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1.
Muscle Glycogen Content during Endurance Training under Low Energy Availability.
Kojima, C, Ishibashi, A, Tanabe, Y, Iwayama, K, Kamei, A, Takahashi, H, Goto, K
Medicine and science in sports and exercise. 2020;(1):187-195
Abstract
PURPOSE The present study investigated the effects of three consecutive days of endurance training under conditions of low energy availability (LEA) on the muscle glycogen content, muscle damage markers, endocrine regulation, and endurance capacity in male runners. METHODS Seven male long-distance runners (19.9 ± 1.1 yr, 175.6 ± 4.7 cm, 61.4 ± 5.3 kg, maximal oxygen uptake [V˙O2max]: 67.5 ± 4.3 mL·kg·min) completed two trials consisting of three consecutive days of endurance training under LEA (18.9 ± 1.9 kcal·kg FFM·d) or normal energy availability (NEA) (52.9 ± 5.0 kcal·kg FFM·d). The order of the two trials was randomized, with a 2-wk interval between trials. The endurance training consisted of 75 min of treadmill running at 70% of V˙O2max. Muscle glycogen content, respiratory gas variables, and blood and urine variables were measured in the morning for three consecutive days of training (days 1-3) and on the following morning after training (day 4). As an indication of endurance capacity, time to exhaustion at 19.0 ± 0.8 km·h to elicit 90% of V˙O2max was evaluated on day 4. RESULTS During the training period, body weight, fat-free mass, and skeletal muscle volume were significantly reduced in LEA (P = 0.02 for body weight and skeletal muscle volume, P = 0.01 for fat-free mass). Additionally, muscle glycogen content was significantly reduced in LEA (~30%, P < 0.001), with significantly lower values than those in NEA (P < 0.001). Time to exhaustion was not significantly different between the two trials (~20 min, P = 0.39). CONCLUSIONS Three consecutive days of endurance training under LEA decreased muscle glycogen content with lowered body weight. However, endurance capacity was not significantly impaired.
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2.
Caffeine Supplementation for 4 Days Does Not Induce Tolerance to the Ergogenic Effects Promoted by Acute Intake on Physiological, Metabolic, and Performance Parameters of Cyclists: A Randomized, Double-Blind, Crossover, Placebo-Controlled Study.
Morales, AP, Sampaio-Jorge, F, Barth, T, Pierucci, APTR, Ribeiro, BG
Nutrients. 2020;(7)
Abstract
The present study investigated whether the caffeine supplementation for four days would induce tolerance to the ergogenic effects promoted by acute intake on physiological, metabolic, and performance parameters of cyclists. A double-blind placebo-controlled cross-over design was employed, involving four experimental trials; placebo (4-day)-placebo (acute)/PP, placebo (4-day)-caffeine (acute)/PC, caffeine (4-day)-caffeine (acute)/CC and caffeine (4-day)-placebo (acute)/CP. Fourteen male recreationally-trained cyclists ingested capsules containing either placebo or caffeine (6 mg∙kg-1) for 4 days. On day 5 (acute), capsules containing placebo or caffeine (6 mg∙kg-1) were ingested 60 min before completing a 16 km time-trial (TT). CC and PC showed improvements in time (3.54%, ES = 0.72; 2.53%, ES = 0.51) and in output power (2.85%, ES = 0.25; 2.53%, ES = 0.20) (p < 0.05) compared to CP and PP conditions, respectively. These effects were accompanied by increased heart rate (2.63%, ES = 0.47; 1.99%, ES = 0.34), minute volume (13.11%, ES = 0.61; 16.32%, ES = 0.75), expired O2 fraction (3.29%, ES = 0.96; 2.87, ES = 0.72), lactate blood concentration (immediately after, 29.51% ES = 0.78; 28.21% ES = 0.73 recovery (10 min), 36.01% ES = 0.84; 31.22% ES = 0.81), and reduction in expired CO2 fraction (7.64%, ES = 0.64; 7.75%, ES = 0.56). In conclusion, these results indicate that caffeine, when ingested by cyclists in a dose of 6 mg∙kg-1 for 4 days, does not induce tolerance to the ergogenic effects promoted by acute intake on physiological, metabolic, and performance parameters.
