bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Choline Supplementation on Physical Performance
Authors: Warber John P. , Patton John F. , Tharion William J. , Zeisel Steven H. , Mello Robert P. , Kemnitz Christopher P. , Lieberman Harris R.
Published: August 2016

It has been reported that plasma choline levels decrease following certain types of strenuous exercise. Preliminary findings also suggest that a drop in plasma choline may limit physical performance, while choline supplementation may delay fatigue during prolonged efforts. A double-blind crossover design was used to determine the relationship between plasma choline and performance during and after 4 hr of strenuous exercise. Volunteers (N = 14) received either a placebo or treatment beverage (8.425 g choline citrate) prior to and midway through a 4-hr load carriage treadmill exercise (3% grade at 5.6 km/h × 20 km) carrying a total load of 34.1 kg. Following the treadmill test, run time-to-exhaustion and squat tests were performed, and perceived exertion, plasma choline, glycerophosphocholine, and phosphatidylcholine were measured. Plasma choline levels increased 128% after the run-to-exhaustion with the choline supplemented beverage but remained unchanged with the placebo beverage. No significant effects were seen with choline supplementation on any outcome performance measure. Consequently, soldiers conditioned to carry heavy loads over long distances do not deplete plasma choline as a result of a prolonged exhaustive exercise under a placebo beverage, nor do they benefit from choline supplementation to delay fatigue under the same conditions.
Predictive Accuracy of Omron® Body Logic Analyzer in Estimating Relative Body Fat of Adults
Authors: Gibson Ann L. , Heyward Vivian H. , Mermier Christine M.
Published: August 2016

This study assessed the predictive accuracy of a new hand-held, segmental, bioimpedance (BI) analyzer in estimating the relative body fat (%BF) of a sample of 25 men and 23 women (18–55 years, 7.0 to 42.8%BFHW). The reference method was hydrostatic weighing (HW) at residual lung volume. The %BF estimates obtained from manufacturer’s (Omron) gender-specific equations were cross-validated. There were high validity coefficients ( and .83, for men and women, respectively), moderate prediction errors (SEE = 3.46%, E = 3.64%BF for men; SEE = 4.04%, E = 3.87%BF for women), and no significant difference (p >.05) between the average and for women (21.8% vs. 2I.6%BF, respectively). For men, there was a small but significant (p < .05) difference in (18.7%) and (20.1 %). For both men and women, the line of identity did not differ significantly (p > .05) from the line of best fit. The Omron® BI equations accurately estimated the %BF of 72% of the men and 65% of the women in this sample within ±3.5%BF. Therefore, use of the Omron® BI analyzer is suitable for assessing the %BF of adults having demographic characteristics similar to those of this sample.
Plasma B-6 Vitamer Changes Following a 50-km Ultramarathon
Authors: Leonard Scott W. , Leklem James E.
Published: August 2016

The purpose of this study was to measure plasma B-6 vitamers, and other factors which may affect the plasma concentrations of these vitamers under extreme physical conditions. Blood samples were drawn from 8 men and 3 women (43.7 ± 8.6 years) 30 min prior to the start of a 50-km ultramarathon race (pre), and at 5 (PST) and 60 (PST60) min post race. HPLC was used to measure plasma pyridoxal 5’-phosphate (PLP), pyridoxal (PL), pyridoxine (PN), and 4-pyridoxic acid (4-PA). Plasma glucose, albumin, lactate, and alkaline phosphatase activity, as well as hematocrit, and hemoglobin levels were measured. Food and liquid intake was assessed during the run. There was a significant (p < .001) decrease in the plasma PLP concentration between pre and PST, with a mean decrease of 12.9 ± 8.8 nmol/L (31% decrease). At PST60, there was a further decrease in plasma PLP concentration bringing the total decrease to 17.9 nmol/L (44%). The plasma TB6 concentration also decreased after the run, but the mean decrease was only 13.5 nmol/L (pre to PST60). PL increased 25% after the run, and did not change further at PST60. The mean plasma 4-PA concentration increased 21% post run and decreased to just below the pre-run value 1 hr post race. The plasma PLP decrease measured in the current study is not consistent with what has previously been reported during shorter length endurance studies.
Assessment of Under-Reporting of Energy Intake by Elite Female Gymnasts
Authors: Jonnalagadda Satya S. , Benardot Dan , Dill Marian N.
Published: August 2016

This study examines the degree of under-reporting of energy intake by elite, female gymnasts, and the impact this predicted under-reporting has on associated macro and micro nutrient intake. Twenty-eight female U.S. national team artistic gymnasts participated in the study. Dietary intake was assessed using 3-day food records, and the degree of under-reporting was predicted from the ratio of reported energy intake (EI) to predicted basal metabolic rate (BMRestd), using the standards described by Goldberg et al. (10). Sixty-one percent of the subjects had an EI/BMRestd ratio of < 1.44, and were classified as under-reporters. The under-reporters had higher BMIs and percent body fat, and lower reported total energy intakes than the adequate energy reporters. Additionally, under-reporting of energy intake had a significant impact on reported micro nutrient intake. The under-reporting of energy intake seen in these subjects has an impact on the reported intake of macro and micro nutrients that can influence the interpretation of the nutritional status of these athletes and the strategy for nutrition intervention. Therefore, when assessing dietary intakes of elite gymnasts, some means of determining the accuracy of the reported energy and nutrient intake should be employed to more accurately identify the true nutritional problems experienced by these elite athletes.
Effects of Ingesting a Large Volume of Carbohydrate-Electrolyte Solution on Rehydration during Recovery and Subsequent Exercise Capacity
Authors: Wong Stephen H. , Williams Clyde , Adams Neville
Published: August 2016

