Introduction to Sports Nutrition
Original Editor - Wanda van Niekerk
Basics of Nutrition[edit | edit source]
Macronutrients[edit | edit source]
Macronutrients provide calories or energy to the body. Their function is to promote:
- cellular growth
- maintenance of normal bodily functions
Macronutrients are necessary in large amounts to have a full and proper effect. The three types of macronutrients are:
Micronutrients[edit | edit source]
Micronutrients are essential, but we need these in smaller amounts. Micronutrients are necessary for cell growth and function. The human body cannot produce micronutrients, so they must be consumed.
|Vitamins||Minerals and their function|
Water[edit | edit source]
- Water is best for hydration, but any calorie-free, non-caffeinated, non-alcoholic fluid can work
- Caffeine and alcohol function as diuretics
Food Groups[edit | edit source]
MyPlate provides good examples of healthy eating. Read more here.
Sports Nutrition[edit | edit source]
Energy Balance and Exercise[edit | edit source]
Some considerations with energy balance and exercise include:
- Energy balance is important for athletes wanting to change their body mass and/or body composition in order to improve performance or make a specified weight category for their sport.
- Insufficient energy consumption in relation to expended energy will result in the effects of training being lost, as muscle and fat will be used as energy sources.
- Restricted energy intake may compromise an athlete's ability to obtain necessary nutrients.
- Athletes need to consume enough energy to cover the energy costs of:
- daily living
- their sport
- building and repairing muscle tissue
- Energy balance = Ein = Eout
- Ein = energy consumed
- Eout = expended energy
- Energy balance is a dynamic process
- for example, if energy intake is changed through a different diet, this can affect the physiological and biological components of energy expenditure.
- Factors that influence energy balance can be:
|Energy intake||Energy expenditure|
Training Consequences of a Negative Energy Balance[edit | edit source]
- Increased risk of stress fractures
- Decreased athletic performance
- Slower phospocreatine recovery rates
- Athlete enters a hypometabolic catabolic state (low insulin growth factors, high cortisol-releasing hormone, high cortisol levels), which means it is more difficult for athletes to increase their lean muscle mass.
- Increased risk of injury
- Changes (decrease) in metabolic rate
- Breakdown of lean tissue
How Many Calories Do Athletes Need?[edit | edit source]
- TEE = REE x AL x TAE
- TEE = Total energy expenditure
- REE = Resting energy expenditure
- AL = Active lifestyle
- TAE = Training activity energy
- Adequate calories are a vital component of nutrition for athletes
- Quality is just as important as quantity (i.e. what you eat is just as important as how much you eat)
Carbohydrate Intake and Needs for Athletes[edit | edit source]
Carbohydrates for athletes:
- Provide energy
- They contribute:
- dietary fibre
- Vitamins, for example, vitamin B complex
- Antioxidants in fruits and vegetables
Considerations when discussing carbohydrates with athletes:
- quality of carbohydrates (low versus high quality)
- high versus low glycaemic index
- timing of intake
- variety of sources necessary
- vegetables, fruits, sweet potatoes, quinoa, brown rice, wild rice, nuts, seeds
Amount of Carbohydrates Required[edit | edit source]
- Carbohydrate intake ranges from 3 to 10 g/kg BW/day (it may reach 12g/kg BW/day for extreme and prolonged activities) - BW = body weight
- Intake ranges are dependent on:
- fuel demands of training and competition
- balance between performance and training adaptation goals
- total energy requirement of the athlete
- body composition goals of the athlete
|Activity Level||Carbohydrate targets|
|Light (low-intensity exercise or skill-based training activities)||3 - 5 g/kg of athlete's BW/day|
|Moderate (moderate training/exercise for about an hour/day||5 - 7 g/kg of athlete's BW/day|
|High (endurance training programme, 1 to 3 hours/day, moderate to high-intensity exercise)||6 - 10 g/kg of athlete's BW/day|
