Nutrition For The Endurance Athlete

The number of participants in endurance events has increased both nationally and globally, with 2.5 million individuals participating in triathlons in the US in 2015, and 3.5 million people participating worldwide. Over the past few years, there has been a shift in the type of running races, moving away from standard marathons towards “other distance” races such as mud runs, colour runs, and obstacle course races. Additionally, ultra-endurance events are also becoming more popular. These events typically last for at least 4 to 6 hours. Previous studies have shown the physical challenges that ultra-endurance exercise poses on the body, including fatigue, suboptimal nutrition, and energy deficit. These studies also highlight the potential medical complications of ultra-endurance exercise, emphasizing the importance of an individualized nutritional approach. Given the growing popularity of endurance and ultra-endurance events, it is necessary to establish the specific nutritional requirements for athletes participating in these events.

Despite the significant progress in comprehending the nutritional needs of endurance athletes, there are several gaps in the existing literature. The field of nutrition is intricate, constantly evolving, and occasionally contradictory. “Sports nutrition” encompasses various disciplines, including sports medicine, sports science, dietetics, cultural influences, and popular media. Particularly concerning elite athletes and dietary recommendations, there is often disagreement among nutritionists, registered dietitians, sports scientists, physicians, and other healthcare professionals.

Carbohydrate

The topic of carbohydrate requirements for endurance athletes can be a contentious one, often leading to intense debates within the fitness and medical communities. According to the joint position stand of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine, moderate exercise (1 hour per day) requires a carbohydrate intake of 5-7 grams per kilogram of body weight per day. For moderate to high-intensity exercise (1-3 hours per day), the recommended intake is 6-10 grams per kilogram of body weight per day. Ultra-endurance athletes who engage in 4-5 hours of moderate to high-intensity exercise daily may need as much as 8-12 grams per kilogram of body weight per day. The International Society of Sports Nutrition recommends that athletes aiming to maximize their glycogen stores should follow a high carbohydrate diet with an intake of 8-12 grams per kilogram of body weight per day.

Carbohydrate, in the form of blood glucose and muscle glycogen, has a greater ability to produce ATP per volume of oxygen when compared to fat. However, when liver and muscle carbohydrate stores are depleted, it can lead to fatigue, decreased performance, and difficulty concentrating. This is commonly experienced by athletes as “hitting the wall” or “bonking.” Clinicians need to note that even after 4.5 hours of cycling at 70% of maximum oxygen consumption, when carbohydrate stores should be completely exhausted, elite athletes are still able to run at 16 km/h for an additional 2.5 hours at 66% of maximum oxygen consumption. Therefore, depletion of glycogen should not be the only factor considered when determining fatigue. Other sources of carbohydrates, such as lactate utilization, as well as other mechanisms like increased fat oxidation, may contribute to this phenomenon. Clinicians should keep this in mind when advising athletes.

Protein

In the past, endurance athletes have not given protein as much importance as carbohydrates. Nevertheless, it is essential for all athletes, regardless of whether they are involved in endurance or resistance training, to consume enough protein and consume it at the right time. The old method of nitrogen balance, which was initially created to prevent nutrient deficiencies rather than enhance performance, is no longer applicable. Athletes need to consume higher amounts of protein than the current Recommended Daily Allowance (RDA) of 0.8 g/kg/day to maximize their training results and enhance their performance.

Fat

In comparison to carbohydrates, endurance athletes tend to pay less attention to proper fat intake, even though it can be a valuable source of fuel. This is because the oxidation of fat can provide significantly more energy, around 70,000-75,000 kilocalories, compared to the ~2500 kilocalories provided by the oxidation of glycogen before it is depleted, even in lean adults. While the typical endurance athlete may favour a diet that is rich in carbohydrates due to the explained benefits, there has been a recent interest among some ultra-endurance athletes in keto-adaptation. This involves following a high-fat, low-carbohydrate diet to become “fat-adapted” or “training low.” This renewed interest is based on the fact that fat gets oxidized at a higher rate than glucose during lower-intensity exercise states typically encountered in ultra-endurance events. During the “train low” state, where carbohydrates are not readily available, the pathways for lipid oxidation, such as citrate synthase and 3-hydroxyacyl-CoA dehydrogenase (3HAD), are upregulated. However, this comes at the expense of downregulating carbohydrate metabolism. If performance is not the primary concern, becoming fat-adapted and engaging in low-intensity exercise (<70% VO2 max) may improve the breakdown of fats and promote weight loss in overweight athletes. However, if the athlete’s focus is on racing and improving performance times, following a high-fat, low-carbohydrate diet may limit their ability to train and race at higher intensities and could hurt their race results.

