Resource allocation in mammalian systems

Cells execute biological functions to support phenotypes such as growth, migration, and secretion. Complementarily, each function of a cell has resource costs that constrain phenotype. Resource allocation by a cell allows it to manage these costs and optimize their phenotypes. In fact, the management of resource constraints (e.g., nutrient availability, bioenergetic capacity, and macromolecular machinery production) shape activity and ultimately impact phenotype. In mammalian systems, quantification of resource allocation provides important insights into higher-order multicellular functions; it shapes intercellular interactions and relays environmental cues for tissues to coordinate individual cells to overcome resource constraints and achieve population-level behavior. Furthermore, these constraints, objectives, and phenotypes are context-dependent, with cells adapting their behavior according to their microenvironment, resulting in distinct steady-states. This review will highlight the biological insights gained from probing resource allocation in mammalian cells and tissues.

Effect of a cajuína hydroelectrolytic drink on the physical performance and hydration status of recreational runners

Cajuína is a processed drink derived from cashew and is widely consumed in the northeast region of Brazil. This study evaluated the effect of a cajuína-based hydroelectrolytic drink on the aerobic performance and hydration status of recreational runners. Seventeen males (31.9 ± 1.6 years, 51.0 ± 1.4 ml/kg/min) performed three time-to-exhaustion running sessions on a treadmill at 70% VO2max, ingesting cajuína hydroelectrolytic drink (CJ), high carbohydrate commercial hydroelectrolytic drink (CH) and mineral water (W) every 15 min during the running test. The participants ran 80.3 ± 8.4 min in CJ, 70.3 ± 6.8 min in CH and 71.8 ± 6.9 min in W, with no statistical difference between procedures. Nevertheless, an effect size of η2 = 0.10 (moderate) was observed. No statistical difference was observed in the concentrations of sodium, potassium, and osmolality in both serum and urine between the three conditions. However, the effect size was moderate (urine sodium) and high (serum sodium, potassium, and osmolality). Urine specific gravity, sweating rate and heart rate were not significantly different between drinks. The cajuína-based hydroelectrolytic drink promotes similar effects compared to commercial hydroelectrolytic drink and water, considering specific urine gravity, heart rate, sweating, and time to exhaustion in recreational runners.

What if gastrointestinal complications in endurance athletes were gut injuries in response to a high consumption of ultra-processed foods? Please take care of your bugs if you want to improve endurance performance: a narrative review

To improve performance and recovery faster, athletes are advised to eat more often than usual and consume higher doses of simple carbohydrates, during and after exercise. Sports energetic supplements contain food additives, such as artificial sweeteners, emulsifiers, acidity regulators, preservatives, and salts, which could be harmful to the gut microbiota and impair the intestinal barrier function. The intestinal barrier plays a critical function in bidirectionally regulation of the selective transfer of nutrients, water, and electrolytes, while preventing at the same time, the entrance of harmful substances (selective permeability). The gut microbiota helps to the host to regulate intestinal homeostasis through metabolic, protective, and immune functions. Globally, the gut health is essential to maintain systemic homeostasis in athletes, and to ensure proper digestion, metabolization, and substrate absorption. Gastrointestinal complaints are an important cause of underperformance and dropout during endurance events. These complications are directly related to the loss of gut equilibrium, mainly linked to microbiota dysbiosis and leaky gut. In summary, athletes must be cautious with the elevated intake of ultra-processed foods and specifically those contained on sports nutrition supplements. This review points out the specific nutritional interventions that should be implemented and/or discontinued depending on individual gut functionality.

Combined Exercise Training and Nutritional Interventions or Pharmacological Treatments to Improve Exercise Capacity and Body Composition in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease that is associated with significant morbidity, mortality, and healthcare costs. The burden of respiratory symptoms and airflow limitation can translate to reduced physical activity, in turn contributing to poor exercise capacity, muscle dysfunction, and body composition abnormalities. These extrapulmonary features of the disease are targeted during pulmonary rehabilitation, which provides patients with tailored therapies to improve the physical and emotional status. Patients with COPD can be divided into metabolic phenotypes, including cachectic, sarcopenic, normal weight, obese, and sarcopenic with hidden obesity. To date, there have been many studies performed investigating the individual effects of exercise training programs as well as nutritional and pharmacological treatments to improve exercise capacity and body composition in patients with COPD. However, little research is available investigating the combined effect of exercise training with nutritional or pharmacological treatments on these outcomes. Therefore, this review focuses on exploring the potential additional beneficial effects of combinations of exercise training and nutritional or pharmacological treatments to target exercise capacity and body composition in patients with COPD with different metabolic phenotypes.

Recovery Methods in Basketball: A Systematic Review

Although different strategies have been implemented to manage recovery-fatigue status in athletes, there is still a lack of consensus on which recovery protocols have the greatest impact and effectiveness when implemented with basketball players, including both physiological and psychological recovery methods. Thus, the purpose of this systematic review is to: (a) determine which recovery methods attain the greatest benefit in restoring the process of attenuating fatigue and (b) provide sports practitioners with guidelines on how some of the most effective recovery strategies can be used to optimize athletes' recovery and ultimately enhance their performance. Using the PRISMA guidelines, a total of 3931 research reports were obtained through four database searches (i.e., PubMed, Scopus, Cochrane, and Web of Science), from which only 25 met the inclusion and exclusion criteria. The recovery protocols analyzed in this systematic review were: sleep, nutrition, hydration, ergogenic aids, cold-water immersion, compression garments, massage, acupuncture, tapering, mindfulness, and red-light irradiation. The results revealed that all recovery strategies are capable of attenuating fatigue and enhancing recovery in basketball players to a certain degree. However, an individualized approach should be promoted, where a combination of proactive recovery modalities appears to result in the most rapid rates of recovery and athletes' ability to maintain high-level performance. Recovery should be programmed as an integral component of training regimens. Also, cooperation and communication between coaches, players, and the rest of the team staff members are essential in minimizing the risk of non-functional overreaching or injury and optimizing basketball players' on-court performance.

Eicosapentaenoic Acid and Medium-Chain Triacylglycerol Structured Lipids Improve Endurance Performance

PURPOSE

The effects of intake of STGs containing esterified eicosapentaenoic acid (EPA) and medium-chain triglycerides (MCTs) on cardiorespiratory endurance have not yet been reported. This study aimed to examine the efficacy of interesterified structured lipids EPA and MCTs on cardiorespiratory endurance.

METHODS

This 8-week randomized double-blind placebo-controlled parallel-group study involved 19 healthy men. The participants were randomly assigned to a group that received interesterified structured lipids EPA and MCTs (STG group, 9 participants) or a group receiving a PM of EPA and MCTs (PM group, 10 participants). The outcome measures were time to exhaustion (TTE) and time to reach the anaerobic threshold in the peak oxygen uptake (VO2peak) test, VO2peak, and anaerobic threshold.

RESULTS

The increase in TTE in the VO2peak test after the intervention period compared with before the intervention period was significantly greater in the STG group (53 ± 53 s) than in the PM group (-10 ± 63 s; p < 0.05). Similarly, the increase in time to reach the anaerobic threshold was significantly greater in the STG group (82 ± 55 s) than in the PM group (-26 ± 52 s; p < 0.001).

CONCLUSION

This study demonstrated that the consumption of interesterified structured lipids EPA and MCTs improved endurance in humans.

Development of an Instrument to Evaluate the Intake of Liquids, Food and Supplements in Endurance Competitions: Nutritional Intake Questionnaire for Endurance Competitions-NIQEC

BACKGROUND

In the last few years endurance sports have experienced a great increase in the number of competitions and participants. Dietary-nutritional planning is key for performing well during such competitions. To date, there is no questionnaire expressly developed to be able to analyze the consumption of liquids, foods, and supplements, as well as gastrointestinal problems in these events. This study describes the development of the Nutritional Intake Questionnaire for Endurance Competitions (NIQEC).

METHODS

The study was composed in the following phases: (1) Bibliographic search for the most important nutrients, (2) focus groups (17 dietitian-nutritionists and 15 experienced athletes) and generation of items, (3) Delphi surveys, and (4) cognitive interviews.

RESULTS

After an initial shaping of the questionnaire with the items that emerged in the focus groups, their relevance was evaluated by means of the Delphi survey, which showed more than 80% approval for most items. Finally, the cognitive interviews indicated that the questionnaire was simple and complete for its purpose. The final NIQEC (n = 50 items) was divided in 5 sections: Demographic data; sports data; consumption of liquids, food and supplements before, during, and after the competition; gastrointestinal complaints, and dietary-nutritional planning for the competition.