This randomized, double-blind study examined the effects of rehydration per se and rehydration plus carbohydrate (CHO) ingestion during recovery (REC) on subsequent endurance running capacity. Nine men ran at 70% V̇O2max on a level treadmill for 90 min (Tl) on two occasions, followed by a 4 hour REC and a further exhaustive run at the same speed (T2). During the first 3 hours of REC, subjects drank either a 6.9% CHO-electrolyte solution (CE) or a CHO- and electrolyte-free sweetened placebo (PL) every 30 min. Volumes prescribed were 200% of the fluid lost after Tl. but the actual volume of fluid ingested during the REC ranged from 113–200% and 88.5–200% of the body mass lost for the CE and PL trials (NS). However, positive fluid balance was found in both trials after REC. During T2. run time was 24.3 ± 4.4 min longer in the CE trial (69.3 ± 5.5 vs. 45.0 ± 4.2 min; p < .05). Higher blood glucose concentrations were observed throughout REC in the CE trial. These results suggest that ingesting a CHO-electrolyte solution is more effective in restoring endurance capacity compared to the same large volume of placebo, even though complete rehydration was achieved in both trials.
Gastric Emptying of Cold Beverages in Humans: Effect of Transportable Carbohydrates
Authors: Shi Xiaocai , Bartoli William , Horn Mary , Murray Robert
Published: August 2016

Eight healthy subjects, aged 39.0 ± 2.4 years, consumed four 6% carbohydrate-electrolyte solutions containing either one (glucose or fructose) or two transportable carbohydrates in single (glucose + fructose) or bound (sucrose) forms. Solution osmolalities ranged from 250 to 434 mOsm/kg H2O. The test solutions were ingested at rest in the amount of 6 ml/kg of body weight at a temperature of 12 °C. Gastric emptying rate was measured by repeated aspirations via a nasogastric tube using the modified George double-sampling technique. The intragastric temperature was determined by a temperature probe attached to the nasogastric tube. There were no significant differences in gastric emptying rates and gastric volumes among the solutions. Intragastric temperature dropped from 36.5 °C to 23.3±3 °C immediately after beverage ingestion but recovered to above 30 °C within 5 min. These data suggest that the gastric emptying rate of the specified beverages is not affected by the number and type of carbohydrates or by solution osmolalities within the tested range. Within 5 min after ingestion, cold beverages are warmed to above 30 °C in the stomach. This infers that the effect of cold solution temperature on gastric emptying rate is likely to be small and transitory.
Active Recovery Counteracts the Post-Exercise Rise in Plasma-Free Fatty Acids
Authors: Wigernæs Ine , Strømme Sigmund B. , Høstmark Arne T.
Published: August 2016

The present study investigated the effect of active recovery (AR) as compared to rest recovery (RR) upon FFA concentrations following moderate- (MI) or high-intensity (HI) running. Fourteen well-trained males (23.7±6 years. V̇O2max = 69.5±1.8ml · min−1kg−1) were randomly assigned into two trials (HI = 30 min at 82% of V̇O2max; MI = 60 min at 75% of V̇O2max). Within each group, the subject completed two sets of experiments of running followed by either AR (15 min running at 50% of V̇O2max) or RR (complete rest in the supine position). Plasma volume changes after the exercise did not deviate between the AR or RR trials. In both the HI and Ml trials, AR resulted in lower FFA peaks and lower overall FFA concentrations while performing AR (p<.05). However, upon discontinuing AR. there was a rise in the FFA concentration. At 120-min post-exercise, the FFA concentrations after AR and RR were not significantly different. The changes in the FFA/albumin ratio were similar to the FFA responses. It is concluded that AR may counteract the rise in FFA 5–15 minutes after exercise.
The Effect of Siberian Ginseng (Eleutherococcus Senticosus) on Substrate Utilization and Performance during Prolonged Cycling
Authors: Eschbach L. Christopher , Webster Michael J. , Boyd Joseph C. , McArthur Patrick D. , Evetovich Tammy K.
Published: August 2016

It has been suggested that Eleutherococcus senticosus (ES). also known as Siberian ginseng or ciwuija. increases fat utilization in humans. The purpose of this study was to examine the physiological responses to supplementation with ES in endurance cyclists. Using arandomized. double-blind crossover design. 9 highly-trained men (28 ± 2 years. V̇O2max 57.3±2.0 ml · kg−1 · min−1) cycled for 120 min at 60% V̇O2max followed by a simulated 10-km lime trial. Diet was controlled, and ES (1,200 mg · day−1) or a placebo (P) were administered for 7 days prior to each of the two trials. Oxygen consumption, respiratory exchange ratio, and heart rate were recorded every 30 min, and rating of perceived exertion. plasma [lactate], and plasma [glucose j were recorded every 20 min during the 120 min of steady state cycling. There were no significant differences (p > .05) between the ES and P groups at any steady-state time interval or during the cycling time trial (ES = 18.10 ± 0.42, P = 17.83 ± 0.47 min). In contrast with previous reports, the results of this study suggest that ES supplementation does not alter steady-state substrate utilization or 10-km cycling performance time.
Effects of Carbohydrate and Chromium Ingestion during Intermittent High-Intensity Exercise to Fatigue
Authors: Davis J. Mark , Welsh Ralph S. , Alderson Nathan A.
Published: August 2016

Purpose:

This study was designed to test the hypothesis that addition of chromium (Cr) to a carbohydrate-electrolyte drink would enhance the reported benefits of carbohydrate on exercise capacity during intermittent high-intensity shuttle running.