Although fat intake may not be considered important for athletes, it should be noted that fats are essential for various functions in the body. They are necessary for the structure of cell membranes and play roles in signalling, transport, nerve function, insulation, and protection of vital organs. Additionally, fats are the primary source of essential dietary fatty acids. Athletes who consistently limit their fat intake to less than 20% of their total energy are at risk of insufficient consumption of fat-soluble vitamins, carotenoids, essential fatty acids such as n-3 (omega-3) fatty acids, and potentially conjugated linoleic acids (CLA).

Conjugated linoleic acids, which are isomers of the essential n-6 linoleic acid, are produced by gut bacteria and are found in dairy products and ruminant meats (such as cow, sheep, goat, and deer). There is limited evidence suggesting that CLA may have the ability to inhibit the development of atherosclerosis and cancer, which is important for the overall health of athletes. Additionally, for endurance athletes looking to maintain their body weight, CLA may reduce the uptake of lipids by adipocytes. However, there is currently limited and conflicting knowledge about the effects of CLA on endurance exercise, with most research conducted on overweight individuals. In one study that used a placebo control, athletes who consumed 0.9 g/day of CLA for 14 days experienced a significant increase in exercise time and a possible decrease in perceived exertion. However, another study found no effect on exercise time, VO2 max, or body composition in healthy young men who consumed 0.8 g/day of CLA for 8 weeks. The International Society of Sports Nutrition (ISSN) recognizes that although animal studies on CLA are impressive, human studies do not yet provide convincing evidence for its supplementation.

The proposed mechanism of action for fish oil and CLA is to modulate the enzymes CYP17A1 and HSD3B2, resulting in decreased metabolism of glucocorticoids and increased metabolism of androgen pathway sex hormones. This modulation promotes an anabolic environment, which is important for endurance athletes who may experience declines in testosterone due to overtraining. This supplement option should be considered for endurance athletes during periodization training, especially during high-intensity training or for any athlete at risk of testosterone suppression from overreaching or overtraining.

Medium-chain triglycerides (MCTs) have become a topic of interest in recent years because they can easily enter mitochondria and be used as an energy source through beta-oxidation. Theoretically, this could benefit athletes by providing a readily accessible fat source for energy and preserving glycogen. However, while certain studies indicate enhanced cycling performance with MCTs, other studies show negative effects on performance compared to carbohydrates. Additionally, most studies report gastrointestinal issues. As a result, the ISSN currently categorizes MCTs as having insufficient evidence to support their effectiveness and safety.

Endurance athletes should adhere to public health guidelines to ensure they consume enough fat, and should only restrict fat intake before a race during a CHO loading phase or if they have concerns about gastrointestinal comfort. While conjugated linoleic acids, fish oil, and MCTs may show potential, further research is required to precisely determine their impact on endurance athletes.

Hydration

The recommendations for fluid intake for endurance athletes have changed over time. Previously, coaches and training staff would advise athletes that feeling thirsty was not a reliable indication of hydration levels. The belief was that if you were already feeling thirsty, it meant you were already dehydrated. In a significant study conducted in 1969 by Wyndham, marathon participants who lost more than 2% of their body weight experienced elevated rectal temperatures, putting them at risk of hyperthermia. This led some to suggest that increasing fluid intake was necessary, as the sensation of thirst was not an accurate indicator of hydration. Interestingly, the winner of both races in the Wyndham study actually had the highest rectal temperature overall and showed no symptoms at the end of the race. In hindsight, this should have caused further consideration, as the health risk may not have been as severe as initially believed. As recently as 1996, the ACSM acknowledged in their position on fluid replacement that relying solely on the perception of thirst was inadequate for fully replenishing the fluids lost through sweating. They recommended that athletes begin drinking early and regularly, or consume the maximum amount they can handle.

