Sports Nutrition Considerations for Athletes

Recently (2016) the American College of Sports Medicine, the Academy of Nutrition and Dietetics, and Dietitians of Canada published a joint position statement that summarized current recommendations for energy, nutrient, and fluid consumption for both active and athletic populations.

The underpinnings of these recommendations were developed as a result of an evidence-based examination of the Academy of Nutrition and Dietetics Evidence Analysis Library (EAL).  The publication range for this analysis was from March 2006 to November 2014.

The topic of nutrition sparks energetic debate and conversation among health and fitness professionals. This is especially true in situations where the goal is performance-related (competing in an athletic event, training for a marathon, etc.) rather than health-related (lowering blood pressure, increasing endurance, etc.).

EAL Questions and Evidence Synthesized

The researchers involved in crafting this position statement sought to answer specific questions related to energy and exercise. They are as follows and taken directly from the position statement. The evidence statements were graded based on Good, Fair, and Limited (ACSM, 2016).

In adult athletes, what effect does negative energy balance have on exercise performance?
Fair, but mixed results. Some studies noted no impact while others saw a decline in both anaerobic and aerobic performance.

In adult athletes, what is the time, energy, and macronutrient requirement to gain lean body mass?
Limited. Increasing protein over a period of 4-12 weeks during low-calorie intake maintains lean body mass in resistance-trained athletes. When energy intake is adequate, an increase in lean body mass may result.

In adult athletes, what is the effect of consuming carbohydrates on carbohydrate- and protein-specific metabolic responses and/or exercise performance during recovery?
Limited. No clear effects noted.

What is the effect of consuming CHO on exercise performance during recovery?
Limited. No clear effects noted.

In adult athletes, what is the effect of consuming carbohydrate and protein together on carbohydrate and protein-specific metabolic responses during recovery?

Good – When compared to carb-only ingestion, combining carbs and protein showed no difference in the rate of synthesis. Combining carbs and protein during recover resulted in increased protein-balance.

No conclusive evidence with respect to creatine kinase levels.

Fair – No clear evidence with regard to strength and sprint power.

In adult athletes, what is the effect of consuming carbohydrate and protein together on exercise performance during recovery?
Fair. Consuming protein during recovery resulted in faster recovery of force (static) and power (dynamic) production during DOMS. More repetitions performed following intense resistance-training.

In adult athletes, what is the effect of consuming protein on carbohydrate and protein-specific metabolic responses during recovery?
Good. Consuming 20-30g (with 10g of essential amino acids) during exercise or following exercise resulted in increased protein synthesis and nitrogen balance.

In adult athletes, what is the optimal blend of carbohydrates for maximal carbohydrate oxidation during exercise?
Limited. Carb oxidation was greater in carb conditions compared to placebo. No difference between the two carb blends tested was noted in male cyclists. A single study noted that exogenous carb oxidation was greater in the glucose + fructose combo vs. glucose-only.

In adult athletes, what effect does training with limited carbohydrate availability have on metabolic adaptations that lead to performance improvements?

Fair. Training with limited carb availability impaired training and duration.

In adult athletes, what effect does consuming high carbohydrate or low glycemic meals or foods have on training related metabolic responses and exercise performance?

Good. Neither glycemic index or load impacted endurance nor metabolic responses when conditions were matched for carb and energy.

Resulting Themes

Throughout the process of analyzing the body of sports nutrition literature available in the EAL repository, eleven themes were discovered based on the results of nearly 10 years of research.

1.    Nutrition goals and needs are dynamic and should be periodized to support training and performance.
2.    Nutrition programs need to be personalized to each individual athlete.
3.    Competition nutrition strategies are valuable when focused on providing adequate substrate stores.
4.    Energy availability provides a foundation for health and success of nutrition strategies.
5.    Achievement of body composition which will optimize performance is recognized as a necessary, but an extremely challenging, goal. Individualized and periodized programming is paramount.
6.    Training and nutrition have a strong interrelationship.
7.    Specific nutrients should be recommended based on amount recommendation per kilogram (kg) body weight. Sports nutrition guidelines should also consider nutrient timing and its role in athletic performance.
8.    Highly trained athletes are challenged to strike a balance between training maximally to perform well and avoid injury/illness.
9.    Competition nutrition strategies should be based on reducing or delaying those factors which may result in fatigue during an event. Recommendations are specific to the event and environment.
10.  New research has emerged that suggests the presence of carbohydrate (along with other nutritional components) in the oral-cavity may enhance feelings of well-being and increase work rates. These findings expand upon previously established energy intake recommendations for short-duration events based on the belief that it may result in enhanced performance through a more central effect versus a direct metabolic benefit.
11.  Dietary supplement interest and use remain high among athletic populations. Therefore, a pragmatic guided approach is required when discussing the use of such aids or supplements.

Take Away Messages

This position stand is a pivotal piece of work in that it lends new insight into how fitness professionals and sports nutritionists can most effectively guide their clients toward performance success.

Some of the most significant take away messages are summarized as follows.

• Adequate and appropriate energy intake support optimal performance and function and assists in modifying body composition.
• Carbohydrates belong in the center of the plate and are more likely to be under-consumed than protein.
• Any nutritional programming recommendations must first consider the individual athlete followed by the sport, the event, the timing of the season, the environment, etc.
• No evidence that training in carb-restricted (training “low”) state will enhance performance. Training low can result in illness and injury.
• Carb needs are lower for non-athlete, but active individuals.
• New protein intake guidelines are based on the three T’s – total, timing, and type.

Aside from the information presented and interpretation by the organizations involved in publishing this statement, it’s important to respect your professional scope of practice and refer to a registered dietitian for assistance in establishing nutritional guidelines and programs for athletes and non-athletes alike.

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Resource
ACSM (2016). Nutrition & Athletic Performance. Medicine and Science in Sports and Exercise, 48(3), p. 543-568.