CONCLUSIONS

The NICEQ is a useful tool that allows collecting information from participants on sociodemographic factors and gastrointestinal complaints, and estimating the intake of liquid, food, and supplements, for endurance competitions.

The Role of Diets and Dietitians for Para-Athletes: A Pilot Study Based on Interviews

Efforts to provide nutrition support to para-athletes have not been established to date, and are far behind those established for athletes without disabilities. In the present study, we attempted to clarify the actual situation regarding dietary challenges of para-athletes. The aim of this study was to obtain clues to effective intervention methods that encourage the practice of sports nutrition. Six active elite para-athletes (30–70 years, four males) and a female physical therapist without physical disability participated in semi-structured interviews. All para-athletes had lower-limb disabilities and participated in the international wheelchair sports competitions (tennis, softball, and table tennis, with 2–26 years of player history). The interview items were on the ideal diet for improving competitive performance, evaluation of their typical diets, and the role of the dietitian as support. Responses obtained from participants were analyzed using quantitative content analysis by language analysis software. There are differences in the ideal diet based on the characteristics of the sport, but most participants believed that a nutritionally well-balanced diet with abundant vegetables was ideal for improving competitive performance. Para-athletes who use a wheelchair daily pay attention to their total calorie intake, because gaining weight is a critical issue for operating their wheelchairs and transferring themselves to and from their wheelchairs. Despite their world-class competition levels, none of them received routine dietary advice from dietitians. Some para-athletes did not even feel the need to engage with dietitians. Even for these para-athletes at a high level of competition, the “ideal diet” they considered was not always the optimal diet for improving their competitive performance. In addition, there are various barriers to practicing their optimal diet due to disability characteristics. Dietitians need to understand these barriers, their concerns and conflicts, and how to help them plan the optimal diet to improve their performance and maintain overall health.

Effects of the ketogenic diet on performance and body composition in athletes and trained adults: a systematic review and Bayesian multivariate multilevel meta-analysis and meta-regression

This systematic review with meta-analysis aimed to determine the effects of the ketogenic diet (KD) against carbohydrate (CHO)-rich diets on physical performance and body composition in trained individuals. The MEDLINE, EMBASE, CINAHL, SPORTDiscus, and The Cochrane Library were searched. Randomized and non-randomized controlled trials in athletes/trained adults were included. Meta-analytic models were carried out using Bayesian multilevel models. Eighteen studies were included providing estimates on cyclic exercise modes and strength one-maximum repetition (1-RM) performances and for total, fat, and free-fat masses. There were more favorable effects for CHO-rich than KD on time-trial performance (mode [95% credible interval]; -3.3% [-8.5%, 1.7%]), 1-RM (-5.7% [-14.9%, 2.6%]), and free-fat mass (-0.8 [-3.4, 1.9] kg); effects were more favorable to KD on total (-2.4 [-6.2, 1.8] kg) and fat mass losses (-2.4 [-5.4, 0.2] kg). Likely modifying effects on cyclic performance were the subject's sex and VO2max, intervention and performance durations, and mode of exercise. The intervention duration and subjects' sex were likely to modify effects on total body mass. KD can be a useful strategy for total and fat body losses, but a small negative effect on free-fat mass was observed. KD was not suitable for enhancing strength 1-RM or high-intensity cyclic performances.

Carbohydrate Intake Practices and Determinants of Food Choices During Training in Recreational, Amateur, and Professional Endurance Athletes: A Survey Analysis

Carbohydrate (CHO) intake during exercise can optimize endurance performance. However, there is limited information regarding fueling practices of endurance athletes during training. Accordingly, an anonymous German-language online survey was circulated examining the determinants of CHO choices, and intake practices among runners, triathletes, and cyclists during training. Survey questions included predefined answers, and a Likert scale with response of CHO food choice intakes from 1 = never to 5 = always. 1,081 endurance participants (58.0% male, 68.6% aged 18–39 years) of varying competitive levels were included in the analysis. Overall, most participants consumed a combination of commercial sport nutrition products and everyday foods (67.4%, n = 729) with their primary reason that food-first was preferred, but in some exercise scenarios, commercial sport nutrition products were deemed more convenient (61.3%, n = 447). Participants consuming commercial sport nutrition products only (19.3%, n = 209) most often valued their ease of intake during exercise (85.2%, n = 178). Among those consuming everyday foods only (13.2%, n = 143), the most common reason was the perceived importance of eating wholesome foods/natural ingredients (84.6%, n = 121). Between the most frequently consumed CHO sources during training at low-to-moderate intensities (n = 1032), sports drinks (mean ± SD; 2.56 ± 1.33) were consumed significantly more often than bananas (2.27 ± 1.14, p &lt; 0.001), with no significant difference in intake frequency between bananas and traditional muesli/fruit/energy bars (2.25 ± 1.14, p = 0.616). Whereas during high intensities (n = 1,077), sports drinks (3.31 ± 1.51) were significantly more often consumed than gels (2.79 ± 1.37), and gels significantly more often than energy bars (2.43 ± 1.28), all commercial sport nutrition products (all, p &lt; 0.001). Overall, 95.1% (n = 1028) of all participants consumed CHO during training at all exercise intensities, with males (n = 602; 2.35 ± 0.70) consuming significantly more often commercial sport nutrition products than females (n = 424; 2.14 ± 0.79, p &lt; 0.001); females consumed significantly more often everyday foods than males (1.66 ± 0.47 vs. 1.54 ± 0.42, p &lt; 0.001). Most participants used mixed CHO forms during low-to-moderate (87.9%), and high exercise intensities (94.7%). 67.6% (n = 731) of all participants reported guiding their CHO intake rates during training by gut feeling. These large-scale survey findings suggest a preference of endurance participants’ CHO intake during training in liquid form independent of exercise intensities and offer novel insights into CHO intake practices to guide sports nutrition strategies and education.

The Impact of Sodium Alginate Hydrogel on Exogenous Glucose Oxidation Rate and Gastrointestinal Comfort in Well-Trained Runners

Purpose

The purpose of this study is to quantify the effect of adding sodium alginate and pectin to a carbohydrate (CHO) beverage on exogenous glucose (ExGluc) oxidation rate compared with an isocaloric CHO beverage.

Methods

Following familiarization, eight well-trained endurance athletes performed four bouts of prolonged running (105 min; 71 ± 4% of VO₂max) while ingesting 175 mL of one of the experimental beverages every 15 min. In randomized order, participants consumed either 70 g^.h⁻¹ of maltodextrin and fructose (10% CHO; NORM), 70 g^.h⁻¹ of maltodextrin, fructose, sodium alginate, and pectin (10% CHO; ENCAP), 180 g^.h⁻¹ of maltodextrin, fructose, sodium alginate, and pectin (26% CHO; HiENCAP), or water (WAT). All CHO beverages had a maltodextrin:fructose ratio of 1:0.7 and contained 1.5 g^.L⁻¹ of sodium chloride. Total substrate oxidation, ExGluc oxidation rate, blood glucose, blood lactate, serum non-esterified fatty acid (NEFA) concentration, and RPE were measured for every 15 min. Every 30 min participants provided information regarding their gastrointestinal discomfort (GID).

Results

There was no significant difference in peak ExGluc oxidation between NORM and ENCAP (0.63 ± 0.07 and 0.64 ± 0.11 g^.min⁻¹, respectively; p > 0.5), both of which were significantly lower than HiENCAP (1.13 ± 0.13 g^.min⁻¹, p < 0.01). Both NORM and HiENCAP demonstrated higher total CHO oxidation than WAT from 60 and 75 min, respectively, until the end of exercise, with no differences between CHO trials. During the first 60 min, blood glucose was significantly lower in WAT compared with NORM and HiENCAP, but no differences were found between CHO beverages. Both ENCAP and HiENCAP demonstrated a higher blood glucose concentration from 60–105 min than WAT, and ENCAP was significantly higher than HiENCAP. There were no significant differences in reported GID symptoms between the trials.

Conclusions

At moderate ingestion rates (i.e., 70 g^.h⁻¹), the addition of sodium alginate and pectin did not influence the ExGluc oxidation rate compared with an isocaloric CHO beverage. At very high ingestion rates (i.e., 180 g^.h⁻¹), high rates of ExGluc oxidation were achieved in line with the literature.

