in SS. Despite these changes, skin and muscle temperatures and circulating catecholamines were not different between trials. Accordingly, no differences were observed in muscle glycogenolysis, lactate accumulation, adenine nucleotide, and phosphocreatine degradation or inosine 5′-monophosphate accumulation when comparing GLY with CON. Of note, the work performed during PC was 5% greater in GLY (252 ± 10 vs. 240 ± 9 kJ;p < .05). These results demonstrate that glycerol, when ingested with a bolus of water 2 hours prior to exercise, results in fluid retention, which is capable of reducing cardiovascular strain and enhancing thermoregulation. Furthermore, this practice increases exercise performance in the heat by mechanisms other than alterations in muscle metabolism.