Everyone knows that nutrition is important, but this is especially true for athletes. Nutrition requirements are individual –based on age, gender, lifestyle, health status, level of physical activity, physical conditioning, and type of activity.
You diet affects your performance now – but also in the future. Good nutrition will improve your performance and will also help to prevent injuries, or decrease recovery time.
To start with I’m going to give a brief rundown of the three macronutrients – carbs, proteins and fats – and why each is so important to athletes.
- Primary function is to provide energy to the cells of the body – particularly the brain
- Facilitates fat metabolism
- Spares muscle protein
- Provides the body’s tissues and organs (including the heart) most of their energy
- Note: Fat is an ideal fuel because its energy-dense, weighs less than carbs and is easily transported and stored
- Phospholipids (a type of fat) make up part of the cell membrane
- Fat is critical for transmitting nerve signals that generate muscle contractions
- Transportation of fat soluble vitamins (A, D, E, K)
- Protection of vital organs and insulation from thermal stress of cold environments
- Produces antibodies for the immune system
- Produces enzymes required for chemical reactions in the body (i.e., digestion and absorption, blood coagulation, and contractibility and excitability of muscle tissue).
- Component of structural hormones
- Component of transport proteins (i.e., albumin, prealbumin, hemoglobin, ceruloplasmin, transferrin, and retinol-binding protein).
- Component of peptide hormones (i.e., insulin, glucagon, parathyroid hormone, thyroid hormone, growth hormone, adrenocorticotropic hormone, and antidiuretic hormone).
- Source of fuel when muscle glycogen levels are low (i.e. during prolonged, intense exercise).
Nutrition for Endurance Athletes:
Endurance athletes have unique challenges to meeting their nutrition needs. Optimal intake of nutrition is very important – as is the timing of nutrition.
Signs of suboptimal nutrition in endurance athletes include nagging injuries, frequent upper respiratory illnesses and slow recovery from training.
Endurance athletes are at increased risk of dehydration due to increased fluid losses from sweating (particularly when exercising in warm or humid weather and at altitude). Fluid requirements are very individualized based on fitness levels, sweat rates, and environmental conditions.
Proper hydration improves endurance and protects against heat stroke. Even minimal dehydration (1-2% of body weight loss) negatively affects performance.
How to calculate baseline fluid requirements:
- 1 ml per calorie of estimated energy requirements
- 1500ml + (20ml/kg x body weight in kg)
- Body weight (kg) x 35ml/kg
Note: Most young, active people will require 2.5-3L fluid at baseline.
How to calculate fluid losses/rehydration requirements:
- To calculate exercise-induced fluid losses, weigh yourself before and after exercise to determine the amount of fluid lost through sweating.
- For every pound “lost” after exercise, you should rehydrate with 20 ounces (2.5 cups or 625ml) of fluid over the next few hours *so if you lost 1.5lbs of fluid during a run, you would need to rehydrate with 3.75 cups of fluid/950ml in addition to your baseline fluid requirements
Pre-exercise fluid recommendations:
- Make sure you have properly rehydrated from previous days exercise
- Drink ~16 oz (2 cups) of fluids 2 hours before exercise
Risk of over-hydration:
- Athletes who gain weight during exercise will need to hydrate less.
- Therefore, athletes should not be counseled to “drink as much as possible” during exercise, but more according to thirst, with a general recommendation of no more than 400-800mL per hour during exercise.
- Athletes must consume enough calories on a day-to-day basis to cover the calories expended during exercise
- There are various devices and calculations that can be used to calculate energy requirements
- To calculate resting metabolic rate (RMR) use 30kcal/kg body weight or Harris-Benedict
The Harris-Benedict Equation:
> Women: RMR = 655.1 + (9.56 x mass) + (1.85 x height) – (4.68 x age)
> Men: RMR = 66.47 + (13.75 x mass) + (5.0 x height) – (6.76 x age)
- The RMR is then multiplied by an activity factor to estimate total energy expenditure
Physical Activity Factors:
1. Sedentary: Activity Factor of 1.39
Description: office work, no vigorous activity/formal exercise, standing and sitting only
2. Low Active: Activity Factor of 1.49
Description: sedentary lifestyle + 30 minutes of moderate intensity activity; i.e. most office workers with additional planned exercise routines
3. Active: Activity Factor of 1.75
Description: an additional 3 hours of activity (daily) such as: bicycle 10-1 2 mph, stair-treadmill, walk 4.5 miles/hour, run 6 miles/hour; individuals with active jobs or with 3 hours of planned vigorous exercise each day
4. Very Active: Activity Factor of 2.06
Decription: full-time athletes, unskilled laborers, military on active duty, steel workers, etc.
