bluuebunny/crossref_metadata_2025 huggingface dataset:
Consistency in Preventing Voluntary Dehydration in Boys Who Drink a Flavored Carbohydrate-NaCl Beverage During Exercise in the Heat
Authors: Wilk Boguslaw , Kriemler Susi , Keller Heidemarie , Bar-Or Oded
Published: August 2016

Twelve 10- to 12-year-old healthy boys performed six 70-min intermittent exercise sessions (three 20-min cycling bouts at 50%VO2max with 5 min rest in between) over a 2-week period at 35 ± 1 °C, 50 ± 5% or 60 ± 5% relative humidity. Subjects drank grape-flavored solution with 6% carbohydrate (2% glucose, 4% sucrose) and 18.0 mmol ⋅ L−1 NaCl ad libitum. Body weight (BW), heart rate, rectal temperature, thirst, and stomach fullness perception were monitored periodically. There were no differences among the six sessions in voluntary drink intake (765-902 g). hydration level (+0.75 to +1.07 %BW), sweating rate (245-263 g ⋅ m−2 ⋅ hr−1), and the other physiological and perceptual variables. A positive fluid balance was achieved in 67 out of 72 sessions. Voluntary drink intake of grape-flavored carbohydraie-NaCl beverage was consistently sufficient to prevent dehydration in 10- to 12-year-old boys during repeated exposures of exercise in the heat. This effect is likely to be achieved through a combination of physiological and behavioral mechanisms.
Body Composition and Nutritional Assessments in Soccer
Authors: Rico-Sanz JesÚs
Published: August 2016

This review summarizes results from studies investigating the physical characteristics, daily energy expenditures, diets, and effects of nutritional supplements to the habitual diets of soecer players. The results show that players fall within a wide range of stature and body weight, and they are classified as mesomorphs. The body fat of male players is about 10% of body weight, whereas the average for females is about 21%. Energy expenditure for males is about 4,000 kcal on training days and 3,800 keal on match day. while energy intake reported in other studies is on the order of 3,700 kcal. Carbohydrate (CHO), fat, and protein intakes are about 53,30, and 14% of energy intake, respectively, the remaining being from alcohol intake. There are indications that CHO supplements might be beneficial during soccer performance. However, more research is needed to clarity the importance of branched-chain amino acid and creatine supplementation in soccer.
Effective Fluid Replacement
Authors: Horswill Craig A.
Published: August 2016

As a result of exercise-induced sweating, athletes and trained individuals can lose up to 3 L of fluid per hour. Fluid replacement is required to maintain hydration and allow the athlete to continue to perform. Inadequate fluid intake will adversely affect temperature regulation, cardiovascular function, and muscle metabolism. To maximize fluid intake and effectively replace fluid, athletes must employ behavioral strategies. Athletes can also select beverages with characteristics that complement their behavioral efforts. Palatability, rapid absorption, retention of the fluid, and ergogenicity are the major attributes to consider for enhancing hydration during training and physical activity.
Serum Ferritin and Anemia in Trained Female Athletes
Authors: Ashenden Michael J. , Martin David T. , Dobson Geoffrey P. , Mackintosh Colin , Hahn Allan G.
Published: August 2016

The aim of this study was to establish whether extremely low serum ferritin values in female athletes were associated with indications of iron deficiency anemia and whether serum ferritin values were influenced by the type of training or participants' body size. Hematological data collected during 6 years at the Australian Institute of Sport were reviewed to quantify changes in serum ferritin concentration associated with training and to establish whether decrements in serum ferritin were associated with any change in hemoglobin concentration, mean corpuscular volume, or mean corpuscular hemoglobin concentration. Mean serum ferritin concentrations of 7.5 μg ⋅ L−1 were not associated with any indication of iron-deficiency anemia. Serum ferritin declined by approximately 25% with the onset of rigorous daily training (p <.01) whether training was predominantly weight-bearing or non-weight-bearing. Rowers had significantly higher ferritin concentrations than basketball players of similar stature (p = .02). We conclude that considerable background information such as the stage of training, specific sport, and previous blood results should be sought when interpreting serum ferritin concentrations in female athletes.
Effective Nutrition Support Programs for College Athletes
Authors: Vinci Debra M.
Published: August 2016

This paper presents an overview of the Husky Sport Nutrition Program at the University of Washington. This program is a component of the Department of Intercollegiate Athletics Total Student–Athlete Program, an NCAA-sponsored CHAMPS/Life Skills Program that provides life skills assistance to student–athletes. Successful integration of a sport nutrition program requires an understanding of the athletic culture, physiological milestones, and life stressors faced by college athletes. The sport nutritionist functions as an educator, counselor, and administrator. Team presentations and individual nutrition counseling provide athletes with accurate information on healthy eating behaviors for optimal performance. For women's sports, a multidisciplinary team including the sport nutritionist, team physician, clinical psychologist, and athletic trainer work to prevent and treat eating disorders. Case studies are presented illustrating the breadth of nutrition-related issues faced by a sport nutritionist working with college athletes.
Urinary Indices during Dehydration, Exercise, and Rehydration
Authors: Armstrong Lawrence E. , Herrera Soto Jorge A. , Hacker Frank T. , Casa Douglas J. , Kavouras Stavros A. , Maresh Carl M.
Published: August 2016

