Here are some other tips for endurance athletes concerned about carbohydrate intake:

Before exercise:

1. 1. For events lasting longer than 90 minutes, consider carbohydrate loading of 10-12 g/kg of body weight per day for 36-48 h prior to competition.
   2. 1-4 h before exercise, consume a fairly large meal containing 1-4 g/kg of body weight of carbohydrates.
   3. If well tolerated, consider consuming 25-30 g of carbohydrates 30-60 min before exercise.

During exercise: Consume high glycemic index foods or mouth rinse with carbohydrates.

During endurance exercise:

1. If your event is between 45 and 75 min, consume 0-20 g of carbohydrates per hour.
2. If your event is between 60 min and 2.5 h, consume 30-60 g of carbohydrates per hour.
3. If your event is over 2.5 h, consume up to 90 g of carbohydrates per hour, which includes both glucose and fructose.
4. Team sport athletes should consider 36-60 of carbohydrates per hour during exercise.

Following endurance exercise:

• 1. Consume moderate to high glycemic index foods immediately post-exercise (vs. 2 hours post) to help with glycogen resynthesis.
  2. Consume 1.2 g/kg of body weight of carbohydrates per hour for 4 hours.

Fat Needs

Fat is a necessary component of a healthy diet to provide energy and essential fatty acids and to facilitate the absorption of fat-soluble vitamins. Athletes are recommended to consume the same amount of fat in their diet as the general population, which is 20-35% of their energy intake. Some individuals have touted the benefits of a low-carbohydrate diet on athletic performance. However, considering that most intense activities involve the use of carbohydrates as a fuel, it’s no surprise that following a 3.5-week adaptation to a ketogenic low-carbohydrate, high-fat diet reduced exercise economy and impaired performance of a real-life endurance event in elite athletes.^[3]

Protein Needs

Although protein accounts for only about 5% of energy expended, dietary protein is necessary to support metabolic reactions (that generate ATP), and to help muscles with maintenance, growth, and repair. During exercise, these metabolic reactions for generating ATP rely heavily on proteins such as enzymes and transport proteins. It is recommended that athletes consume 1.2 to 2.2 g/kg/day of proteins to support these functions. Higher intakes may also be needed for short periods of intense training or when reducing energy intake.^[4] See Table 13.2 “The recommended protein intakes for athletes” below for a better representation of protein needs depending on the extent of training and dietary sources.

It is important to consume adequate amounts of protein and to understand that the quality of the protein consumed affects the amount needed. High protein foods such as meats, dairy, and eggs contain all of the essential amino acids in relative amounts that most efficiently meet the body’s needs for growth, maintenance and repair of muscles. Vegetarian diets contain protein that has lower digestibility and amino acid patterns that do not match human needs as closely as most animal proteins. To compensate for this and the fact that plant food protein sources also contain higher amounts of fibre, higher protein intakes are recommended for vegetarian athletes. (See Table 13.2 “The recommended protein intakes for individuals”)

Here are some other tips for athletes concerned about protein intake:

1. Space protein intake equally throughout the day by having regular meals every 3-4 hours.
2. To stimulate maximal muscle protein synthesis, consume 0.25-0.4 g/ kg of body weight of protein.
3. Whey protein, followed by soy, followed by casein, will result in the most muscle protein synthesis.
4. Branched-chain amino acid supplements don’t enhance muscle growth.
5. Muscle protein synthesis can be impaired by alcohol consumption.

Post-exercise:

1. 1. Consume 0.25-0.4 g/ kg of body weight of protein.
   2. If your strength workout includes sets until failure, you can consume this meal within 24 h.
   3. If your strength workout does not include sets until failure, consume this meal within 1 h.
   4. Include 3 g of leucine and 8-10 g of essential amino acids.

