bluuebunny/crossref_metadata_2025 huggingface dataset:
Acute Exercise and Thioredoxin-1 in Rat Brain, and Alpha-Lipoic Acid and Thioredoxin-Interacting Protein Response, in Diabetes
Authors: Lappalainen Zekine , Lappalainen Jani , Laaksonen David E. , Oksala Niku K.J , Khanna Savita , Sen Chandan K. , Atalay Mustafa
Published: August 2016

Thioredoxin (TRX) is a protein disulfide reductase that plays an important role in many thiol-dependent cellular reductive processes, antioxidant protection, and signal transduction. Moreover, TRX reduces and maintains the function of many proteins during oxidative stress, which is increased in diabetes. The authors recently reported that diabetes impairs brain redox status and TRX response to exercise training. As a continuation of their studies, they hypothesized that alpha-lipoic acid, a natural thiol antioxidant, has a favorable effect on the brain TRX and glutathione (GSH) system in diabetes. Streptozotocin-induced diabetes was used as a chronic model and exhaustive exercise as an acute model for disrupted redox balance. Half the diabetic and nondiabetic animals were subjected to a bout of exhaustive exercise after 8 wk with or without lipoic acid and analyzed for key thiol antioxidants. Lipoic acid neither altered diabetes-induced oxidative stress as assessed by the increased ratio of oxidized to total GSH nor had any impact on the antioxidant protein response to exercise. However, lipoic acid increased mRNA of TRX-interacting protein, an inhibitor of TRX-1, and glutaredoxin-1 in diabetes. Exercise increased TRX-1 mRNA in both diabetic and nondiabetic animals but had no effect on TRX-1 protein. Cytosolic superoxide dismutase mRNA was only increased in diabetes, whereas exercise increased the protein levels in nondiabetic animals. The findings suggest that exhaustive exercise induces mRNA of TRX-1 in the brain and that lipoic acid cannot prevent diabetes-induced disturbances in GSH homeostasis. Because lipoic acid increased TRX-interacting protein transcription in diabetes, high doses may impair TRX-1 homeostasis.
Comparison of Strategies for Assessing Nutritional Adequacy in Elite Female Athletes’ Dietary Intake
Authors: Heaney Susan , O’Connor Helen , Gifford Janelle , Naughton Geraldine
Published: August 2016

Purpose:

This study aimed to compare strategies for assessing nutritional adequacy in the dietary intake of elite female athletes.

Methods:

Dietary intake was assessed using an adapted food-frequency questionnaire in 72 elite female athletes from a variety of sports. Nutritional adequacy was evaluated and compared using mean intake; the proportion of participants with intakes below Australian nutrient reference values (NRV), U.S. military dietary reference intakes (MDRI), and current sports nutrition recommendations; and probability estimates of nutrient inadequacy.

Results:

Mean energy intake was 10,551 ± 3,836 kJ/day with macronutrient distribution 18% protein, 31% fat, and 46% carbohydrate, consistent with Australian acceptable macronutrient distribution ranges. Mean protein intake (1.6 g · kg−1 · d−1) was consistent with (>1.2 g · kg−1 · d−1), and carbohydrate intake (4.5 g · kg−1 · d−1), below, current sports nutrition recommendations (>5 g · kg−1 · d−1), with 30% and 65% of individuals not meeting these levels, respectively. Mean micronutrient intake met the relevant NRV and MDRI except for vitamin D and folate. A proportion of participants failed to meet the estimated average requirement for folate (48%), calcium (24%), magnesium (19%), and iron (4%). Probability estimates of inadequacy identified intake of folate (44%), calcium (22%), iron (19%), and magnesium (15%) as inadequate.

Conclusion:

Interpretation of dietary adequacy is complex and varies depending on whether the mean, proportion of participants below the relevant NRV, or statistical probability estimate of inadequacy is used. Further research on methods to determine dietary adequacy in athlete populations is required.
Altered Antioxidant and Trace-Element Status in Adolescent Female Gymnasts
Authors: Alshammari Eyad , Shafi Shahida , Nurmi-Lawton Jaana , Taylor Andrew , Lanham-New Susan , Ferns Gordon
Published: August 2016

Physical activity is associated with the generation of reactive oxygen species and may lead to decreased levels of plasma antioxidants and increased oxidant stress. Some studies have reported that antioxidant supplements can reduce the consequences of oxidative stress during exercise. In this study the authors aimed to assess the chronic effects of exercise on endogenous serum antioxidant enzyme concentrations. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity were measured in adolescent girls who were either competitive gymnasts or sedentary controls. The relationship between age, body-mass index, dietary intake, trace-element status, and serum GPx and SOD was determined. The participants in the study were part of a 3-yr longitudinal investigation of exercise and peak bone-mass development in 38 competitive gymnasts and 40 healthy sedentary adolescent females 8–17 yr of age. Serum GPx and SOD were measured using colorimetric assays, and trace elements were measured using inductively coupled plasma mass spectrometry. The mean serum GPx concentrations were significantly higher in the gymnasts than in the sedentary females (157 ± 11.1 vs. 126 ± 8.8 U/ml, p < .05). In contrast, serum SOD concentrations were significantly lower in the gymnasts than in the sedentary group (7.24 ± 2.6 vs. 8.57 ± 2.3 U/ml, p < .05). Serum selenium, zinc, and copper were higher in the physically active group than in the inactive group (0.89 ± 0.03, 10.86 ± 0.39, 14.50 ± 0.50 vs. 0.81 ± 0.03, 10.32 ± 0.28, and 14.38 ± 0.42 μmol/L, respectively), although only serum selenium reached statistical significance (p < .05). The findings show that young female gymnasts have an altered antioxidant enzyme profile compared with their less physically active peers.
Race-Day Carbohydrate Intakes of Elite Triathletes Contesting Olympic-Distance Triathlon Events
Authors: Cox Gregory R. , Snow Rodney J. , Burke Louise M.
Published: August 2016

