Nutrition and Athletic Performance

The following post highlights some of the key points provided in the most recent position paper on Nutrition and Athletic Performance. It should be noted that this position paper was produced based on the the current state of the literature and that an Evidence Analysis Process (American Dietetic Association) was utilized to standardize this review.

This paper was jointly provided by the  Dietitians of Canada, the American College of Sports Medicine, and the American Dietetic Association, and it was their position that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of food and fluids, timing of intake, and supplement choices for optimal health and exercise performance.

​Highlights of this Position paper

Carbohydrate recommendations: 6-10g/kg (2.7-4.5 g/lb) BW per day or ~60% of total energy intake

Protein recommendations: 1.2-1.7 g/kg (0.5-0.8 g/lb) BW per day

• Endurance Athletes: 1.2-1.4 g/kg/day to support nitrogen balance. May need to be slightly higher for ultra endurance athletes. Carbohydrates are important for protein metabolism.
• Strength Athletes: 1.2-1.7 g/kg/day especially in the early phases of training. The more experienced athlete will utilize protein more efficiently and therefore requirements may be lower.
• Supplementation should only be directed primarily at optimizing the training response to and the recovery period following exercise. No evidence it directly improves performance.

Fat recommendations: 20%-35% of total energy intake.

• Fatty acid proportion: 10% each of saturated, polyunsaturated, and monounsaturated.

Dehydration occurs when there is a water deficit > 2%-3% body mass.

• 5-7 ml/kg BW of water or sports beverage 4 hours before exercise
• Sodium/Potassium replaces electrolytes while sodium also stimulates thirst and fluid retention. Recommendation is a 6%-8%  carbohydrate beverage for events >1hr
• Hyponatremia: Serum sodium concentration less than 130 mmol/L. May be due to prolonged, heavy sweating with failure to replace sodium or excessive water intake (i.e. beginner marathoners who don’t know how to replenish fuel properly)
• 16-24 oz (450-675 mL) of fluid for every pound (0.5kg) of BW lost for replacement

Fuel during exercise: carbohydrates approx. 30-60g per hour especially in endurance events

After Exercise: carbohydrates approx. 1.0-1.5 g/kg (0.5-0.7 g/lb) BW during first 30 min. Also every 2 hours for 4 to 6 hours

Multivitamin/mineral supplement may be appropriate if athlete is dieting, lacking in a particular food group, sick or injured, or has a specific deficiency. Athletic vegetarians may be at risk for low intakes of energy, protein, fat and key micronutrients (i.e. iron, calcium, vit. D, riboflavin, zinc, and B-12). Therefore, athletes who are at greatest risk for poor micronutrient status and MAY benefit from a daily supplement are those:

Who restrict energy intake or have severe weight loss practices
Who eliminate one or more of the food groups from their diet
Who consume unbalanced and low macronutrient dense diets

• Riboflavin, pyridoxine, folate and B-12 are frequently low in female athlete diets (especially vegetarians and those with disordered eating patterns)
• Athletes in northern climates or train indoors throughout the year are at risk for poor Vit. D status. Should supplement at Dietary Reference Intake level (5 ug/day or 200IU ages 19-49)
• Vit E: Endurance athletes may have higher need for Vit. E (reduce lipid peroxidation)
• Vit C: 100-1000 mg/day for those who participate in regular prolonged, strenuous exercise.
• Calcium: Low levels of Ca and Vit. D increase increase the risk for decreased bone mineral density and stress fractures. Females at greatest risk if energy intakes are low, dairy products are restricted, and menstrual dysfunction is present. 1500 mg of Ca and 400-800 of Vit. D are recommended for those with disordered eating, amenorrhea, and risk for early osteoporosis.
• Iron: Usually low in females due to energy restriction or avoidance of animal products. Requirements for endurance athletes (distance runners) are increased by approx 70%. Vegetarian or blood donating athletes should aim for higher than RDA (>18mg women and >8mg men)
• Magnesium: deficiency impairs performance by increasing O2 requirements to complete submaximal exercise. Athletes in weight-class sports (wrestling) may be deficient.

Endurance athletes may require much more than the tolerable upper intake level for sodium (2.3g/day) and chloride (3.6 g/day).

Sports drinks containing 0.5-0.7 g/L of sodium and 0.8-2.0 g/L of potassium, as well as carbohydrates are recommended for endurance sports > 2hr

Pre-exercise

• 200-300 g of carbs 3-4 hours prior to enhance performance (Glycemic index research is equivocal/inconclusive)

During Exercise

• 6-8% carb sports drink for events < 1hr
• 0.7 g carb/kg BW per hour (aka 30-60 g per hour) for endurance events. 15-20 minute intervals is better than a single bolus every hour. Should be primarily glucose but may also be a mixture
• Adding protein (to a carbohydrate drink) for performance enhancement is still inconclusive
• Timing and composition depends on the length and intensity of the session as well as when the next event will occur.
• 1.0 – 1.5 g of carbs/kg (glucose and sucrose) within 30 min and at 2 hour intervals up to 6 hours. However, if an athlete isn’t training until 2 days later, timing is not as important

Classification of Supplements and Ergogenic Aids

Those that perform as claimed

• Creatine: sprinting and weight lifting but not endurance sports

• Caffeine: CNS stimulant. Does not cause dehydration or electrolyte imbalance if used in moderation

• Sodium Bicarbonate: a blood buffer but may cause side effects (diarrhea)

• Protein/Amino Acids: no more or less effective than food IF energy is adequate

That may perform as claimed by evidence is still insufficient

• Glutamine, beta hydroxymethylbutrate, colostrum, ribose

That DO NOT perform as claimed

• Amino acids, bee pollen, BCAAs, carnitine, chromium picolinate, CoQ10, CLA, ginseng, oxygenated water

That are dangerous, banned or illegal

• Androstenedione, dehydroepiandrosterone, 19-noreandrostendione, 19-norandrostenediol, ephedra, human growth hormone

Vegetarian Athletes

• May be a red flag for disordered eating and increase the risk of female athlete triad

• Protein quality of plant-based diets should be sufficient for energy. But they are less well digested (than animal sources) so a 10% increased intake is advised. Protein recommendations for vegetarian athletes = 1.3 - 1.8 g/kg/day

• Vegetarian athletes may be at risk for low intakes of energy, fat, B12, riboflavin, Vit. D, calcium, iron, and zinc. especially iron…due to low bioavailability of non-heme plant sources.

​Therefore, female, vegetarian athletes may be at greater risk for developing iron deficiency anemia and need routine monitoring

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