bluuebunny/crossref_metadata_2025 huggingface dataset:
An Isocaloric Glucose-Fructose Beverage’s Effect on Simulated 100-km Cycling Performance Compared With a Glucose-Only Beverage
Authors: Triplett Darren , Doyle J. Andrew , Rupp Jeffrey C. , Benardot Dan
Published: August 2016

A number of recent research studies have demonstrated that providing glucose and fructose together in a beverage consumed during exercise results in significantly higher oxidation rates of exogenous carbohydrate (CHO) than consuming glucose alone. However, there is insufficient evidence to determine whether the increased exogenous CHO oxidation improves endurance performance. The purpose of this study was to determine whether consuming a beverage containing glucose and fructose (GF) would result in improved cycling performance compared with an isocaloric glucose-only beverage (G). Nine male competitive cyclists (32.6 ± 5.8 years, peak oxygen uptake 61.5 ± 7.9 ml · kg-1 · min-1) completed a familiarization trial and then 2 simulated 100-km cycling time trials on an electronically braked Lode cycle ergometer separated by 5–7 d. During the randomly ordered experimental trials, participants received 36 g of CHO of either G or GF in 250 ml of water every 15 min. All 9 participants completed the 100-km time trial significantly faster when they received the GF beverage than with G (204.0 ± 23.7 vs. 220.6 ± 36.6 min; p = .023). There was no difference at any time point between trials for blood glucose or for blood lactate. Total CHO oxidation increased significantly from rest during exercise but was not statistically significant between the GF and G trials, although there was a trend for CHO oxidation to be higher with GF in the latter stages of the time trial. Consumption of a CHO beverage containing glucose and fructose results in improved 100-km cycling performance compared with an isocaloric glucose-only beverage.
Pseudoephedrine Ingestion and Cycling Time-Trial Performance
Authors: Pritchard-Peschek Kellie R. , Jenkins David G. , Osborne Mark A. , Slater Gary J.
Published: August 2016

The aim of the current study was to investigate the effect of 180 mg of pseudoephedrine (PSE) on cycling time-trial (TT) performance. Six well-trained male cyclists and triathletes (age 33 ± 2 yr, mass 81 ± 8 kg, height 182.0 ± 6.7 cm, VO2max 56.8 ± 6.8 ml ⋅ kg−1 ⋅ min−1; M ± SD) underwent 2 performance trials in which they completed a 25-min variable-intensity (50–90% maximal aerobic power) warm-up, followed by a cycling TT in which they completed a fixed amount of work (7 kJ/kg body mass) in the shortest possible time. Sixty minutes before the start of exercise, they orally ingested 180 mg of PSE or a cornstarch placebo (PLA) in a randomized, crossover, double-blind manner. Venous blood was sampled immediately pre- and postexercise for the analysis of pH plus lactate, glucose, and norepinephrine (NE). PSE improved cycling TT performance by 5.1% (95% CI 0–10%) compared with PLA (28:58.9 ± 4:26.5 and 30:31.7 ± 4:36.7 min, respectively). There was a significant Treatment × Time interaction (p = .04) for NE, with NE increasing during the PSE trial only. Similarly, blood glucose also showed a trend (p = .06) for increased levels postexercise in the PSE trial. The ingestion of 180 mg of PSE 60 min before the onset of high-intensity exercise improved cycling TT performance in well-trained athletes. It is possible that changes in metabolism or an increase in central nervous system stimulation is responsible for the observed ergogenic effect of PSE.
Effects of Metered Versus Bolus Water Consumption on Urine Production and Rehydration
Authors: Jones Eric J. , Bishop Phil A. , Green James M. , Richardson Mark T.
Published: August 2016

This study compared the effects of a rapid bolus and a slower metered water-consumption rate on urine production and postexercise rehydration. Participants (n = 8) dehydrated by 2% body weight through moderate exercise in an environmentally controlled chamber (35 °C, 55% relative humidity). Breakfast and lunch were standardized for all participants during each 8-hr data-collection period. Rehydration was performed using a volume of water equal to that lost during exercise either as bolus consumption (100% of volume consumed in 1hr; BOL) or metered consumption (12.5% of volume every 30 min for 4 hr; MET). Urine volume was used to assess hydration efficiency (water retained vs. water lost) and net fluid balance at 8 hr. Mean urine outputs were 420 ml (MET) and 700 ml (BOL). A paired-samples t test showed that hydration efficiency was greater for MET (75%) than for BOL (55%; p = .018). These data suggest that metered administration was more effective in maintaining fluid balance. These findings suggest that rehydration rate is a factor in fluid-balance response. For situations in which available fluid volume is restricted, greater hydration efficiency is highly desirable.
Glycemic Index and Endurance Performance
Authors: Donaldson Carolyn M. , Perry Tracy L. , Rose Meredith C.
Published: August 2016

The aim of this review is to provide an up-to-date summary of the evidence surrounding glycemic index (GI) and endurance performance. Athletes are commonly instructed to consume low-GI (LGI) carbohydrate (CHO) before exercise, but this recommendation appears to be based on the results of only a few studies, whereas others have found that the GI of CHO ingested before exercise has no impact on performance. Only 1 study was designed to directly investigate the impact of the GI of CHO ingested during exercise on endurance performance. Although the results indicate that GI is not as important as consuming CHO itself, more research in this area is clearly needed. Initial research investigating the impact of GI on postexercise recovery indicated consuming high-GI (HGI) CHO increased muscle glycogen resynthesis. However, recent studies indicate an interaction between LGI CHO and fat oxidation, which may play a role in enhancing performance in subsequent exercise. Despite the fact that the relationship between GI and sporting performance has been a topic of research for more than 15 yr, there is no consensus on whether consuming CHO of differing GI improves endurance performance. Until further well-designed research is carried out, athletes are encouraged to follow standard recommendations for CHO consumption and let practical issues and individual experience dictate the use of HGI or LGI meals and supplements before, during, and after exercise.
Influence of Beverage Temperature on Exercise Performance in the Heat: A Systematic Review
Authors: Burdon Catriona A. , O’Connor Helen T. , Gifford Janelle A. , Shirreffs Susan M.
Published: August 2016

Purpose:

Increased core temperature (Tc), impaired cardiovascular function, and dehydration contribute to fatigue during prolonged exercise in the heat. Although many studies have examined mechanisms addressing these factors, few have investigated the effect of cold beverage temperature on thermoregulation and exercise performance in the heat.