Methods:

Eight physically active men performed 3 exercise trials while ingesting 6% carbohydrate-electrolyte (CHO), CHO plus chromium picolinate (400 μg) (CHO + Cr+3). or placebo (P) using a double-blind, counterbalanced design. Each trial consisted of 5 × 15 min bouts of shuttle running (walk, sprint, and run at 95 and 55% of estimated V̇O2max, separated by 3-min rest). This was followed by a fatigue test (running alternating 20-m lengths at 55 and 95% of estimated V̇O2, until fatigue).

Results:

During the standardized shuttle running, blood glucose was higher with both CHO and CHO + Cr+3 than P. Plasma free fatty acid was higher in P than both CHO and CHO + Cr+3 at 75 min of exercise and at fatigue. In the fatigue test, subjects ran longer with both CHO and CHO + Cr+3 than P.

Conclusions:

The data confirm an ergogenic benefit of ingesting CHO during exercise designed to imitate sports like basketball, soccer, and hockey, but do not support the hypothesis that the addition of Cr would enhance this effect.
The Relationship of Mode and Intensity of Training on Resting Metabolic Rate in Women
Authors: Byrne Heidi K. , Wilmore Jack H.
Published: August 2016

The present cross-sectional study was designed to investigate the relationship between exercise training and resting metabolic rate (RMR). The focus of this investigation was to compare RMR in aerobically trained (AT), resistance trained (RT), and untrained (UNT) women. Subjects were also classified as highly trained (HT), moderately trained (MT), or untrained (UNT) in order to examine the relationship between RMR and level of training. Sixty-one women between the ages of 18 and 46 years volunteered to serve as subjects in this study. Each subject completed measurements of body composition, maximal oxygen uptake (V̇O2max), and two consecutive measurements of RMR. The data presented show that there was no significant difference in resting metabolic rate between resistance-trained, aerobically trained, and control subjects. However, when grouped by intensity of training, there was a trend for an increased resting metabolic rate (kcal/day) in the highly trained subjects, regardless of mode of training.
Antioxidant Status and Oxidative Stress in Elite Alpine Ski Racers
Authors: Subudhi Andrew W. , Davis Scott L. , Kipp Ronald W. , Askew E. Wayne
Published: August 2016

The goal of this field study was to assess antioxidant status and markers of oxidative damage in elite alpine ski racers during routine training. Subjects included 12 members of the U.S. Men’s Alpine Ski Team attending a 10-day summer training camp. Blood draws were collected at rest and after exercise: (a) prior to training, (b) following 2 days of dry land training, and (c) after 4 days of on-snow skiing. Seven measures of antioxidant status were determined using colorimetric and HPLC methods (Trolox “equivalent antioxidant capacity, uric acid, α-tocopherol, β-tocopherol, total glutathione, cytosolic glutathione peroxidase, and superoxide dismutase). Oxidative stress was assessed using 2 markers of lipid peroxidation (malondialdehyde and lipid hydroperoxides) and 2 markers of protein oxidation (carbonylated total proteins and carbonylated hemoglobin). The results of this study suggest that antioxidant status of elite alpine skiers may decline over a period of intense training. However, elevations in markers of oxidative stress were not evident.
The Assessment of Frequency of Iron Deficiency in Athletes from the Transferrin Receptor-Ferritin Index
Authors: Malczewska Jadwiga , Szczepańska Beata , Stupnicki Romuald , Sendecki Witold
Published: August 2016

The transferrin receptor-ferritin index (sTfR/logFerr) was determined in 131 male and 121 female athletes in order to assess the frequency of iron deficiency (threshold value of that index taken as 1.8). Blood was drawn for determining morphological indices as well as sTfR, ferritin, iron, total iron binding capacity (TIBC), and haptoglobin. A significantly (p < .01) higher incidence of iron deficiency was observed in women (26%) than in men (11%). The iron deficiency was latent, since no subject was found to be anemic. The plasma iron was significantly lower and TIBC higher (p < .001) in both iron-deficient subgroups than in the non-deficient ones. This confirmed the latent character of iron deficiency. Some hematological indices (Hb, MCH, MCHC, MCV) were significantly lower in iron-deficient female athletes than in male athletes, which suggested a more profound iron deficiency in the former. The sTfR/logFerr index might thus be useful in detecting iron deficiency in athletes, especially in those with erythropoiesis disorders, since physical loads may affect the widely used ferritin levels.
Effect of Potassium Phosphate Supplementation on Perceptual and Physiological Responses to Maximal Graded Exercise
Authors: Goss Fredric , Robertson Robert , Riechman Steve , Zoeller Robert , Dabayebeh Ibrahim , Moyna Niall , Boer Nicholas , Peoples Jennifer , Metz Kenneth
Published: August 2016

This investigation evaluated the effect of oral potassium phosphate supplementation on ratings of perceived exertion (RPE) and physiological responses during maximal graded exercise tests (GXT). Eight highly trained endurance runners completed a GXT to anchor the Borg 15-point RPE scale and two double-blind counterbalanced GXTs. Subjects ingested either 4,000 mg · day−1 of phosphate (PHOS) or a placebo (PLA) for 2 days. Two weeks separated GXTs. Phosphate levels obtained immediately prior to the GXTs were greater in PHOS than PLA. No differences between PHOS and PLA were noted for the submaximal and maximal physiological responses. RPE for the overall body were lower during PHOS than PLA at intensities corresponding to 70–80% of V̇O2max. This suggests that oral potassium phosphate supplementation mediates perceived exertion during moderately intense exercise.
Effectiveness of Glycerol as a Rehydrating Agent
Authors: Scheett Timothy P. , Webster Michael J. , Wagoner Kent D.
Published: August 2016