- The limiting fuel source during exercise (primary source of energy during exercise)
- Therefore, endurance athletes always need to consume enough carb-rich foods to support their activity level
- High amounts of carbohydrates are required to saturate the muscles with glycogen – the storage form of carbohydrate that fuels endurance exercise
If training <1 hour per day:
- 45-65% of total energy requirements (daily calories) should be provided from carbohydrate
- Example: 2000kcal diet x 0.55 (55%) = 1100kcal from carb/4kcal/g of carb = 275g carb
- So, if you were consuming a 2000kcal diet and you were aiming for 55% carb, you would need 275g of carbohydrate per day – which might seem high but it’s really not when you think of it divided between 3 meals + 2 snacks
60-75g carbohydrate per meal + 15-30g of carbohydrate per snack
- Bagel = 60g carb
- 2 cups of cooked pasta = 60g carb
- 2 slices of bread = 30-40g carb
- 1 cup of cooked rice = 45g carb
- 1 cup of cold cereal = 30g carb
- 1 slice of pizza = 30g carb
- 1 medium banana = 30g carb
- 1 small sweet potato = 30g carb
If training >60-minutes/day:
- 7-12g/kg per day
- 7 g/kg if training 1 hour per day
- 8 g/kg if training 2 hours per day
- 10 g/kg if training 3-4 hours per day
- 10-12g/kg if training 4-6 hours per day or more
- Endurance athletes have increased protein needs to meet their performance and recovery demands.
- Most north American diets provide excessive quantities of protein – those most likely to consume inadequate amounts of protein are elite athletes with very high training demands as well as those athletes with low or suboptimal energy intakes (i.e. restrictive or disordered eating)
- Although protein is not a primary energy source during exercise, an increased breakdown of certain amino acids occurs during prolonged exercise.
- Protein typically provides ~5% of energy needs at rest and during exercise, however at the end stages of prolonged exercise protein may provide up to 10% of energy requirements
Protein needs for endurance athletes vary greatly:
- Adults require 0.8-1.0g/kg body weight protein at baseline
- If energy and carbohydrate intakes are adequate, engaging in low- and moderate-intensity endurance exercise does not seem to increase daily dietary protein requirements
- Endurance activity for ~60-minutes 4-5 days/week requires only a very modest increase in protein (-1.1 g/kg/day). If you are routinely (3-4 days/week) doing strength training exercise protein recommendations increase to 1.2-1.4g/kg body weight
- Elite athletes may require up to 1.6g/kg/day
- Example: A 150-lb runner who runs 4-5 days/week would have protein requirements of ~75g/day or ~85g/day if they were also strength training
- Protein goal should be ~20-30g/meal + 5-10g/snack
Protein content of common foods:
- 3 oz chicken = 28g
- 3 oz steak = 26g
- 3 oz turkey = 25g
- 3 oz pork = 22 g
- 1 large egg = 6g
- 3 oz salmon/tuna = 22g
- 1 cup beans/lentils = 16-22g
- 1 cup quinoa= 8g
- 2 Tbsp PB = 8g
- ¾ cup greek yogurt = 18g
- Historically, endurance athletes often consumed low-fat diets (usually with the goal of lower body mass and/or improved digestion). However, low-fat diets (<15% of calories from fat) have not been shown to be any more beneficial than diets containing 20%-25% of energy from fat.
- 20-35% of your total dietary calories should be coming from fat (so for example on a 2000-kcal diet you would have 40-70g of fat)
- High fat diets (such as keto) have emerged over the past few years as an ongoing topic of discussion among researchers.
- Premise: high-fat diets (studies have examined fat intake anywhere from 42-70% of total calories for 1-4 weeks prior to competition) have been proposed as performance-enhancing
- Keto diet: 60-75% fat, 15-30% protein, 5-10% carbs
- Results: individuals’ responses to high fat diets seem to vary tremendously
- Overall: this practice is not recommended at this time because it is unlikely that the majority of endurance athletes would benefit performance or health wise (especially long term because of the associated health risks of a high-fat intake – increased risk of heart disease, damage to gut microbiota). Some athletes engaged in ultra-endurance exercise could potentially see an improvement in performance, because of an increase in fat oxidation (breaking down fatty acids) and a decreased reliance on muscle glycogen, but it has not been consistently demonstrated in the literature
Timing of Nutrition:
- The goal of nutrition for endurance athletes is to minimize fatigue, illness, and injury.