Meta-Analysis of Carbohydrate Solution Intake during Prolonged Exercise in Adults: From the Last 45+ Years' Perspective

Carbohydrate (CHO) supplementation during prolonged exercise postpones fatigue. However, the optimum administration timing, dosage, type of CHO intake, and possible interaction of the ergogenic effect with athletes' cardiorespiratory fitness (CRF) are not clear. Ninety-six studies (from relevant databases based on predefined eligibility criteria) were selected for meta-analysis to investigate the acute effect of ≤20% CHO solutions on prolonged exercise performance. The between-subject standardized mean difference [SMD = ([mean post-value treatment group-mean post-value control group]/pooled variance)] was assessed. Overall, SMD [95% CI] of 0.43 [0.35, 0.51] was significant (p < 0.001). Subgroup analysis showed that SMD was reduced as the subjects' CRF level increased, with a 6-8% CHO solution composed of GL:FRU improving performance (exercise: 1-4 h); administration during the event led to a superior performance compared to administration before the exercise, with a 6-8% single-source CHO solution increasing performance in intermittent and 'stop and start' sports and an ~6% CHO solution appearing beneficial for 45-60 min exercises, but there were no significant differences between subjects' gender and age groups, varied CHO concentrations, doses, or types in the effect measurement. The evidence found was sound enough to support the hypothesis that CHO solutions, when ingested during endurance exercise, have ergogenic action and a possible crossover interaction with the subject's CRF.

The Impact of Vegan and Vegetarian Diets on Physical Performance and Molecular Signaling in Skeletal Muscle

Muscular adaptations can be triggered by exercise and diet. As vegan and vegetarian diets differ in nutrient composition compared to an omnivorous diet, a change in dietary regimen might alter physiological responses to physical exercise and influence physical performance. Mitochondria abundance, muscle capillary density, hemoglobin concentration, endothelial function, functional heart morphology and availability of carbohydrates affect endurance performance and can be influenced by diet. Based on these factors, a vegan and vegetarian diet possesses potentially advantageous properties for endurance performance. Properties of the contractile elements, muscle protein synthesis, the neuromuscular system and phosphagen availability affect strength performance and can also be influenced by diet. However, a vegan and vegetarian diet possesses potentially disadvantageous properties for strength performance. Current research has failed to demonstrate consistent differences of performance between diets but a trend towards improved performance after vegetarian and vegan diets for both endurance and strength exercise has been shown. Importantly, diet alters molecular signaling via leucine, creatine, DHA and EPA that directly modulates skeletal muscle adaptation. By changing the gut microbiome, diet can modulate signaling through the production of SFCA.

The perceived benefit of intraoperative stress modifiers for surgeons: an experimental simulation study in volunteers

Background

During surgery, surgeons often work under stressful conditions, which could affect patient safety. Reducing intraoperative stress for surgeons could benefit surgeons and subsequently patients. It is difficult to study stress and stress relief in real life situations due to the multitude of confounding factors. The aim of this study was to evaluate simulated intraoperative stressors on surgeons’ stress levels and the effect of an intervention (pause including a sugar-containing drink) during standardized experiments (simulated operations).

Methods

An experimental interventional study was conducted using a simulator. The healthy surgeon volunteers were randomized to intervention and control in a cross-over design. Primary endpoint was salivary cortisol difference between a pause including a sugar containing drink (intervention) and controls. Secondary endpoints were change in heart rate, change in self-perceived stress measured by the State Trait Anxiety Inventory (STAI), and experience of the intraoperative pause. Endpoints were calculated with a mixed effect analysis of covariance (ANCOVA) model.

Results

Seventeen surgeons performed 32 experiments. There was no statistically significant difference in salivary cortisol between simulations with and without a pause including a sugar-containing drink; percent reduction, 8% (0.92 (95%CI:0.72;1.18)), p-value = 0.469. The surgeons’ self-estimation of intervention was positive, but there was no statistically significant difference in heart rate or STAI.

Conclusions

The surgeons’ experience of a pause including a drink was positive but there were no differences in physiological outcomes of the intervention. Lessons learned from this study could contribute to optimizing design of future studies.

Trial registration

Clinicaltrials.gov NCT04626648, Registered November 6, 2020, retrospectively registered.

A Syrup–Water Mixture Increases Performance in the Yo-Yo Intermittent Recovery Test after a Soccer-Specific Preload in the Hoff Test: A Double-Blind Crossover Study

Background: The positive effect of carbohydrates from commercial beverages on soccer-specific exercise has been clearly demonstrated. However, no study is available that uses a home-mixed beverage in a test where technical skills were required. Methods: Nine subjects participated voluntarily in this double-blind, randomized, placebo-controlled crossover study. On three testing days, the subjects performed six Hoff tests with a 3-min active break as a preload and then the Yo-Yo Intermittent Running Test Level 1 (Yo-Yo IR1) until exhaustion. On test days 2 and 3, the subjects received either a 69 g carbohydrate-containing drink (syrup–water mixture) or a carbohydrate-free drink (aromatic water). Beverages were given in several doses of 250 mL each: 30 min before and immediately before the exercise and after 18 and 39 min of exercise. The primary target parameters were the running performance in the Hoff test and Yo-Yo IR1, body mass and heart rate. Statistical differences between the variables of both conditions were analyzed using paired samples t-tests. Results: The maximum heart rate in Yo-Yo IR1 showed significant differences (syrup: 191.1 ± 6.2 bpm; placebo: 188.0 ± 6.89 bpm; t(6) = −2.556; p = 0.043; dz = 0.97). The running performance in Yo-Yo IR1 under the condition syrup significantly increased by 93.33 ± 84.85 m (0–240 m) on average (p = 0.011). Conclusions: The intake of a syrup–water mixture with a total of 69 g carbohydrates leads to an increase in high-intensive running performance after soccer specific loads. Therefore, the intake of carbohydrate solutions is recommended for intermittent loads and should be increasingly considered by coaches and players.

The Effects of Sports Drinks During High-Intensity Exercise on the Carbohydrate Oxidation Rate Among Athletes: A Systematic Review and Meta-Analysis

Background: This study examines the effects of sports drinks ingestion during high-intensity exercise for carbohydrate oxidation rate (CHO-O) among athletes.

Methods: PubMed, Embase, and the Cochrane library were searched for available papers published up to November 2019. The primary outcome is the carbohydrate oxidation rate (CHO-O), and the secondary outcome is the fat oxidation rate (Fat-O). Statistical heterogeneity among the included studies was evaluated using Cochran's Q test and the I² index. The random-effects model was used for all analyses, regardless of the I² index.

Results: Five studies are included, with a total of 58 participants (range, 8–14/study). All five studies are randomized crossover trials. Compared to the control beverages, sports drinks have no impact on the CHO-O of athletes [weighted mean difference (WMD) = 0.29; 95% CI, −0.06 to 0.65, P = 0.106; I² = 97.4%, P < 0.001] and on the Fat-O of athletes (WMD = −0.074; 95% CI, −0.19 to 0.06, P = 0.297; I² = 97.5%, P < 0.001). Carbohydrate–electrolyte solutions increase CHO-O (WMD = 0.47; 95% CI, 0.08–0.87, P = 0.020; I² = 97.8%, P < 0.001) but not Fat-O (WMD = −0.14; 95% CI, −0.31 to 0.03, P = 0.103; I² = 98.2%, P < 0.001). Caffeine has a borderline effect on Fat-O (WMD = 0.05; 95% CI, 0.00–0.10, P = 0.050).

Conclusions: Compared with the control beverages, sports drinks show no significant improvement in CHO-O and Fat-O in athletes. Carbohydrate–electrolyte solutions increase CHO-O in athletes but not Fat-O.

Carbohydrate supplementation: a critical review of recent innovations

PURPOSE

To critically examine the research on novel supplements and strategies designed to enhance carbohydrate delivery and/or availability.

METHODS

Narrative review.

RESULTS

Available data would suggest that there are varying levels of effectiveness based on the supplement/supplementation strategy in question and mechanism of action. Novel carbohydrate supplements including multiple transportable carbohydrate (MTC), modified carbohydrate (MC), and hydrogels (HGEL) have been generally effective at modifying gastric emptying and/or intestinal absorption. Moreover, these effects often correlate with altered fuel utilization patterns and/or glycogen storage. Nevertheless, performance effects differ widely based on supplement and study design. MTC consistently enhances performance, but the magnitude of the effect is yet to be fully elucidated. MC and HGEL seem unlikely to be beneficial when compared to supplementation strategies that align with current sport nutrition recommendations. Combining carbohydrate with other ergogenic substances may, in some cases, result in additive or synergistic effects on metabolism and/or performance; however, data are often lacking and results vary based on the quantity, timing, and inter-individual responses to different treatments. Altering dietary carbohydrate intake likely influences absorption, oxidation, and and/or storage of acutely ingested carbohydrate, but how this affects the ergogenicity of carbohydrate is still mostly unknown.