As a result, athletes have historically sought to prevent dehydration by drinking fluids before they felt thirsty. However, the dangers of overhydration became more evident as clinical observations increased. During the Boston Marathon, it was found that a concerning 13% of finishers experienced hyponatremia, with even more cases likely going unreported. Among these cases, 0.6% (90 finishers) were critically affected with a sodium concentration of ≤120 mmol/L. The excessive consumption of fluids was identified as the most significant risk factor for developing hyponatremia. Additionally, lighter and slower runners are also susceptible to maintaining a positive fluid balance. Exercise-associated hyponatremia (EAH) is the term used to describe hyponatremia that occurs either during physical activity or within 24 hours. EAH is characterized by a serum, plasma, or blood sodium concentration below the normal range, which is typically <135 mmol/L for most laboratories. This condition is severe and can lead to exercise-associated collapse, which can be fatal. While EAH may sometimes show no symptoms, it can also present with a range of signs and symptoms similar to other medical conditions. These can include confusion, difficulty breathing, nausea, delirium, and in serious cases, even coma and death.

Noakes et al. conducted studies on ultra-endurance athletes to highlight the importance of EAH. These studies showed that EAH is caused by voluntary hyperhydration, increased sweat sodium loss, and loss of normal anti-diuretic hormone (ADH) suppression, known as the syndrome of inappropriate ADH secretion (SIADH). The kidneys can excrete around 800-1000 mL/h of fluid, and exercise can lead to an additional fluid loss of about 500 mL/h. According to this, athletes could theoretically consume up to 1.5 L/h without retaining water. However, EAH commonly occurs at lower water intake rates, putting the athlete at risk. Clinicians can explain to athletes that if they consume 1 L of fluid at rest, it would probably be excreted normally. However, during exercise, even small increases in ADH can significantly reduce kidney excretory capacity, causing fluid retention even with intake below 800-1000 mL/h. Stimuli for SIADH include nausea/vomiting, hypoglycemia, hypotension, release of interleukin-6 (IL-6), and hyperthermia, all of which can occur during prolonged exercise. Athletes should monitor for SIADH stimuli, such as nausea, although the clinical symptoms of EAH may not be specific.

Noakes’ pivotal study in 2003 was the first to clearly describe the dangers of over-drinking and led to updated recommendations. In the Advisory Statement by Noakes and the International Marathon Medical Directors Association, it is suggested that athletes begin with a hydration plan ranging from 400-800 mL/h. This recommendation was also adopted in the 2007 ACSM Position Stand, which advises athletes to drink ad libitum within the same range. However, the specific hydration plan for each athlete varies depending on factors such as sweat rates, sweat sodium content, exercise intensity, body temperature, ambient temperature, body weight, kidney function, and other variables. The ACSM recommends higher hydration rates for larger, faster athletes competing in warm environments, and lower rates for smaller, slower athletes competing in cooler environments. A simulation study suggests that a 70 kg athlete running at speeds of 8.5-15 km/h in cool or temperate (18 °C) conditions may benefit from a hydration rate of 600 mL/h. However, this rate may result in overhydration for a 50 kg athlete running ≤10 km/h, or dehydration for a 90 kg athlete running ≥12.5 km/h. All athletes are at risk of dehydration in warmer (28 °C) environments, but 50 kg athletes face a higher risk of overhydration at higher intake levels (800 mL/h) and lower speeds (≤12.5 km/h). This further supports the need for individualized hydration plans, particularly for lighter, slower runners.

Customizing a sodium intake plan for athletes involves considering factors such as their experience, sweat rate, sweat sodium content, exercise intensity, and environmental conditions. The AND, DC, and ACSM all agree that athletes with high sweat rates (>1.2 L/h), those who excessively sweat salt, and those participating in prolonged exercise (>2 h) should consume sodium during exercise. Although sweat rates can vary, the average range is between 0.3 to 2.4 L/h, with an average sodium content of 1 g/L (50 mmol/L). To ensure optimal absorption and prevent hyponatremia, a sports drink containing sodium in the range of 10–30 mmol/L (230–690 mg/L) is recommended, which is commonly found in commercial sports drinks. According to the ACSM, athletes should start with an intake of approximately 300–600 mg/h (1.7–2.9 g salt) during prolonged exercise and adjust accordingly.