This investigation evaluated the validity and sensitivity of urine color (Ucol), specific gravity (Usg), and osmolality (Uosm) as indices of hydration status, by comparing them to changes in body water. Nine highly trained males underwent a 42-hr protocol involving dehydration to 3.7% of body mass (Day 1, −2.64 kg), cycling to exhaustion (Day 2, −5.2% of body mass, −3.68 kg), and oral rehydration for 21 hr. The ranges of mean (across time) blood and urine values were Ucol, 1-7; Usg, 1.004-1.029; U08m, 117-1,081 mOsm • kg−1; and plasma osmolality (Posm), 280-298 mOsm ⋅ kg−1. Urine color tracked changes in body water as effectively as (or better than) Uosm, Usg, urine volume, Posm, plasma sodium, and plasma total protein. We concluded that (a) Ucol, Uosm, and Usg are valid indices of hydration status, and (b) marked dehydration, exercise, and rehydration had little effect on the validity and sensitivity of these indices.
Fasting and Energy Intake Influence Bone Turnover in Lightweight Male Rowers
Authors: Talbott Shawn M. , Shapses Sue A.
Published: August 2016

The purpose of this study was to investigate the influence of an acute 24-hr fast versus usual 24-hr dietary intake on markers of bone turnover in collegiate lightweight male rowers. Bone turnover was measured by serum osteocalcin (OC) and urinary excretion of pyridinium cross-links (pyridinoline [PYD] and deoxypyridinoline [DPD]). Fasting subjects (F) (n = 14) reduced body weight by 1.7 ± 0.5 kg but there was no significant change among nonfasting subjects (NF) (n = 13). Following 24 hr of fasting, PYD and DPD were lower in F (14.1 ± 2.2 and 5.2 ± 0.7 nmol/mmol creatinine, respectively) compared to NF (16.4 ± 3.6 and 6.0 ± 0.8 nmol/mmol creatinine) (p < .05). Fasting also reduced OC levels (4.8 ± 0.4 ng/ml) compared to NF (6.1 ± 0.9 ng/ml) (p < .01). Stepwise regression analysis of NF dietary intake indicated that energy intake explained a greater portion of the variation in bone turnover for PYD (34%), DPD (36%), and osteocalcin (46%) compared to other nutrients (p < .05). These results indicate that bone turnover is reduced by 24 hr of fasting and suggest a role for dietary energy intake in regulating bone turnover.
Interrelationships among Food Intake, Somatic Traits, and Physical Fitness in 10.5- to 15.5-Year-Old Children From Eastern Poland
Authors: Raczyński Grzegorz , Czeczelewski Jan , Skład Maciej , Stupnicki Romuald
Published: August 2016

The aim of the study was to establish the relationships between energy intake and dietary quality with somatic variables and physical fitness. Energy intake and nutrition quality were assessed from 24-hr dietary recall questionnaires, and physical fitness was measured by applying the EUROFIT tests. Interrelationships between all those variables (simple, partial, and multiple correlation coefficients) were computed from standardized values. The somatic and physical fitness variables related more strongly on the nutrition quality than on the energy intake. Well-nourished children were taller, heavier, and more physically fit than the poorly nourished ones. We believe that dietary quality affected physical fitness indirectly by influencing somatic development. Energy intake did not contribute significantly to the total variance of the physical fitness factor.
Effect of Q10 Supplementation on Tissue Q10 Levels and Adenine Nucleotide Catabolism During High-Intensity Exercise
Authors: Svensson Michael , Malm Christer , Tonkonogi Michail , Ekblom Bjǒrn , Sjödin Bertil , Sahlin Kent
Published: August 2016

The aim of the present study was to investigate the concentration of ubiquinone-10 (Q10), at rest, in human skeletal muscle and blood plasma before and after a period of high-intensity training with or without Q10 supplementation. Another aim was to explore whether adenine nucleotide catabolism, lipid peroxidation, and mitochondrial function were affected by Q10 treatment. Seventeen young healthy men were assigned to either a control (placebo) or a Q10-supplementation (120 mg/day) group. Q10 supplementation resulted in a significantly higher plasma Q10/lotal cholesterol level on Days 11 and20compared with Day 1. There was no significant change in the concentration of Q10 in skeletal muscle or in isolated skeletal muscle mitochondria in either group. Plasma hypoxanthine and uric acid concentrations increased markedly after each exercise test session in both groups. After the training period, the postexercise increase in plasma hypoxanthine was markedly reduced in both groups, but the response was partially reversed after the recovery period. It was concluded that Q10 supplementation increases the concentration of Q1O in plasma but not in skeletal muscle.
Metabolic Effects of a Protein-Supplemented Carbohydrate Drink in Marathon Runners
Authors: Colombani Paolo C. , Kovacs Eva , Frey-Rindova Petra , Frey Walter , Langhans Wolfgang , Arnold Myrtha , Wenk Caspar
Published: August 2016

A field study was performed to investigate the acute influence of a milk protein hydrolysate supplemented drink (CHO+PRO) on metabolism during and after a marathon run compared to the same drink without protein (CHO). Carbohydrate metabolites and hormones were not influenced by CHO+PRO. Levels of plasma free fatty acids were significantly lower and levels of urea and most amino acids were significantly higher with CHO+PRO. Sweat urea and ammonia nitrogen excretion during the run as well as urinary 3-methylhistidine excretion during the entire exercise day was similar with both treatments. Urinary total nitrogen was significantly increased and urinary pH decreased with CHO+PRO. It was concluded that the supplemented protein was absorbed and probably at least partially oxidized during the run and that no obvious negative metabolic effects occurred. CHO+PRO did not acutely affect myofibrillar protein breakdown as assessed by the 3-methylhistidine method: however, total body protein breakdown was not measured.
Effect of Oral Glutamine Supplementation on Human Neutrophil Lipopolysaccharide-Stimulated Degranulation Following Prolonged Exercise
Authors: Walsh Neil P. , Blannin Andrew K. , Bishop Nicolette C. , Robson Paula J. , Gleeson Michael
Published: August 2016