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3.
Pre-Exercise Glucose Ingestion May Improve Endurance Capacity in East Asian Student Athletes with Lower Blood Glucose Response.
Koma, R, Terasawa, N
Journal of nutritional science and vitaminology. 2020;(2):150-157
Abstract
The main purpose of this study was to investigate the influence of pre-exercise glucose ingestion after a 2.5-h fast on the endurance capacity and blood glucose response in East Asian athletes who is expected to have genetically low insulin response. A total of 8 Japanese student athletes ingested 1.5 g/kg body mass of glucose (G trial) or 0.5 g/kg body mass of artificial sweetener dissolved in water (P trial) 30 min before exercise test after consuming a standardized breakfast. The exercise test comprised 40 min cycling exercise at 50% maximal oxygen uptake (VO2max), immediately followed by cycling to exhaustion at 70% VO2max. Before analyzing the data, we grouped the subjects into two groups depending on whether they showed rapid increase in blood glucose at the onset of exercise (increase rate in LOW group is <20% and HIGH group is ≥20%) to evaluate subject's insulin response to glucose feeding. No subjects developed rebound hypoglycemia (<70 mg/dL) in the G trial of both group. Significantly higher blood glucose during exercise was recognized only in the G trial of LOW group. Although no significant difference was observed between the two trials of both group, cycling time to exhaustion in the LOW group tended to increase because of glucose ingestion. These results suggest that pre-exercise ingestion of glucose in East Asian student athletes does not induce rebound hypoglycemia regardless of difference in individual insulin responses. Furthermore, individuals with low insulin responses seem to improve endurance performance with glucose ingestion before exercise.
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Carbohydrate Hydrogel Products Do Not Improve Performance or Gastrointestinal Distress During Moderate-Intensity Endurance Exercise.
King, AJ, Rowe, JT, Burke, LM
International journal of sport nutrition and exercise metabolism. 2020;(5):305-314
Abstract
The benefits of ingesting exogenous carbohydrate (CHO) during prolonged exercise performance are well established. A recent food technology innovation has seen sodium alginate and pectin included in solutions of multiple transportable CHO, to encapsulate them at pH levels found in the stomach. Marketing claims include enhanced gastric emptying and delivery of CHO to the muscle with less gastrointestinal distress, leading to better sports performance. Emerging literature around such claims was identified by searching electronic databases; inclusion criteria were randomized controlled trials investigating metabolic and/or exercise performance parameters during endurance exercise >1 hr, with CHO hydrogels versus traditional CHO fluids and/or noncaloric hydrogels. Limitations associated with the heterogeneity of exercise protocols and control comparisons are noted. To date, improvements in exercise performance/capacity have not been clearly demonstrated with ingestion of CHO hydrogels above traditional CHO fluids. Studies utilizing isotopic tracers demonstrate similar rates of exogenous CHO oxidation, and subjective ratings of gastrointestinal distress do not appear to be different. Overall, data do not support any metabolic or performance advantages to exogenous CHO delivery in hydrogel form over traditional CHO preparations; although, one study demonstrates a possible glycogen sparing effect. The authors note that the current literature has largely failed to investigate the conditions under which maximal CHO availability is needed; high-performance athletes undertaking prolonged events at high relative and absolute exercise intensities. Although investigations are needed to better target the testimonials provided about CHO hydrogels, current evidence suggests that they are similar in outcome and a benefit to traditional CHO sources.
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Multi-ingredient pre-workout supplementation changes energy system contribution and improves performance during high-intensity intermittent exercise in physically active individuals: a double-blind and placebo controlled study.