On two occasions, 8 male subjects completed a dehydration protocol, immediately followed by a 180-min rehydration protocol, then a subsequent exercise bout. During each dehydration session, subjects lost 3.1 ± 0.4% body weight (BW) following discontinuous exercise in the heat (40 °C, 33 % rh). During the first 30 min of rehydration, subjects ingested either 1.0-g glycerol · kg body weight−1 + 30% of the total rehydration water volume (GLY), or 30% of the total rehydration water volume without glycerol (CON). The five remaining ingestions (every 30 min) were equal to 14% of the remaining fluid volume and were identical in nature. Fluid volume ingested equaled fluid volume lost during dehydration. Following the 180 min rehydration period, subjects cycled (~50% V̇O2peak) in the heat (40 °C, 33% rh) until volitional exhaustion. Three observations were made: (a) Following glycerol-induced rehydration, time to volitional exhaustion was greater during the subsequent exercise bout in the heat (CON: 38.0 ± 2.0, GLY 42.8 ± 1.0 min, p < .05); (b) glycerol-induced rehydration significantly increased plasma volume restoration within 60 min and at the end of the 180-min rehydration period; and (c) total urine volume was lower and percent rehydration was greater following GLY, but neither was significantly different.
Free Living Energy Expenditure in Post Menopausal Women before and after Exercise Training
Authors: Keytel Lara R. , Lambert Michael I. , Johnson Judith , Noakes Timothy D. , Lambert Estelle V.
Published: August 2016

The aim of the study was to determine the effects of 8 weeks of moderate exercise training, on 24-hour free living energy expenditure in previously sedentary post-menopausal women. The experimental group (EX) included 9 women. Ten non-exercising control subjects (CON) were recruited to undergo pre- and post-testing. Estimated total daily energy expenditure (TDEE), total 24-hour heart beats (HB), total energy intake (TEI), resting metabolic rate, maximal oxygen consumption (V̇O2max), body composition, and submaximal heart rate were measured before and after the exercise intervention. Body composition did not change (body fat % in CON 34.0 ± 4.0% vs. 33.9 ± 3.6% and EX 34.1 ± 4.0% vs. 34.0 ± 3.4%). Mean submaximal heart rate during steady-state exercise in EX was lower after training compared to CON (p < .05); however, V̇O2max did not significantly (CON 1.96 ± 0.23 vs. 1.99 ± 0.241 LO2/min and EX 1.86 ± 0.39 vs. 1.94 ± 0.30 LO2/min). Neither estimated TDEE (CON, 11.6 ± 2.0 vs. 11.4 ± 2.78 MJ; and EX 11.4 ± 3.3 vs. 11.5 ± 2.5 MJ, pre vs. post, respectively), RMR (CON 134.2 ± 9.4 vs. 136.9 ± 15.0 KJ/kgFFM/day, and EX 138.4 ± 6.4 vs. 140.7 ± 14.2 KJ/kgFFM/day, pre vs. post, respectively), TEI (CON 7.9 ± 2.2 vs. 8.2 ± 2.5 MJ, and EX 9.4 ±1.6 vs. 8.3 ± 2.8 MJ), nor HB (CON 110,808 ± 12,574 vs. 107,366 ± 12,864 beats, and EX 110,188 ± 9,219 vs. 114,590 ± 12,750 beats) change over 8 weeks in either group. These data suggest that a moderate exercise program may not impact on TDEE, RMR, TEI, or HB in previously sedentary, older women.
The Effects of Restricted Energy and Fluid Intake on Simulated Amateur Boxing Performance
Authors: Smith Marcus , Dyson Rosemary , Hale Tudor , Hamilton Matthew , Kelly John , Wellington Peggy
Published: August 2016

This study examined the effects of serial reductions in energy and fluid intake on two simulated boxing performances separated by 2 days recovery. Eight amateur boxers (age: 23.6 ± 3.2 years; height 175 ± 5 cm; body mass [BM] 73.3 ± 8.3 kg [Mean ± SD]) performed two simulated boxing bouts (BB) under normal (N-trial) and restricted (R-trial) diets in a counterbalanced design over 5 days. The trials were separated by a 9-day period of normal dietary behavior (X-trial). BM was recorded on days 1, 3, and 5 of each trial. Simulated bouts of three, 3-min rounds with 1-min recovery were completed on days 3 (BB1) and 5 (BB2) of each 5-day trial. Punching force (N) was recorded from 8 sets of 7 punches by a purpose-built boxing ergometer. Heart rate (fC) was monitored continuously (PE3000 Polar Sports Tester, Kempele, Finland), and blood lactate (BLa) and glucose (BG) were determined 4-min post-performance (2300 StaPlus, YSI, Ohio). Energy and fluid intakes were significantly lower in the R-trial (p < .05). Body mass was maintained during the N-trial but fell 3% (p < .05) during the R-trial. There were no significant differences in end-of-bout fC or post-bout BG, but BLa was higher in the N- than the R-trial (p < .05). R-trial punching forces were 3.2% and 4.6% lower, respectively, compared to the corresponding N-trial bouts, but the differences did not reach statistical significance. These results suggest that energy and fluid restrictions in weight-governed sports do not always lead to a significant decrease in performance, but because of the small sample size and big variations in individual performances, these findings should be interpreted with care.
Short-Term High-Fat Diet Alters Substrate Utilization during Exercise but Not Glucose Tolerance in Highly Trained Athletes
Authors: Staudacher Heidi M. , Carey Andrew L. , Cummings Nicola K. , Hawley John A. , Burke Louise M.
Published: August 2016