Recent studies have shown that neutrophils can utilize glutamine and that glutamine supplementation can improve neutrophil function in postoperative and burn patients. The present study investigated the influence of oral glutamine supplementation on stimulated neutrophil degranulation and oxidative burst activity following prolonged exercise. Subjects, 7 well-trained men, reported to the laboratory following an overnight fast and cycled for 2 hrs at 60% on two occasions a week apart. They were randomly assigned to either a glutamine or placebo treatment. For both trials, subjects consumed a sugar-free lemon drink at 15-min intervals until 90 minutes, then a lemon flavored glutamine drink (GLN) or sugar-free lemon drink (PLA) was consumed at 15-min intervals for the remaining exercise and the 2-hr recovery period. Venous blood samples were taken pre-, during, and postexercise. Glutamine supplementation had no effect on the magnitude of postexercise leukocytosis, the plasma elastase concentration following exercise (which increased in both trials), or the plasma elastase release in response to bacterial stimulation (which fell in both trials). Neutrophil function assessed by oxidative burst activity of isolated cells did not change following exercise in either trial. These findings therefore suggest that the fall in plasma glutamine concentration does not account for the decrease in neutrophil function (degranulation response) following prolonged exercise.
L-Carnitine Supplementation Combined with Aerobic Training Does Not Promote Weight Loss in Moderately Obese Women
Authors: Villani Rudolph G. , Gannon Jenelle , Self Megan , Rich Peter A.
Published: August 2016

L-Carnitine (L-C) transports fatty acids into mitochondria for oxidation and is marketed as a weight loss supplement. In a double-blind investigation to test the weight loss efficacy of L-C, 36 moderately overweight premenopausal women were pair matched on Body Mass Index (BMI) and randomly assigned to two groups (N = 18). For 8 weeks the L-C group ingested 2 g twice daily of L-C, while the placebo (P) group ingested the same amount of lactose. All subjects walked for 30 min (60—70% maximum heart rate) 4 days/ week. Body composition, resting energy expenditure (REE) and substrate utilization were estimated before and after treatment. For the subjects who completed the study (15 P, 13 L-C), no significant changes in mean total body mass (TBM), fat mass FM, and resting lipid utilization occurred over time, nor were there any significant differences between groups for any variable. Conversely REE increased significantly for all subjects, but no between group differences existed. Five of the L-C group experienced nausea or diarrhea and consequently did not complete the study. Eight weeks of L-C ingestion and walking did not significantly alter the TBM or FM of overweight women, thereby casting doubt on the efficacy of L-C supplementation for weight loss.
The Effects of Tribulus Terrestris on Body Composition and Exercise Performance in Resistance-Trained Males
Authors: Antonio Jose , Uelmen John , Rodriguez Ramsey , Earnest Conrad
Published: August 2016

The purpose of this study was to determine the effects of the herbal preparation Tribulus terrestris (tribulus) on body composition and exercise performance in resistance-trained males. Fifteen subjects were randomly assigned to a placebo or tribulus (3.21 mg per kg body weight daily) group. Body weight, body composition, maximal strength, dietary intake, and mood states were determined before and after an 8-week exercise (periodized resistance training) and supplementation period. There were no changes in body weight, percentage fat, total body water, dietary intake, or mood states in either group. Muscle endurance (determined by the maximal number of repetitions at 100—200% of body weight) increased for the bench and leg press exercises in the placebo group (p < .05; bench press ±28.4%. leg press ±28.6%), while the tribulus group experienced an increase in leg press strength only (bench press ±3.1 %, not significant; leg press ±28.6%, p < .05). Supplementation with tribulus does not enhance body composition or exercise performance in resistance-trained males.
Iron Status in Female Endurance Athletes and in Non-Athletes
Authors: Malczewska Jadwiga , Raczynski Grzegorz , Stupnicki Romuald
Published: August 2016

Iron status was studied in 126 female endurance athletes and 52 control subjects, all aged 16–20 years. The study aimed at identifying factors responsible for iron deficiency. Twenty-six percent of athletes and 50% of controls had latent iron-deficiency without anemia symptoms. A too low intake of iron (especially heme iron: 0.3 mg daily), and of nutrients influencing iron metabolism, were identified as main causes of iron deficiency in control subjects. In athletes, whose iron intake was sufficient (14.6 mg), the principal cause of iron deficiency were blood losses due to menstruation. High level of physical activity, expressed as training volume and experience, did not adversely affect iron stores, as these were higher than in control subjects and the incidence of iron deficiency was much lower than in the control group. It was concluded that an increased intake of iron and of dietary factors involved in iron metabolism prevented possible exercise-induced losses of iron in young athletes.
Effect of Training Mode and Calcium Intake on Bone Mineral Density in Female Master Cyclists, Runners, and Non-Athletes
Authors: Beshgetoor Donna , Nichols Jeanne F. , Rego Inah
Published: August 2016