Methods:

Citations from MEDLINE (Ovid), Sport Discus (EBSCOhost), AUSPORT and AusportMed (Informit), Web of Science, and SCOPUS were identified from the earliest record until September 2008 using the search terms drink temperature, beverage temperature, fluid temperature, water temperature, and cold fluid combined with body temperature and thermoregulation. To be included, studies needed to assess core or rectal temperature during exercise in moderate or hot environmental conditions. After quality rating was completed by two reviewers, the difference in mean Tc and exercise performance was calculated.

Results:

Ten studies meeting search inclusion criteria were available for analysis. Three were excluded because sufficient detail or statistical data were not reported. A meta-analysis was not performed because the studies were deemed too different to group. Three of the remaining 7 studies found modulated Tc with cold beverage consumption, and from the 4 that conducted exercise performance tests, performance improved by 10% with cold fluids.

Conclusion:

Cold fluid may attenuate Tc rise and improve exercise performance in the heat; however, study findings are mixed. Research using well-trained athletes and fluid-ingestion protocols replicating competition scenarios is required. Potential sensory effects of cold fluid in maintaining motivation also need to be assessed as a mechanism underpinning improved performance.
Combination of Sago and Soy-Protein Supplementation During Endurance Cycling Exercise and Subsequent High-Intensity Endurance Capacity
Authors: Ghosh Asok Kumar , Rahaman A. Abdul , Singh Rabindarjeet
Published: August 2016

The purpose of the study was to investigate whether a combination of sago and soy protein ingested during moderate-intensity cycling exercise can improve subsequent high-intensity endurance capacity compared with a carbohydrate in the form of sago and with a placebo. The participants were 8 male recreational cyclists with age, weight, and VO2max of 21.5 ± 1.1 yr, 63.3 ± 2.4 kg, and 39.9 ± 1.1 ml · kg−1 · min−1, respectively. The design of the study was a randomized, double-blind placebo-controlled crossover comprising 60 min of exercise on a cycle ergometer at 60% VO2max followed by a time-to-exhaustion ride at 90% VO2max. The sago feeding provided 60 g of carbohydrate, and the sago-soy combination provided 52.5 g of carbohydrate and 15 g of protein, both at 20-min intervals during exercise. Times to exhaustion for the placebo, sago, and sago-soy supplementations were 4.09 ± 1.28, 5.49 ± 1.20, and 7.53 ± 2.02 min, respectively. Sago-soy supplementation increased endurance by 84% (44–140%; p < .001) and by 37% (15–63%; p < .05) relative to placebo and sago, respectively. The plasma insulin response was elevated above that with placebo during sago and sago-soy supplementations. The authors conclude that a combination of sago and soy protein can delay fatigue during high-intensity cycling.
Effect of Bovine Colostrum Supplementation on Respiratory Tract Mucosal Defenses in Swimmers
Authors: Crooks Christine , Cross Martin L. , Wall Clare , Ali Ajmol
Published: August 2016

Purpose:

This study investigated the effect of bovine colostrum (BC) on mucosal defense in the respiratory tracts of athletes and a nonexercising control group.

Methods:

An athlete cohort (ATH) of 25 (12 male, 13 female) elite swimmers (age 14–23 yr) and a control cohort (CON) of 28 (9M, 19F) students (age 18–27 yr) were randomly allocated in a double-blind manner to receive either 25 g BC (low-protein colostrum powder) or isocaloric placebo (PL) per day for 10 wk. Postprandial saliva samples were analyzed for immunoglobulins (A, G, and M) and osmolality at baseline, after 4 and 10 wk, and 2 wk postsupplementation. Blood samples were analyzed for immunoglobulins and C-reactive protein at baseline, after 5 and 10 wk, and 2 wk postsupplementation. Dietary intake was assessed by self-recorded dietary records. Upper respiratory tract symptoms (URS) and exercise were also self-recorded daily.

Results:

There was no significant time-related effect of the BC supplement on either saliva or plasma immunoglobulin levels for either cohort. After 4 wk supplementation fewer ATH/BC (25%) than ATH/PL participants (61%) reported URS incidents (p = .062). No significant difference occurred in URS reports in the control group.

