Nutrition and Athletic Performance – What are the energy requirements for different intensity of exercise?

From: Joint Position Statement of the American Dietetic Association and Dieticians of Canada.

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  • A review of all identifiable studies with specific exclusions.


  • The paper is a systematic review / meta analysis of all relevant trials.
  • This means that the data from all similar trials has been grouped to form an overall outcome.


Short duration exercise

  • Adenosine triphosphate (ATP) and creatine phosphate provide the readily available, but short duration, energy present within the muscle.
  • Creatine phosphate is an ATP reserve in muscle that can be readily converted to sustain activity for 3–5 min.
  • Creatine phosphate is the primary fuel used for high-intensity, short-duration activities such as the clean and jerk in weight lifting or the fast break in basketball. 
  • Muscle glycogen and glucose can support events lasting 60–180s. Approximately 25%–35% of total muscle glycogen stores are used during a single 30s sprint or resistance exercise bout.

Medium/long duration exercise

  • The oxidative pathway fuels events lasting longer than 2–3 min. The major substrates include muscle and liver glycogen, intramuscular, blood, and adipose tissue triglycerides and negligible amounts of amino acids from muscle, blood, liver, and the gut. Examples of events for which the major fuel pathway is the oxidative pathway include a 1500m run, marathon, half-marathon, and endurance cycling or 1500m swimming events.
  • Approximately 50%–60% of energy during 1–4 h of continuous exercise at 70% of maximal oxygen capacity is derived from carbohydrates and the rest from free fatty acid oxidation
  • Training does not alter the total amount of energy expended but rather the proportion of energy derived from carbohydrates and fat.
  • As a result of aerobic training, the energy derived from fat increases and from carbohydrates decreases. A trained individual uses a greater percentage of fat than an untrained person does at the same workload.
  • Long-chain fatty aids derived from stored muscle triglycerides are the preferred fuel for aerobic exercise for individuals involved in mild- to moderate- intensity exercise


  • As per the results above