CONCLUSIONS

In conclusion, novel carbohydrate supplements and strategies alter carbohydrate delivery through various mechanisms. However, more research is needed to determine if/when interventions are ergogenic based on different contexts, populations, and applications.

Sustainable solutions to mitigate occupational heat strain - an umbrella review of physiological effects and global health perspectives

BACKGROUND

Climate change is set to exacerbate occupational heat strain, the combined effect of environmental and internal heat stress on the body, threatening human health and wellbeing. Therefore, identifying effective, affordable, feasible and sustainable solutions to mitigate the negative effects on worker health and productivity, is an increasingly urgent need.

OBJECTIVES

To systematically identify and evaluate methods that mitigate occupational heat strain in order to provide scientific-based guidance for practitioners.

METHODS

An umbrella review was conducted in biomedical databases employing the following eligibility criteria: 1) ambient temperatures > 28 °C or hypohydrated participants, 2) healthy adults, 3) reported psychophysiological (thermal comfort, heart rate or core temperature) and/or performance (physical or cognitive) outcomes, 4) written in English, and 5) published before November 6, 2019. A second search for original research articles was performed to identify interventions of relevance but lacking systematic reviews. All identified interventions were independently evaluated by all co-authors on four point scales for effectiveness, cost, feasibility and environmental impact.

RESULTS

Following screening, 36 systematic reviews fulfilled the inclusion criteria. The most effective solutions at mitigating occupational heat strain were wearing specialized cooling garments, (physiological) heat acclimation, improving aerobic fitness, cold water immersion, and applying ventilation. Although air-conditioning and cooling garments in ideal settings provide best scores for effectiveness, the limited applicability in certain industrial settings, high economic cost and high environmental impact are drawbacks for these solutions. However, (physiological) acclimatization, planned breaks, shading and optimized clothing properties are attractive alternative solutions when economic and ecological sustainability aspects are included in the overall evaluation.

DISCUSSION

Choosing the most effective solution or combinations of methods to mitigate occupational heat strain will be scenario-specific. However, this paper provides a framework for integrating effectiveness, cost, feasibility (indoors and outdoor) and ecologic sustainability to provide occupational health and safety professionals with evidence-based guidelines.

Nutrition and Exercise Performance in Adults With Type 1 Diabetes

The best nutritional practices for exercise and sports performance are largely activity specific. The presence of type 1 diabetes undeniably bestows additional factors to consider to manage exercise and ensure adequate nutrients and fuels are available for optimal performance. Whether participating in sports or physical activity on a recreational basis or striving to achieve a high level of athletic performance, individuals with type 1 diabetes must pay attention to their nutritional and dietary patterns, including intake of macronutrients, micronutrients, fluids and supplements, such as caffeine to maintain metabolic and glycemic balance. Performance aside, nutritional recommendations may also differ on an individual basis relative to exercise, glycemic management and body weight goals. Balancing all these dietary factors can be challenging for individuals with type 1 diabetes, and many related aspects have yet to be fully researched in this population.

A Hydrogel Drink With High Fructose Content Generates Higher Exogenous Carbohydrate Oxidation and Lower Dental Biofilm pH Compared to Two Other, Commercially Available, Carbohydrate Sports Drinks

The purpose of this study was to evaluate the substrate oxidation of three commercially available, 14%-carbohydrate sports drinks with different compositions, osmolality, and pH for their impact on dental exposure to low pH. In a cross-over, randomized double-blinded design, 12 endurance athletes (age 31. 2 ± 7.7 years, V ˙ O_2max 65.6 ± 5.0 mL·kg^-1) completed 180 min of cycling at 55% W_max. During the first 100 min of cycling, athletes consumed amylopectin starch (AP), maltodextrin+sucrose (MD+SUC), or maltodextrin+fructose hydrogel (MD+FRU) drinks providing 95 g carbohydrate·h^-1, followed by water intake only at 120 and 160 min. Fuel use was determined using indirect calorimetry and stable-isotope techniques. Additionally, dental biofilm pH was measured using the microtouch method in a subsample of participants (n = 6) during resting conditions before, and at different time intervals up to 45 min following a single bolus of drink. Exogenous carbohydrate oxidation (CHO_EXO) during the 2nd hour of exercise was significantly (P < 0.05) different between all three drinks: MD+FRU (1.17 ± 0.17 g·min^-1), MD+SUC (1.01 ± 0.13 g·min^-1), and AP (0.84 ± 0.11 g·min^-1). At the end of exercise, CHO_EXO and blood glucose concentrations (3.54 ± 0.50, 4.07 ± 0.67, and 4.28 ± 0.47 mmol·L^-1, respectively) were significantly lower post MD+FRU consumption than post MD+SUC and AP consumption (P < 0.05). Biofilm acidogenicity at rest demonstrated a less pronounced pH fall for MD+FRU compared to the acidulant-containing MD+SUC and AP (P < 0.05). In conclusion, while total intake of MD+FRU showed signs of completed uptake before end of monitoring, this was less so for MD+SUC, and not at all the case for AP. Thus, this study showed that despite carbohydrates being encapsulated in a hydrogel, a higher CHO_EXO was observed following MD+FRU drink ingestion compared to AP and MD+SUC consumption upon exposure to the acidic environment of the stomach. This finding may be related to the higher fructose content of the MD+FRU drink compared with the MD+SUC and AP drinks. Furthermore, a carbohydrate solution without added acidulants, which are commonly included in commercial sport drinks, may have less deleterious effects on oral health.

Addition of pectin-alginate to a carbohydrate beverage does not maintain gastrointestinal barrier function during exercise in hot-humid conditions better than carbohydrate ingestion alone

The objective of this study was to compare the effects of consuming a 16% maltodextrin+fructose+pectin-alginate (MAL+FRU+PEC+ALG) drink against a nutrient-matched maltodextrin+fructose (MAL+FRU) drink on enterocyte damage and gastrointestinal permeability after cycling in hot and humid conditions. Fourteen recreational cyclists (7 men) completed 3 experimental trials in a randomized placebo-controlled design. Participants cycled for 90 min (45% maximal aerobic capacity) and completed a 15-min time-trial in hot (32 °C) humid (70% relative humidity) conditions. Every 15 min, cyclists consumed 143 mL of either (i) water; (ii) MAL+FRU+PEC+ALG (90 g·h^-1 CHO/16% w/v); or (iii) a ratio-matched MAL+FRU drink (90 g·h^-1 CHO/16% w/v). Blood was sampled before and after exercise and gastrointestinal (GI) permeability, which was determined by serum measurements of intestinal fatty acid binding protein (I-FABP) and the percent ratio of lactulose (5 g) to rhamnose (2 g) recovered in postexercise urine. Compared with water, I-FABP decreased by 349 ± 67pg·mL^-1 with MAL+FRU+PEC+ALG (p = 0.007) and by 427 ± 56 pg·mL^-1 with MAL+FRU (p = 0.02). GI permeability was reduced in both the MAL+FRU+PEC+ALG (by 0.019 ± 0.01, p = 0.0003) and MAL+FRU (by 0.014 ± 0.01, p = 0.002) conditions relative to water. In conclusion, both CHO beverages attenuated GI barrier damage to a similar extent relative to water. No metabolic, cardiovascular, thermoregulatory, or performance differences were observed between the CHO beverages. Novelty Consumption of multiple-transportable CHO, with or without hydrogel properties, preserves GI barrier integrity and reduces enterocyte damage during prolonged cycling in hot-humid conditions.