To maintain the same meaning while thinking step by step, the text can be rephrased as: By instinctively following the thirst mechanism and monitoring various bodily parameters such as body weight, urine colour, race pace, body temperature, and environmental temperature during each workout, athletes can better understand their specific hydration needs and prevent complications from exercise-associated hyponatremia (EAH). Athletes who tend to overdrink should consider the advice presented in the 2007 ACSM position stand, which highlights the importance of finding a balance. Dehydration can impair exercise performance and contribute to heat illness or exacerbate exertional rhabdomyolysis, but overhydration leading to exercise-associated hyponatremia can result in serious illness or even death.

Nitrates

Dietary nitrate has been utilized for a long time in medical conditions like cardiovascular disease and hypertension. After a notable study conducted by Larsen in 2007, which demonstrated a reduction in the oxygen cost for submaximal exercise workloads, it has gained significant attention among endurance athletes. Several publications have emerged since then, with a PubMed search on “nitrate supplementation exercise” revealing only 52 publications in the preceding 10 years (2004-2013), but over 180 publications in the last 5 years (2014-2018). Certain vegetables, such as beets and beetroot juice, have high levels of inorganic nitrate (NO3−). When consumed, NO3− is converted by oral bacteria to NO2−, which then becomes nitric oxide (NO) in the gut. Nitric oxide has various effects on the body that are relevant to endurance athletes, including vasodilation, regulation of blood flow and oxygen in working muscles, stimulation of mitochondrial respiration and biogenesis, enhancement of glucose uptake, and overall facilitation of muscle contraction and relaxation. Taken together, these effects can improve muscle efficiency and economy, reduce fatigue, decrease effort required at submaximal workloads, and, in some studies, enhance time trial performance (primarily in non-elite athletes).

Studies have specifically focused on the effects of beetroot juice on athletes compared to other forms of dietary nitrate. Taking beetroot juice up to 2–3 hours before endurance exercise has been found to decrease the amount of oxygen required during exercise, potentially improving the duration of exercise, cardiorespiratory performance at the anaerobic threshold, and VO2 max. However, the results of these studies are currently mixed and sometimes conflicting. Many positive studies have involved small sample sizes of 10 or fewer participants, and the effects of beetroot juice may be less significant or non-existent for athletes who already have a well-balanced nutrition plan that includes sufficient nitrate or who have maximized their training adaptations to improve metabolic efficiency. Additionally, consuming a high-nitrate diet or supplementing with nitrate over multiple days may increase nitrate levels and enhance performance compared to a control diet. For instance, one study found that consuming a high nitrate diet for 6 days (8.2 mmol/day from vegetables and fruits) led to a significant increase in plasma nitrate levels and was associated with reduced oxygen cost during moderate intensity cycling, increased muscle work during high-intensity fatiguing leg exercise, and improved performance during repeated sprints. This study helps shed light on the varying results obtained from acute single-day supplementation and aids athletes in identifying appropriate nitrate intake levels for optimal health.

The dosing of nitrate supplements can vary. In studies, it typically ranges from 300–600 mg or up to 10 mg/kg, 0.1 mmol/kg with a minimum total of 6–8 mmol. Another option is consuming 500 mL of beetroot juice, which is approximately equivalent to 3–6 whole beets. The timing of consumption may also affect the results. Recent data suggests that beetroot juice should ideally be consumed within 90 minutes of exercise, rather than 2–3 hours beforehand as previously studied. This is because nitric oxide (NO) levels peak at 2–3 hours and then sharply decrease, leaving the athlete in a potentially suboptimal time frame for exercise. The way the supplement is ingested is also important to consider when interpreting study results. Using mouth rinse, oral antiseptics, or limiting the contact time of the nitrate supplement can all hinder the conversion of nitrate (NO3−) to nitrite (NO2−). Some athletes may experience gastrointestinal distress from consuming 500 mL of beetroot juice before a race, and it may also contribute to overhydration. As a result, commercially developed options such as beetroot juice concentrate, powders, and “shots” have been created and may be an alternative.