The focus of this prospective, observational study was to determine the effect of sport-specific training and calcium intake on bone mineral density (BMD) in female master cyclists, runners and non-athletes. Thirty women (12 cyclists, 9 runners, 9 controls), mean age of 49.6 ±7.9 years, were assessed at baseline and 18 months for calcium intake (4-day records), current exercise activity (recall questionnaire), and BMD of the lumbar spine and hip (DXA). A three (cyclists, runners, controls) by two (0 and 18 months) repeated measures ANOVA demonstrated a significant interaction effect of sport and time at the femoral neck (p < .04). Tukey post hoc analysis indicated that the BMD of the femur was maintained in cyclists and runners but declined in controls (p < .05). A significant time effect was noted in BMD at the lumbar spine (p < .001) and the trochanter (p < .003). BMD of the lumbar spine was maintained in runners but declined in cyclists (p < .007) and in controls (p < .03), while trochanteric BMD declined in all groups (p < .01). No significant interaction effect of sport and dietary calcium intake was noted for BMD at any site.
Intravenous versus Oral Rehydration during a Brief Period: Stress Hormone Responses to Subsequent Exhaustive Exercise in the Heat
Authors: Casa Douglas J. , Maresh Carl M. , Armstrong Lawrence E. , Kavouras Stavros A. , Herrera-Soto Jorge A. , Hacker Frank T. , Scheett Timothy P. , Stoppani James
Published: August 2016

The purpose of this study was to determine if intravenous fluid rehydration, versus oral rehydration. during a brief period (20 min) differentially affects plasma ACTH, cortisol, and norepinephrine concentrations during subsequent exhaustive exercise in the heat. Following dehydration (DHY) to −4% of body weight, 8 nonacclimated highly trained males (age = 23.5 ± 1.2 years, V̇O2peak = 61.4±0.8 ml · kg · min−1, % body fat = 13.5±0.6%) cycled to exhaustion at 74% V̇O2peak in 36.8 °C on three different occasions. These included: (a) no fluid (NF), where no fluid was provided during the rehydration period; (b) DRINK, where oral rehydration (0.45% NaCl) was provided equal to 50% of the prior DHY; and (c) IV, where intravenous infusion (0.45% NaCl) was provided equal to 50%’ of the prior DHY. Exercise time to exhaustion was not different p = .07) between the DRINK (34.86 ±4.01) and IV (29.48 ± 3.50) trials, but both were significantly p < .05) longer than the NF (18.95 ± 2.73) trial. No differences (p > .05) were found for any of the hormone measures among trials. The endocrine responses at exhaustion were similar regardless of hydration state and mode of rehydration, but rehydration prolonged the exercise time to exhaustion.
Effects of Meal Form and Composition on Plasma Testosterone, Cortisol, and Insulin Following Resistance Exercise
Authors: Bloomer Richard J. , Sforzo Gary A. , Keller Betsy A.
Published: August 2016

The purpose of this study was to examine the effects of postexercise feeding on plasma levels of insulin, testosterone, cortisol, and testosteronexortisol (T:C). Ten experienced, resistance trained males (20.7 ± 0.95 years) were given whole food (WF: protein 38 g; carbohydrate 70 g; fat 7 g), a supplemental drink (SD; isocaloric and isonitrogenous to WF), an isocaloric carbohydrate beverage (C), or a placebo beverage (P) immediately, 2 and 4 hours after a standardized weight training protocol on 4 days, each separated by 1 week, in a repeated measures design. Subjects also received a standardized meal at 7 and 12 hours postexercise. Insulin, testosterone, and cortisol were measured pre-exercise and during 24 hours of recovery (at 0.5,2.5,4.5,8, and 24 hours) using venous blood samples. Significant (condition × time) interactions were found for insulin, testosterone, and T:C, but not for cortisol (p < .05). The SD yielded a greater response for insulin than all other conditions. Conversely. P demonstrated the greatest values for testosterone and T:C at 2.5 and 4.5 hours postexercise. Cortisol did not vary between conditions and there were no condition effects for insulin, testosterone, cortisol, and T:C at 8 or 24 hours. In conclusion, the efficacy of postexercise feeding for optimizing T:C and muscle growth is unclear; however, consumption of SD appears to maximize circulating insulin for several hours following resistance exercise.
Exercise, Protein Metabolism, and Muscle Growth
Authors: Tipton Kevin D. , Wolfe Robert R.
Published: August 2016

Exercise has a profound effect on muscle growth, which can occur only if muscle protein synthesis exceeds muscle protein breakdown; there must be a positive muscle protein balance. Resistance exercise improves muscle protein balance, but, in the absence of food intake, the balance remains negative (i.e., catabolic). The response of muscle protein metabolism to a resistance exercise bout lasts for 24-48 hours; thus, the interaction between protein metabolism and any meals consumed in this period will determine the impact of the diet on muscle hypertrophy. Amino acid availability is an important regulator of muscle protein metabolism. The interaction of postexercise metabolic processes and increased amino acid availability maximizes the stimulation of muscle protein synthesis and results in even greater muscle anabolism than when dietary amino acids are not present. Hormones, especially insulin and testosterone, have important roles as regulators of muscle protein synthesis and muscle hypertrophy. Following exercise, insulin has only a permissive role on muscle protein synthesis, but it appears to inhibit the increase in muscle protein breakdown. Ingestion of only small amounts of amino acids, combined with carbohydrates, can transiently increase muscle protein anabolism, but it has yet to be determined if these transient responses translate into an appreciable increase in muscle mass over a prolonged training period.
Interactions among Dietary Fat, Mineral Status, and Performance of Endurance Athletes: A Case Study
Authors: Lukaski Henry C. , Bolonchuk William W. , Klevay Leslie M. , Milne David B. , Sandstead Harold H.
Published: August 2016