Conclusion:

There was no measurable effect on immunoglobulin levels of consuming BC, which is in contrast to effects that have been reported previously in marathon runners, indicating that the effect of BC supplementation is not universal in all groups of athletes. Fewer athletes reported URS (although cause unknown) when consuming BC, which may be advantageous for training.
Aerobic Exercise Training-Induced Decrease in Plasma Visfatin and Insulin Resistance in Obese Female Adolescents
Authors: Lee Kyu-Jin , Shin Yun-A. , Lee Kyoung-Young , Jun Tae-Won , Song Wook
Published: August 2016

The purpose of this study was to assess differences in the levels of plasma visfatin among female adolescents and changes in plasma visfatin and insulin resistance in obese female adolescents after 12 wk of aerobic exercise training. Twenty normal-weight female students (body-mass index [BMI] <22.9 kg/m2 and body fat ≤29.9) and 18 obese female students (BMI ≥25 kg/m2 and body fat ≥30%) participated in this study. Eleven obese students were assigned to an exercise group and completed a 12-wk aerobic exercise-training program that included four 40- to 50-min sessions per wk with an energy expenditure of 300–400 kcal/d. Seven obese students were assigned to a control group that received no exercise sessions or dietary restriction. The plasma visfatin levels of obese female adolescents were significantly higher (p < .05) than those of the normal-weight female adolescents. The plasma visfatin levels (294.00 ± 124.74 ng/ml to 185.55 ± 67.30 ng/ml, p < .01) and insulin resistance (p < .05) were significantly reduced after 12 wk of aerobic exercise. The results suggest that aerobic exercise resulting in an energy expenditure of 1,200–1,600 kcal/wk for 12 wk decreases plasma visfatin and insulin resistance in obese female adolescents.
Molecular Responses to Moderate Endurance Exercise in Skeletal Muscle
Authors: Pasiakos Stefan M. , McClung Holly L. , McClung James P. , Urso Maria L. , Pikosky Matthew A. , Cloutier Gregory J. , Fielding Roger A. , Young Andrew J.
Published: August 2016

This study examined alterations in skeletal-muscle growth and atrophy-related molecular events after a single bout of moderate-intensity endurance exercise. Muscle biopsies were obtained from 10 men (23 ± 1 yr, body mass 80 ± 2 kg, and VO2peak 45 ± 1 ml · kg−1 · min−1) immediately (0 hr) and 3 hr after a 60-min bout of cycle exercise (60% ± 5% VO2peak). Corresponding muscle biopsies were also obtained under resting conditions. The phosphorylation status of insulin/IGF-PI3K molecular-signaling proteins, ubiquitin-proteasome-related gene expression, FOXO transcription factors, and myogenic regulatory factors in muscle samples was analyzed using multiplex analysis, Western blotting, and quantitative real-time polymerase chain reaction (qRT-PCR). A condition–time interaction was observed for Akt phosphorylation (p < .05) with multiplexing. Regardless of endurance exercise, Akt phosphorylation decreased and ERK phosphorylation increased at 3 hr compared with 0 hr (p < .05). Levels of p70S6K phosphorylation were 110% greater (p < .05) at 3 hr than at 0 hr using Western blots. MuRF mRNA expression postexercise increased; levels were 4.7- and 5.7-fold greater (p < .05) at 0 hr and 3 hr, respectively, than at rest with qRT-PCR. Atrogin mRNA expression was up-regulated 3.2-fold 3 hr postexercise compared with rest. These findings demonstrate modest changes in the molecular responses to moderate endurance exercise in the absence of nutrition. This study provides the groundwork for future investigations designed to optimize the metabolic conditions necessary to positively influence the cellular mechanisms specific to skeletal-muscle protein turnover during recovery from endurance exercise.
Lack of Effect of Exercise Time of Day on Acute Energy Intake in Healthy Men
Authors: O’Donoghue Katriona J.M , Fournier Paul A. , Guelfi Kym J.
Published: August 2016

Although the manipulation of exercise and dietary intake to achieve successful weight loss has been extensively studied, it is unclear how the time of day that exercise is performed may affect subsequent energy intake. The purpose of the current study was to investigate the effect of an acute bout of exercise performed in the morning compared with an equivalent bout of exercise performed in the afternoon on short-term energy intake. Nine healthy male participants completed 3 trials: morning exercise (AM), afternoon exercise (PM), or control (no exercise; CON) in a randomized counterbalanced design. Exercise consisted of 45 min of treadmill running at 75% VO2peak. Energy intake was assessed over a 26-hr period with the participants eating ad libitum from a standard assortment of food items of known quantity and composition. There was no significant difference in overall energy intake (M ± SD; CON 23,505 ± 6,938 kJ, AM 24,957 ± 5,607 kJ, PM 24,560 ± 5,988 kJ; p = .590) or macronutrient preferences during the 26-hr period examined between trials. Likewise, no differences in energy intake or macronutrient preferences were observed at any of the specific individual meal periods examined (i.e., breakfast, lunch, dinner) between trials. These results suggest that the time of day that exercise is performed does not significantly affect short-term energy intake in healthy men.
The Effects of Postexercise Consumption of High-Molecular-Weight Versus Low-Molecular-Weight Carbohydrate Solutions on Subsequent High-Intensity Interval-Running Capacity
Authors: McGlory Chris , Morton James P.
Published: August 2016

The aim of this study was to determine the effects of postexercise ingestion of different-molecular-weight glucose polymer solutions on subsequent high-intensity interval-running capacity. In a repeated-measures design, 6 men ran for 60 min in the morning at 70% VO2max. Immediately post- and at 1 and 2 hr postexercise, participants consumed a 15% low-molecular-weight (LMW) or high-molecular-weight (HMW) carbohydrate solution, at a rate of 1.2 g of carbohydrate/kg body mass, or an equivalent volume of flavored water (WAT). After recovery, participants performed repeated 1-min intervals at 90% VO2max interspersed with 1 min active recovery (walking) until volitional exhaustion. Throughout the 3-hr recovery period, plasma glucose concentrations were higher (p = .002) during the HMW and LMW conditions than with WAT (M 7.0 ± 0.8, 7.5 ± 1.0, and 5.6 ± 0.2 mmol/L, respectively), although there was no difference (p = .723) between HMW and LMW conditions. Exercise capacity was 13 (43 ± 10 min; 95% CI for differences: 8–18; p = .001) and 11 min (41 ± 9 min; 95% CI for differences; 2–18: p = .016) longer with HMW and LMW solutions, respectively, than with WAT (30 ± 9 min). There was no substantial difference (2 min; 95% CI for differences: –5 to 10; p = .709) in exercise capacity between LMW and HMW solutions. Although this magnitude of difference is most likely trivial in nature, the uncertainty allows for a possible small substantial enhancement of physiological significance, and further research is required to clarify the true nature of the effect.
Effects of a Mineral Antioxidant Complex on Clinical Safety, Body Water, Lactate Response, and Aerobic Performance in Response to Exhaustive Exercise
Authors: Dalbo Vincent J. , Roberts Michael D. , Hassell Scott E. , Moon Jordan R. , Kerksick Chad M.
Published: August 2016