The aim of this study was to investigate the prerace and during-race carbohydrate intakes of elite-level triathletes contesting draft-legal Olympic-distance triathlon (ODT) events. Self-reported prerace and during-race nutrition data were collected at 3 separate ODT events from 51 elite senior and under-23 triathletes. One hundred twenty-nine observations of food and fluid intake representing actual prerace (n = 62) and during-race (n = 67) nutrition practices from 36 male and 15 female triathletes were used in the final analysis of this study. Female triathletes consumed significantly more carbohydrate on the morning before race start when corrected for body mass and race start time than their male counterparts (p < .05). Male and female triathletes consumed 26% more energy (kJ/kg) and 24% more carbohydrate (g/kg) when commencing a race after midday (1:00–1:30 p.m.) than for a late morning (11:00–11:15 a.m.) race start. During the race, triathletes consumed less than 60 g of carbohydrate on 66% of occasions, with average total race intakes of 48 ± 25 and 49 ± 25 g carbohydrate for men and women, respectively. Given average race times of 1:57:07 hr and 2:08:12 hr, hourly carbohydrate intakes were ~25 g and ~23 g for men and women, respectively. Although most elite ODT triathletes consume sufficient carbohydrate to meet recommended prerace carbohydrate intake guidelines, during-race carbohydrate intakes varied considerably, with many failing to meet recommended levels.
Increased Blood pH but Not Performance With Sodium Bicarbonate Supplementation in Elite Rugby Union Players
Authors: Cameron Sonya L. , McLay-Cooke Rebecca T. , Brown Rachel C. , Gray Andrew R. , Fairbairn Kirsty A.
Published: August 2016

Purpose:

This study investigated the effect of ingesting 0.3 g/kg body weight (BW) of sodium bicarbonate (NaHCO3) on physiological responses, gastrointestinal (GI) tolerability, and sprint performance in elite rugby union players.

Methods:

Twenty-five male rugby players, age 21.6 (2.6) yr, participated in a randomized, double-blind, placebo-controlled crossover trial. Sixty-five minutes after consuming 0.3 g/kg BW of either NaHCO3 or placebo, participants completed a 25-min warm-up followed by 9 min of high-intensity rugby-specific training followed by a rugby-specific repeated-sprint test (RSRST). Whole-blood samples were collected to determine lactate and bicarbonate concentrations and pH at baseline, after supplement ingestion, and immediately after the RSRST. Acute GI discomfort was assessed by questionnaire throughout the trials, and chronic GI discomfort was assessed during the 24 hr postingestion.

Results:

After supplement ingestion and immediately after the RSRST, blood HCO3 − concentration and pH were higher for the NaHCO3 condition than for the placebo condition (p < .001). After the RSRST, blood lactate concentrations were significantly higher for the NaHCO3 than for the placebo condition (p < .001). There was no difference in performance on the RSRST between the 2 conditions. The incidence of belching, stomachache, diarrhea, stomach bloating, and nausea was higher after ingestion of NaHCO3 than with placebo (all p < .050). The severity of stomach cramps, belching, stomachache, bowel urgency, diarrhea, vomiting, stomach bloating, and flatulence was rated worse after ingestion of NaHCO3 than with placebo (p < .050).

Conclusions:

NaHCO3 supplementation increased blood HCO3 − concentration and attenuated the decline in blood pH compared with placebo during high-intensity exercise in well-trained rugby players but did not significantly improve exercise performance. The higher incidence and greater severity of GI symptoms after ingestion of NaHCO3 may negatively affect physical performance, and the authors strongly recommend testing this supplement during training before use in competitive situations.
Relationship Between Changes in Upon-Waking Urinary Indices of Hydration Status and Body Mass in Adolescent Singaporean Athletes
Authors: Lew Chin Han , Slater Gary , Nair Gobinathan , Miller Michelle
Published: August 2016

This study investigated the relationship between changes in upon-waking body mass (BM) and changes in urine specific gravity (Usg) and urine color (Ucol) from 1 day to the next. Throughout the 5-day investigation, healthy adolescent Singaporean athletes (n = 66) had their upon-waking, bladder-voided BM measured. A small aliquot of the first bladder void each day was collected and analyzed for Usg and Ucol, the latter by both an investigator (IUcol) and individual participants (SUcol). Results revealed a significant inverse relationship between changes in BM and changes in Usg (p = .003) and Ucol (p = .001). On average, Usg and Ucol changed by ~0.003 units and ~1 color (across a 9-unit scale), respectively, with every 1% change in BM from 1 day to the next. There was a stronger relationship between Usg and IUcol (r = .82, p < .001) than between Usg and SUcol (r = .60, p < .001). These results suggest that the degree of fluid deficit may be predicted from the Usg measurements among moderately hypohydrated athletes. In addition, training athletes to interpret and use the Ucol chart is recommended.
The Influence of 8 Weeks of Whey-Protein and Leucine Supplementation on Physical and Cognitive Performance
Authors: Walker Thomas B. , Smith Jessica , Herrera Monica , Lebegue Breck , Pinchak Andrea , Fischer Joseph
Published: August 2016