In a pilot study, performance measures and mineral metabolism were assessed in 3 male endurance cyclists who consumed isoenergetic, isonitrogenous diets for 28-day periods in a randomized, crossover design in which dietary carbohydrate, polyunsaturated, or saturated fat contributed about 50% of daily energy intake. Peak aerobic capacity [62 ml/(kg · min)] was unaffected by diet. Endurance capacity at 70–75% peak aerobic capacity decreased with the polyunsaturated fat diet. Copper retention tended to be positive only with saturated fat. Less iron and zinc were retained (intake – losses), and fecal losses of these minerals increased with the polyunsaturated fat. Blood biochemical measures of trace element nutritional status were unaffected by diet, except serum ferritin, which tended to decrease during consumption of the polyunsaturated fat diet. These preliminary results suggest that diets high in polyunsaturated fat, particularly linoleic acid, impair absorption and utilization of iron and zinc, and possibly magnesium, and may reduce endurance performance.
Educational Strategies Used in Increasing Fluid Intake and Enhancing Hydration Status in Field Hockey Players Preparing for Competition in a Hot and Humid Environment: A Case Study
Authors: Dabinett Jackie A. , Reid Karen , James Nic
Published: August 2016

The purpose of the present study was to develop a hydration strategy for use by female English field hockey players at the 1998 Commonwealth Games in Malaysia. An additional aim was to initiate the process of acclimation. Fifteen elite players, mean age (±SEM) 24.1 ± 1.19 years, height 1.67 ± 0.01 m, and body mass 62.8 ± 1.76 kg, took part in a 5-day training camp immediately prior to departure for the Games. In order to develop the hydration strategy, training took place under similar environmental conditions to those to be experienced in Malaysia (i.e., 32 °C, 80% humidity). Acclimation training consisted of 30–50 min of either continuous, low intensity cycling or high intensity intermittent cycling, which more closely replicated the pattern of activity in field hockey. Body mass measures taken each morning, and pre and post training, together with urine color measures, were used to assess hydration status. Pre-loading with up to 1 L of a 3% carbohydrate-electrolyte solution or water immediately prior to acclimation training, as well as regular drinks throughout, ensured that players avoided significant dehydration, with percent body mass changes ranging from −0.34% to +4.24% post training. Furthermore, the protocol used was sufficient to initiate the process of acclimation as demonstrated by a significant reduction in exercising heart rate and core temperature at all time points by days 4 and 5. In conclusion, although labor intensive and time consuming, the camp was successful in developing a hydration strategy that players were able to utilize once at the Games.
Testosterone Responses after Resistance Exercise in Women: Influence of Regional Fat Distribution
Authors: Nindl Bradley C. , Kraemer William J. , Gotshalk Lincoln A. , Marx James O. , Volek Jeff S. , Bush Jill A. , Häkkinen Keijo , Newton Robert U. , Fleck Steve J.
Published: August 2016

Regional fat distribution (RFD) has been associated with metabolic derangements in populations with obesity. For example, upper body fat patterning is associated with higher levels of free testosterone (FT) and lower levels of sex-hormone binding globulin (SHBG). We sought to determine the extent to which this relationship was true in a healthy (i.e., non-obese) female population and whether RFD influenced androgen responses to resistance exercise. This study examined the effects of RFD on total testosterone (TT), FT, and SHBG responses to an acute resistance exercise test (ARET) among 47 women (22 ± 3 years; 165 ± 6 cm; 62 ± 8 kg; 25 ± 5 %BF; 23 ± 3 BMI). RFD was characterized by 3 separate indices: waist-to-hip ratio (WHR), ratio of upper arm fat to mid-thigh fat assessed with magnetic resonance imaging (MRI ratio), and ratio of subscapular to triceps ratio (SB/TRi ratio). Skinfolds were measured for the triceps, chest, subscapular, mid-axillary, suprailaic, abdomen, and thigh regions. The ARET consisted of 6 sets of 10 RM squats separated by 2-min rest periods. Blood was obtained pre- and post- ARET. TT, FT, and SHBG concentrations were determined by radioimmunoassay. Subjects were divided into tertiles from the indices of RFD, and statistical analyses were performed by an ANOVA with repeated measures (RFD and exercise as main effects). Significant (p < .05) increases following the AHRET were observed for TT (~25%), FT (~25%), and SHBG (4%). With multiple regression analysis, anthropometric measures significantly predicted pre- concentrations of FT, post-concentrations of TT, and pre-concentrations of SHBG. The SB/TRi and MRI ratios but not the WHR, were discriminant for hormonal concentrations among the tertiles. In young, healthy women, resistance exercise can induce transient increases in testosterone, and anthropometric markers of adiposity correlate with testosterone concentrations.
Effects of Resistance Training on the Rate of Muscle Protein Synthesis in Frail Elderly People
Authors: Schulte Jill N. , Yarasheski Kevin E.
Published: August 2016

Advancing age is associated with a reduction in skeletal muscle protein, muscle strength, muscle quality, and chemical modifications that may impair protein function. Sarcopenia has been coupled with physical disability, frailty, and a loss of independent function (5, 19). Using stable isotope tracer methodologies and mass spectrometric detection, we observed: (a) 76–92-year-old physically frail and 62–74-year-old middle-age adults have lower mixed muscle protein synthetic rates than 20–32-year-old men and women; (b) 2 weeks and 3 months of weightlifting exercise increased the synthetic rate of myosin heavy chain (MHC) and mixed muscle proteins to a similar magnitude in frail, middle-age, and young women and men; (c) Serum myostatin-immunoreactive protein levels were elevated in physically frail women and were inversely correlated with lean mass. This suggests that the protein synthetic machinery adapts rapidly to increased contractile activity and that the adaptive response(s) are maintained even in frail elders.
The Aging Cardiovascular System: Changes in Autonomic Function at Rest and in Response to Exercise
Authors: Seals Douglas R. , Monahan Kevin D. , Bell Christopher , Tanaka Hirofumi , Jones Pamela P.
Published: August 2016