Background:

This investigation examined the safety and efficacy of a silica-based mineral antioxidant complex (MAC) that has been suggested to influence body water and buffer lactate.

Methods:

In a double-blind, randomized crossover design, male participants completed testing for 3 conditions: water only (baseline), rice flour (placebo), and MAC supplementation. Participants visited the laboratory on 5 occasions: familiarization, baseline, Testing Day 1, washout, and Testing Day 2. Baseline and Testing Days 1 and 2 consisted of fasting blood, pre- to postexercise body-water assessment and determination of VO2peak on a cycle ergometer. The supplementation protocols were separated by 1 wk and balanced to minimize an order effect.

Results:

No differences between conditions were found for heart rate, blood pressure, or serum-safety markers (p > .05). Before exercise there were no differences between conditions for total body water (TBW), intracellular water (ICW), or extracellular water (ECW). No significant interactive effects for supplementation and exercise were found for TBW, ICW, or ECW (p > .05). A time effect for TBW (p < .01) and ICW (p < .001) was present. Within-group changes in TBW occurred in the MAC condition, and within-group changes for ICW occurred in the MAC and placebo conditions. Ratings of perceived exertion and blood lactate increased (p < .05) with exercise. No significant effects were found for performance variables.

Conclusions:

MAC supplementation had no impact on aerobic exercise performance and lactate response. Increases in TBW and ICW occurred after MAC consumption, but these changes appeared to have minimal physiological impact.
Lack of Effect of a High-Calorie Dextrose or Maltodextrin Meal on Postprandial Oxidative Stress in Healthy Young Men
Authors: Fisher-Wellman Kelsey H. , Bloomer Richard J.
Published: August 2016

Background:

Carbohydrate powder in the form of maltodextrin is widely used by athletes for postexercise glycogen resynthesis. There is some concern that such a practice may be associated with a postprandial rise in reactive oxygen and nitrogen species production and subsequent oxidation of macromolecules. This is largely supported by findings of increased oxidative-stress biomarkers and associated endothelial dysfunction after intake of dextrose.

Purpose:

To compare the effects of isocaloric dextrose and maltodextrin meals on blood glucose, triglycerides (TAG), and oxidative-stress biomarkers in a sample of young healthy men.

Methods:

10 men consumed isocaloric dextrose and maltodextrin powder drinks (2.25 g/kg) in a random-order, crossover design. Blood samples were collected premeal (fasting) and at 1, 2, 4, and 6 hr postmeal and assayed for glucose, TAG, malondialdehyde, hydrogen peroxide, nitrate/nitrite, and Trolox-equivalent antioxidant capacity.

Results:

Significant meal effects were noted for glucose total area under the curve (p = .004), with values higher for the dextrose meal. No other statistically significant meal effects were noted (p > .05). With respect to the 2 (meal) × 5 (time) ANOVA, no significant interaction, time, or meal effects were noted for any variable (p > .05), with the exception of glucose, for which a main effect for both meal (p < .0001) and time (p = .0002) was noted.

Conclusions:

These data indicate that carbohydrate meals, consumed as either dextrose or maltodextrin, pose little postprandial oxidative insult to young, healthy men. As such, there should be minimal concern over such feedings, even at high dosages, assuming adequate glucose metabolism.
Water and Solute Absorption From Carbohydrate-Electrolyte Solutions in the Human Proximal Small Intestine: A Review and Statistical Analysis
Authors: Shi Xiaocai , Passe Dennis H.
Published: August 2016

The purpose of this study is to summarize water, carbohydrate (CHO), and electrolyte absorption from carbohydrate- electrolyte (CHO-E) solutions based on all of the triple-lumen-perfusion studies in humans since the early 1960s. The current statistical analysis included 30 reports from which were obtained information on water absorption, CHO absorption, total solute absorption, CHO concentration, CHO type, osmolality, sodium concentration, and sodium absorption in the different gut segments during exercise and at rest. Mean differences were assessed using independent-samples t tests. Exploratory multiple-regression analyses were conducted to create prediction models for intestinal water absorption. The factors influencing water and solute absorption are carefully evaluated and extensively discussed. The authors suggest that in the human proximal small intestine, water absorption is related to both total solute and CHO absorption; osmolality exerts various impacts on water absorption in the different segments; the multiple types of CHO in the ingested CHO-E solutions play a critical role in stimulating CHO, sodium, total solute, and water absorption; CHO concentration is negatively related to water absorption; and exercise may result in greater water absorption than rest. A potential regression model for predicting water absorption is also proposed for future research and practical application. In conclusion, water absorption in the human small intestine is influenced by osmolality, solute absorption, and the anatomical structures of gut segments. Multiple types of CHO in a CHO-E solution facilitate water absorption by stimulating CHO and solute absorption and lowering osmolality in the intestinal lumen.
Effects of a Purported Aromatase and 5 α-Reductase Inhibitor on Hormone Profiles in College-Age Men
Authors: Wilborn Colin , Taylor Lem , Poole Chris , Foster Cliffa , Willoughby Darryn , Kreider Richard
Published: August 2016