We determined the effect of a high-fat diet and carbohydrate (CHO) restoration on substrate oxidation and glucose tolerance in 7 competitive ultra-endurance athletes (peak oxygen uptake [V̇O2peak] 68 ± 1 ml · kg−1 · min−1; mean±SEM). For 6 days, subjects consumed a random order of a high-fat (69% fat; FAT-adapt) or a high-CHO (70% CHO; HCHO) diet, each followed by 1 day of a high-CHO diet. Treatments were separated by an 18-day wash out. Substrate oxidation was determined during submaximal cycling (20 min at 65% V̇O2peak) prior to and following the 6 day dietary interventions. Fat oxidation at baseline was not different between treatments (17.4 ± 2.1 vs. 16.1 ± 1.3 g · 20 min−1 for FAT-adapt and HCHO, respectively) but increased 34% after 6 days of FAT-adapt (to 23.3 ± 0.9 g · 20 min−1, p < .05) and decreased 30% after HCHO (to 11.3±1.4 g · 20 min−1, p < .05). Glucose tolerance, determined by the area under the plasma [glucose] versus time curve during an oral glucose tolerance (OGTT) test, was similar at baseline (545±21 vs. 520±28 mmol · L−1 · 90 min−1), after 5-d of dietary intervention (563 ± 26 vs. 520 ± 18 mmol · L−1 · 90 min−1) and after 1 d of high-CHO (491 ± 28 vs. 489 ± 22 mmol · L−1 · 90min−1 for FAT- adapt and HCHO, respectively). An index of whole-body insulin sensitivity (SI 10000/÷fasting [glucose] × fasting [insulin] × mean [glucose] during OGTT × mean [insulin] during OGTT) was similar at baseline (15 ± 2 vs. 17 ± 5 arbitrary units), after 5-d of dietary intervention (15 ± 2 vs. 15 ± 2) and after 24 h of CHO loading (17 ± 3 vs. 18 ± 2 for FAT- adapt and HCHO, respectively). We conclude that despite marked changes in the pattern of substrate oxidation during submaximal exercise, short-term adaptation to a high-fat diet does not alter whole-body glucose tolerance or an index of insulin sensitivity in highly-trained individuals.
Three Days Fast in Sportsmen Decreases Physical Work Capacity but Not Strength or Perception-Reaction Time
Authors: Gutiérrez Ángel , González-Gross Marcela , Delgado Manuel , Castillo Manuel J.
Published: August 2016

This study investigates, in young nonobese healthy athletes, the consequences of a 3-day fast coupled, or not, to enhanced physical activity. Eight male subjects, aged 21 ± 2 years, fasted for 3 days on two separate occasions, 4 weeks apart. On the first occasion, subjects continued their daily training activities. On the second occasion, a daily physical exercise program was added to these activities. Subjects were evaluated before and after 24 hours and 72 hours of fasting. Evaluation consisted of body composition, basal respiratory exchange ratio, plasma metabolic parameters, perception-reaction time (both simple and discriminant), hand grip strength, and physical work capacity at 170 beats per minute (PWC170). Fasting determined significant reductions in body weight, body fat, and muscle mass. These reductions were not affected by enhanced physical activity. Basal respiratory exchange ratio decreased with fasting but was not influenced by increased training activities. Fasting determined a significant decrease in blood glucose levels, while plasma proteins, urea, uric acid, and free fatty acids increased. Perception-reaction time and hand grip strength were unmodified during fasting. By contrast, PWC170 was significantly and progressively reduced during fasting, and this decrease was not reversed by an increase in training activities.
Carbohydrate-Loading during the Follicular Phase of the Menstrual Cycle: Effects on Muscle Glycogen and Exercise Performance
Authors: Paul D.R. , Mulroy S.M. , Horner J.A. , Jacobs K.A. , Lamb D.R.
Published: August 2016

The effects of employing a high-carbohydrate diet (carbohydrate-loading) to increase glycogen storage in skeletal muscle are not well established in female athletes. On 4 occasions—2 familiarization trials and 2 experimental trials—6 well-trained female subjects completed 6 × 15-min continuous intervals of cycling (12 min at 72% V̇O2max, 1 min at maximal effort, and 2 min at 50% V̇O2max), followed by a time trial 15 min later. The women consumed their habitual diets (HD; 6–7 g carbohydrate/kg lean body mass) for 3 days after the second familiarization trial and before the first experimental trial. During the 3 days following the first experimental trial, the subjects consumed a high-carbohydrate diet (CD; 9–10 g carbohydrate/kg lean body mass) prior to the second experimental trial. Mean (±SEM) pre-exercise muscle glycogen concentrations were greater after CD versus HD (171.9 ± 8.7 vs. 131.4 ± 10.3 mmol/kg wet weight, P < 0.003). Although 4 of the 6 subjects improved their time-trial performance after CD, mean performance for the time trial was not significantly different between diets (HD: 763.9 ± 35.6 s; CD: 752.9 ± 30.1 s). Thus, female cyclists can increase their muscle glycogen stores after a carbohydrate-loading diet during the follicular phase of the menstrual cycle, but we found no compelling evidence of a dietary effect on performance of a cycling time trial performed after 90 min of moderate-intensity exercise.
Prolonged Vitamin C Supplementation and Recovery from Demanding Exercise
Authors: Thompson Dylan , Williams Clyde , McGregor Stephen J. , Nicholas Ceri W. , McArdle Frank , Jackson Malcolm J. , Powell Jonathan R.
Published: August 2016

The aim of the present study was to investigate whether 2 weeks of vitamin C supplementation affects recovery from an unaccustomed bout of exercise. Sixteen male subjects were allocated to either a placebo (P; n = 8) or vitamin C group (VC; n = 8). The VC group consumed 200 mg of ascorbic acid twice a day, whereas the P group consumed identical capsules containing 200 mg of lactose. Subjects performed a prolonged (90-min) intermittent shuttle-running test 14 days after supplementation began. Post-exercise serum creatine kinase activities and myoglobin concentrations were unaffected by supplementation. However, vitamin C supplementation had modest beneficial effects on muscle soreness, muscle function, and plasma concentrations of malondialdehyde. Furthermore, although plasma interleukin-6 increased immediately after exercise in both groups, values in the VC group were lower than in the P group 2 hours after exercise (p < .05). These results suggest that prolonged vitamin C supplementation has some modest beneficial effects on recovery from unaccustomed exercise.
Osteoporosis Knowledge, Attitudes, and Behaviors of Female Collegiate Athletes
Authors: Turner Lori W. , Bass Martha A.
Published: August 2016