Tonic vagal modulation of cardiac period (R-R interval) decreases with advancing age, but is greater in middle-aged and older adults who habitually perform aerobic exercise compared with their sedentary peers. Cardiovagal baroreflex sensitivity also declines markedly with age in sedentary adults but only 50% as much in regularly exercising adults. In previously sedentary middle-aged and older adults, a 3-month program of moderate aerobic exercise increases cardiovagal baroreflex sensitivity by 25%. Tonic (basal) sympathetic nervous system (SNS) activity increases with advancing age in both sedentary and habitually exercising adults. Despite this, SNS b-adrenergic support of energy metabolism (resting metabolic rate-RMR) declines with age in sedentary individuals. However, SNS b-adrenergic support of RMR is maintained with age inenduranceexercise-trainedadultsandthereforeismuchgreaterinmiddle-aged and older individuals who exercise regularly compared with their sedentary peers. Thus, regular aerobic (endurance) exercise modulates selective age associated impairments in autonomic nervous system-physiological function.
The Effect of Pre-exercise Glucose Ingestion on Performance during Prolonged Swimming
Authors: Smith Gareth J. , Rhodes Edward C. , Langill Robert H.
Published: August 2016

The purpose of this study was to determine if pre-exercise glucose ingestion would improve distance swimming performance. Additionally, pre-exercise glucose was provided at 2 different feeding intervals to investigate the affects of the timing of administration. Ten male triathletes (: age, 29.5 ± 5.0 years; V̇O2peak, 48.8 ± 3.2 ml · kg’1 · min’) swam 4000 m on 3 occasions following the consumption of either a 10% glucose solution 5 min prior to exercise (G5), a 10% glucose solution 35 min prior to exercise (G35), or a similar volume of placebo (PL). Despite a significant difference (p < ,01) in blood glucose concentration prior to exercise ( in mmol · L ’: G" 8.4 ± 1.1 vs. G5 5.2 ± 0.5 or PL 5.3 ± 0.4), no significant differences were observed in total time ( in minutes: G* 70.7 ± 7.6, Gs 70.1 ± 7.6. PL 71.9 ± 8.4). post-exercise blood glucose ( inmmol · L−1: G35 5.1 ± 1.1, G5 5.1 ± 0.9, PL 5.3 ± 0.4), and average heart rate ( in bpnv.G" 155.8±10.8, G5 153.6±12.6. PL 152.0± 12.5; p > .05). While not reaching statistical significance, glucose feedings did result in improved individual performance times, ranging from 24 s to 5 min in 8 of the 10 subjects compared to the placebo. These results were found despite significant differences in blood glucose between trials immediately prior to exercise.
The Effects of a Pre-exercise Feeding with or Without Fungal Carbohydrases (Carbogen™) on Blood Parameters and Exercise Performance in Elite Cyclists: A Preliminary Study
Authors: Frank Laura Lewis , Baer Janine T. , Lambert Charles P. , Anderson Mark L.
Published: August 2016

The effect of fungal carbohydrases (Carbogen™ [C]) consumed with a meal replacement bar (MBR) on glucose metabolism and exercise performance was determined in 5 male competitive cyclists. After a 12-hour fast, subjects performed two 60-min cycling bouts at 80% V̇O2max followed by a time-to-exhaustion (TE) ride at 100% V̇O2max. One hour prior to each cycling bout, subjects ingested a MRB + 160-mg C or 160-mg CaCO3 placebo (PL) in a double-blind, counterbalanced fashion. Blood was drawn for determination of glucose, insulin, and lactate at: fasting, 1 hour post-feeding, minutes 30 and 60 of exercise, and after TE. Two-way ANOVA revealed a significant (p < .05) treatment and time effect for glucose, with C being higher than PL. Interaction effects were ob-· served for insulin and lactate. An increase in TE (min) at 100% V̇O2max was observed in the C versus PL trial (6.3 ± 3.4 vs. 4.4 ± 2.9, p < .001). A MRB+C may benefit cyclists due to increased BG and improved exercise performance.
Effect of High-Fat, High-Carbohydrate, and High-Protein Meals on Metabolism and Performance during Endurance Cycling
Authors: Rowlands David S. , Hopkins Will G.
Published: August 2016

The effect of pre-exercise meal composition on metabolism and performance in cycling were investigated in a crossover study. Twelve competitive cyclists ingested high-fat, high-carbohydrate, or high-protein meals 90 min before a weekly exercise test. The test consisted of a 1-hour pre-load at 55% peak power, five 10-min incremental loads from 55 to 82% peak power (to measure the peak fat-oxidation rate), and a 50-km time trial that included three 1-km and 4-km sprints. A carbohydrate supplement was ingested throughout the exercise. Relative to the high-protein and high-fat meals, the high-carbohydrate meal halved the peak fat-oxidation rate and reduced the fat oxidation across all workloads by a factor of 0.20 to 0.58 (p = .002–.0001). Reduced fat availability may have accounted for this reduction, as indicated by lower plasma fatty acid, lower glycerol, and higher pre-exercise insulin concentrations relative to the other meals (p = .04–.0001). In contrast, fat oxidation following the high-protein meal was similar to that following the high-fat meal. This similarity was linked to evidence suggesting greater lipolysis and plasma fat availability following high-protein relative to high-carbohydrate meals. Despite these substantial effects on metabolism, meal composition had no clear effect on sprint or 50-km performance.
Effects of Long-term Creatine Supplementation on Liver and Kidney Functions in American College Football Players
Authors: Mayhew David L. , Mayhew Jerry L. , Ware John S.
Published: August 2016