The purpose of this study was to determine the effects of an alleged aromatase and 5-α reductase inhibitor (AI) on strength, body composition, and hormonal profiles in resistance-trained men. Thirty resistance-trained men were randomly assigned in a double-blind manner to ingest 500 mg of either a placebo (PL) or AI once per day for 8 wk. Participants participated in a 4-d/wk resistance-training program for 8 wk. At Weeks 0, 4, and 8, body composition, 1-repetition-maximum (1RM) bench press and leg press, muscle endurance, anaerobic power, and hormonal profiles were assessed. Statistical analyses used a 2-way ANOVA with repeated measures for all criterion variables (p ≤ .05). Significant Group × Time interaction effects occurred over the 8-wk period for percent body fat (AI: –1.77% ± 1.52%, PL: –0.55% ± 1.72%; p = .048), total testosterone (AI: 0.97 ± 2.67 ng/ml, PL: –2.10 ± 3.75 ng/ml; p = .018), and bioavailable testosterone (AI: 1.32 ± 3.45 ng/ml, PL: –1.69 ± 3.94 ng/ml; p = .049). Significant main effects for time (p ≤ .05) were noted for bench- and leg-press 1RM, lean body mass, and estradiol. No significant changes were detected among groups for Wingate peak or mean power, total body weight, dihydrotestosterone, hemodynamic variables, or clinical safety data (p > .05). The authors concluded that 500 mg of daily AI supplementation significantly affected percent body fat, total testosterone, and bioavailable testosterone compared with a placebo in a double-blind fashion.
Effects of Dietary Omega-3 Polyunsaturated Fatty Acids on the Skeletal-Muscle Blood-Flow Response to Exercise in Rats
Authors: Stebbins Charles L. , Hammel Lauren E. , Marshal Benjamin J. , Spangenberg Espen E. , Musch Timothy I.
Published: August 2016

The polyunsaturated fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) affect vascular relaxation and involve factors (e.g., nitric oxide) that contribute to exercise-induced increases in skeletal-muscle blood flow (Q). The authors investigated whether DHA and EPA supplementation augments skeletal-muscle Q and vascular conductance (VC) and attenuates renal and splanchnic Q and VC in exercising rats. Rats were fed a diet of 5% lipids by weight, of which 20% was DHA and 30% EPA (PUFA group, n = 9), or 5% safflower oil (SO group, n = 8) for 6 wk. Heart rate (HR), blood pressure (MAP), and hind-limb, renal, and splanchnic Q were measured at rest and during moderate treadmill running. MAP, HR, and renal and splanchnic Q and VC were similar between the 2 groups at rest and during exercise. In the PUFA group, Q (158 ± 27 vs. 128 ± 28 ml · min−1 · 100 g−1) and VC (1.16 ± 0.21 vs. 0.92 ± 0.23 ml · min−1 · 100 g−1 · mm Hg−1) were greater in the exercising hind-limb muscle. Q and VC were also higher in 8 of 28 and 11 of 28 muscles and muscle parts, respectively. These increases were positively correlated to the percent sum of Types I and IIa fibers. Results suggest that DHA+EPA (a) enhances Q and VC in active skeletal muscle (especially Type I and IIa fibers) and that the increase in Q is due to an increase in cardiac output secondary to increases in VC and (b) has no apparent influence on vasoconstriction in renal and splanchnic tissue.
Utility of the Actiheart Accelerometer for Estimating Exercise Energy Expenditure in Female Adolescent Runners
Authors: Nichols Jeanne F. , Aralis Hilary , Merino Sonia Garcia , Barrack Michelle T. , Stalker-Fader Lindsay , Rauh Mitchell J.
Published: August 2016

There is a growing need to accurately assess exercise energy expenditure (EEE) in athletic populations that may be at risk for health disorders because of an imbalance between energy intake and energy expenditure. The Actiheart combines heart rate and uniaxial accelerometry to estimate energy expenditure above rest. The authors’ purpose was to determine the utility of the Actiheart for predicting EEE in female adolescent runners (N = 39, age 15.7 ± 1.1 yr). EEE was measured by indirect calorimetry and predicted by the Actiheart during three 8-min stages of treadmill running at individualized velocities corresponding to each runner’s training, including recovery, tempo, and 5-km-race pace. Repeated-measures ANOVA with Bonferroni post hoc comparisons across the 3 running stages indicated that the Actiheart was sensitive to changes in intensity (p < .01), but accelerometer output tended to plateau at race pace. Pairwise comparisons of the mean difference between Actiheart- and criterion-measured EEE yielded values of 0.0436, 0.0539, and 0.0753 kcal · kg−1 · min−1 during recovery, tempo, and race pace, respectively (p < .0001). Bland–Altman plots indicated that the Actiheart consistently underestimated EEE except in 1 runner’s recovery bout. A linear mixed-model regression analysis with height as a covariate provided an improved EEE prediction model, with the overall standard error of the estimate for the 3 speeds reduced to 0.0101 kcal · kg−1 · min−1. Using the manufacturer’s equation that combines heart rate and uniaxial motion, the Actiheart may have limited use in accurately assessing EEE, and therefore energy availability, in young, female competitive runners.
Effect of 6 Weeks of n-3 Fatty-Acid Supplementation on Oxidative Stress in Judo Athletes
Authors: Filaire Edith , Massart Alain , Portier Hugues , Rouveix Matthieu , Rosado Fatima , Bage Anne S. , Gobert Mylène , Durand Denys
Published: August 2016