The purpose of this study was to investigate the ability of whey-protein and leucine supplementation to enhance physical and cognitive performance and body composition. Thirty moderately fit participants completed a modified Air Force fitness test, a computer-based cognition test, and a dual-energy X-ray-absorptiometry scan for body composition before and after supplementing their daily diet for 8 wk with either 19.7 g of whey protein and 6.2 g leucine (WPL) or a calorie-equivalent placebo (P). Bench-press performance increased significantly from Week 1 to Week 8 in the WPL group, whereas the increase in the P group was not significant. Push-up performance increased significantly for WPL, and P showed a nonsignificant increase. Total mass, fat-free mass, and lean body mass all increased significantly in the WPL group but showed no change in the P group. No differences were observed within or between groups for crunches, chin-ups, 3-mile-run time, or cognition. The authors conclude that supplementing with whey protein and leucine may provide an advantage to people whose performance benefits from increased upper body strength and/or lean body mass.
Effect of Low- and High-Glycemic-Index Meals on Metabolism and Performance During High-Intensity, Intermittent Exercise
Authors: Little Jonathan P. , Chilibeck Philip D. , Ciona Dawn , Forbes Scott , Rees Huw , Vandenberg Albert , Zello Gordon A.
Published: August 2016

Consuming carbohydrate-rich meals before continuous endurance exercise improves performance, yet few studies have evaluated the ideal preexercise meal for high-intensity intermittent exercise, which is characteristic of many team sports. The authors’ purpose was to investigate the effects of low- and high-glycemic-index (GI) meals on metabolism and performance during high-intensity, intermittent exercise. Sixteen male participants completed three 90-min high-intensity intermittent running trials in a single-blinded random order, separated by ~7 d, while fasted (control) and 2 hr after ingesting an isoenergetic low-GI (lentil), or high-GI (potato and egg white) preexercise meal. Serum free fatty acids were higher and insulin lower throughout exercise in the fasted condition (p < .05), but there were no differences in blood glucose during exercise between conditions. Distance covered on a repeated-sprint test at the end of exercise was significantly greater in the low-GI and high-GI conditions than in the control (p < .05). Rating of perceived exertion was lower in the low-GI condition than in the control (p = .01). In a subsample of 5 participants, muscle glycogen availability was greater in the low- and high-GI conditions versus fasted control before the repeated-sprint test (p < .05), with no differences between low and high GI. When exogenous carbohydrates are not provided during exercise both low- and high-GI preexercise meals improve high-intensity, intermittent exercise performance, probably by increasing the availability of muscle glycogen. However, the GI does not influence markers of substrate oxidation during high-intensity, intermittent exercise.
The Influence of Habitual Exercise Training and Meal Form on Diet-Induced Thermogenesis in College-Age Men
Authors: Ratcliff Lance , Gropper Sareen S. , White B. Douglas , Shannon David M. , Huggins Kevin W.
Published: August 2016

This study compared type of habitual exercise and meal form on diet-induced thermogenesis (DIT) in 29 men age 19–28 yr. Resting metabolic rate (RMR) and DIT response to solid-meal (bar) vs. liquid-meal (shake) ingestion were measured via indirect calorimetry; classifications were sedentary (n = 9), endurance trained (n = 11), or resistance trained (n = 9). Height, weight, and body composition (using bioelectrical impedance) were measured for each subject. Energy expenditure was determined before and every 30 min after meal consumption for 210 min. RMR was significantly (p = .045) higher in the endurance- and resistance-trained groups. However, when expressed per kilogram fat-free mass (FFM; relative RMR), differences were not significant. Both DIT (kcal/min) and relative DIT (kcal · min−1 · kg FFM−1) significantly increased with time (p < .0001) from RMR for each meal form. There was no significant exercise-group effect on DIT or relative DIT. There was a significant (p = .012) effect of meal form on DIT; shakes elicited a higher DIT. This significant difference was not found for relative DIT. There was a significant interaction between group and meal form for DIT (p = .008) and relative DIT (p < .0001). Shakes elicited a significantly greater DIT (p = .0002) and relative DIT (p = .0001) in the resistance-trained group. In the sedentary group, relative DIT from shakes was significantly lower than from bars (p = .019). In conclusion, habitual exercise appears to increase RMR, and meal form may impart changes in relative DIT depending on exercise status.
Does Caffeine Added to Carbohydrate Provide Additional Ergogenic Benefit for Endurance?
Authors: Conger Scott A. , Warren Gordon L. , Hardy Michelle A. , Millard-Stafford Mindy L.
Published: August 2016

Context:

Carbohydrate (CHO) and caffeine (CAF) both improve endurance performance.

Purpose:

To determine by systematic literature review coupled with meta-analysis whether CAF ingested with CHO (CHO+CAF) improves endurance performance more than CHO alone.

Methods:

Databases were searched using the keywords caffeine, endurance, exercise, carbohydrate, and performance. Criteria for inclusion were studies that used human subjects performing an endurance-exercise performance task and included both a CHO and CHO+CAF condition. Effect sizes (ESs) were calculated as the standardized mean difference.

Results:

Twenty-one studies met the criteria for analysis. ESs for individual studies ranged from –0.08 (trivial effect favoring CHO) to 1.01 (large effect favoring CHO+CAF). The overall ES equaled 0.26 (95% CI 0.15–0.38, p < .001), indicating that CHO+CAF provides a small but significant performance benefit over CHO. ES was not significantly (p > .05) related to CAF dose, exercise duration, or performance-assessment method. To determine whether ES of CHO+CAF vs. CHO was different than CAF compared with water (placebo), a subgroup meta-analysis compared 36 CAF vs. placebo studies against the 21 CHO+CAF vs. CHO studies. The overall ES for the former group of studies (ES = 0.51, 95% CI 0.40–0.61) was nearly 2-fold greater than in CHO+CAF vs. CHO studies (p = .006).