Female athletes often engage in harmful dietary and weight control practices that can impair bone health and hinder performance. To promote related positive health behavior practices, nutrition educators may be more effective if they understand the osteoporosis knowledge, attitudes, and behaviors among female athletes. A questionnaire including items related to osteoporosis and dietary calcium knowledge, attitudes, and behavioral practices was administered to 114 female collegiate athletes (19.6 ± 1.4 years). Self-reported intakes of dairy product consumption were also obtained; subjects were asked how many times per week they drank milk and ate cheese, yogurt, and ice cream. The mean score for osteoporosis knowledge was 7.1 ± 1.9 (out of 10 items). The mean score for favorable responses to attitude items was 2.1 ± 0.8 (out of 3 items). Correct responses to dietary calcium knowledge items were 2.2 ± 0.7 (out of 3 items). On average, subjects consumed 2.4 ± 1.6 servings of dairy products per day; 31% of subjects consumed the recommended 3 or more servings per day. Osteoporosis knowledge, osteoporosis attitudes, and dietary calcium knowledge were not correlated (p > .05) with dairy product intake. Because of the importance of achieving a high peak bone mass to prevent osteoporosis, our data suggest that further research is needed regarding other factors that might influence dairy product intake among female athletes.
Pre-Exercise Carbohydrate Status and Immune Responses to Prolonged Cycling: II. Effect on Plasma Cytokine Concentration
Authors: Bishop Nicolette C. , Walsh Neil P. , Haines Donna L. , Richards Emily E. , Gleeson Michael
Published: August 2016

Ingesting carbohydrate (CHO) beverages during heavy exercise is associated with smaller changes in the plasma concentrations of several cytokines. The influence of dietary CHO availability on these responses has not been determined. Therefore, the present study investigated the influence of pre-exercise CHO status on plasma interleukin (IL)-6, IL-10, and IL-1 receptor antagonist (IL-1ra) responses to prolonged cycling. Seven trained male cyclists performed a glycogen-lowering bout of cycling and were randomly assigned to follow a diet ensuring either greater than 70% (HIGH) or less than 10% (LOW) of daily energy intake from CHO for the next 3 days. On day 4 subjects performed an exercise test that comprised cycling for 1 hour at 60% Wmax immediately followed by a time-trial (TT) ensuring an energy expenditure equivalent to cycling for 30 min at 80% Wmax. Subjects repeated the protocol after 7 days, this time following the second diet. The order of the trials was counterbalanced. At 1 and 2 hours post-TT, plasma concentrations of IL-6 and IL-10 were 2-fold greater on the LOW trial than on the HIGH trial, and peak plasma concentrations of TL-1ra were 9-fold greater on the LOW trial than on the HIGH trial. These findings suggest that pre-exercise CHO status can influence the plasma cytokine response to prolonged cycling.
Translational Control of Protein Synthesis: Implications for Understanding Changes in Skeletal Muscle Mass
Authors: Jefferson Leonard S. , Kimball Scot R.
Published: August 2016

Gain or loss of skeletal muscle mass is due largely to the establishment of an imbalance between rates of protein synthesis and degradation. A key determinant of the rate of protein synthesis is translation initiation, a process regulated in part through binding of initiator methionyl-tRNA (met-tRNAi) and messenger RNA (mRNA) to a 40S ribosomal subunit. Either the met-tRNAi or mRNA binding step can become limiting for protein synthesis. Furthermore, the mRNA binding step can modulate translation of specific mRNAs with or without changes in the overall rate of protein synthesis. This report highlights molecular mechanisms involved in mediating control of the mRNA binding step in translation initiation. Particular attention is given to the effect of exercise on this step and to how the branched-chain amino acid leucine stimulates muscle protein synthesis after exercise. Potential mechanisms for exercise induced increase in muscle mass are discussed.
Control of Muscle Protein Breakdown: Effects of Activity and Nutritional States
Authors: Wolfe Robert R.
Published: August 2016

We propose that there is a link between muscle protein synthesis and breakdown that is regulated, in part, through maintenance of the free intracellular pool of essential amino acids. For example, we propose that muscle protein breakdown is paradoxically elevated in the anabolic state following resistance exercise in part because the even greater stimulation of synthesis would otherwise deplete this pool. Thus, factors regulating muscle protein breakdown must be evaluated in the context of the prevailing rate of muscle protein synthesis. Further, the direct effect of factors on breakdown may depend on the physiological state. For example, local hyperinsulinemia suppresses accelerated muscle protein breakdown after exercise, but not normal resting breakdown. Thus, factors regulating muscle protein breakdown in human subjects are complex and interactive.
mTOR-Dependent Control of Skeletal Muscle Protein Synthesis
Authors: Lawrence John C.
Published: August 2016

Muscle mass is influenced by many factors including genetically programmed changes, hormonal state, level of activity, and disease processes. Ultimately, whether or not a muscle hypertrophies or atrophies is determined by a simple relationship between the rates of protein synthesis and degradation. When synthesis exceeds degradation, the muscle hypertrophies, and vice versa. In contrast to this simple relationship, the processes that control muscle protein synthesis and degradation are complex. Recently, significant progress has been made in understanding the biochemical mechanisms that control the rate of translation initiation, which is generally the limiting phase in protein synthesis.
Master Athletes
Authors: Trappe Scott
Published: August 2016