Figueiredo, C, Lira, FS, Rossi, FE, Billaut, F, Loschi, R, Padilha, CS
Journal of the International Society of Sports Nutrition. 2020;(1):30
Abstract
BACKGROUND Nutritional ergogenic aids are commonly used to boost physiological adaptations to exercise and promote greater fitness gains. However, there is a paucity of data about multi-ingredient pre-workout supplementation (MIPS). Therefore, the aim of the present study was to investigate the acute effects of MIPS on the oxidative, glycolytic and ATP-CP energy systems contribution, time spent above 90% V̇O2max (T90% V̇O2max), excess post-exercise oxygen consumption (EPOC) magnitude, number of efforts and time to exhaustion during a high-intensity interval exercise (HIIE) session. METHODS Twelve physically-active and healthy men completed the HIIE sessions that involved running bouts of 15 s on the treadmill at 120% of the maximum aerobic speed (MAS), interspersed with 15 s of passive recovery. Blood lactate was collected at immediately post, 3, 5, and 7 min post exercise. The contribution of ATP-CP, glycolytic and oxidative systems was analyzed at rest, during the HIIE sessions and for 20 min post. Performance variables (time to exhaustion, number of efforts) and oxygen consumption were also analyzed. RESULTS MIPS significantly increased the number of efforts performed (MIPS: 41 ± 10 vs Placebo: 36 ± 12, p = 0.0220) and time to exhaustion (MIPS: 20.1 ± 6 min vs Placebo: 17 ± 5 min, p = 0.0226). There was no difference between supplements for both T90% V̇O2max (p = 0.9705) and EPOC (p = 0.4930). Consuming MIPS significantly increased the absolute oxidative energy system contribution by 23.8% (p = 0.0163) and the absolute ATP-CP contribution by 28.4% (p = 0.0055) compared to placebo. There was only a non-significant tendency for a higher glycolytic system contribution after MIPS ingestion (p = 0.0683). CONCLUSION Acute MIPS ingestion appears effective at increasing both aerobic and anaerobic alactic energy contribution and time to exhaustion during a HIIE protocol.
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Effect of Almond Supplementation on Non-Esterified Fatty Acid Values and Exercise Performance.
Esquius, L, Segura, R, Oviedo, GR, Massip-Salcedo, M, Javierre, C
Nutrients. 2020;(3)
Abstract
Several studies have investigated the effects of fat intake before exercise on subsequent substrate oxidation and exercise performance. While some studies have reported that unsaturated fatty acid supplementation slightly increases fat oxidation, the changes have not been reflected in the maximum oxygen uptake or in other performance and physiological parameters. We selected almonds as a fatty acid (FA) source for acute supplementation and investigated their effect on non-esterified fatty acid (NEFA) values and exercise performance. Five physically active male subjects (age 32.9 ± 12.7 years, height 178.5 ± 3.3 cm, and weight 81.3 ± 9.7 kg) were randomly assigned to take an almond or placebo supplement 2 h before participating in two cycling resistance training sessions separated by an interval of 7-10 days. Their performance was evaluated with a maximal incremental test until exhaustion. Blood samples collected before, during, and after testing were biochemically analysed. The results indicated a NEFA value average increase of 0.09 mg·dL-1 (95% CI: 0.05-0.14; p < 0.001) after active supplement intake and enhanced performance (5389 ± 1795 W vs. placebo 4470 ± 2053 W, p = 0.043) after almond supplementation compared to the placebo. The almond supplementation did not cause gastrointestinal disturbances. Our study suggests that acute almond supplementation 2 h before exercise can improve performance in endurance exercise in trained subjects.
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No Influence of Low-, Medium-, or High-Dose Tyrosine on Exercise in a Warm Environment.