Conclusions:

CHO+CAF ingestion provides a significant but small effect to improve endurance performance compared with CHO alone. However, the magnitude of the performance benefit that CAF provides is less when added to CHO than when added to placebo.
Effect of a High and Low Dose of Caffeine on Antigen-Stimulated Activation of Human Natural Killer Cells After Prolonged Cycling
Authors: Fletcher Deborah K. , Bishop Nicolette C.
Published: August 2016

This study investigated the effect of a high and low dose of caffeine on antigen-stimulated natural killer (NK) cell (CD3−CD56+) activation after prolonged, strenuous cycling, as assessed by the early-activation molecule CD69. In a randomized crossover design, 12 healthy male endurance-trained cyclists cycled for 90 min at 70% VO2peak 60 min after ingesting either 0 (PLA), 2 (2CAF), or 6 (6CAF) mg/kg body mass of caffeine. Whole blood was stimulated with Pediacel (5 in 1) vaccine. A high dose of caffeine (6CAF) increased the number of CD3−CD56+ cells in the circulation immediately postexercise compared with PLA (p < .05). For both 2CAF and 6CAF, the geometric mean fluorescence intensity (GMFI) of CD69+ expression on unstimulated CD3−CD56+ cells was significantly higher than with PLA (both p < .05). When cells were stimulated with antigen, the GMFI of CD69 expression remained significantly higher with 2CAF than with PLA 1 hr postexercise (p < .05). Although not achieving statistical significance, 6CAF also followed a similar trend when stimulated (p = .09). There were no differences in GMFI of CD69 expression between 2CAF and 6CAF. These results suggest that a high (6 mg/kg) dose of caffeine was associated with the recruitment of NK cells into the circulation and that both a high and low (2 mg/kg) dose of caffeine increased unstimulated and antigen-stimulated NK-cell activation 1 hr after high-intensity exercise. Furthermore, there does not appear to be a dose-dependent effect of caffeine on NK-cell activation 1 hr after prolonged intensive cycling.
Effects of Immediate Postexercise Carbohydrate Ingestion With and Without Protein on Neutrophil Degranulation
Authors: Costa Ricardo J.S. , Walters Robert , Bilzon James L.J. , Walsh Neil P.
Published: August 2016

The purpose of the study was to determine the effects of carbohydrate (CHO) intake, with and without protein (PRO), immediately after prolonged strenuous exercise on circulating bacterially stimulated neutrophil degranulation. Twelve male runners completed 3 feeding interventions, 1 week apart, in randomized order after 2 hr of running at 75% VO2max. The feeding interventions included a placebo solution, a CHO solution equal to 1.2 g CHO~/kg body mass (BM), and a CHO-PRO solution equal to 1.2 g CHO/kg BM and 0.4 g PRO/kg BM (CHO+PRO) immediately postexercise. All solutions were flavor and water-volume equivalent (12 ml/kg BM). Circulating leukocyte counts, bacterially stimulated neutrophil degranulation, plasma insulin, and cortisol were determined from blood samples collected preexercise, immediately postexercise, and every 30 min until 180 min postexercise. The immediate postexercise circulating leukocytosis, neutrophilia, and lymphocytosis (p < .01 vs. preexercise) and the delayed lymphopenia (90 min postexercise, p < .05 vs. preexercise) were similar on all trials. Bacterially stimulated neutrophil degranulation decreased during recovery in control (23% at 180 min, p < .01 vs. preexercise) but remained above preexercise levels with CHO and CHO+PRO. In conclusion, CHO ingestion, with or without PRO, immediately after prolonged strenuous exercise prevented the decrease in bacterially stimulated neutrophil degranulation during recovery.
Exercise-Induced Trace Mineral Element Concentration in Regional Versus Whole-Body Wash-Down Sweat
Authors: Baker Lindsay B. , Stofan John R. , Lukaski Henry C. , Horswill Craig A.
Published: August 2016

Simultaneous whole-body wash-down (WBW) and regional skin surface sweat collections were completed to compare regional patch and WBW sweat calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) concentrations. Athletes (4 men, 4 women) cycled in a plastic open-air chamber for 90 min in the heat. Before exercise, the subjects and cycle ergometer (covered in plastic) were washed with deionized water. After the onset of sweating, sterile patches were attached to the forearm, back, chest, forehead, and thigh and removed on saturation. After exercise, the subjects and cycle ergometer were washed with 5 L of 15-mM ammonium sulfate solution to collect all sweat minerals and determine the volume of unevaporated sweat. Control trials were performed to measure mineral contamination in regional and WBW methods. Because background contamination in the collection system was high for WBW Mn, Fe, and Zn, method comparisons were not made for these minerals. After correction for minimal background contamination, WBW sweat [Ca], [Mg], and [Cu] were 44.6 ± 20.0, 9.8 ± 4.8, and 0.125 ± 0.069 mg/L, respectively, and 5-site regional (weighted for local sweat rate and body surface area) sweat [Ca], [Mg], and [Cu] were 59.0 ± 15.9, 14.5 ± 4.8, and 0.166 ± 0.031 mg/L, respectively. Five-site regional [Ca], [Mg], and [Cu] overestimated WBW by 32%, 48%, and 33%, respectively. No individual regional patch site or 5-site regional was significantly correlated with WBW sweat [Ca] (r = –.21, p = .65), [Mg] (r = .49, p = .33), or [Cu] (r = .17, p = .74). In conclusion, regional sweat [Ca], [Mg], and [Cu] are not accurate surrogates for or significantly correlated with WBW sweat composition.
Fluid Balance and Sodium Losses During Indoor Tennis Match Play
Authors: Lott Matthew J.E. , Galloway Stuart D.R.
Published: August 2016