[Analysis of nutritional intake in trail runners during competition]

Introduction

Introduction: there has been an increase in the number of endurance sports events during the last 20 years, as well as in the number of their participants. An adequate nutritional plan is essential for a satisfactory performance in this type of events, both in professional and amateur athletes. Objectives: the objective was to determine, evaluate, and compare with the current scientific recommendations the consumption of carbohydrates, water, and sodium by participants in a trail-running event. Methods: the competition completed by the athletes was the "Medio Trail de Alcoy 2019" (Alcoy, Spain), with a distance of 30 km. After completing the race, participants filled out a questionnaire about their food and drink consumption during the event, in addition to other questions about their nutritional habits in general. Eleven participants who met the inclusion criteria were included in the study. Results: the result obtained for average carbohydrate intake was 14.93 g/h, for sodium intake was 146.42 mg/h, and for water intake was 399.73 mL/h. In all, 27 % of participants visited a dietitian-nutritionist on a regular basis, and none reported gastrointestinal tract issues during the race. Conclusions: the carbohydrate and sodium consumption of participants was low as compared to current scientific recommendations; however, water consumption was adequate according to them. Our advice for endurance athletes is visit a specialized dietitian-nutritionist to achieve optimal performance in competitions.

Effects of supplementing with an 18% carbohydrate-hydrogel drink versus a placebo during whole-body exercise in -5 °C with elite cross-country ski athletes: a crossover study

Background

Whilst the ergogenic effects of carbohydrate intake during prolonged exercise are well-documented, few investigations have studied the effects of carbohydrate ingestion during cross-country skiing, a mode of exercise that presents unique metabolic demands on athletes due to the combined use of large upper- and lower-body muscle masses. Moreover, no previous studies have investigated exogenous carbohydrate oxidation rates during cross-country skiing. The current study investigated the effects of a ¹³C-enriched 18% multiple-transportable carbohydrate solution (1:0.8 maltodextrin:fructose) with additional gelling polysaccharides (CHO-HG) on substrate utilization and gastrointestinal symptoms during prolonged cross-country skiing exercise in the cold, and subsequent double-poling time-trial performance in ~ 20 °C.

Methods

Twelve elite cross-country ski athletes (6 females, 6 males) performed 120-min of submaximal roller-skiing (69.3 ± 2.9% of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}} $$\end{document}V˙O₂peak) in −5 °C while receiving either 2.2 g CHO-HG·min^− 1 or a non-caloric placebo administered in a double-blind, randomized manner. Whole-body substrate utilization and exogenous carbohydrate oxidation was calculated for the last 60 min of the submaximal exercise. The maximal time-trial (2000 m for females, 2400 m for males) immediately followed the 120-min submaximal bout. Repeated-measures ANOVAs with univariate follow-ups were conducted, as well as independent and paired t-tests, and significance was set at P < 0.05. Data are presented as mean ± SD.

Results

Exogenous carbohydrate oxidation contributed 27.6 ± 6.6% to the total energy yield with CHO-HG and the peak exogenous carbohydrate oxidation rate reached 1.33 ± 0.27 g·min^− 1. Compared to placebo, fat oxidation decreased by 9.5 ± 4.8% with CHO-HG, total carbohydrate oxidation increased by 9.5 ± 4.8% and endogenous carbohydrate utilization decreased by 18.1 ± 6.4% (all P < 0.05). No severe gastrointestinal symptoms were reported in either trial and euhydration was maintained in both trials. Time-trial performance (8.4 ± 0.4 min) was not improved following CHO-HG compared to placebo (− 0.8 ± 3.5 s; 95% confidence interval − 3.0 to 1.5 s; P = 0.46). No sex differences were identified in substrate utilization or relative performance.

Conclusions

Ingestion of an 18% multiple-transportable carbohydrate solution with gelling polysaccharides was found to be well-tolerated during 120 min of submaximal whole-body exercise, but did not improve subsequent maximal double-poling performance.

Effect of carbohydrate-electrolyte consumption on insulin, cortisol hormones and blood glucose after high-intensity exercise

Objective: This study aimed to examine the effect of CHO-E consumption after high-intensity exercise on insulin, cortisol hormones and blood glucose responses, which is important for performance and recovery in athletes. Methods: Sixteen volunteers, male athletes, participated into this study. Athletes were divided into two groups as experiment (CHO-E) and placebo (PLA). Blood was taken from the athletes three times as basal, post-exercise (PE) and 2 h after ingestion of supplement (PS). Results: When inter-group comparisons, insulin was significantly higher in the CHO-E group than the PLA group at the PS phase (p < .05). Cortisol significantly decreased in the CHO-E group at the PS compared to the PE (p < .05). Conclusions: Carbohydrate-electrolyte consumption after high-intensity exercise, accelerates the recovery process by providing optimal recovery, and enable the metabolism to remain in the anabolic state by preventing it from entering in the catabolic process as well as provides hormonal balance in metabolism.

Fructose co-ingestion to increase carbohydrate availability in athletes

Carbohydrate availability is important to maximize endurance performance during prolonged bouts of moderate- to high-intensity exercise as well as for acute post-exercise recovery. The primary form of carbohydrates that are typically ingested during and after exercise are glucose (polymers). However, intestinal glucose absorption can be limited by the capacity of the intestinal glucose transport system (SGLT1). Intestinal fructose uptake is not regulated by the same transport system, as it largely depends on GLUT5 as opposed to SGLT1 transporters. Combining the intake of glucose plus fructose can further increase total exogenous carbohydrate availability and, as such, allow higher exogenous carbohydrate oxidation rates. Ingesting a mixture of both glucose and fructose can improve endurance exercise performance compared to equivalent amounts of glucose (polymers) only. Fructose co-ingestion can also accelerate post-exercise (liver) glycogen repletion rates, which may be relevant when rapid (<24 h) recovery is required. Furthermore, fructose co-ingestion can lower gastrointestinal distress when relatively large amounts of carbohydrate (>1.2 g/kg/h) are ingested during post-exercise recovery. In conclusion, combined ingestion of fructose with glucose may be preferred over the ingestion of glucose (polymers) only to help trained athletes maximize endurance performance during prolonged moderate- to high-intensity exercise sessions and accelerate post-exercise (liver) glycogen repletion.

Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers

Distance events in Athletics include cross country, 10,000-m track race, half-marathon and marathon road races, and 20- and 50-km race walking events over different terrain and environmental conditions. Race times for elite performers span ∼26 min to >4 hr, with key factors for success being a high aerobic power, the ability to exercise at a large fraction of this power, and high running/walking economy. Nutrition-related contributors include body mass and anthropometry, capacity to use fuels, particularly carbohydrate (CHO) to produce adenosine triphosphate economically over the duration of the event, and maintenance of reasonable hydration status in the face of sweat losses induced by exercise intensity and the environment. Race nutrition strategies include CHO-rich eating in the hours per days prior to the event to store glycogen in amounts sufficient for event fuel needs, and in some cases, in-race consumption of CHO and fluid to offset event losses. Beneficial CHO intakes range from small amounts, including mouth rinsing, in the case of shorter events to high rates of intake (75-90 g/hr) in the longest races. A personalized and practiced race nutrition plan should balance the benefits of fluid and CHO consumed within practical opportunities, against the time, cost, and risk of gut discomfort. In hot environments, prerace hyperhydration or cooling strategies may provide a small but useful offset to the accrued thermal challenge and fluid deficit. Sports foods (drinks, gels, etc.) may assist in meeting training/race nutrition plans, with caffeine, and, perhaps nitrate being used as evidence-based performance supplements.

Oxidative stress and metabolic parameters are differently affected by fructose when rats were kept sedentary or underwent swimming exercise

The current study evaluated whether fructose supplementation affects oxidative stress and metabolic parameters in the liver and gastrocnemius muscle of rats subjected to swimming exercise. Male adult Wistar rats received a fructose solution (10%) or water during 1 h before exercise and during the rest interval by the intragastric route. The swimming protocol consisted of 6 days: each day, rats underwent 3 sessions of 17 min each, with a load of 5% of body mass, and rest intervals of 3 min. Fructose supplementation changed metabolic and oxidative parameters in the liver and gastrocnemius muscle of sedentary rats. Swimming exercise counteracted the increase of triglyceride levels in plasma and liver induced by fructose supplementation. It also reduced thiobarbituric acid reactive species levels in the liver, and catalase and superoxide dismutase activities in the gastrocnemius muscle of supplemented rats. However, fructose supplementation worsened metabolic (hepatic triglyceride levels) and oxidative parameters (thiobarbituric acid reactive species levels) in the liver and gastrocnemius of exercised rats. This study demonstrates that oxidative stress and metabolic parameters were differently affected by fructose supplementation when rats were kept sedentary or underwent swimming exercise. The present results indicate the need of a new insight of the role of fructose supplementation during physical exercise.