The purpose of this study was to determine the effect of long-term Cr supplementation on blood parameters reflecting liver and kidney function. Twenty-three members of an NCAA Division II American football team (ages = 19–24 years) with at least 2 years of strength training experience were divided into a Cr monohydrate group (CrM, n = 10) in which they voluntarily and spontaneously ingested creatine, and a control group (n = 13) in which they took no supplements. Individuals in the CrM group averaged regular daily consumption of 5 to 20 g (mean ± SD = 13.9 ± 5.8 g) for 0.25 to 5.6 years (2.9 ± 1.8 years). Venous blood analysis for serum albumin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, urea, and creatinine produced no significant differences between groups. Creatinine clearance was estimated from serum creatinine and was not significantly different between groups. Within the CrM group, correlations between all blood parameters and either daily dosage or duration of supplementation were nonsignificant. Therefore, it appears that oral supplementation with CrM has no long-term detrimental effects on kidney or liver functions in highly trained college athletes in the absence of other nutritional supplements.
Effects of Muscle Glycogen on Performance of Repeated Sprints and Mechanisms of Fatigue
Authors: Rockwell Michelle Smith , Rankin Janet Walberg , Dixon Helen
Published: August 2016

This study investigated the effect of initial muscle glycogen on performance of repeated sprints and some potential mechanisms for an effect of glycogen on fatigue. Eight subjects performed 2 cycling trials (repeated 60-s sprints) following consumption of either a high carbohydrate (HC) or a low carbohydrate (LC) diet. Muscle biopsies and blood samples were collected at baseline, following a 15% (15% fatigue) and a 30% decline in sprint performance (30% fatigue), when exercise was terminated. Baseline muscle glycogen levels [346 ± 19 HC (SEM) vs. 222 ± 19 mmol/kg dw LC] and total exercise time to 30% fatigue were higher following HC than LC (57.5 ± 10.0 vs. 42.0 ± 3.6 min; p < .05). Similar significant (p < .05) decreases over the entire exercise bout were seen in muscle glycogen (43%), creatine phosphate (CP; 35%), and sarcoplasmic reticu-lum (SR) Ca2+-uptake in isolated homogenized muscle (56%) for both trials (p > .05 between trials). The percentage decline in SR Ca2+-release was less for HC than LC (36% and 53%, respectively), but this was not statistically different. In summary, HC delayed fatigue during repeated sprints. As the reductions in muscle glycogen, CP, and SR function during exercise were not different by dietary treatment, these data do not support a link between whole muscle glyco-gen and SR function or CP reduction during repeated sprint exercise.
Physical Sports Activity during Leisure Time and Dietary Intake of Foods and Nutrients in a Large Spanish Cohort
Authors: Tormo Maria José , Navarro Carmen , Chirlaque Maria-Dolores , Barber Xavier , Argilaga Silvia , Agudo Antonio , Amiano Pilar , Barricarte Aurelio , Beguiristain Jose M. , Dorronsoro Miren , González Carlos Alberto , Martínez Carmen , Quirós José Ramón , Rodríguez Mauricio
Published: August 2016

This study evaluated the dietary pattern of foods and nutrients according to levels of vigorous leisure time physical activity (PA) assessed at recruitment within the Spanish cohort of the European Prospective Investigation on Cancer (EPIC) study (37,287 healthy volunteers with complete information). We used a validated PA questionnaire (PAQ) to measure the weekly frequency and duration of different kinds of sport activities. For dietary assessment, we used a validated diet history questionnaire that included all items consumed with a frequency of at least twice a month. We tested differences in food and nutrient intake according to PA duration by means of both an analysis of variance and an analysis of covariance adjusted for confounding factors. Linear increases or decreases in food and nutrient intake across PA levels were tested by means of a regression analysis. Only 11% of men and 6% of women performed at least 3 hours/week of intense PA, which is similar to current recommendations. Overall, main nutrient and total energy intakes were similar across different PA levels (<2% change in total energy intake between extreme PA categories). However, the intake of some foods and vitamins did significantly (p ≤ .05) increase as PA increased. The average gender-weighted percentage change in the intake of food and vitamins increased when moving from the lowest levels of PA to the highest. There was an increase in the intake of the following: 15.9% in vegetables, 6.7% in fruit, 9% in fish, 5.6% in dairy products, 10% in vitamin C, 5.9% in vitamin E, 7.2% in retinol, 19.7% in total carotene, 40.1% in α-carotene, 20.4% in ß-carotene, 11.2% in licopene, and 26.1% in lutein. BMI, which was above average for the cohort (mean ± SD: 28.4 ± 4.2), decreased steadily when PA increased. To sum up, in this large Spanish cohort, the differences in dietary intake relative to levels of PA were not found either in the amount of total energy consumed nor in the number of main macronutrients but rather in the intake of certain foods which, while having very little or moderate caloric content, are very rich in highly bioactive elements such as vitamins and provitamins.
Effects of Oral D-Ribose Supplementation on Anaerobic Capacity and Selected Metabolic Markers in Healthy Males
Authors: Kreider R.B. , Melton C. , Greenwood M. , Rasmussen C. , Lundberg J. , Earnest C. , Almada A.
Published: August 2016