- Recovery requires restoring nutrient and fuel stores and repairing damaged muscle fibers.
- A pre-exercise snack is likely not necessary if you are running <60-minutes and have eaten within the past 3-4 hours.
- If you are running first thing in the morning/haven’t had a meal recently/feel hungry a pre-exercise carbohydrate snack 15-60 minutes before exercise consisting of ~30g of will help to top up glycogen stores and increase carbohydrate availability for exercise
Examples of 30g of carbohydrate:
- 1 medium banana
- ½ PB sandwich
- Granola bar
- 10-12 crackers
- ¼ cup dried fruit
- Runners should consume a carbohydrate-rich meal (1.2g/kg) (*80g-CHO for 150-lb person) that is low in fat and moderate in protein (10-20g) 2-4 hours before exercise
Nutrition During Prolonged-Exercise (i.e. during a marathon):
- When eating during a training run or event, a runner should consume a food item that is high in easily digestible carbohydrate and low in fat and protein.
- Since fat, protein, and fiber slow down the digestive process, runners should avoid these nutrients to keep their stomach calm. Digestion during exercise is difficult enough since the blood supply is diverted to the working muscles at a time when it would normally be focused on the stomach and proper digestion.
- Supplemental carbohydrate during prolonged exercise improves performance. General guidelines advise athletes to aim for an intake of approximately 30-60g of carbohydrate per hour they are engaged in exercise, or approximately 150-300 calories per hour *this is often provided through sports drinks and energy gels and bars specifically designed for use during exercise.
Recovery Nutrition for Endurance Athletes:
- Muscle glycogen depletion is detrimental to optimal performance and results in increased muscle soreness, poor recovery and increased risk of injury. Repeated bouts of exercise accompanied by an inadequate intake of carbohydrate will produce a day-to-day decrease in muscle glycogen.
- Because it takes almost 24 hours to fully replenish muscle glycogen stores, endurance athletes will benefit from consuming a daily diet adequate in carbohydrate to match their activity level.
- Capitalize on the “carbohydrate window” immediately after exercise. During the first few hours after exercise (especially the initial 15-30 minutes after exercise), muscles convert carbohydrate-rich foods and beverages into glycogen up to 3 times faster than at other times.
- Consuming a small amount of protein (10-20g) immediately (within 2 hours) after exercise also seems to be beneficial, by enhancing glycogen replenishment, as well as limiting post exercise muscle damage and initiating the muscle repair process.
- Runners should consume a real meal within two hours of run completion that contains carbohydrate and protein in a 3:1 ratio to adequately replenish glycogen stores and rebuild muscles. They should also consume plenty of liquids until urine is pale yellow or clear.
I’m often asked when an electrolyte drink is warranted. Short answer: any time you do intense exercise for >60-minutes an oral rehydration solution (electrolyte drink like Gatorade, PowerAde, Pedialyte etc) is warranted. If you are performing exercise multiple times/day (i.e. tournament, multiple workouts) for a total of >60-minutes/24-hour period of intense activity an electrolyte solution should be taken.
Endurance athlete’s performance is negatively affected by two fluid and electrolyte-related issues: hyponatremia and muscle cramps
- Symptoms of hyponatremia: Feeling weak, lethargic, nauseated, bloated, confused, or developing muscle cramps, a headache, slurred speech, or swollen hands and feet during or after prolonged exercise – left untreated can progress to seizures, coma, brain damage and even death
- Endurance athletes are at an increased risk for hyponatremia because of prolonged or excessive sweating resulting in increased losses of sodium or excessive fluid intake during/after exercise, which dilutes concentrations of sodium
- The exact cause of muscle cramps is unknown – likely related to muscle overexertion, dehydration or electrolyte imbalances
Treatment of muscle cramps:
- Note: A symptom of both potassium and magnesium deficiency is muscle cramping
- Try a high potassium food (bananas, oranges/OJ, avocado, potatoes, milk)
- Make sure you have enough magnesium-containing foods in your diet (beans & legumes, nuts & seeds, fish, leafy greens, whole grains) or take a magnesium supplement or epson salt (magnesium sulfate) bath
- Stretching, rest days
- Adequate hydration
- Consider an electrolyte solution if running in very hot temperatures, prolonged exercise or excessive sweating