Caffeine Ingestion With or Without Low-Dose Carbohydrate Improves Exercise Tolerance in Sedentary Adults

Caffeine (CAF) and carbohydrate (CHO) ingestion delay fatigue during prolonged exercise; however, this is primarily documented in endurance trained (ET) athletes. Our purpose was to determine if these ergogenic aids are also effective to improve exercise tolerance in age-matched sedentary (SED) adults. Using a double-blind crossover design, ET and SED (n = 12 each group) completed four exercise trials consisting of 30 min cycling at standardized matched work rates 10% below lactate threshold (MOD-EX) followed by a time to fatigue (TTF) ride at individually prescribed intensity of 5% above lactate threshold. After standardized breakfast, the following drink treatments were given before and throughout exercise: CAF (3 mg/kg of body mass, equivalent to 1.5 cups premium brewed coffee), low calorie CHO (LCHO) (0.4% solution, 2 g total CHO), CAF+LCHO, and artificially-sweetened placebo (PLA). SED and ET had similar perceived exertion (RPE) during MOD-EX and TTF (23.8 ± 3.1 and 24.1 ± 2.6 min in ET, SED, respectively). LCHO did not benefit exercise tolerance compared to PLA and was less effective (p < 0.05) compared to CAF+LCHO for all participants combined. Thus, the two CAF treatments were averaged, resulting in ~5% lower RPE (p < 0.05) and 21% longer TTF (26.3 ± 10.4 min) compared to the no-CAF (21.7 ± 9.9 min) treatments. Blood glucose and lactate were higher (p < 0.05) with CAF vs. no-CAF. SED and ET only differed in metabolic oxidation rates during exercise (higher overall fat oxidation with ET compared to SED). CAF reduces the perceived effort during exercise and increases the capacity for sedentary individuals, as well as trained athletes, to tolerate higher intensity exercise for greater duration; and, these benefits were not further enhanced by ingesting doses of low carbohydrate regularly during exercise.

Postexercise Fructose-Maltodextrin Ingestion Enhances Subsequent Endurance Capacity

PURPOSE

Restoring skeletal muscle and hepatic glycogen content during short-term (<6 h) recovery from prolonged exercise is pertinent for athletes seeking to maximize performance in repeated exercise bouts. Previous research suggests that coingestion of fructose-glucose carbohydrate sources augments hepatic and has equivalent effects on skeletal muscle glycogen storage during short-term recovery from prolonged exercise compared with isocaloric glucose ingestion. The aim of the present investigation was to determine whether this has a discernible effect on subsequent exercise capacity.

METHODS

Eight trained endurance runners and triathletes performed two experimental trials in a single-blind, randomized, and counterbalanced crossover design. Trials involved treadmill running to exhaustion at 70% V˙O2max, a 4-h recovery with 90 g·h of glucose-maltodextrin (GLU + MAL) or fructose-maltodextrin (FRU + MAL) ingestion (1:1.5 ratio), and a second bout of treadmill running to exhaustion at 70% V˙O2max.

RESULTS

Exercise capacity in bout 2 was significantly greater with FRU + MAL (81.4 ± 22.3 vs 61.4 ± 9.6 min, P = 0.02), a large magnitude effect (effect size = 1.84 ± 1.12, 32.4% ± 19.9%). Total carbohydrate oxidation rates were not significantly different during bout 1 or 2 between trials, although total carbohydrate oxidized in bout 2 was significantly greater with FRU + MAL (223 ± 66 vs 157 ± 26 g, P = 0.02). Ingested carbohydrate oxidation rates were greater during bout 2 with FRU + MAL (P = 0.001). Plasma glucose and nonesterified fatty acid concentrations were not significantly different between trials. Plasma lactate concentrations were significantly greater during recovery before bout 2 with FRU + MAL (P = 0.001). Self-reported nausea and stomach fullness during bout 2 were marginally in favor of FRU + MAL.

CONCLUSION

Short-term recovery of endurance capacity was significantly enhanced with FRU + MAL versus GLU + MAL ingestion during recovery.

Immunometabolism: A Multi-Omics Approach to Interpreting the Influence of Exercise and Diet on the Immune System

Immunometabolism is an evolving field of scientific endeavor that merges immunology and metabolism and has provided valuable context when evaluating the influence of dietary interventions on exercise-induced immune dysfunction. Metabolomics, lipidomics, and proteomics provide a system-wide view of the metabolic response to exercise by simultaneously measuring and identifying a large number of small-molecule metabolites, lipids, and proteins. Many of these are involved with immune function and regulation and are sensitive to dietary influences, especially acute carbohydrate ingestion from either sugar beverages or fruits such as bananas. Emerging evidence using large multi-omics data sets supports the combined intake of fruit sugars and phytochemicals by athletes during heavy exertion as an effective strategy to improve metabolic recovery, augment viral defense, and counter postexercise inflammation and immune dysfunction at the cell level. Multi-omics methodologies have given investigators new outcome targets to assess the efficacy of various dietary interventions for physiologically stressed athletes.

Effect of pre-exercise ingestion of α-lactalbumin on subsequent endurance exercise performance and mood states

This study investigated the effect of pre-exercise α-lactalbumin ingestion on subsequent endurance exercise performance, muscle pain and mood states. In a two-stage cross-over counterbalance design, eleven male endurance runners (age: 31 (se 2) years, height: 169·5 (se 4·4) cm, weight: 63·6 (se 5·1) kg, V̇O2max: 58·8 (se 6·3) ml/kg per min) consumed two solutions (carbohydrate+α-lactalbumin, CA; carbohydrate+whey protein isolate, CW) 2 h before a self-paced 21-km run. Creatine kinase, IL-6, muscle pain, pressure pain threshold (PPT) and mood states were assessed 2 h before exercise, immediately before exercise (Pre-ex0) and immediately after exercise (Post-ex0). No difference was found in 21-km running performance between two trials (CA v. CW: 115·85 (se 5·20) v. 118·85 (se 5·51) min, P=0·48). Compared with CW, CA led to higher PPT at Pre-ex0 (41·77 (se 2·27) v. 35·56 (se 2·10) N/cm2, P<0·01) and Post-ex0 (38·76 (se 3·23) v. 35·30 (se 3·55) N/cm2, P=0·047). Compared with CW, CA reduced the feeling of fatigue at Post-ex0 (P<0·01); CA also reduced salivary cortisol levels at Post-ex0 (0·72 (se 0·07) v. 0·83 (se 0·13) ng/ml, P<0·01). In conclusion, the ingestion of α-lactalbumin did not improve the 21-km time-trial performance. However, compared with the pre-exercise ingestion of whey protein, that of α-lactalbumin led to superior results during similar levels of endurance exercise: it elevated PPT and reduced the feeling of fatigue and the cortisol levels.

Carbohydrate Supplementation Does Not Improve 10 km Swimming Intermittent Training

The aim of the present study was to test the effectiveness of carbohydrate (CHO) feeding supplemented every 2.5-km, as in official races, on the performance, rating of perceived exertion (RPE), and glycaemia during a 10-km intermittent training workout in elite open-water swimmers. A randomized crossover design was used. Participants completed two 10-km intermittent training sessions (20 × 500-m). The relative velocity was expressed in percentage of a single 500-m. Glycaemia was monitored by continuous glucose monitoring. Participants had to ingest either 1 L of tap water (WAT; 0.50 L·h⁻¹) or 120 g of CHO in the form of 8% solution (60 g·h⁻¹). The 15-point RPE scale was used during the trials. A two-way ANOVA for repeated measures was performed (p < 0.05). The relative velocity of each 500-m was not significantly different between the two trials. No significant differences emerged in the relative velocity of the last 500-m between trials. Average RPE was not statistically different between the two trials (11 ± 3 in WAT and 12 ± 3 in CHO). In the last 500-m, glycaemia was significantly higher in the CHO trial (5.92 ± 0.47 mmol·L⁻¹ in CHO; 5.61 ± 0.61 mmol·L⁻¹ in WAT). CHO ingestion did not improve performance or affect RPE during a 10-km intermittent training in elite open-water swimmers.

Post-exercise Ingestion of Carbohydrate, Protein and Water: A Systematic Review and Meta-analysis for Effects on Subsequent Athletic Performance

BACKGROUND

Athletes may complete consecutive exercise sessions with limited recovery time between bouts (e.g. ≤ 4 h). Nutritional strategies that optimise post-exercise recovery in these situations are therefore important.

OBJECTIVE

This two-part review investigated the effect of consuming carbohydrate (CHO) and protein with water (W) following exercise on subsequent athletic (endurance/anaerobic exercise) performance.

DATA SOURCES

Studies were identified by searching the online databases SPORTDiscus, PubMed, Web of Science and Scopus.