There are a few practical points that are often overlooked but deserve mention. One point is that commercial nitrate or beet supplements can be quite expensive. Instead, athletes could consider consuming enough high-nitrate vegetables or actual beets that provide similar levels of nitrates. According to the Larsen study, the daily nitrate dose used can be obtained through a diet rich in vegetables, specifically in an amount that is typically found in 150 to 250 g of a nitrate-rich vegetable like spinach, beetroot, or lettuce. Athletes should also be aware that beeturia and red bowel movements may occur, which is considered normal. Lastly, it’s important to note that dietary nitrate supplements can slightly lower diastolic and mean arterial blood pressure. This may be a concern for individuals with low blood pressure, orthostasis, or those at risk for hypotension.

Antioxidants

Gomez-Cabrera questioned the role of antioxidant supplements in sports, specifically noting that they may hinder the body’s response to exercise during training. Consuming high doses of individual antioxidants like vitamins C and E may prevent the normal signalling pathways triggered by exercise-induced oxidative stress. The oxidative environment from exercise leads to adaptations such as increased levels of superoxide dismutase and glutathione peroxidase enzymes, muscle repair, and mitochondrial biogenesis pathways. While athletes should naturally incorporate a variety of antioxidants into their diet, taking excessive doses of single antioxidants can hinder or prevent training adaptations in endurance athletes. Therefore, it is not recommended. However, once an endurance athlete has reached their peak in training and their focus is on timely recovery, a diet or supplement containing a mix of antioxidants (such as dark berries and dark leafy greens) may aid in speedy recovery and return to competition. According to a review, consuming tart cherry juice at a dose of 8-12 oz twice a day (or 1 oz if concentrated) for 4-5 days before and 2-3 days after an event may promote recovery. This may be particularly beneficial for endurance events that span multiple days, such as cycling tours or multi-stage races.

Green tea includes various bioactive phytochemicals like polyphenols such as epigallocatechin gallate (EGCG), catechin, epicatechin, epigallocatechin, and epicatechin gallate, which are known as catechins. The antioxidant properties of green tea are believed to contribute to its proposed health benefits by combating ROS and free radicals linked to chronic diseases. Green tea extracts have been found to increase fat oxidation and promote weight loss in endurance athletes when taken at doses ranging from 270-1200 mg/day. Catechins act as inhibitors of catechol-o-methyltransferase (COMT), enhancing the effects of norepinephrine, thermogenesis, and fat oxidation, as well as inhibitors of phosphodiesterase, preventing the breakdown of cyclic adenosine monophosphate (cAMP) that stimulates hormone-sensitive lipase. A review has demonstrated that green tea extract can enhance fat oxidation and improve performance in endurance exercise, particularly when supplemented with caffeine. This may be beneficial for endurance athletes aiming to maximize fat oxidation and conserve glycogen during longer, lower-intensity events. It should be noted that Asian populations have a higher prevalence of high-activity COMT polymorphism compared to Caucasians, suggesting a potential population-specific effect in Asians. Nevertheless, there is a lack of human studies examining the effects of green tea extract on athletic performance. The studies commonly cited to support claims of increased time to exhaustion in swimming (8-24%) and running (30%) due to enhanced fat oxidation were actually conducted on animals, not humans. In later studies involving humans, green tea did not show a similar performance enhancement and the few studies that did suggest improvements were conducted on untrained sedentary individuals. Therefore, it is uncertain if green tea catechins have a significant performance effect on trained athletes who are not overweight. Additionally, athletes should exercise caution as the methods of cultivating, harvesting, and preparing green tea can vary greatly, and some supplements may contain contaminants or banned substances.

Caffeine

Caffeine, which is widely used by the general population, has been extensively studied in sports for its performance-enhancing effects. It is a type of trimethylxanthine with a chemical structure similar to adenosine. There are several suggested mechanisms of action for caffeine. In the central nervous system, it acts as a stimulant by blocking adenosine receptors, leading to increased release of neurotransmitters, improved cognitive performance, and pain reduction through increased β-endorphin levels. In the peripheral system, caffeine increases the recruitment of motor units and aids in calcium mobilization, thereby enhancing muscle contraction. At a systemic level, caffeine helps mobilize fatty acids for energy, reducing reliance on glycogen, and increasing thermogenesis. Consensus has been reached on the optimal dosage and timing of caffeine intake for maximum effects. Meta-analyses and reviews consistently recommend a moderate dose of caffeine, ranging from 3 to 6 mg/kg, to be consumed 30 to 90 minutes before exercise. This dosing strategy has been shown to improve endurance performance, particularly in sustained maximal endurance activities like time trials, and enhance vigilance during endurance tasks. Additionally, the combination of caffeine with carbohydrates has been found to have a synergistic effect on cycling work production, surpassing the effects of consuming caffeine or carbohydrates alone, while the perceived effort remains unchanged. It is worth mentioning that in one study, it was suggested that anhydrous supplemental caffeine may have a stronger performance-enhancing effect compared to consuming coffee, although it is important to note that in this study, the caffeine capsule was actually taken with water. Therefore, the authors raise a question as to whether this is ultimately comparable to the effects of drinking coffee.