Over the past 3 decades, there has been a continued increase in the number of “older” participants in sporting events such as running, swimming, cycling, rowing, and weightlifting. Some master athletes come from a background with years of training and competition experience, while others have only begun to compete as they approach middle-aged and older. The majority of what we currently know about master athletes and aging has been gained from both cross-sectional and longitudinal testing and re-testing master athletes and recreational athletes. The focus of this paper is on the physiological profile of athletes and individuals performing regular exercise training. Physiological data from elite and non-elite, recreational, sedentary, and senior athletes clearly indicate that human skeletal muscle has a high degree of plasticity that is maintained late into life. Muscle fiber protein expression and single muscle fiber contractile properties are greatly influenced by exercise training. It appears that skeletal muscle can quickly adapt to accommodate a wide range of functionality to meet the demands (or lack of demands) placed upon it.
The Molecular Responses of Skeletal Muscle Satellite Cells to Continuous Expression of IGF-1: Implications for the Rescue of Induced Muscular Atrophy in Aged Rats
Authors: Chakravarthy Manu V. , Booth Frank W. , Spangenburg Espen E.
Published: August 2016

Approximately 50% of humans older than 85 years have physical frailty due to weak skeletal muscles. This indicates a need for determining mechanisms to combat this problem. A critical cellular factor for postnatal muscle growth is a population of myogenic precursor cells called satellite cells. Given the complex process of sarcopenia, it has been postulated that, at some point in this process, a limited satellite cell proliferation potential could become rate-limiting to the regrowth of old muscles. It is conceivable that if satellite cell proliferative capacity can be maintained or enhanced with advanced age, sarcopenia could potentially be delayed or prevented. Therefore, the purposes of this paper are to describe whether IGF-I can prevent muscular atrophy induced by repeated cycles of hindlimb immobilization, increase the in vitro proliferation in satellite cells from these muscles and, if so, the molecular mechanisms by which IGF-1 mediates this increased proliferation. Our results provide evidence that IGFI can enhance aged muscle regrowth possibly through increased satellite cell proliferation. The results also suggest that IGF-I enhances satellite cell proliferation by decreasing the cell cycle inhibitor, p27Kip1, through the PI3’-K/Akt pathway. These data provide molecular evidence for IGF-I’s rescue effect upon aging-associated skeletal muscle atrophy.
Molecular Characteristics of Aged Muscle Reflect an Altered Ability to Respond to Exercise
Authors: Jozsi Alison C. , Dupont-Versteegden Esther E. , Taylor-Jones Jane M. , Evans William J. , Trappe Todd A. , Campbell Wayne W. , Peterson Charlotte A.
Published: August 2016

Studies have been performed in humans to identify changes in gene expression that may account for the relatively weak and variable response of aged muscle to resistance exercise. The gene expression profile of skeletal muscle from elderly (62–75 years old) compared to younger (20–30 years old) men demonstrated elevated expression of genes typical of a stress or damage response. The expression of the majority of these genes was unaffected by a single bout of high-intensity resistance exercise in elderly subjects but was altered acutely by exercise in younger subjects so as to approach the pre-exercise levels observed in older subjects. The inability of muscle from elderly subjects to respond to resistance exercise was also apparent in the expression of inflammatory response genes, which increased within 24 hours of the exercise bout only in younger subjects. Other genes with potentially important roles in the adaptation of muscle to exercise, showed a similar or even more robust response in older compared to younger subjects. Taken together, these results may help to explain the variable hypertrophic response of muscle from older individuals to resistance training.
Skeletal Muscle Fatty Acid Transport and Transporters
Authors: Luiken J.J.F.P. , Miskovic D. , Arumugam Y. , Glatz J.F.C. , Bonen A.
Published: August 2016

While it has long been assumed that long chain fatty acids (LCFA) can freely diffuse across the plasma membrane, recent work has shown that LCFA uptake also involves a protein-mediated mechanism. Three putative LCFA transporters have been identified (FABPpm, FATP, and FAT/CD36), and all are expressed in rodent and human muscles. In a new model system (giant vesicles), we have demonstrated that (a) LCFA transport rates are scaled with the oxidative capacity of heart and muscle, (b) only FABPpm and FAT/CD36, but not FATP1, correlate with vesicular LCFA transport, and (c) LCFA transport can be increased by increasing (1) the FAT/CD36 protein of muscle (chronic adaptation) or (2) via the translocation of FAT/CD36 from an intracellular pool to the plasma membrane during muscle contraction (acute adaptation).
Weight Management and Weight Loss Strategies of Professional Jockeys
Authors: Moore Jan M. , Timperio Anna F. , Crawford David A. , Burns Cate M. , Cameron-Smith David
Published: August 2016

Jockeys are required to maintain very low body weight and precise weight control during competition. This study examined the weight loss and weight management strategies of professional horseracing jockeys in the state of Victoria, Australia. An anonymous, self-completed questionnaire was administered (55% response rate, n=116). Almost half (43%) reported that maintaining riding weight was difficult or very difficult, with 75% routinely skipping meals. In preparation for racing, 60% reported that they typically required additional weight loss, with 81% restricting food intake in the 24 hours prior to racing. Additionally, sauna-induced sweating (29%) and diuretics (22%) were frequently employed to further aid in weight loss prior to racing. These rapid weight loss methods did not differ between the 51% of jockeys who followed a weight management plan compared to those who did not. The impact of these extreme weight loss practices on riding performance and health remains unknown.
Energy Balance during an Ironman Triathlon in Male and Female Triathletes
Authors: Kimber Nicholas E. , Ross Jenny J. , Mason Sue L. , Speedy Dale B.
Published: August 2016