STUDY ELIGIBILITY CRITERIA AND INTERVENTIONS

Investigations that measured endurance performance (≥ 5 min duration) ≤ 4 h after a standardised exercise bout (any type) under the following control vs. intervention conditions were included: Part 1: W vs. CHO ingested with an equal volume of W (CHO + W); and, Part 2: CHO + W vs. protein (PRO) ingested with CHO and an equal volume of W (PRO + CHO + W), where CHO or energy intake was matched.

STUDY APPRAISAL AND SYNTHESIS METHODS

Publications were examined for bias using the Rosendal scale. Random-effects meta-analyses and meta-regression analyses were conducted to evaluate intervention efficacy.

RESULTS

The quality assessment yielded a Rosendal score of 63 ± 9% (mean ± standard deviation). Part 1: 45 trials (n = 486) were reviewed. Ingesting CHO + W (102 ± 50 g CHO; 0.8 ± 0.6 g CHO kg^-1 h^-1) improved exercise performance compared with W (1.6 ± 0.7 L); %_Δ mean power output = 4.0, 95% confidence interval 3.2-4.7 (I ² = 43.9). Improvement was attenuated when participants were 'Fed' (a meal 2-4 h prior to the initial bout) as opposed to 'Fasted' (p = 0.012). Part 2: 13 trials (n = 125) were reviewed. Ingesting PRO + CHO + W (35 ± 26 g PRO; 0.5 ± 0.4 g PRO kg^-1) did not affect exercise performance compared with CHO + W (115 ± 61 g CHO; 0.6 ± 0.3 g CHO·kg body mass^-1 h^-1; 1.2 ± 0.6 L); %_Δ mean power output = 0.5, 95% confidence interval - 0.5 to 1.6 (I ² = 72.9).

CONCLUSIONS

Athletes with limited time for recovery between consecutive exercise sessions should prioritise CHO and fluid ingestion to enhance subsequent athletic performance. PROSPERO REGISTRATION NUMBER: CRD42016046807.

Role of Functional Beverages on Sport Performance and Recovery

Functional beverages represent a palatable and efficient way to hydrate and reintegrate electrolytes, carbohydrates, and other nutrients employed and/or lost during physical training and/or competitions. Bodily hydration during sporting activity is one of the best indicators of health in athletes and can be a limiting factor for sport performance. Indeed, dehydration strongly decreases athletic performance until it is a risk to health. As for other nutrients, each of them is reported to support athletes' needs both during the physical activity and/or in the post-workout. In this study, we review the current knowledge of macronutrient-enriched functional beverages in sport taking into account the athletes' health, sports performance, and recovery.

Training the Gut for Athletes

The gastrointestinal (GI) tract plays a critical role in delivering carbohydrate and fluid during prolonged exercise and can therefore be a major determinant of performance. The incidence of GI problems in athletes participating in endurance events is high, indicating that GI function is not always optimal in those conditions. A substantial body of evidence suggests that the GI system is highly adaptable. Gastric emptying as well as stomach comfort can be “trained” and perceptions of fullness decreased; some studies have suggested that nutrient-specific increases in gastric emptying may occur. Evidence also shows that diet has an impact on the capacity of the intestine to absorb nutrients. Again, the adaptations that occur appear to be nutrient specific. For example, a high-carbohydrate diet will increase the density of sodium-dependent glucose-1 (SGLT1) transporters in the intestine as well as the activity of the transporter, allowing greater carbohydrate absorption and oxidation during exercise. It is also likely that, when such adaptations occur, the chances of developing GI distress are smaller. Future studies should include more human studies and focus on a number of areas, including the most effective methods to induce gut adaptations and the timeline of adaptations. To develop effective strategies, a better understanding of the exact mechanisms underlying these adaptations is important. It is clear that “nutritional training” can improve gastric emptying and absorption and likely reduce the chances and/or severity of GI problems, thereby improving endurance performance as well as providing a better experience for the athlete. The gut is an important organ for endurance athletes and should be trained for the conditions in which it will be required to function.

Biomarkers in Sports and Exercise: Tracking Health, Performance, and Recovery in Athletes

Lee, EC, Fragala, MS, Kavouras, SA, Queen, RM, Pryor, JL, and Casa, DJ. Biomarkers in sports and exercise: tracking health, performance, and recovery in athletes. J Strength Cond Res 31(10): 2920–2937, 2017—Biomarker discovery and validation is a critical aim of the medical and scientific community. Research into exercise and diet-related biomarkers aims to improve health, performance, and recovery in military personnel, athletes, and lay persons. Exercise physiology research has identified individual biomarkers for assessing health, performance, and recovery during exercise training. However, there are few recommendations for biomarker panels for tracking changes in individuals participating in physical activity and exercise training programs. Our approach was to review the current literature and recommend a collection of validated biomarkers in key categories of health, performance, and recovery that could be used for this purpose. We determined that a comprehensive performance set of biomarkers should include key markers of (a) nutrition and metabolic health, (b) hydration status, (c) muscle status, (d) endurance performance, (e) injury status and risk, and (f) inflammation. Our review will help coaches, clinical sport professionals, researchers, and athletes better understand how to comprehensively monitor physiologic changes, as they design training cycles that elicit maximal improvements in performance while minimizing overtraining and injury risk.

The effect of additional carbohydrate supplements for 7 days after prolonged interval exercise on exercise performance and energy metabolism during submaximal exercise in team-sports athletes

[Purpose]

The purpose of our study was to determine the effectiveness of carbohydrate loading by additional carbohydrate supplements for 7 days after prolonged interval exercise on exercise performance and energy metabolism during submaximal exercise in team-sports athletes.

[Methods]

Twenty male team-sports athletes (14 soccer and 6 rugby players) volunteered to participate in the study and were equally divided into the experimental group (EXP, n=10) performing additional carbohydrate supplementation for 7 days after prolonged interval exercise until blood glucose level reaches 50 mg/dL or less and the control group (CON, n=10). Then, maximal oxygen consumption (VO_2max) and minute ventilation (VE), oxygen consumption (VO₂), carbon dioxide excretion (VCO₂), respiratory exchange ratio (RER), blood glucose level, and blood lactate level were measured in all team-sports players during submaximal exercise corresponding to 70% VO2max before and after intervention.

[Results]

There was no significant interaction in all parameters, but team-sports players in the EXP presented more improved VO2max (CON vs EXP = vs 5.3% vs 6.3%), VE (CON vs EXP = vs 3.8% vs 6.6%), VO2 (CON vs EXP = vs 8.5% vs 9.9%), VCO2 (CON vs EXP = vs 2.8% vs 4.0%), blood glucose level (CON vs EXP = vs -12.9% vs -7.6%), and blood lactate level (CON vs EXP = -18.2% vs -25%) compared to those in the CON.

[Conclusion]

These findings showed that additional carbohydrate supplementation conducted in our study is not effective in exercise performance and energy metabolism during submaximal exercise.

No Superior Adaptations to Carbohydrate Periodization in Elite Endurance Athletes

PURPOSE

The present study investigated the effects of periodic carbohydrate (CHO) restriction on endurance performance and metabolic markers in elite endurance athletes.

METHODS

Twenty-six male elite endurance athletes (maximal oxygen consumption (V˙O2max), 65.0 mL O2·kg·min) completed 4 wk of regular endurance training while being matched and randomized into two groups training with (low) or without (high) CHO manipulation 3 d·wk. The CHO manipulation days consisted of a 1-h high-intensity bike session in the morning, recovery for 7 h while consuming isocaloric diets containing either high CHO (414 ± 2.4 g) or low CHO (79.5 ± 1.0 g), and a 2-h moderate bike session in the afternoon with or without CHO. V˙O2max, maximal fat oxidation, and power output during a 30-min time trial (TT) were determined before and after the training period. The TT was undertaken after 90 min of intermittent exercise with CHO provision before the training period and both CHO and placebo after the training period. Muscle biopsies were analyzed for glycogen, citrate synthase (CS) and β-hydroxyacyl-coenzyme A dehydrogenase (HAD) activity, carnitine palmitoyltransferase (CPT1b), and phosphorylated acetyl-CoA carboxylase (pACC).

RESULTS

The training effects were similar in both groups for all parameters. On average, V˙O2max and power output during the 30-min TT increased by 5% ± 1% (P < 0.05) and TT performance was similar after CHO and placebo during the preload phase. Training promoted overall increases in glycogen content (18% ± 5%), CS activity (11% ± 5%), and pACC (38% ± 19%; P < 0.05) with no differences between groups. HAD activity and CPT1b protein content remained unchanged.