Higher doses of caffeine, at 9 mg/kg, do not produce any additional performance enhancement and can lead to unwanted side effects such as gastrointestinal distress, nervousness, confusion, and disrupted sleep. There is also concern among athletes regarding the possibility of severe or systemic side effects with this level of dosage. Despite this, a recent review suggests that caffeine does not cause more severe complications such as imbalances in water and electrolytes, dehydration, increased body temperature, or reduced ability to tolerate exercise in heat. However, doses above 9 mg/kg may result in the detection of caffeine in urine and are considered to be above the doping threshold in many professional sports organizations. Fortunately, lower doses below 3 mg/kg can still provide similar benefits in endurance cycling and running studies, such as improved alertness, mood, and cognitive function, without any major adverse effects.

There has traditionally been a belief that regularly consuming caffeine may reduce the positive effects of consuming caffeine shortly before exercising. Studies have shown that the performance benefits of caffeine decrease after 15-18 days of consuming a low dose (3 mg/kg) of caffeine daily during peak cycling power tests. After 4 weeks of continuing this dose, the performance benefits were no longer apparent in time trial performance. However, other studies have shown that athletes with different levels of regular caffeine intake experience similar improvements in cycling time-trial performance when given a one-time dose of 6 mg/kg of caffeine.

Additionally, during prolonged exercise lasting more than 2 hours, caffeine may provide benefits. In a specific study, athletes engaged in a 2-hour cycling session at 60% of their maximum oxygen uptake (VO2max), with intermittent periods of high-intensity exercise at 82% of VO2max. After 80 minutes into the cycling challenge, participants were given either a low dose (1.5 mg/kg) or a moderate dose (2.9 mg/kg) of caffeine. Both groups experienced faster completion times in a subsequent cycling time trial compared to the placebo group. Furthermore, the moderate-dose group exhibited greater performance improvements than the low-dose group. This study indicates the potential usefulness of periodically supplementing caffeine during prolonged exercise, which may also benefit ultra-endurance events.

The authors suggest that athletes who are not tolerant to caffeine should start with lower doses and adjust accordingly. Some athletes find it helpful to alternate between consuming caffeine and abstaining from coffee during periods of lower-intensity training or before races, and then resuming coffee consumption during high-intensity training or on race days. A safe initial dose could be up to 3 mg/kg. The performance benefit from daily caffeine intake begins to decrease after about 15-18 days and may disappear by 4 weeks. For athletes who regularly drink coffee, taking 6 mg/kg of caffeine as a one-time supplement on race day may be an option if tolerated. Additionally, periodically replenishing caffeine during prolonged exercise (as recommended by the authors, every 1-2 hours as needed) may also be beneficial.

Probiotics

Probiotics, which are live substances found in fermented foods like yoghurt, kimchee, sauerkraut, miso, and natto or can be taken as a supplement, are considered “live food ingredients” that have a positive impact on the host organism. The main species used are usually Lactobacillus and Bifidobacteria, and they produce lactic acid from carbohydrates to give fermented foods their sour taste. Probiotics have numerous suggested health benefits, including improving digestive conditions, reducing infections, aiding lactose intolerance, preventing constipation, boosting the immune system, and potentially even having anti-cancer effects on the colon. Endurance athletes are particularly prone to upper respiratory infections (URI), with elite athletes experiencing higher rates of URIs than recreational athletes. Probiotics might help in decreasing these symptoms. However, research on probiotics in athletes is still in its early stages, and only a limited number of studies have been conducted, with only six studies found in a review of the literature. While two studies did show enhanced performance as a result of probiotics, it is worth noting that one study involved mice.

