Introduction to Sports Nutrition

Original Editor - Wanda van Niekerk

Top Contributors - Wanda van Niekerk, Jess Bell and Lucinda hampton  

Basics of Nutrition[edit | edit source]

Macronutrients[edit | edit source]

Macronutrients provide calories or energy to the body.[1] Their function is to promote:

  • cellular growth
  • metabolism
  • maintenance of normal bodily functions

Macronutrients are necessary in large amounts to have a full and proper effect. The three types of macronutrients are[1]:

Table 1. Summary of macronutrients and their function
Carbohydrates Proteins Fats
  • Body's main fuel source[2]
  • Broken down into blood glucose
    • Red blood cells and the brain only use glucose for energy[3]
  • Types: sugars, starch, fibre[4]
  • Chemical foundation for all cells, antibodies, enzymes and hormones[5]
  • Amino acids are the building blocks of proteins[5]
  • Promotes wound healing[6]
    • Plays a role in the development and repair of bone, muscle and skin
    • Protein needs are increased during more stressful times and/or during illness
  • Essential for transport of oxygen around the body[7]
  • An essential nutrient, necessary for the normal functioning of the body
  • Concentrated form of energy[8]
  • Help maintain body temperature and insulation of body organs[9]
  • Necessary for healthy skin and normal nerve function[10]
  • Carry the fat-soluble vitamins A, D, E, and K[11]

Micronutrients[edit | edit source]

Micronutrients are essential, but we need these in smaller amounts.[12] Micronutrients are necessary for cell growth and function. The human body cannot produce micronutrients, so they must be consumed.[12]

Table 2. Micronutrients in nutrition
Vitamins Minerals and their function
  • Fat-soluble - absorbed through intestines with fat (Vitamins A, D, E, K)[12]
  • Water soluble - dissolve in water (Vitamins B complex and C)[12]
  • Fluid and electrolyte balance (sodium, potassium)[13]
  • Bone health (calcium, magnesium)[13]
  • Oxygenation of blood (iron)[13]

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[14]

Food Groups[edit | edit source]

Table 3. The main food groups and examples
Fruits Vegetables Protein Grains/starch Dairy Fats
  • Apples
  • Strawberries
  • Pears
  • Bananas
  • Carrots
  • Broccoli
  • Cauliflower
  • Butternut
  • Plant-based sources
    • beans, lentils, legumes
    • nuts, nut butter, seeds
  • Animal-based sources
    • poultry
    • lean cuts of beef and pork
    • oily fish
  • Grains/starch
    • whole grains
      • quinoa, oats, barley
    • popcorn
    • potatoes, corn, peas (the nutritional make-up of these foods is more similar to grains than vegetables)
  • Milk, yoghurt, cheese
  • Non-dairy milk and yoghurt
  • Kefir
  • Plant-based fats are better
    • avocado, olives, nuts/seeds

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[15]:

  • 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[15]:
    • 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.[15]
  • Factors that influence energy balance can be[15]:
    • internal
    • external
      • environmental
      • social
      • behavioural
Table 4. Influencing factors on energy intake and expenditure[15]
Energy intake Energy expenditure
  • Diet composition
  • Timing of intake
  • Exercise intensity
  • Types of food
  • Diet composition
  • Exercise intensity
  • Sedentary behaviour
  • Resting metabolic rate

Training Consequences of a Negative Energy Balance[edit | edit source]

  • Increased risk of stress fractures[16]
  • Decreased athletic performance[17]
  • Slower phospocreatine recovery rates[18]
  • 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.[18]
  • Increased risk of injury[19]
  • Changes (decrease) in metabolic rate[20]
  • Breakdown of lean tissue[21]

How Many Calories Do Athletes Need?[edit | edit source]

  • TEE = REE x AL x TAE[18]
    • 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)[18]

Carbohydrate Intake and Needs for Athletes[edit | edit source]

Carbohydrates for athletes:

  • Provide energy[22]
  • They contribute:
    • dietary fibre
    • Vitamins, for example, vitamin B complex
    • Antioxidants in fruits and vegetables

Considerations when discussing carbohydrates with athletes[18]:

  • 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)[23] - BW = body weight
  • Intake ranges are dependent on[23]:
    • 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
Table 5. Guidelines for Carbohydrate Intake by Athletes[23]
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[23]
  • Fat is an essential component of cell membranes
  • Fat facilitates the absorption of fat-soluble vitamins[11]
  • Fat aids in recovery
  • Fat helps[23]:
    • nervous system repair
    • cognitive function
    • decrease body inflammation
  • Considerations with fat intake[18]:
    • 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[23]
  • Typically between 20% to 35% of total energy intake is acceptable[23]
  • Recommended: 0.5 to 1.0 g/kg of athlete's BW/day[23]

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[23]
    • 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:[23]
    • 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[23]
  • Regular spacing of intakes of modest amounts of protein after exercise and throughout the day is recommended[23]

Water[edit | edit source]

  • Euhydrated = when an individual has normal body water content[24]
  • Hypohydrated = when an individual has lower than normal body water content[24]

Hydration Goals for Athletes[edit | edit source]

  • Begin exercise in a euhydrated state[25]
  • Prevent excessive hypohydration during exercise[25]
  • Replace fluid losses following exercise prior to the next training session/exercise bout[25]
  • Avoid exercise associated hyponatremia[26]

Fluid needs for athletes are individual and depend on factors such as[25]:

  • 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.[27]

American College of Sports Medicine (ACSM) Current Recommendations on Hydration[23]:

  • 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[28]:

  • 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[28]:

  • Rehydrate
    • enough water to compensate for weight loss during training (1.25 - 1.5 litres for every kg BW lost)
  • Refuel
    • a combination of carbohydrates and protein is a good strategy for glycogen replenishment and tissue repair
  • Repair
    • ingestion of high-quality protein can contribute to faster tissue growth and repair
  • Rest
    • optimal sleeping time and good quality sleep are necessary for recovery