CONCLUSIONS

Superimposing periodic CHO restriction to 4 wk of regular endurance training had no superior effects on performance and muscle adaptations in elite endurance athletes.

Protein supplementation enhances cerebral oxygenation during exercise in elite basketball players

OBJECTIVE

The aim of the present study was to examine cerebral oxygenation during high-intensity exercise in elite basketball players who consumed supplements with different whey protein contents after a short postexercise recovery to determine whether changing whey protein content in carbohydrate-based supplementation influences cerebral hemodynamic response when the supplement was consumed during a 2-h recovery after a 1-h exercise challenge.

METHODS

This was a randomized, counterbalanced crossover study. Fifteen Division 1 collegiate basketball players (18-20 y) consumed 6.25 kcal/kg of either high-protein (36% protein in total calorie) or an isocaloric low-protein (12% protein in total calorie) control supplement in a carbohydrate-based drink immediately after a 1-h cycling (70% of maximal oxygen consumption [VO_2max]). After a 2-h rest, the athletes were challenged on a cycloergometer at 80% VO_2max. Blood perfusion (total hemoglobin) and oxygen saturation of frontal brain were continuously measured by near-infrared spectroscopy during the cycling.

RESULTS

Before the cycloergometer test, high-protein supplementation increased peak insulin response and lowered glucose increases during the recovery compared with the low-protein trial. High-protein supplementation enhanced increases in cerebral oxygen saturation (P < 0.01) and attenuated increases in cerebral blood perfusion (total hemoglobin; P < 0.01) during the cycloergometer exercise; and resulted in a 16% longer cycling time (from 474 ± 49 s to 553 ± 78 s, P < 0.05), compared with the low-protein trial.

CONCLUSION

Enhanced fatigue recovery after consumption of a high-protein supplement is associated with enhanced cerebral oxygenation against exercise challenge, which spares brain blood demand for periphery.

Effect of Number of Sprints in an SIT Session on Change in V˙O2max: A Meta-analysis

PURPOSE

Recent meta-analyses indicate that sprint interval training (SIT) improves cardiorespiratory fitness (V˙O2max), but the effects of various training parameters on the magnitude of the improvement remain unknown. The present meta-analysis examined the modifying effect of the number of sprint repetitions in an SIT session on improvements in V˙O2max.

METHODS

The databases PubMed and Web of Science were searched for original studies that have examined pre- and posttraining V˙O2max in adults after ≥2 wk of training consisting of repeated (≥2) Wingate-type cycle sprints, published up to May 1, 2016. Articles were excluded if they were not in English; if they involved patients, athletes, or participants with a mean baseline V˙O2max of >55 mL·kg·min or a mean age <18 yr; and if an SIT trial was combined with another intervention or used intervals shorter than 10 s. A total of 38 SIT trials from 34 studies were included in the meta-analysis. Probabilistic magnitude-based inferences were made to interpret the outcome of the analysis.

RESULTS

The meta-analysis revealed a likely large effect of a typical SIT intervention on V˙O2max (mean ± 90% confidence limits = 7.8% ± 4.0%) with a possibly small modifying effect of the maximum number of sprint repetitions in a training session (-1.2% ± 0.8% decrease per two additional sprint repetitions). Apart from possibly small effects of baseline V˙O2max and age, all other modifying effects were unclear or trivial.

CONCLUSION

We conclude that the improvement in V˙O2max with SIT is not attenuated with fewer sprint repetitions, and possibly even enhanced. This means that SIT protocols can be made more time efficient, which may help SIT to be developed into a viable strategy to impact public health.

Cognitive Performance Enhancement Induced by Caffeine, Carbohydrate and Guarana Mouth Rinsing during Submaximal Exercise

The aim of this study was to investigate the influence of serial mouth rinsing (MR) with nutritional supplements on cognitive performance (i.e., cognitive control and time perception) during a 40-min submaximal exercise. Twenty-four participants completed 4 counterbalanced experimental sessions, during which they performed MR with either placebo (PL), carbohydrate (CHO: 1.6 g/25 mL), guarana complex (GUAc: 0.4 g/25 mL) or caffeine (CAF: 67 mg/25 mL) before and twice during exercise. The present study provided some important new insights regarding the specific changes in cognitive performance induced by nutritional supplements. The main results were: (1) CHO, CAF and GUA MR likely led participants to improve temporal performance; (2) CAF MR likely improved cognitive control; and (3) CHO MR led to a likely decrease in subjective perception of effort at the end of the exercise compared to PL, GUA and CAF. Moreover, results have shown that performing 40-min submaximal exercise enhances information processing in terms of both speed and accuracy, improves temporal performance and does not alter cognitive control. The present study opens up new perspectives regarding the use of MR to optimize cognitive performance during physical exercise.

Potential Impact of Nutrition on Immune System Recovery from Heavy Exertion: A Metabolomics Perspective

This review describes effective and ineffective immunonutrition support strategies for the athlete, with a focus on the benefits of carbohydrates and polyphenols as determined from metabolomics-based procedures. Athletes experience regular cycles of physiological stress accompanied by transient inflammation, oxidative stress, and immune perturbations, and there are increasing data indicating that these are sensitive to nutritional influences. The most effective nutritional countermeasures, especially when considered from a metabolomics perspective, include acute and chronic increases in dietary carbohydrate and polyphenols. Carbohydrate supplementation reduces post-exercise stress hormone levels, inflammation, and fatty acid mobilization and oxidation. Ingestion of fruits high in carbohydrates, polyphenols, and metabolites effectively supports performance, with added benefits including enhancement of oxidative and anti-viral capacity through fruit metabolites, and increased plasma levels of gut-derived phenolics. Metabolomics and lipidomics data indicate that intensive and prolonged exercise is associated with extensive lipid mobilization and oxidation, including many components of the linoleic acid conversion pathway and related oxidized derivatives called oxylipins. Many of the oxylipins are elevated with increased adiposity, and although low in resting athletes, rise to high levels during recovery. Future targeted lipidomics-based studies will help discover whether n-3-polyunsaturated fatty acid (n-3-PUFA) supplementation enhances inflammation resolution in athletes post-exercise.

Multiple-Transportable Carbohydrate Effect on Long-Distance Triathlon Performance

The ingestion of multiple (2:1 glucose-fructose) transportable carbohydrate in beverages at high rates (>78 g·h) during endurance exercise enhances exogenous carbohydrate oxidation, fluid absorption, gut comfort, and performance relative to glucose alone. However, during long-distance endurance competition, athletes prefer a solid-gel-drink format, and the effect size of multiple-transportable carbohydrate is unknown.

PURPOSE

This study aimed to determine the effect of multiple-transportable carbohydrate on triathlon competition performance when ingested within bars, gels, and drinks.

METHODS

A double-blind randomized controlled trial was conducted within two national-body sanctioned half-ironman triathlon races held 3 wk apart in 74 well-trained male triathletes (18-60 yr; >2 yr competition experience). Carbohydrate comprising glucose/maltodextrin-fructose (2:1 ratio) or standard isocaloric carbohydrate (glucose/maltodextrin only) was ingested before (94 g) and during the cycle (2.5 g·km) and run (7.8 g·km) sections, averaging 78.6 ± 6.6 g·h, partitioned to bars (25%), gels (35%), and drink (40%). Postrace, 0- to 10-unit Likert-type scales were completed to assess gut comfort and energy.

RESULTS

The trial returned low dropout rate (9%), high compliance, and sensitivity (typical error 2.2%). The effect of multiple-transportable carbohydrate on performance time was -0.53% (95% confidence interval = -1.30% to 0.24%; small benefit threshold = -0.54%), with likelihood-based risk analysis supporting adoption (benefit-harm ratio = 48.9%:0.3%; odds ratio = 285:1). Covariate adjustments for preexercise body weight and heat stress had negligible impact performance. Multiple-transportable carbohydrate possibly lowered nausea during the swim and bike; otherwise, effects on gut comfort and perceived energy were negligible.

CONCLUSIONS

Multiple-transportable (2:1 maltodextrin/glucose-fructose) compared with single-transportable carbohydrate ingested in differing format provided a small benefit to long-distance triathlon performance, inferred as adoption worthy. Large sample in-competition randomized trials offer ecological validity, high participant throughput, compliance, and sensitivity for evaluation of health and performance interventions in athletes.