This study assessed fluid balance, sodium losses, and effort intensity during indoor tennis match play (17 ± 2 °C, 42% ± 9% relative humidity) over a mean match duration of 68.1 ± 12.8 min in 16 male tennis players. Ad libitum fluid intake was recorded throughout the match. Sweat loss from change in nude body mass; sweat electrolyte content from patches applied to the forearm, calf, and thigh, and back of each player; and electrolyte balance derived from sweat, urine, and daily food-intake analysis were measured. Effort intensity was assessed from on-court heart rate compared with data obtained during a maximal treadmill test. Sweat rate (M ± SD) was 1.1 ± 0.4 L/hr, and fluid-ingestion rate was 1.0 ± 0.6 L/hr (replacing 93% ± 47% of fluid lost), resulting in only a small mean loss in body mass of 0.15% ± 0.74%. Large interindividual variabilities in sweat rate (range 0.3–2.0 L/hr) and fluid intake (range 0.31–2.52 L/hr) were noted. Whole-body sweat sodium concentration was 38 ± 12 mmol/L, and total sodium losses during match play were 1.1 ± 0.4 g (range 0.5–1.8 g). Daily sodium intake was 2.8 ± 1.1 g. Indoor match play largely consisted of low-intensity exercise below ventilatory threshold (mean match heart rate was 138 ± 24 beats/min). This study shows that in moderate indoor temperature conditions players ingest sufficient fluid to replace sweat losses. However, the wide range in data obtained highlights the need for individualized fluid-replacement guidance.
Impact of Iron Depletion Without Anemia on Performance in Trained Endurance Athletes at the Beginning of a Training Season: A Study of Female Collegiate Rowers
Authors: DellaValle Diane M. , Haas Jere D.
Published: August 2016

The objective of this study was to determine the impact of iron depletion without anemia on performance in a sample of female collegiate rowers at the beginning of a training season (August 2008, January 2009, and September 2009). One hundred sixty-five female collegiate rowers from 5 colleges and universities in central New York State participated in a screening of iron status. Blood hemoglobin (Hgb), serum ferritin (sFer), and soluble transferrin receptor were measured to determine prevalence of iron depletion and anemia. Rowers’ habitual moderate and vigorous physical activity, as well as their best time to complete a 2-km simulated race during the previous 3 months, were self-reported. Sixteen rowers (10%) were identified as anemic (Hgb <12.0 g/dl). Using a sFer cutoff of <20.0 μg/L, 30% (n = 44) of the nonanemic rowers were identified as iron depleted without anemia and reported 2-km times ~21 s slower (p < .004) than rowers with normal iron status. Given the high prevalence of iron depletion reported in this and other studies, screening for low iron stores at the start of a training program in female athletes involved in an endurance sport may be clinically useful. In this study, irondepleted rowers (sFer <20–25 μg/L) reported a decrease in performance time compared with those with normal iron stores.
Case Study: Simulated and Real-Life Energy Expenditure During a 3-Week Expedition
Authors: Koehler Karsten , Huelsemann Frank , de Marees Markus , Braunstein Bjoern , Braun Hans , Schaenzer Wilhelm
Published: August 2016

During prolonged periods of high energy expenditure (EE), restricted food intake can lead to a loss of body mass. This case study describes the preexpedition support for an unsupported 3-wk crossing of the Atacama Desert in Chile. The goals were to simulate the energy requirements of walking under varying conditions and to predict energy intake and EE to evaluate whether the expected weight loss was in acceptable limits. The expeditionist (male, 35 yr, 197 cm, basal weight 80 ± 0.5 kg) was a well-trained endurance athlete with experience of multiple expeditions. During the simulation, he walked on a treadmill at speeds of 2–7 km/hr under varying conditions of inclination (0%, 7.5%), backpack weight (0 kg, 30 kg), and altitude (sea level, simulated altitude of 3,500 m). Under all conditions, the lowest EE was observed at 5 km/hr. Based on the simulation data, we predicted an average EE of 4,944 kcal/day for the expedition. Because energy intake was restricted to 2,249 kcal/day, we expected the expeditionist to lose considerable weight and consequently advised him to gain 5 kg of body-fat reserves. During the actual desert crossing, he covered a distance of 26 ± 7 km/day at an average speed of 3.8 ± 0.4 km/hr. Daily EE (4,817 ± 794 kcal/day) exceeded energy intake (1,771 ± 685 kcal/day), and the negative energy balance was in agreement with the actual weight loss of 10.5 kg, which was most notable in the lower trunk.
A Comparative Analysis Between the Effects of Galactose and Glucose Supplementation on Endurance Performance
Authors: Macdermid Paul W. , Stannard Stephen , Rankin Dean , Shillington David
Published: August 2016

Purpose:

To determine beneficial effects of short-term galactose (GAL) supplementation over a 50:50 glucose–maltodextrin (GLUC) equivalent on self-paced endurance cycling performance.

Methods:

On 2 separate occasions, subjects performed a 100-km self-paced time trial (randomized and balanced order). This was interspersed with four 1-km and four 4-km maximal efforts reflecting the physical requirements of racing. Before each trial 38 ± 3 g of GAL or GLUC was ingested in a 6% concentrate fluid form 1 hr preexercise and then during exercise at a rate of 37 ± 3 g/hr. Performance variables were recorded for all 1- and 4-km efforts, all interspersed intervals, and the total 100-km distance. Noninvasive indicators of work intensity (heart rate [HR] and rating of perceived exertion) were also recorded.