The aim of this investigation was to assess the effects of 6 wk of eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) supplementation on resting and exercise-induced lipid peroxidation and antioxidant status in judoists. Subjects were randomly assigned to receive a placebo or a capsule of polyunsaturated fatty acids (PUFAs; 600 mg EPA and 400 mg DHA). Blood samples were collected in preexercise and postexercise conditions (judo-training session), both before and after the supplementation period. The following parameters were analyzed: α-tocopherol, retinol, lag phase, maximum rate of oxidation (Rmax) during the propagating chain reaction, maximum amount of conjugated dienes (CDmax) accumulated after the propagation phase, nitric oxide (NO) and malondyaldehide (MDA) concentrations, salivary glutathione peroxidase activity, and the lipid profile. Dietary data were collected using a 7-day dietary record. A significant interaction effect between supplementation and time (p < .01) on triglycerides was noted, with values significantly lower in the n-3 long-chain-PUFA (LCPUFA) group after supplementation than in the placebo group. Significant interaction effects between supplementation and time on resting MDA concentrations and Rmax were found (p = .03 and p = .04, respectively), with elevated values in the n-3 LCPUFA group after supplementation and no change in the placebo group’s levels. The authors observed a significantly greater NO and oxidative-stress increase with exercise (MDA, Rmax, CDmax, and NO) in the n-3 LCPUFA group than with placebo. No main or interaction effects were found for retinol and α-tocopherol. These results indicate that supplementation with n-3 LCPUFAs significantly increased oxidative stress at rest and after a judo-training session.
Glycemic and Insulinemic Responses to Different Preexercise Snacks in Participants With Impaired Fasting Glucose
Authors: Byrne Heidi K. , Kim Yeonsoo , Hertzler Steven R. , Watt Celia A. , Mattern Craig O.
Published: August 2016

Purpose:

To compare serum glucose and insulin responses to 3 preexercise snacks before, during, and after exercise in individuals with impaired fasting glucose (IFG) and healthy (H) men. In addition, in an IFG population, the authors sought to determine whether a natural fruit snack (i.e., raisins) yields more desirable glucose and insulin concentrations than an energy bar or a glucose solution.

Methods:

The IFG (n = 11, age = 54.5 ± 1.3 yr, fasting blood glucose [BG] = 6.3 ± 0.1 mmol/L) and H groups (n = 9, age = 48.0 ± 3.1 yr, fasting BG = 4.9 ± 0.1 mmol/L) cycled at 50% of VO2peak for 45 min on 4 occasions after consuming water or 50 g of carbohydrate from raisins (R), an energy bar (EB), or a glucose beverage (GLU). Metabolic markers were measured before, during, and after exercise.

Results:

In all nutritional conditions, glucose concentrations of the IFG group were consistently higher than in the H group. Differences between IFG and H groups in insulin concentrations were sporadic and isolated. In the IFG group, preexercise glucose concentration was lower in the R condition than in GLU. Ten and 20 min into exercise, glucose concentrations in the R and EB conditions were lower than in GLU. Insulin concentrations were lower in the R condition than in EB and GLU immediately before exercise and at Minute 10 but at 20 min R remained lower than only GLU.

Conclusion:

Glucose concentrations were higher in the IFG group regardless of preexercise snack. Compared with the glucose solution, raisins lowered both the postprandial glycemic and insulinemic responses, whereas the energy bar reduced glycemia but not insulinemia.
Failure of Glycine-Arginine-α-Ketoisocaproic Acid to Improve High-Intensity Exercise Performance in Trained Cyclists
Authors: Beis Lukas , Mohammad Yaser , Easton Chris , Pitsiladis Yannis P.
Published: August 2016

Oral supplementation with glycine-arginine-α-ketoisocaproic acid (GAKIC) has previously been shown to improve exhaustive high-intensity exercise performance. There are no controlled studies involving GAKIC supplementation in well-trained subjects. The aim of the current study was to examine the effects of GAKIC supplementation on fatigue during high-intensity, repeated cycle sprints in trained cyclists. After at least 2 familiarization trials, 10 well-trained male cyclists completed 2 supramaximal sprint tests each involving 10 sprints of 10 s separated by 50-s rest intervals on an electrically braked cycle ergometer. Subjects ingested 11.2 g of GAKIC or placebo (Pl) during a period of 45 min before the 2 experimental trials, administered in a randomized and double-blind fashion. Peak power declined from the 1st sprint (M ± SD; Pl 1,332 ± 307 W, GAKIC 1,367 ± 342 W) to the 10th sprint (Pl 1,091 ± 229 W, GAKIC 1,061 ± 272 W) and did not differ between conditions (p = .88). Mean power declined from the 1st sprint (Pl 892 ± 151 W, GAKIC 892 ± 153 W) to the 10th sprint (Pl 766 ± 120 W, GAKIC 752 ± 138 W) and did not differ between conditions (p = .96). The fatigue index remained at ~38% throughout the series of sprints and did not differ between conditions (p = .99). Heart rate and ratings of perceived exertion increased from the 1st sprint to the 10th sprint and did not differ between conditions (p = .11 and p = .83, respectively). In contrast to previous studies in untrained individuals, these results suggest that GAKIC has no ergogenic effect on repeated bouts of high-intensity exercise in trained individuals.
Exercising Fasting or Fed to Enhance Fat Loss? Influence of Food Intake on Respiratory Ratio and Excess Postexercise Oxygen Consumption After a Bout of Endurance Training
Authors: Paoli Antonio , Marcolin Giuseppe , Zonin Fabio , Neri Marco , Sivieri Andrea , Pacelli Quirico F.
Published: August 2016