Energy balance of 10 male and 8 female triathletes participating in an Ironman event (3.8-km swim, 180-km cycle, 42.2-km run) was investigated. Energy intake (EI) was monitored at 7 designated points by dietary recall of food and fluid consumption. Energy expenditure (EE) during cycling and running was calculated using heart rate-V̇O2 regression equations and during swimming by the multiple regression equation: Y = 3.65v + 0.02 W − 2.545 where Y is V̇O2 in L · min−1, v is the velocity in m · s−1, Wis the body weight in kilograms. Total EE (10.036 ± 931 and 8570 ± 1014 kcal) was significantly greater than total El (3940 ± 868 and 3115 ± 914kcal, p < .001) formales and females, respectively, although energy balance was not different between genders. Finishing time was inversely related to carbohydrate (CHO) intake (g · kg−1 · h−1) during the marathonrun formales (r=−.75, p < .05), and not females, suggesting that increasing CHO ingestion during the run may have been a useful strategy for improving Ironman performance in male triathletes.
Macro- and Micro-nutrient Intake of Adolescent Greek Female Volleyball Players
Authors: Papadopoulou Souzana K. , Papadopoulou Sophia D. , Gallos George K.
Published: August 2016

Adequate nutrition is critically important for the achievement of the adolescent athlete’s optimal performance. The purpose of the present study was to evaluate the adequacy of macro- and micro-nutrients in the adolescent Greek female volleyball players’ diet. The subjects of the study consisted of 16 players who were members of the Junior National Team (NP) and 49 players who participated in the Junior National Championship (CP). Dietary intake was assessed using a 3-day food record. Protein intake (16.0 ± 4.9% of total energy intake) was satisfactory, whereas fat consumption (37.5 ± 11.1%) was above recommended values and at the expense of carbohydrate intake (45.9 ± 12.5%). There were no significant differences between NP and CP concerning the intake of macronutrients, except for the fat intake (when this is expressed in grams per day and grams per kilogram of body weight and the saturated fat intake, which were both higher in NP compared to CP players (p < .05). The mean energy intake was 2013 ± 971 and 1529 ± 675 kcal for NP and CP, respectively (p < .05). NP, in particular, consumed fat and especially saturated fat in order to meet their energy needs. As for micronutrients, the volleyball players fell short of meeting the RDA values for calcium, iron, folk acid, magnesium, zinc, and vitamins A, B1, B2, and B6. There was no difference between NP and CP in micronutrient intake. In conclusion, subjects in the current study lacked proper nutrition in terms of quantity and quality.
Energy Balance and Luteal Phase Progesterone Levels in Elite Adolescent Aesthetic Athletes
Authors: Reading Karen J. , McCargar Linda J. , Harber Vicki J.
Published: August 2016

Menstrual abnormalities are associated with negative energy balance and reduced energy expenditure (REE). To examine this relationship in elite adolescent aesthetic athletes, 3 groups of females (aged 15-18 years) were studied: 10 oligo/amenorrheic athletes (OA), 11 eumenorrheic athletes (EA), and 8 non-athlete controls (C). Components of energy balance, body composition, dietary restraint, pubertal maturation, and luteal phase salivary progesterone were assessed in all groups. Both groups of athletes had a later age of menarche and lowerpubertal development score compared to the non-athletes (p < .05). With the exception of salivary progesterone (ng/ml; OA = 0.15±0.01 <EA = 0.29± 0.1 and C = 0.30 ± 0.13, /p = .007), there were no differences between the athlete groups. Energy balance (kcal/d) in the OA group was lower (−290 ± 677) compared to either EA (−5±461) or C (179 ± 592) but did not reach significance (p = .24). Dietary energy intake and absolute REE (kcal/d) were not different among groups, despite detectable differences in reproductive status, and thus could not be attributed to differences in energy balance or REE.
Influence of Carbohydrate Supplementation on Plasma Cytokine and Neutrophil Degranulation Responses to High Intensity Intermittent Exercise
Authors: Bishop Nicolette C. , Gleeson Michael , Nicholas Ceri W. , Ali Ajmol
Published: August 2016

Ingesting carbohydrate (CHO) beverages during prolonged, continuous heavy exercise results in smaller changes in the plasma concentrations of several cytokines and attenuates a decline in neutrophil function. In contrast, ingesting CHO during prolonged intermittent exercise appears to have negligible influence on these responses, probably due to the overall moderate intensity of these intermittent exercise protocols. Therefore, we examined the effect of CHO ingestion on plasma interIeukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and lipopolysaccharide (LPS)-stimuIated neutrophil degranulation responses to high-intensity intermittent running. Six trained male soccer players performed 2 exercise trials, 7 days apart, in a randomized, counterbalanced design. On each occasion, they completed six 15-min periods of intermittent running consisting of maximal sprinting interspersed with less intense periods of running and walking. Subjects consumed either CHO or artificially sweetened placebo(PLA) beverages immediately before and at 15-min intervals during the exercise. At 30 min post-exercise, CHO versus PLA was associated with a higher plasma glucose concentration (p< .01), a lower plasma cortisol and IL-6 concentration (p < .02), and fewer numbers of circulating neutrophils (p < .05). Following the exercise, LPS-stimulated elastase release per neutrophil fell 31 % below baseline values on the PLA trial (p = .06) compared with 11% on the CHO trial (p = .30). Plasma TNF-α concentration increased following the exercise (main effect of time, p < .001) but was not affected by CHO. These data indicate that CHO ingestion attenuates changes in plasma IL-6 concentration, neutrophil trafficking, and LPS-stimulated neutrophil degranulation in response to intermittent exercise that involves bouts of very high intensity exercise.