Resources[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 Costa-Pinto R, Gantner D. Macronutrients, minerals, vitamins and energy. Anaesthesia & Intensive Care Medicine. 2020 Mar 1;21(3):157-61.
  2. Slavin J, Carlson J. Carbohydrates. Advances in nutrition. 2014 Nov;5(6):760.
  3. Nimgampalle M, Chakravarthy H, Devanathan V. Glucose metabolism in the brain: An update. InRecent Developments in Applied Microbiology and Biochemistry 2021 Jan 1 (pp. 77-88). Academic Press.
  4. Blaak EE, Riccardi G, Cho L. Carbohydrates: Separating fact from fiction. Atherosclerosis. 2021 Jul 1;328:114-23.
  5. 5.0 5.1 Whitford D. Proteins: structure and function. John Wiley & Sons; 2013 Apr 25.
  6. Roefs MT, Sluijter JP, Vader P. Extracellular vesicle-associated proteins in tissue repair. Trends in cell biology. 2020 Dec 1;30(12):990-1013.
  7. Bellelli A, Tame JR. Hemoglobin allostery and pharmacology. Molecular Aspects of Medicine. 2022 Apr 1;84:101037.
  8. Muscella A, Stefàno E, Lunetti P, Capobianco L, Marsigliante S. The regulation of fat metabolism during aerobic exercise. Biomolecules. 2020 Dec 21;10(12):1699.
  9. Mohajan D, Mohajan HK. A Study on Body Fat Percentage for Physical Fitness and Prevention of Obesity: A Two Compartment Model. Journal of Innovations in Medical Research. 2023 Apr 21;2(4):1-0.
  10. Yildiran H, Macit MS, Özata Uyar G. New approach to peripheral nerve injury: nutritional therapy. Nutritional neuroscience. 2020 Oct 2;23(10):744-55.
  11. 11.0 11.1 Meijaard E, Abrams JF, Slavin JL, Sheil D. Dietary fats, human nutrition and the environment: Balance and sustainability. Frontiers in Nutrition. 2022 Apr 25;9:878644.
  12. 12.0 12.1 12.2 12.3 Beck KL, von Hurst PR, O'Brien WJ, Badenhorst CE. Micronutrients and athletic performance: A review. Food and Chemical Toxicology. 2021 Dec 1;158:112618.
  13. 13.0 13.1 13.2 Godswill AG, Somtochukwu IV, Ikechukwu AO, Kate EC. Health benefits of micronutrients (vitamins and minerals) and their associated deficiency diseases: A systematic review. International Journal of Food Sciences. 2020 Jan 7;3(1):1-32.
  14. Alwis US, Haddad R, Monaghan TF, Abrams P, Dmochowski R, Bower W, Wein AJ, Roggeman S, Weiss JP, Mourad S, Delanghe J. Impact of food and drinks on urine production: A systematic review. International Journal of Clinical Practice. 2020 Sep;74(9):e13539.
  15. 15.0 15.1 15.2 15.3 15.4 Manore, M. Chapter 5: Energy Requirements and Measurement of Energy Expenditure. In Burke, L, Deakin, V, Minehan M. Clinical Sports Nutrition. 6th Edition. Sydney. McGraw Hill. 2021
  16. Abbott A, Bird ML, Wild E, Brown SM, Stewart G, Mulcahey MK. Part I: epidemiology and risk factors for stress fractures in female athletes. The Physician and Sportsmedicine. 2020 Jan 2;48(1):17-24.
  17. Rupasinghe WA, Perera TS, Silva KD, Samita S, Wickramaratne MN. Nutritional intake of sport undergraduates in Sabaragamuwa University of Sri Lanka. BMC nutrition. 2023 Jan 2;9(1):2.
  18. 18.0 18.1 18.2 18.3 18.4 18.5 Mancini, L. Sports Nutrition. National Fellow Online Lecture Series. Available from (last accessed 06 July 2023)
  19. Logue DM, Madigan SM, Melin A, Delahunt E, Heinen M, Donnell SJ, Corish CA. Low energy availability in athletes 2020: an updated narrative review of prevalence, risk, within-day energy balance, knowledge, and impact on sports performance. Nutrients. 2020 Mar 20;12(3):835.
  20. Siedler MR, De Souza MJ, Albracht-Schulte K, Sekiguchi Y, Tinsley GM. The Influence of Energy Balance and Availability on Resting Metabolic Rate: Implications for Assessment and Future Research Directions. Sports Medicine. 2023 May 22:1-20.
  21. Benardot D. Nutritional concerns for the artistic athlete. Physical Medicine and Rehabilitation Clinics. 2021 Feb 1;32(1):51-64.
  22. Moore DR, Sygo J, Morton JP. Fuelling the female athlete: Carbohydrate and protein recommendations. European Journal of Sport Science. 2022 May 4;22(5):684-96.
  23. 23.00 23.01 23.02 23.03 23.04 23.05 23.06 23.07 23.08 23.09 23.10 23.11 23.12 23.13 Thomas DT, Erdman KA, Burke LM. Nutrition and athletic performance. Med Sci Sports Exerc. 2016 Mar;48(3):543-68.
  24. 24.0 24.1 Barley OR, Chapman DW, Abbiss CR. Reviewing the current methods of assessing hydration in athletes. Journal of the International Society of Sports Nutrition. 2020 Dec;17:1-3.
  25. 25.0 25.1 25.2 25.3 Belval LN, Hosokawa Y, Casa DJ, Adams WM, Armstrong LE, Baker LB, Burke L, Cheuvront S, Chiampas G, González-Alonso J, Huggins RA. Practical hydration solutions for sports. Nutrients. 2019 Jul 9;11(7):1550.
  26. Seal AD, Kavouras SA. A review of risk factors and prevention strategies for exercise-associated hyponatremia. Autonomic Neuroscience. 2022 Mar 1;238:102930.
  27. Carlton A, Orr RM. The effects of fluid loss on physical performance: A critical review. Journal of Sport and Health Science. 2015 Dec 1;4(4):357-63.
  28. 28.0 28.1 Bonilla DA, Pérez-Idárraga A, Odriozola-Martínez A, Kreider RB. The 4R’s framework of nutritional strategies for post-exercise recovery: A review with emphasis on new generation of carbohydrates. International journal of environmental research and public health. 2021 Jan;18(1):103.