Exercise and nutrition are often used in combination to lose body fat and reduce weight. In this respect, exercise programs are as important as correct nutrition. Several issues are still controversial in this field, and among them there are contrasting reports on whether training in a fasting condition can enhance weight loss by stimulating lipolytic activity. The authors’ purpose was to verify differences in fat metabolism during training in fasting or feeding conditions. They compared the effect on oxygen consumption (VO2) and substrate utilization, estimated by the respiratory-exchange ratio (RER), in 8 healthy young men who performed the same moderate-intensity training session (36 min of cardiovascular training on treadmill at 65% maximum heart rate) in the morning in 2 tests in random sequence: FST test (fasting condition) without any food intake or FED test (feeding condition) after breakfast. In both cases, the same total amount and quality of food was assumed in the 24 hr after the training session. The breakfast, per se, increased both VO2 and RER significantly (4.21 vs. 3.74 and 0.96 vs. 0.84, respectively). Twelve hours after the training session, VO2 was still higher in the FED test, whereas RER was significantly lower in the FED test, indicating greater lipid utilization. The difference was still significant 24 hr after exercise. The authors conclude that when moderate endurance exercise is done to lose body fat, fasting before exercise does not enhance lipid utilization; rather, physical activity after a light meal is advisable.
Development and Validation of a Food-Frequency Questionnaire to Assess Short-Term Antioxidant Intake in Athletes
Authors: Braakhuis Andrea J. , Hopkins Will G. , Lowe Timothy E. , Rush Elaine C.
Published: August 2016

A quantitative food-frequency questionnaire (FFQ) was developed to determine antioxidant intake in athletes. The questionnaire will be valuable for researchers wishing to standardize antioxidant intake or simply document habitual intake during an intervention trial. One hundred thirteen athletes participated in the validity study, of whom 96 completed the questionnaire and blood test, 81 completed the 7-d food diary and questionnaire, and 63 completed the 7-d food diary and blood test. Validity was investigated by comparing total and food-group antioxidant intakes from the questionnaire with those from a subsequent 7-d food diary. Measures of construct validity were determined by comparing a biomarker of antioxidant capacity (ferric-reducing ability of plasma) in a blood sample with antioxidant intakes from the questionnaire and diary. The correlation between the diary and questionnaire energy-adjusted estimates of total antioxidant intake was modest (.38; 90% confidence limits, ± .14); the correlation was highest for antioxidants from cereals (.55; ± .11), which contributed the greatest proportion (31%) of the total antioxidant intake. Correlations were also high for coffee and tea (.51; ± .15) and moderate for vegetables (.34; ± .16) and fruit (.31; ± .16). The correlation of the plasma biomarker with the questionnaire estimate was small (.28; ± .15), but the correlation with the diary estimate was inconsequential (–.03; ± .15). One-week test–retest reliability of the questionnaire’s estimates of antioxidant intake in 20 participants was high (.83; ± .16). In conclusion, the FFQ is less labor intensive for participants and researchers than a 7-d diary and appears to be at least as trustworthy for estimating antioxidant intake.
Bovine Colostrum Supplementation’s Lack of Effect on Immune Variables During Short-Term Intense Exercise in Well-Trained Athletes
Authors: Carol Arnoud , Witkamp Renger F. , Wichers Harry J. , Mensink Marco
Published: August 2016

The purpose of this study was to investigate the potential of bovine colostrum to attenuate postexercise decline in immune function. The authors evaluated the time course of a number of immune variables after short-term intense exercise in 9 male athletes after 10 d of supplementation with either colostrum or skim-milk powder. To increase the stress on the immune system subjects performed a glycogen-depletion trial the evening before the endurance trial (90 min at 50% Wmax). Blood samples were taken before the glycogen-depletion trial, before and after the endurance trial, and the next morning, ~22 hr after cessation of the exercise. Plasma cortisol levels increased over time, reaching the highest level directly after exercise, and were still elevated ~22 hr after exercise compared with baseline values (p < .001). Neutrophil cell count was increased after exercise and dropped below starting values 22 hr after exercise (time effect p < .001). Circulating immunoglobulins did not change over time. A significant time effect was seen for interleukin (IL)-6, IL-10, IL-1-receptor agonist, and C-reactive protein, with levels being higher directly after exercise (p < .05). Other cytokines (interferon-γ, IL-1a, IL-8, tumor necrosis factor-a) did not show a time effect. No differences were seen between colostrum and skim-milk powder in any of the investigated variables. Our results are consistent with the hypothesis that intense exercise affects several variables of the immune system. Colostrum did not alter any of the postexercise immune variables compared with skimmilk powder, suggesting no role for bovine colostrum supplementation in preventing postexercise immune suppression after short-term intense exercise.
N-Acetylcysteine in Handgrip Exercise: Plasma Thiols and Adverse Reactions
Authors: Ferreira Leonardo F. , Campbell Kenneth S. , Reid Michael B.
Published: August 2016

N-acetylcysteine (NAC) is a thiol donor with antioxidant properties that has potential use as an ergogenic aid. However, NAC is associated with adverse reactions that limit its use in humans.

Purpose:

The authors evaluated NAC efficacy as a thiol donor before handgrip exercise, measuring changes in serum cysteine and glutathione status and recording adverse reactions in adult subjects across a range of doses.

Methods:

Healthy individuals ingested NAC capsules (9 ± 2 or 18 ± 4 mg/kg) or solution (0, 35, 70, or 140 mg/kg). Venous blood samples were collected and subjects answered a questionnaire about adverse reactions.