Micronutrient Needs

Vitamins and minerals are essential for energy metabolism, the delivery of oxygen, protection against oxidative damage, and the repair of body structures. When exercise increases, the amount of many vitamins and minerals needed also increases due to the excess loss of nutrients.  Currently, there are no special micronutrient recommendations made for athletes, but most athletes will meet their micronutrient needs by consuming a balanced diet that fulfils their energy needs. Because the energy needs of athletes increase, they often consume extra vitamins and minerals. The major micronutrients of concern for athletes include iron, calcium, vitamin D, and some antioxidants.^[5]

Common Nutrient Deficiencies for Athletes

Energy deficiency

For athletes, consuming sufficient amounts of calories to support their energy expenditure is vital to maintaining health and bodily functions. When athletes’ energy intakes do not meet the high demands of exercise, a syndrome referred to as relative deficiency in sport (RED-S) occurs. RED-S has a negative effect on performance and health in both male and female athletes, as shown in Figure 13.7  “The effects of Relative Energy Deficiency in sport”. Athletes in sports with weight classes, such as wrestling, may put their health at risk by rapid weight loss to hit a specific weight for a match. These athletes are vulnerable to eating disorders due to sporadic dieting (several of which will restrict energy intake). The long-term effects of these practices result in impaired performance and other serious repercussions that affect heart and kidney function, temperature regulation and electrolyte balance.

Iron Deficiency

Iron deficiency is very common in athletes. During exercise, iron-containing proteins like hemoglobin and myoglobin are needed in great amounts. An iron deficiency can impair muscle function to limit work capacity, leading to compromised training performance. Some athletes engaging in intense exercise may experience increased iron loss through sweat, urine, and feces. Iron losses are greater in females than males due to the iron lost in blood every menstrual cycle. Female athletes, distance runners and vegetarians are at the greatest risk for developing iron deficiency.^[7] See Table 13.3 “The potential iron loss in endurance athletes” for the potential amounts of iron lost each day in male and female athletes. An increased recommendation for both genders is shown below. These recommendations are based on the assumption that iron has a 10%  absorption efficiency. As noted above, female athletes have a greater iron loss due to menstruation and therefore must increase their dietary needs more than male athletes.

Sports anemia, which is different from iron deficiency anemia, is an adaptation to training for athletes. Excessive training causes the blood volume to expand to increase the amount of oxygen being delivered to the muscles. During sports anemia, the synthesis of red blood cells lags behind the increase in blood volume, which results in a decreased percentage of red blood cells per a given amount of fluid. The total amount of red blood cells remains the same or may increase slightly to continue the oxygen transport. Eventually, as training progresses, the red blood cell synthesis will increase to catch up with the total blood volume.

Vitamin D and Calcium Deficiencies

Vitamin D regulates calcium and phosphorus absorption, and metabolism while also playing a key role in maintaining optimal bone health. There is also growing evidence that vitamin D is important for other aspects of athletic performance such as injury prevention, rehabilitation, and muscle metabolism. Individuals who primarily practice indoors are at a higher risk for a vitamin D deficiency and should ensure they are consuming foods high in vitamin D to maintain sufficient vitamin D status.^[9]

Calcium is especially important for the growth, maintenance, and repair of bone tissue. Low calcium intake occurs in athletes with RED-S, menstrual dysfunction, and those who avoid dairy products. A diet inadequate in calcium increases the risk for low bone mineral density, ultimately leading to stress fractures.

Antioxidant Nutrient Deficiencies

Antioxidant nutrients play an important role in protecting cell membranes from oxidative damage. During exercise, the amount of oxygen used by the muscles increases and can produce free radicals, which cause an increase in antioxidant systems in the body. These antioxidant systems rely on dietary antioxidants such as beta-carotene, vitamin C, vitamin E, and selenium that can be obtained through a nutrient-dense diet. However, as an athlete, you will want to be cautious about taking antioxidant supplements, as they can blunt adaptations to exercise training. Therefore, it’s recommended to consume antioxidants through the diet and not through high-dose supplements.