Results:

Times taken to complete the 100-km performance trial were 8,298 ± 502 and 8,509 ± 578 s (p = .132), with mean power outputs of 271 ± 37 and 256 ± 45 W (p = .200), for GAL and GLUC, respectively. Mean HR did not differ (GAL 157 ± 7 and GLUC 157 ± 7 beats/min, p = .886). A main effect of carbohydrate (CHO) type on time to complete 4-km efforts occurred, with no CHO Type × Effort Order interaction observed. No main effect of CHO type or interaction of CHO Type × Sequential Order occurred for 1-km efforts.

Conclusion:

A 6% GAL drink does not enhance performance time during a self-paced cycling performance trial in highly trained endurance cyclists compared with a formula typically used by endurance athletes but may improve the ability to produce intermediate self-paced efforts.
Dietary Supplements for Improving Body Composition and Reducing Body Weight: Where Is the Evidence?
Authors: Manore Melinda M.
Published: August 2016

Weight-loss supplements typically fall into 1 of 4 categories depending on their hypothesized mechanism of action: products that block the absorption of fat or carbohydrate, stimulants that increase thermogenesis, products that change metabolism and improve body composition, and products that suppress appetite or give a sense of fullness. Each category is reviewed, and an overview of the current science related to their effectiveness is presented. While some weight-loss supplements produce modest effects (<2 kg weight loss), many have either no or few randomized clinical trials examining their effectiveness. A number of factors confound research results associated with the efficacy of weight-loss supplements, such as small sample sizes, short intervention periods, little or no follow-up, and whether the supplement is given in combination with an energy-restricted diet or increased exercise expenditure. There is no strong research evidence indicating that a specific supplement will produce significant weight loss (>2 kg), especially in the long term. Some foods or supplements such as green tea, fiber, and calcium supplements or dairy products may complement a healthy lifestyle to produce small weight losses or prevent weight gain over time. Weight-loss supplements containing metabolic stimulants (e.g., caffeine, ephedra, synephrine) are most likely to produce adverse side effects and should be avoided.
Acute Caffeine Ingestion’s Increase of Voluntarily Chosen Resistance-Training Load After Limited Sleep
Authors: Cook Christian , Beaven C. Martyn , Kilduff Liam P. , Drawer Scott
Published: August 2016

Introduction:

This study aimed to determine whether caffeine ingestion would increase the workload voluntarily chosen by athletes in a limited-sleep state.

Methods:

In a double-blind, crossover study, 16 professional rugby players ingested either a placebo or 4 mg/kg caffeine 1 hr before exercise. Athletes classified themselves into nondeprived (8 hr+) or sleep-deprived states (6 hr or less). Exercise comprised 4 sets of bench press, squats, and bent rows at 85% 1-repetition maximum. Athletes were asked to perform as many repetitions on each set as possible without failure. Saliva was collected before administration of placebo or caffeine and again before and immediately after exercise and assayed for testosterone and cortisol.

Results:

Sleep deprivation produced a very large decrease in total load (p = 1.98 × 10−7). Caffeine ingestion in the nondeprived state resulted in a moderate increase in total load, with a larger effect in the sleep-deprived state, resulting in total load similar to those observed in the nondeprived placebo condition. Eight of the 16 athletes were identified as caffeine responders. Baseline testosterone was higher (p < .05) and cortisol trended lower in non-sleep-deprived athletes. Changes in hormones from predose to preexercise correlated to individual workload responses to caffeine. Testosterone response to exercise increased with caffeine compared with placebo, as did cortisol response.

Conclusions:

Caffeine increased voluntary workload in professional athletes, even more so under conditions of self-reported limited sleep. Caffeine may prove worthwhile when athletes are tired, especially in those identified as responders.
Case Study of a Female Ocean Racer: Prerace Preparation and Nutritional Intake During the Vendée Globe 2008
Authors: Fearnley Deborah , Sutton Louise , O’Hara John , Brightmore Amy , King Roderick , Cooke Carlton
Published: August 2016

The Vendée Globe is a solo round-the-world sailing race without stopovers or assistance, a physically demanding challenge for which appropriate nutrition should maintain energy balance and ensure optimum performance. This is an account of prerace nutritional preparation with a professional and experienced female racer and assessment of daily nutritional intake (NI) during the race using a multimethod approach. A daily energy intake (EI) of 15.1 MJ/day was recommended for the race and negotiated down by the racer to 12.7 MJ/day, with carbohydrate and fluid intake goals of 480 g/day and 3,020 ml/day, respectively. Throughout the 99-day voyage, daily NI was recorded using electronic food diaries and inventories piloted during training races. NI was assessed and a postrace interview and questionnaire were used to evaluate the intervention. Fat mass (FM) and fat-free mass (FFM) were assessed pre- (37 days) and postrace (11 days) using dual-energy X-ray absorptiometry, and body mass was measured before the racer stepped on the yacht and immediately postrace. Mean EI was 9.2 MJ/day (2.4–14.3 MJ/day), representing a negative energy balance of 3.5 MJ/day under the negotiated EI goal, evidenced by a 7.9-kg loss of body mass (FM –7.5 kg, FFM –0.4 kg) during the voyage, with consequent underconsumption of carbohydrate by ~130 g/day. According to the postrace yacht food inventory, self-reported EI was underreported by 7%. This intervention demonstrates the practicality of the NI approach and assessment, but the racer’s nutrition strategy can be further improved to facilitate meeting more optimal NI goals for performance and health. It also shows that evaluation of NI is possible in this environment over prolonged periods, which can provide important information for optimizing nutritional strategies for ocean racing.
An Alternative Dietary Strategy to Make Weight While Improving Mood, Decreasing Body Fat, and Not Dehydrating: A Case Study of a Professional Jockey
Authors: Wilson George , Chester Neil , Eubank Martin , Crighton Ben , Drust Barry , Morton James P. , Close Graeme L.
Published: August 2016