Results:

Low doses of NAC (capsules) did not affect plasma cysteine or glutathione or cause adverse reactions. Adverse reactions to NAC solution were predominantly mild and gastrointestinal (GI). Intensity of GI reactions to 140 mg/kg NAC was significantly higher than placebo (in a.u., 0.67 ± 0.16 vs. 0.07 ± 0.04; p < .05). Plasma cysteine concentration increased with NAC dose from 9.3 ± 0.7 μM (placebo) to 65.3 ± 6.7 μM (140 mg/kg); however, there was no difference (p > .05) in plasma cysteine for 70 mg/kg vs. 140 mg/kg. Similar increases were observed for the ratio of cysteine to total cysteine, which was directly related to handgrip exercise performance. Plasma glutathione was elevated and oxidized glutathione diminished (p < .05) with NAC 140 mg/kg vs. placebo.

Conclusion:

NAC effects on plasma thiols are maximized by oral administration of 70 mg/kg, a dose that does not cause significant adverse reactions.
Effects of Exercise, Diet, and Their Combination on Metabolic-Syndrome-Related Parameters in OLETF Rats
Authors: Suzuki Masato , Shindo Daisuke , Kimura Masaki , Waki Hidefumi
Published: August 2016

This study was conducted to assess the effects of exercise, diet, and their combination on metabolic syndrome (MS) risk factors including visceral fat mass (VFM), glucose intolerance, and dyslipidemia in OLETF rats. Thirty-two male rats were assigned to exercise (OLETF-Ex), dietary treatment (-DT), combination (-Ex&DT), or sedentary (-Sed) groups. Daily voluntary exercise using a rotary wheel was performed in OLETF-Ex. Each treatment was conducted from 21 to 31 wk of age. An oral glucose tolerance test was performed before and after the treatment period. Absolute levels of VFM, subcutaneous fat mass (SFM), and serum lipids including triglyceride, total cholesterol, and LDL-cholesterol (LDL-C) were measured after the treatment period. All therapeutic treatments resulted in significantly lower levels of body weight, VFM, SFM, and serum lipids than in sedentary control rats. All therapeutic treatments were also found to improve indices of oral glucose tolerance. Of the 3 therapeutic treatments, serum LDL-C levels were significantly lower in OLETF-Ex and OLETF-Ex&DT than in OLETF-Sed. The data demonstrate that all therapeutic approaches tested were effective in improving a number of MS-related parameters in OLETF rats. However, exercise-based therapeutic intervention may provide additional benefits for improving fat metabolism in MS patients.
Dietary Supplementation Habits and Perceptions of Supplement Use Among Elite Finnish Athletes
Authors: Heikkinen Anni , Alaranta Antti , Helenius Ilkka , Vasankari Tommi
Published: August 2016

The aim of this study was to evaluate the frequency of dietary supplement (DS) use among elite Finnish athletes in 2002 and 2009. In 2009, the authors also wanted to examine the reasons for athletes’ DS use, whether athletes feel they have experienced benefits from their supplement use, and whether athletes had had an opportunity to consult dietary specialists. Cross-sectional studies were conducted in 2002 and 2009 among Finnish Olympic athletes. Data were collected using semistructured questionnaires, mainly in national team camps. The study population in 2002 was 446 athletes, and in 2009 it was 372. The number of DS users was high in both study years (81% in 2002 and 73% in 2009). Vitamin D consumption was low in both 2002 and 2009 (0.7% and 2.0%, respectively). An increase was found in consumption of omega-3 fatty acids between study years (11% in 2002 and 19% in 2009; p = .002), and their regular use nearly doubled (8% and 15%, p = .002). For vitamin and mineral users, the main reason for DS use was to prevent nutritional deficiencies, and for nutritional supplement users the main reason was recovery from exercise. Only 27% of all athletes and 30% of DS users had an opportunity to consult dietary specialists in 2009. This survey shows that supplementation rates among elite Finnish athletes are high and there may be over- and underuse of some micronutrient supplements. There is a need for professional nutritional counseling among national elite athletes.
Effects of 7 Days of Arginine-Alpha-Ketoglutarate Supplementation on Blood Flow, Plasma L-Arginine, Nitric Oxide Metabolites, and Asymmetric Dimethyl Arginine After Resistance Exercise
Authors: Willoughby Darryn S. , Boucher Tony , Reid Jeremy , Skelton Garson , Clark Mandy
Published: August 2016

Background:

Arginine-alpha-ketoglutarate (AAKG) supplements are alleged to increase nitric oxide production, thereby resulting in vasodilation during resistance exercise. This study sought to determine the effects of AAKG supplementation on hemodynamics and brachial-artery blood flow and the circulating levels of L-arginine, nitric oxide metabolites (NOx; nitrate/nitrite), asymmetric dimethyl arginine (ADMA), and L-arginine:ADMA ratio after resistance exercise.

Methods:

Twenty-four physically active men underwent 7 days of AAKG supplementation with 12 g/day of either NO2 Platinum or placebo (PLC). Before and after supplementation, a resistance-exercise session involving the elbow flexors was performed involving 3 sets of 15 repetitions with 70–75% of 1-repetition maximum. Data were collected immediately before, immediately after (PST), and 30 min after (30PST) each exercise session. Data were analyzed with factorial ANOVA (p < .05).

Results:

Heart rate, blood pressure, and blood flow were increased in both groups at PST (p = .001) but not different between groups. Plasma L-arginine was increased in the NO2 group (p = .001). NOx was shown to increase in both groups at PST (p = .001) and at 30PST (p = .001) but was not different between groups. ADMA was not affected between tests (p = .26) or time points (p = .31); however, the L-arginine:ADMA ratio was increased in the NO2 group (p = .03).

Conclusion:

NO2 Platinum increased plasma L-arginine levels; however, the effects observed in hemodynamics, brachial-artery blood flow, and NOx can only be attributed to the resistance exercise.