Oral D-ribose supplementation has been reported to increase adenine nucle-otide synthesis and exercise capacity in certain clinical populations. Theoretically, increasing adenine nucleotide availability may enhance high intensity exercise capacity. This study evaluated the potential ergogenic value of D-ribose supplementation on repetitive high-intensity exercise capacity in 19 trained males. Subjects were familiarized to the testing protocol and performed two practice-testing trials before pre-supplementation testing. Each test involved warming up for 5 min on a cycle ergometer and then performing two 30-s Wingate anaerobic sprint tests on a computerized cycle ergometer separated by 3 min of rest recovery. In the pre- and post-supplementation trials, blood samples were obtained at rest, immediately following the first and second sprints, and following 5 min of recovery from exercise. Subjects were then matched according to body mass and anaerobic capacity and assigned to ingest, in a randomized and double blind manner, capsules containing either 5 g of a dextrose placebo (P) or D-ribose (R) twice daily (10 g/d) for 5 d. Subjects then performed post-supplementation tests on the 6th day. Data were analyzed by ANOVA for repeated measures. Results revealed a significant interaction (p = .04) in total work output. Post hoc analysis revealed that work significantly declined (–18 ± 51 J) during the second post-supplementation sprint in the P group while being maintained in the R group (–0.0 ± 31 J). No significant interactions were observed in peak power, average power, torque, fatigue index, lactate, ammonia, glucose, or uric acid. Results indicate that oral ribose supplementation (10 g/d for 5 d) does not affect anaerobic exercise capacity or metabolic markers in trained subjects as evaluated in this study.
Vitamin C: Effects of Exercise and Requirements with Training
Authors: Peake Jonathan M.
Published: August 2016

Ascorbic acid or vitamin C is involved in a number of biochemical pathways that are important to exercise metabolism and the health of exercising individuals. This review reports the results of studies investigating the requirement for vitamin C with exercise on the basis of dietary vitamin C intakes, the response to supplementation and alterations in plasma, serum, and leukocyte ascorbic acid concentration following both acute exercise and regular training. The possible physiological significance of changes in ascorbic acid with exercise is also addressed. Exercise generally causes a transient increase in circulating ascorbic acid in the hours following exercise, but a decline below pre-exercise levels occurs in the days after prolonged exercise. These changes could be associated with increased exercise-induced oxidative stress. On the basis of alterations in the concentration of ascorbic acid within the blood, it remains unclear if regular exercise increases the metabolism of vitamin C. However, the similar dietary intakes and responses to supplementation between athletes and nonathletes suggest that regular exercise does not increase the requirement for vitamin C in athletes. Two novel hypotheses are put forward to explain recent findings of attenuated levels of cortisol postexercise following supplementation with high doses of vitamin C.
Variability in Estimation of Self-reported Dietary Intake Data from Elite Athletes Resulting from Coding by Different Sports Dietitians
Authors: Braakhuis Andrea J. , Meredith Kelly , Cox Gregory R. , Hopkins William G. , Burke Louise M.
Published: August 2016

A routine activity for a sports dietitian is to estimate energy and nutrient intake from an athlete’s self-reported food intake. Decisions made by the dietitian when coding a food record are a source of variability in the data. The aim of the present study was to determine the variability in estimation of the daily energy and key nutrient intakes of elite athletes, when experienced coders analyzed the same food record using the same database and software package. Seven-day food records from a dietary survey of athletes in the 1996 Australian Olympic team were randomly selected to provide 13 sets of records, each set representing the self-reported food intake of an endurance, team, weight restricted, and sprint/power athlete. Each set was coded by 3–5 members of Sports Dietitians Australia, making a total of 52 athletes, 53 dietitians, and 1456 athlete-days of data. We estimated within- and between- athlete and dietitian variances for each dietary nutrient using mixed modeling, and we combined the variances to express variability as a coefficient of variation (typical variation as a percent of the mean). Variability in the mean of 7-day estimates of a nutrient was 2- to 3-fold less than that of a single day. The variability contributed by the coder was less than the true athlete variability for a 1-day record but was of similar magnitude for a 7-day record. The most variable nutrients (e.g., vitamin C, vitamin A, cholesterol) had ~3-fold more variability than least variable nutrients (e.g., energy, carbohydrate, magnesium). These athlete and coder variabilities need to be taken into account in dietary assessment of athletes for counseling and research.
The Effects of ß-Hydroxy-ß-Methylbutyrate (HMB) and HMB/Creatine Supplementation on Indices of Health in Highly Trained Athletes
Authors: Crowe Melissa J. , O’Connor Donna M. , Lukins Joann E.
Published: August 2016

This study aimed to investigate the effects of 6 wk oral supplementation of ß-hydroxy- ß-methylbutyrate (HMB) and HMB combined with creatine monohy-drate (HMBCr) on indices of health in highly trained athletes. Elite, male rugby league players (n = 28) were allocated to 1 of 3 groups: a control group (n = 6), a HMB group (3 g/d; n = 11), or a HMBCr group (3 g/day HMB, 3 g/d Cr; n = 11). Testing prior to, and immediately following, supplementation included a full blood count, plasma testosterone and cortisol, blood electrolytes, lipids, urea and glucose, sperm count and motility, and assessment of psychological state. A 3 X 2 factorial ANOVA revealed no effect of HMB or HMBCr on any of the measured parameters except minor changes in blood bicarbonate and blood monocyte and lymphocyte counts. Blood bicarbonate was significantly decreased in the HMB post-supplementation sample compared to the control and HMBCr groups. Blood monocyte and lymphocyte counts showed no within-group changes for HMB or HMBCr supplementation but were significantly different from the control. However, the majority of these readings remained within normal range. HMB and HMBCr were concluded to have no adverse effects on the parameters evaluated in this study when taken orally by highly trained male athletes over a 6-wk period.