Professional jockeys are unique among weight-making athletes, as they are often required to make weight daily and, in many cases, all year-round. Common methods employed by jockeys include dehydration, severe calorie restriction, and sporadic eating, all of which have adverse health effects. In contrast, this article outlines a structured diet and exercise plan, employed by a 22-yr-old professional National Hunt jockey in an attempt to reduce weight from 70.3 to 62.6 kg, that does not rely on any of the aforementioned techniques. Before the intervention, the client’s typical daily energy intake was 8.2 MJ (42% carbohydrate [CHO], 36% fat, 22% protein) consumed in 2 meals only. During the 9-wk intervention, daily energy intake was approximately equivalent to resting metabolic rate, which the athlete consumed as 6 meals per day (7.6 MJ, 46% CHO, 19% fat, 36% protein). This change in frequency and composition of energy intake combined with structured exercise resulted in a total body-mass loss of 8 kg, corresponding to reductions in body fat from 14.5% to 9%. No form of intentional dehydration occurred throughout this period, and mean urine osmolality was 285 mOsm/kg (SD 115 mOsm/kg). In addition, positive changes in mood scores (BRUMS scale) also occurred. The client was now able to ride light for the first time in his career without dehydrating, thereby challenging the cultural practices inherent in the sport.
Opuntia Ficus-Indica Ingestion Stimulates Peripheral Disposal of Oral Glucose Before and After Exercise in Healthy Men
Authors: Van Proeyen Karen , Ramaekers Monique , Pischel Ivo , Hespel Peter
Published: August 2016

The purpose of this study was to investigate the effect of Opuntia ficus-indica (OFI) cladode and fruit-skin extract on blood glucose and plasma insulin increments due to high-dose carbohydrate ingestion, before and after exercise. Healthy, physically active men (n = 6; 21.0 ± 1.6 years, 78.1 ± 6.0 kg) participated in a doubleblind placebo-controlled crossover study involving 2 experimental sessions. In each session, the subjects successively underwent an oral glucose tolerance test at rest (OGTTR), a 30-min cycling bout at ~75% VO2max, and another OGTT after exercise (OGTTEX). They received capsules containing either 1,000 mg OFI or placebo (PL) 30 min before and immediately after the OGTTR. Blood samples were collected before (t0) and at 30-min intervals after ingestion of 75 g glucose for determination of blood glucose and serum insulin. In OGTTEX an additional 75-g oral glucose bolus was administered at t60. In OGTTR, OFI administration reduced the area under the glucose curve (AUCGLUC) by 26%, mainly due to lower blood glucose levels at t30 and t60 (p < .05). Furthermore, a higher serum insulin concentration was noted after OFI intake at baseline and at t30 (p < .05). In OGTTEX, blood glucose at t60 was ~10% lower in OFI than in PL, which resulted in a decreased AUCGLUC (–37%, p < .05). However, insulin values and AUCINS were not different between OFI and PL. In conclusion, the current study shows that OFI extract can increase plasma insulin and thereby facilitate the clearance of an oral glucose load from the circulation at rest and after endurance exercise in healthy men.
Effects of Quercetin Supplementation on Markers of Muscle Damage and Inflammation after Eccentric Exercise
Authors: O’Fallon Kevin S. , Kaushik Diksha , Michniak-Kohn Bozena , Dunne C. Patrick , Zambraski Edward J. , Clarkson Priscilla M.
Published: August 2016

The flavonoid quercetin is purported to have potent antioxidant and anti-inflammatory properties. This study examined if quercetin supplementation attenuates indicators of exercise-induced muscle damage in a doubleblind laboratory study. Thirty healthy subjects were randomized to quercetin (QU) or placebo (PL) supplementation and performed 2 separate sessions of 24 eccentric contractions of the elbow flexors. Muscle strength, soreness, resting arm angle, upper arm swelling, serum creatine kinase (CK) activity, plasma quercetin (PQ), interleukin-6 (IL-6), and C-reactive protein (CRP) were assessed before and for 5 d after exercise. Subjects then ingested nutrition bars containing 1,000 mg/d QU or PL for 7 d before and 5 d after the second exercise session, using the opposite arm. PQ reached 202 ± 52 ng/ml after 7 d of supplementation and remained elevated during the 5-d postexercise recovery period (p < .05). Subjects experienced strength loss (peak = 47%), muscle soreness (peak = 39 ± 6 mm), reduced arm angle (–7° ± 1°), CK elevations (peak = 3,307 ± 1,481 U/L), and arm swelling (peak = 11 ± 2 mm; p < .0001), indicating muscle damage and inflammation; however, differences between treatments were not detected. Eccentric exercise did not alter plasma IL-6 (peak = 1.9 pg/ml) or CRP (peak = 1.6 mg/L) relative to baseline or by treatment. QU supplementation had no effect on markers of muscle damage or inflammation after eccentric exercise of the elbow flexors.
Chemical Composition of Three Polysaccharides From Gynostemma pentaphyllum and Their Antioxidant Activity in Skeletal Muscle of Exercised Mice
Authors: Chi Aiping , Tang Liang , Zhang Jing , Zhang Kunru
Published: August 2016

Purpose:

To investigate the effects of polysaccharide from Gynostemma pentaphyllum on antioxidant activity in skeletal muscle of mice exercised to exhaustion.

Methods:

Three polysaccharide fractions were obtained from G. pentaphyllum polysaccharide (GPP) and termed GPP1-a, GPP2-b, and GPP3-a. Gas chromatography (GC) and infrared spectrum of the polysaccharides were determined. The fractions were orally administrated to mice once daily for 1 wk. The exercise time to exhaustion was assessed using a forced swim test of mice after a week. The glucose, creatine phosphokinase, and lactic dehydrogenase in serum; the activity of superoxide dismutase and glutathione peroxidase; and the levels of malondialdehyde (MDA) and glycogen in muscle were determined.

