As a sports dietitian, I am often asked, “What is the best diet for an athlete?” To which I always reply, “It depends.” A nutrition plan for an athlete is no different than general nutrition recommendations, in that the plan needs to be individualized. For example, the type of sport, duration, and level of competition each have a role in developing specific nutrition recommendations, as will the athlete’s age, gender, body weight, muscle mass, environment, and more.

Consider trying to devise a single ideal nutrition program for both 100-meter dash competitor Usain Bolt and marathoner Jordan Hasay. You couldn’t do it, because they have different nutrition needs despite both being elite, professional athletes.

Type of Sport

To design a nutrition plan that best meets the needs of a specific athlete, the type of sport needs to be considered. We usually divide the athlete population into two categories:  endurance athletes and strength and power athletes, although many sports can span both categories.

Endurance is the ability of a muscle to exert less than maximum effort over a prolonged period.

Although a strength and power sport often involves an outside resistance, in an endurance sport body weight is generally the source of resistance. The obvious endurance sports include anything happening continuously for close to an hour or more, such as long-distance running, open water swimming, endurance cycling, etc.

Strength is the ability of a muscle to exert a maximum amount of force against resistance, such as against an opponent, a weight load, or the ground.

Power, often confused with strength (they really are different), is the ability to move weight with speed. Examples of sports that are focused around strength and power are football, rugby, boxing, hockey, weightlifting, and some track and field events.


Three Considerations for the Endurance Athlete

The goal for an endurance sport, and the training that accompanies it, is to efficiently perform sub-maximal output over a long period. An event like a marathon can last 2-3 hours for an elite athlete, but it could last 4-5 hours for a recreational athlete. Given the nature of endurance sports, there are several vital nutrients that play an important role in both performance and recovery:


1. Carbohydrates are often the preferred source of fuel for endurance sports, and they become the focus of the nutrition plans of many athletes.

As the body burns through existing glycogen stores, even at a sub-maximal pace, an external source of carbohydrates is generally required to sustain optimal performance. Although there are alternative fueling protocols (like ketoadaptation), most endurance athletes tend to fuel with carbohydrates during training. 

The International Olympic Committee (IOC) has adopted the following carbohydrate recommendations:

General Carbohydrate Guidelines for athletes:  7-12 grams of carbohydrate per kilogram per day (divide weight in pounds by 2.2 to convert to kilograms)

Specific Carbohydrate Guidelines for athletes:

  • Exercise less than 45 minutes: no extra carbohydrates needed.
  • Exercise between 45-75 minutes: small amounts of carbohydrates as tolerated.
  • Exercise between 75-180 minutes: 30-60 grams of carbohydrate per hour.
  • Exercise greater than 180 minutes: 90 grams of carbohydrate per hour.

Pre-competition for events greater than 60 minutes: 1-4 grams of carbohydrate per kilogram consumed 1-4 hours before competition.

Post-competition refueling for events greater than 60 minutes:  1.2 grams of carbohydrate per kilogram per hour for 4 hours, followed by a return to a usual feeding plan.


2. The hydration status of an endurance athlete is another primary consideration.

Endurance training and endurance competition that lasts more than 60 minutes almost always requires replacing fluids and electrolytes that are lost through sweat. Although fluid volume is often the focus, sweat contains electrolytes and other nutrients that also must be considered.

Maintaining hydration status through a longer duration event, as well as between training sessions, becomes imperative for repeated, optimal performance.

General hydration guidelines are based on body weight. An athlete who does not have access to advanced measurements, such as sweat testing and urine specific gravity, is advised to monitor his or her body weight losses during exercise. Weigh yourself in little to no clothing both before and after exercise to avoid over-or-under calculation of weight loss.

The American College of Sports Medicine recommends the following hydration guidelines:

  • Before exercise:  Pre-hydration should be initiated several hours before the competition starts. Focus on sodium-containing beverages and snacks that will increase the sensation of thirst and retain fluids.
  • During exercise:  The objective is to prevent more than two percent of body weight loss during exercise. Fluid choice should be customized based on body weight measurements before and after training and should contain electrolytes and perhaps carbohydrates.
  • After exercise:  Return to hydration status within 24 hours. For more rapid rehydration, consume 1.5 liters (~51 ounces) of fluid per kilogram body weight lost during exercise. Beverages and snacks should contain electrolytes to help with rapid recovery. 

Thorne’s electrolyte replacement product, Catalyte®, is formulated to contain the electrolytes and nutrients similar to the body’s normal composition of sweat.*


3. Iron is an important nutrient for the endurance athlete.

Suboptimal iron status can impair muscle function and limit the body’s capacity to do work. Specific athlete populations, including female athletes, distance runners, and athletes who are vegetarian/vegan are at higher risk for an iron deficiency or insufficiency. Iron needs in female athletes can be 70 percent higher than average requirements.