Tumilty, L, Gregory, N, Beckmann, M, Thatcher, R
Medicine and science in sports and exercise. 2020;(6):1404-1413
Abstract
PURPOSE Tyrosine administration may counter exercise fatigue in a warm environment, but the typical dose is inconclusive, with little known about higher doses. We explored how three tyrosine doses influenced the circulating ratio of tyrosine/amino acids competing for brain uptake and hypothesized that a medium and high dose would enhance exercise performance in a warm environment. METHODS Eight recreationally trained, non-heat-acclimated male individuals (mean ± SD age, 23 ± 4 yr; stature, 181 ± 7 cm; body mass, 76.1 ± 5.9 kg; peak oxygen uptake, 4.1 ± 0.5 L·min) performed a peak oxygen uptake test, two familiarization trials, then four experimental trials in a randomized order separated by 7 d. Before exercise, subjects drank 2 × 300 mL sugar-free drinks delivering 0 (PLA), 150 (LOW), 300 (MED), or 400 (HIGH) mg·kg body mass tyrosine in a double-blind fashion. Subjects performed a 60-min constant intensity cycling then a simulated time trial in 30°C and 60% relative humidity. RESULTS Time trial performance (P = 0.579) was not influenced by tyrosine ingestion. The plasma ratio of tyrosine/∑(free-tryptophan, leucine, isoleucine, valine, phenylalanine, methionine), a key determinant of brain tyrosine influx, increased relative to PLA (P < 0.001). The increase was similar (P > 0.05) in MED (7.7-fold) and HIGH (8.2-fold), and greater than that in LOW (5.3-fold; P < 0.05). No differences existed between trials in core and skin temperature, heart rate, RPE, or thermal sensation (P > 0.05). CONCLUSION Exercise performance in a warm environment was not influenced by tyrosine availability in recreationally trained male individuals. The results provide novel data informing future studies, on the tyrosine dose maximizing the circulating ratio of tyrosine/amino acids competing for brain uptake.
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[Exploiting dietary supplements with antioxidant properties for enhancing physical efficiency at the state of physical fatigue in sports].
Kornyakova, VV, Badtieva, VA, Balandin, MY
Voprosy pitaniia. 2020;(3):86-96
Abstract
The aim of the review was to analyze the current scientific data concerning the dietary supplements (DS) with antioxidant activity to be recommended for using in order to improve physical performance in professional athletes experiencing fatigue. Material and methods. Online publications reviewing has been performed using the PubMed, Web of Science, Google Scholar databases, eLibrary platform, Cyberleninka. Results. Maintaining an athlete organism various systems functioning at the optimum level is known to be represented enough effective only with application of dietary supplements. The results of comprehensive up-to-date foreign and domestic scientific researches concerning dietary supplements including components with antioxidant activity to be recommended for delaying fatigue onset and improving physical performance in athletes have been analyzed. Application of such dietary supplements is dictated by the necessity to increase antioxidant organism defense, to maintain the normal functioning of a number of enzymes and prevent oxidative stress. The effectiveness of dietary supplements containing such components as vitamins E, A, and C; selenium, succinic and alpha-lipoic acid, coenzyme Q10, glutathione and other natural sources of antioxidants have been discussed in the review. The analysis of the data presented in the current scientific literature have confirmed the urgency of additional researches with the aim of receiving sufficient pieces of evidences of effectiveness of a number of dietary supplements with antioxidant activity in physical fatigue. Conclusion. For postponing fatigue and improving physical efficiency in sports there appear to be reasonable to use dietary supplements possessing antioxidant properties with effectiveness confirmed by scientific researches.
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9.
The association of HFE gene H63D polymorphism with endurance athlete status and aerobic capacity: novel findings and a meta-analysis.