|Very high (extreme training, more than 4 to g hours/day moderate to high-intensity exercise)||8 - 12 g/kg of athlete's BW/day|
Timing and Glycemic Index of Carbohydrates[edit | edit source]
- More carbohydrates on game days and days of intense training
- Fewer carbohydrates on off days and recovery days
- Fewer carbohydrates means that the athlete eats more vegetables, leafy greens
- Lower glycaemic index carbohydrates on non-training days
Fat Intake and Needs for Athletes[edit | edit source]
- Healthy diets do include fat
- Fat provides energy
- Fat is an essential component of cell membranes
- Fat facilitates the absorption of fat-soluble vitamins
- Fat aids in recovery
- Growth hormone
- Testosterone levels in athletes
- Fat helps:
- nervous system repair
- cognitive function
- decrease body inflammation
- Considerations with fat intake:
- omega 6: omega 3 ratio
- essential fatty acids
- fish oil fats (omega-3s)
- avoid trans fats
Amount of Fat Required[edit | edit source]
- Fat intake should not be less than 20% of an athlete's daily caloric intake
- Typically between 20% to 35% of total energy intake is acceptable
- Recommended: 0.5 to 1.0 g/kg of athlete's BW/day
Protein Intake and Needs for Athletes[edit | edit source]
- Athletes need more protein than the recommended daily allowance (RDA)
- Recommendations typically range from 1.2 to 2.0 g/kg of athlete's BW/day
- Endurance athletes need 1.2 to 1.7 g/kg of athlete's BW/day
- Strength training athletes need 1.6 - 2.2 g/kg of athlete's BW/day
- Vegetarians need more protein
- Benefits of protein intake at higher levels:
- decreased blood triglyceride levels
- improved body composition
- enhanced weight loss
- stabilised blood glucose levels
- reduced risk of disease
- improved bone health
Timing and Protein Intake[edit | edit source]
- Must have protein with every meal to help with muscle recovery and muscle protein synthesis
- Regular spacing of intakes of modest amounts of protein after exercise and throughout the day is recommended
Water[edit | edit source]
- Euhydrated = when an individual has normal body water content
- Hypohydrated = when an individual has lower than normal body water content
Hydration Goals for Athletes[edit | edit source]
- Begin exercise in a euhydrated state
- Prevent excessive hypohydration during exercise
- Replace fluid losses following exercise prior to the next training session/exercise bout
- Avoid exercise associated hyponatremia
- Read more: Fluid Excess/Intoxication
Fluid needs for athletes are individual and depend on factors such as:
- sweat rate of the individual
- type of exercise
- exercise intensity
- environmental conditions
- duration of exercise
Dehydration has a negative impact on physical performance for activities that last more than 30 seconds, but it has no significant impact on performance for activities that last less than 15 seconds.
American College of Sports Medicine (ACSM) Current Recommendations on Hydration:
- Before exercise:
- 5 - 10 ml/kg BW water, 2 - 4 hours before exercise
- During exercise:
- 0.4 - 0.8 l/h during exercise
- After exercise:
- 1.25 - 1.5 l for every kg BW lost
Post-Workout Nutrition[edit | edit source]
Athletes can apply different strategies for recovery after exercise. The amount, consumption and timing of nutritional strategies differ according to factors such as:
- the type of sport
- the time between training sessions
- the athlete's level of preparation
- the convenience of the specific nutritional strategy
The 4Rs is a useful mnemonic to consider:
- enough water to compensate for weight loss during training (1.25 - 1.5 litres for every kg BW lost)
- a combination of carbohydrates and protein is a good strategy for glycogen replenishment and tissue repair
- ingestion of high-quality protein can contribute to faster tissue growth and repair
- optimal sleeping time and good quality sleep are necessary for recovery
Resources[edit | edit source]
- Nutrition and Athletic Performance
- Ten things you need to know about sports nutrition
- The Athlete's Kitchen: Sports Nutrition Myths BUSTED!
- Australian Institute of Sport. Nutrition resources
References[edit | edit source]
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