Intense endurance training can lead to significant iron losses from the body. Training at altitude, a period of growth or injury, and simply repeated striking the ground with the feet can cause an increase in iron needs above baseline.

A diet that is high in iron-rich foods can supply these increased iron needs, as can supplementing iron, as can a combination of both.

There are two food sources of iron:  heme iron found in animal foods such as red meat, poultry, and fish, and non-heme iron sources such as lentils, beans, and spinach.

Because the body is less efficient at absorbing non-heme iron, it is recommended to consume these sources with a vitamin C source from food or supplements to enhance iron absorption. Iron supplements are notorious for causing gastrointestinal side effects, and they are often not well tolerated immediately after exercise.

When choosing an iron supplement, look for iron bisglycinate, which has been shown to be better absorbed than other forms of iron, which helps to minimize iron’s GI side effects.*

An athlete who does not maintain adequate iron status might need supplemental iron at doses greater than the recommended daily amounts of >18 mg/day for women and >8 mg/day for men. Iron protocols, especially in individuals believed to be iron deficient should be determined with the assistance of a health-care practitioner.


Three Considerations for the Strength and Power Athlete 

Strength and power sports focus on short, intense, or repeated bursts of power. Although it is easy to place athletes such as sprinters and powerlifters into this category, players on team sports like American football can also fall into this category.

The average football game contains just 11 minutes of total action, in 5-second bursts of activity per play. At the elite level, athletes are only involved on offense or defense, which drops the total active time to about four minutes.

In comparison, a hockey shift lasts between 40-50 seconds and a boxing round clock in at three minutes. There are several vital nutrients that play an important role in the performance and recovery of these athletes:


1. Creatine, an amino acid stored mostly in skeletal muscle, is necessary for creating ATP – the body’s readily usable form of energy.*

Creatine is especially needed during high-intensity exercise and training to help recharge the body’s energy pools.* The liver and kidneys can produce up to half of the body’s creatine needs, but the remainder must come from consuming creatine in food – mainly from meat, fish, and eggs – or from supplementation.

Sports nutrition research and exercise physiology research have described numerous physiological changes that occur with creatine monohydrate supplementation, including supporting energy production and helping to maintain and promote lean muscle mass, endurance, and power output.*

Supporting these systems can result in an increased training capacity, which can enhance, improve, or quicken physical adaptations.

The International Olympic Committee recommends the following creatine protocol:


2. Beta-Alanine is an amino acid that combines with histidine, another amino acid, to create carnosine in the muscles.

Carnosine serves as a hydrogen scavenger, which neutralize the acidic hydrogen ions created when muscles convert glucose to energy. An increase in hydrogen ions in the muscles increases the acidity level in the muscles, which is the primary contributor to muscle fatigue and soreness.

Because beta-alanine is the rate-limiting step in determining the carnosine level in muscles, the more beta-alanine that is available, the more carnosine that is available; hence, the better the adverse impact of muscular acidity is mitigated, which, in turn, increases muscle capacity and time-to-failure.* 

Research recommends the following protocol for a strength and power athlete:

  • Six grams of sustained-release beta-alanine per day in two equal doses for 4-6 weeks.

Supplementation of six grams of sustained-release beta-alanine has been shown to increase the carnosine level in muscle by as much as 64 percent after four weeks and as much as 80 percent after 10 weeks.* Following this protocol, one 28-day study showed cyclists had a 9.9-percent increase in training intensity and a 14.9-percent increase in training endurance.*


3. Protein is essential to the strength and power athlete because protein is the nutrient that builds and repairs muscles.*

Adequate protein needs must be met to promote the growth of new tissue and activate the recovery and repair of exercise-induced damage to muscles.* Protein is made up of amino acids, of which leucine is the key to post-exercise recovery and repair.*

While an athlete is training and competing, the body begins to break down and will continue to do so until given the signal to begin the recovery and repair process.

Leucine in the amount of 2.3-2.5 grams can initiate the recovery and repair process.*

Although the leucine content of protein-containing foods can vary, leucine can generally be obtained through 20-35 grams of high-quality protein foods or a protein supplement. Learn more about choosing the best protein to promote recovery and repair.

  • General protein guidelines for athletes:  1.0-1.5 grams of protein per kg of weight daily.
  • General protein guidelines during the day:  20-40 grams of protein per meal, 3-4 meals per day.
  • Advanced training, injury, illness guidelines:  1.5-2.2 grams of protein per kg of weight daily.

Post workout guidelines:  20-25 grams of protein (or 2.3-2.5 grams of leucine provided in an amino acid complex) in the near post-workout window.


An athlete’s knowledge of the unique demands of training and competing in his or her sport is the key to creating an individualized nutrition plan. Identifying your training volume, understanding how your body responds, and adjusting for an optimal fueling, recovery, and repair plan will allow you to perform your best every time.


References

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