Semenova, EA, Miyamoto-Mikami, E, Akimov, EB, Al-Khelaifi, F, Murakami, H, Zempo, H, Kostryukova, ES, Kulemin, NA, Larin, AK, Borisov, OV, et al
European journal of applied physiology. 2020;(3):665-673
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Abstract
PURPOSE Iron is an important component of the oxygen-binding proteins and may be critical to optimal athletic performance. Previous studies have suggested that the G allele of C/G rare variant (rs1799945), which causes H63D amino acid replacement, in the HFE is associated with elevated iron indexes and may give some advantage in endurance-oriented sports. The aim of the present study was to investigate the association between the HFE H63D polymorphism and elite endurance athlete status in Japanese and Russian populations, aerobic capacity and to perform a meta-analysis using current findings and three previous studies. METHODS The study involved 315 international-level endurance athletes (255 Russian and 60 Japanese) and 809 healthy controls (405 Russian and 404 Japanese). Genotyping was performed using micro-array analysis or by PCR. VO2max in 46 male Russian endurance athletes was determined using gas analysis system. RESULTS The frequency of the iron-increasing CG/GG genotypes was significantly higher in Russian (38.0 vs 24.9%; OR 1.85, P = 0.0003) and Japanese (13.3 vs 5.0%; OR 2.95, P = 0.011) endurance athletes compared to ethnically matched controls. The meta-analysis using five cohorts (two French, Japanese, Spanish, and Russian; 586 athletes and 1416 controls) showed significant prevalence of the CG/GG genotypes in endurance athletes compared to controls (OR 1.96, 95% CI 1.58-2.45; P = 1.7 × 10-9). Furthermore, the HFE G allele was associated with high V̇O2max in male athletes [CC: 61.8 (6.1), CG/GG: 66.3 (7.8) ml/min/kg; P = 0.036]. CONCLUSIONS We have shown that the HFE H63D polymorphism is strongly associated with elite endurance athlete status, regardless ethnicities and aerobic capacity in Russian athletes.
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10.
Efficacy of Ingesting an Oral Rehydration Solution after Exercise on Fluid Balance and Endurance Performance.
Fan, PW, Burns, SF, Lee, JKW
Nutrients. 2020;(12)
Abstract
This study investigated the efficacy of ingesting an oral rehydration solution (DD) that has a high electrolyte concentration after exercise on fluid balance and cycling performance in comparison with a sports drink (SD) and water (WA). Nine healthy males aged 24 ± 2 years (mean ± SD), with peak oxygen uptake (VO2 peak) 55 ± 6 mL·kg-1·min-1 completed three experimental trials in a randomised manner ingesting WA, SD (carbohydrates: 62 g·L-1, sodium: 31 ± 3 mmol·L-1) or DD (carbohydrates: 33 g·L-1, sodium: 60 ± 3 mmol·L-1). On all trials, fluid was ingested during 75 min cycling at 65% VO2 peak (temperature: 30.4 ± 0.3 °C, relative humidity: 76 ± 1%, simulated wind speed: 8.0 ± 0.6 m·s-1) and during 2 h of recovery (temperature: 23.0 ± 1.0 °C, relative humidity: 67 ± 2%), with the total volume equivalent to 150% of sweat loss during the ride. A 45 min pre-load cycling time trial at a 65% VO2 peak followed by a 20 km time trial was conducted after a further 3 h of recovery. Fluid retention was higher with DD (30 ± 15%) than WA (-4 ± 19%; p < 0.001) and SD (10 ± 15%; p = 0.002). Mean ratings of palatability were similar among drinks (WA: 4.25 ± 2.60; SD: 5.61 ± 1.79; DD: 5.40 ± 1.58; p = 0.33). Although time trial performance was similar across all three trials (WA: 2365 ± 321 s; SD: 2252 ± 174 s; DD: 2268 ± 184 s; p = 0.65), the completion time was faster in eight participants with SD and seven participants with DD than with WA. Comparing SD with DD, completion time was reduced in five participants and increased in four participants. DD was more effective at restoring the fluid deficit during recovery from exercise than SD and WA without compromising the drink's palatability with increased sodium concentration. Most individuals demonstrated better endurance exercise time trial performance with DD and SD than with WA.