Results:

The results of GC demonstrated that GPP1-a, GPP2-b, and GPP3-a were composed of different monosaccharides with distinct molar ratios. Infrared spectrum showed that the main typicals of GPP1-a and GPP2-b were β-configuration and the main typical of GPP3-a was α-configuration. Among the 3 fractions of GPP, GPP1-a administration significantly prolonged exercise time to exhaustion of mice, increased glycogen level and some of antioxidant enzyme activities, and decreased MDA level in muscle.

Conclusions:

The mechanism by which GPP1-a prolonged exercise time to exhaustion in mice may be associated with scavenging reactive oxygen species excessively produced and further increasing glycogen levels in skeletal muscle.
Prevention of Neutrophil Protein Oxidation With Vitamins C and E Diet Supplementation Without Affecting the Adaptive Response to Exercise
Authors: Sureda Antoni , Ferrer Miguel D. , Mestre Antonia , Tur Josep A. , Pons Antoni
Published: August 2016

The authors studied the effects of antioxidant diet supplementation with an almond-based beverage on neutrophil antioxidants, nitrite, and protein oxidative alterations after exercise. Fourteen trained male amateur runners were randomly assigned in a double-blind fashion to receive antioxidant supplementation (152 mg/d vitamin C and 50 mg/d vitamin E) or placebo using an almond-based beverage for 1 mo and participated in a half-marathon race. Blood samples were taken before and after the half-marathon and after 3 hr recovery. Supplementation significantly increased basal neutrophil vitamin C compared with placebo (p < .05). Exercise increased neutrophil vitamin E levels in the supplemented group and decreased vitamin C in both groups after recovery (p < .05). Neutrophil catalase and glutathione peroxidase gene expression and nitrite levels were significantly increased as result of exercise (p < .05). Nitrotyrosine and protein carbonyl derivates increased only in the placebo group after exercise (p < .05), and these values remained high at recovery. No significant differences were evidenced in caspase-3 activity and DNA damage. Antioxidant supplementation with vitamins C and E reduced the exercise-induced oxidation of proteins in neutrophils, without altering the antioxidant adaptive response, as evidenced by the increased catalase and glutathione peroxidase gene expression.
Grape Consumption’s Effects on Fitness, Muscle Injury, Mood, and Perceived Health
Authors: O’Connor Patrick J. , Caravalho Amanda L. , Freese Eric C. , Cureton Kirk J.
Published: August 2016

Compounds found in the skins of grapes, including catechins, quercetin, and resveratrol, have been added to the diet of rodents and improved run time to exhaustion, fitness, and skeletal-muscle mitochondrial function. It is unknown if such effects occur in humans. The purpose of this experiment was to investigate whether 6 wk of daily grape consumption influenced maximal oxygen uptake (VO2max), work capacity, mood, perceived health status, inflammation, pain, and arm-function responses to a mild eccentric-exercise-induced arm-muscle injury. Forty recreationally active young adults were randomly assigned to consume a grape or placebo drink for 45 consecutive days. Before and after 42 d of supplementation, assessments were made of treadmill-running VO2max, work capacity (treadmill performance time), mood (Profile of Mood States), and perceived health status (SF-36 Health Survey). The day after posttreatment treadmill tests were completed, 18 high-intensity eccentric actions of the nondominant elbow flexors were performed. Arm-muscle inflammation, pain, and function (isometric strength and range of motion) were measured before and on 2 consecutive days after the eccentric exercise. Mixed-model ANOVA showed no significant effect of grape consumption on any of the outcomes. Six weeks of supplemental grape consumption by recreationally active young adults has no effect on VO2max, work capacity, mood, perceived health status, inflammation, pain, or physical-function responses to a mild injury induced by eccentric exercise.
Association of Gastrointestinal Distress in Ultramarathoners With Race Diet
Authors: Stuempfle Kristin J. , Hoffman Martin D. , Hew-Butler Tamara
Published: August 2016

Context:

Gastrointestinal (GI) distress is common during ultrarunning.

Purpose:

To determine if race diet is related to GI distress in a 161-km ultramarathon.

Methods:

Fifteen (10 male, 5 female) consenting runners in the Javelina Jundred (6.5 loops on a desert trail) participated. Body mass was measured immediately prerace and after each loop. Runners reported if they had nausea, vomiting, abdominal cramps, and/or diarrhea after each loop. Subjects were interviewed after each loop to record food, fluid, and electrolyte consumption. Race diets were analyzed using Nutritionist Pro.

Results:

Nine (8 male, 1 female) of 15 runners experienced GI distress including nausea (89%), abdominal cramps (44%), diarrhea (44%), and vomiting (22%). Fluid consumption rate was higher (p = .001) in runners without GI distress (10.9 ± 3.2 ml · kg−1 · hr−1) than in those with GI distress (5.9 ± 1.6 ml · kg−1 · hr−1). Runners without GI distress consumed a higher percentage fat (p = .03) than runners with GI distress (16.5 ± 2.6 vs. 11.1 ± 5.0). In addition, fat intake rate was higher (p = .01) in runners without GI distress (0.06 ± 0.03 g · kg−1 · hr−1) than in runners with GI distress (0.03 ± 0.01 g · kg−1 · hr−1). Lower fluid and fat intake rates were evident in those developing GI distress before the onset of symptoms.

Conclusions:

A race diet with higher percentage fat and higher intake rates of fat and fluid may protect ultramarathoners from GI distress. However, these associations do not indicate cause and effect, and factors other than race diet may have contributed to GI distress.