A recent review found that probiotics may be beneficial for reducing gastrointestinal (GI) and upper respiratory symptoms in healthy physically active individuals and athletes. When endurance athletes become fatigued, they exhibit similar clinical characteristics to patients with reactivated Epstein Barr virus, such as decreased secretion of interferon-gamma by T-cells and diminished natural killer cell activity. However, probiotic supplementation can normalize mucosal T-cell interferon levels and mitigate the decrease in natural killer cell activity. The effectiveness of probiotics may depend on factors such as the specific strain used, dosage, duration of consumption, and form of administration (e.g., capsules, sachets, fermented food). Multiple-strain probiotics, taken in the form of fermented food or sachets for longer periods, seem to yield better results. These benefits can enhance athlete comfort, aid in exercise recovery, and potentially improve performance indirectly. Endurance athletes who are prone to GI or upper respiratory symptoms, have increased susceptibility to infections, or frequently travel for events and are exposed to travel-related illnesses may particularly benefit from probiotic supplementation.

Tips to excel with proper sports nutrition

• Make a plan to eat a variety of fruits and vegetables daily. The goal is to eat at least five servings per day, and include varieties of fruit and vegetable colors. One serving is approximately the size of a baseball. Fruits and vegetables are filled with the energy and nutrients necessary for training and recovery. Plus, these antioxidant-rich foods will help you combat illness like a cold or the flu.
• Choose whole-grain carbohydrate sources such as whole-wheat bread or pasta, and fiber-rich cereals as power-packed energy sources. Limit the refined grains and sugars such as sugary cereals, white bread, and bagels. You’ll benefit more from whole-grain products.
• Choose healthy sources of protein such as chicken, turkey, fish, peanut butter, eggs, nuts, and legumes.
• Stay hydrated with beverages, as a two per cent drop in hydration levels can negatively impact performance. Options include milk, water, 100 per cent fruit juice, and sports drinks. However, realize that sports drinks and 100 per cent fruit juice tend to be higher in overall sugar content and, in the case of fruit juice, lack many of the health benefits present in its whole food counterpart. Also, be sure not to confuse sports drinks such as Gatorade with “energy” drinks such as Red Bull and similar beverages.
• Stick with whole food options as much as possible as opposed to highly processed foods.

Planning a nutritious meal

To successfully reach your performance goals, it is essential to ensure that you consume sufficient calories from the most nutritious food sources. Make a meal plan that includes selecting at least one item from every food category.

Carbohydrates, when thinking systematically, should be rephrased step by step while retaining the original meaning. Additional information is not to be included, and no information is to be omitted.

• Fruit
• Oatmeal
• Starchy vegetables (sweet/white potatoes, squash)
• Non-starchy vegetables (broccoli, leafy greens)
• Whole-grain bread or crackers
• High-fiber, non-sugary cereals
• Quinoa
• Brown or wild rice

Protein, when considering its different functions and importance in the body, can be broken down into individual steps.

• Whole eggs (white and yolk)
• Greek yoghurt
• Milk
• String cheese
• Lean red meats
• Poultry
• Fish
• Hummus

The text below will be rephrased while maintaining the same meaning: Fat that is considered to be beneficial for one’s health.

• Avocado
• Peanut butter
• Nuts and seeds
• Olive or canola oil (the latter, if baking)
• Coconut oil
• Flax seed (add to baking or cooking)

Game day nutrition

When it comes to eating on game day, there are a few golden rules to keep in mind.

• Remember, proper nutrition for the “big tournament/race/meet” does not happen on the day of the event alone. It happens in the days, weeks, and months leading up to the competition
• Never experiment with a new dietary/supplement protocol on game day. First, try it out before a practice/training session to make sure you tolerate it well.
• As you get closer to the game/competition, make your meals smaller. Additionally, you may want to limit dairy, fat, and fibrous carbohydrate sources during the last one to one and one-half hours pre-event/practice, as these may cause GI issues.

As the game/competition approaches, reduce the size of your meals and eliminate fats and dairy products. Fibrous carbohydrates may be helpful as they tend to cause gastrointestinal issues.

The most important aspect of “pre-event” nutrition is ensuring that you have tried it before the actual day of the game. Test the pre-meal/snack routine beforehand to ensure that you can digest it without any issues.

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