Sport Nutrition: Energy, Fuel and Athletic Performance

Sport nutrition links what athletes eat and drink with the energy demands of exercise, training adaptation and recovery. In the second edition of Sport Nutrition: An Introduction to Energy Production and Performance, Asker Jeukendrup and Michael Gleeson use exercise physiology and biochemistry to explain how nutrients support muscle metabolism and athletic performance.

Published in 2010, the book covers fuel sources for muscle, energy requirements, carbohydrate, fat, protein and amino acids, fluid balance, vitamins and minerals, supplements, body composition, weight management, training adaptations and immune function. It is best read as a scientific foundation for understanding why nutrition recommendations differ with exercise demands rather than as a single meal plan for every athlete.

What does sport nutrition actually cover?

Sport nutrition is broader than choosing foods before competition. Jeukendrup and Gleeson organize the subject around the physiological demands of exercise: how nutrients are digested and absorbed, how energy is produced, which fuels working muscle uses, and how food and fluid intake can influence training and recovery. The book's structure moves from basic nutrient concepts toward applied topics such as body composition, weight management, supplements and immune function.

That approach matters because an athlete's nutritional needs are connected to workload, exercise intensity, duration, recovery time and training goals. The book does not reduce performance nutrition to one nutrient. Instead, it places carbohydrate, fat, protein, micronutrients and fluid within a common framework of energy metabolism and exercise physiology.

Why energy production is the starting point

Muscle contraction requires energy, and the body continually converts chemical energy from stored and ingested fuels into forms that cells can use. Carbohydrate and fat are major exercise fuels, while protein has additional structural and metabolic roles. The relative contribution of these fuels changes with exercise intensity, duration, training status and nutrient availability.

The book therefore treats energy metabolism as the bridge between nutrition and performance. Understanding that bridge helps explain why the same eating strategy may not suit a short, high-intensity session, prolonged endurance exercise and a recovery period equally well.

How the second edition expanded the subject

The 2010 edition added or expanded material on training adaptations, overtraining, body composition, weight management, carbohydrate recommendations during training, protein and amino acids, and exercise-related immune function. It also retained foundational material on digestion, absorption, water balance, vitamins, minerals and eating disorders.

Its 16-chapter structure makes the book an educational overview rather than a narrow guide to a single sport. More than 200 illustrations, tables and explanatory features were included to support the physiological concepts described by the authors.

How do carbohydrate and fat fuel exercise?

Carbohydrate and fat are central to exercise metabolism, but they are not interchangeable in every situation. The body stores carbohydrate primarily as glycogen in muscle and liver and can also use circulating glucose. Fat is stored in much larger quantities and can provide substantial energy, particularly during lower-intensity and prolonged exercise.

Exercise intensity is one factor influencing fuel selection. As intensity rises, carbohydrate generally becomes increasingly important because it can support high rates of energy production. During prolonged exercise, available carbohydrate stores can become a limiting consideration, which is why carbohydrate intake before and during endurance activity receives substantial attention in sport nutrition research.

Carbohydrate intake during prolonged exercise

Research reviewed by Jeukendrup before the book's publication found that carbohydrate feeding during exercise can improve endurance capacity and performance. The practical objective is not simply to consume as much carbohydrate as possible: intake must be balanced with absorption, oxidation and gastrointestinal tolerance.

This helps explain the book's emphasis on digestion and gastric emptying alongside carbohydrate metabolism. A nutrient strategy is useful only if the gastrointestinal system can tolerate and deliver the ingested fuel during exercise.

Why fat remains an important fuel

Fat provides a large energy reserve and contributes substantially during many forms of aerobic exercise. Training can alter the capacity to oxidize fat, but increasing fat use does not mean carbohydrate becomes unnecessary. The metabolic demands of high-intensity exercise still make carbohydrate availability important.

Table 1. Major Nutritional Components in Exercise Metabolism

Component	Primary role in the book's framework	Performance relevance
Carbohydrate	Major fuel for muscle; stored as glycogen and available as glucose	Especially important when exercise requires high rates of energy production
Fat	Large stored energy source and substrate for aerobic metabolism	Contributes strongly during prolonged and lower-intensity exercise
Protein	Provides amino acids for tissue turnover and adaptation	Important for recovery, remodeling and training adaptation
Fluids	Supports fluid balance and physiological function	Losses through sweat can affect hydration during exercise
Vitamins and minerals	Support numerous metabolic and physiological processes	Deficiencies may impair normal function and training capacity

What role does protein play in training and recovery?

Protein is often discussed in relation to strength training, but Jeukendrup and Gleeson present amino acids as relevant to both strength and endurance exercise. Exercise creates a stimulus for tissue remodeling, and dietary protein supplies amino acids that contribute to repair, synthesis and adaptation.

The second edition specifically expanded its discussion of protein and amino acids in strength and endurance training. This reflects the shift from viewing protein only as a muscle-building nutrient toward understanding its role in the broader adaptive response to exercise.

Protein is not simply another exercise fuel

Protein can contribute to energy metabolism, but its nutritional importance for athletes extends well beyond direct fuel provision. Amino acids are required for the synthesis and turnover of body proteins, including proteins involved in skeletal muscle structure and metabolism.

For this reason, sport nutrition considers both total dietary intake and the relationship between protein intake, exercise and recovery. The 2010 textbook covers protein needs across different exercise demands without establishing one universal prescription for every athlete. Appropriate intake varies with training conditions and individual requirements.

Why are hydration and digestion part of performance nutrition?

Nutrition reaches working tissues only after food and drink have been ingested, emptied from the stomach, digested and absorbed. The book devotes foundational coverage to gastric emptying, digestion and absorption because these processes affect how nutrients and fluids become available during exercise.

Fluid balance is similarly integrated into exercise physiology. Athletes can lose water and electrolytes through sweat, but the amount varies substantially with exercise conditions and individual sweating responses. The book therefore treats water requirements and fluid balance as a distinct component of sport nutrition.

Gastrointestinal tolerance can limit a fueling plan

A theoretically appropriate intake can become impractical if it causes gastrointestinal discomfort or cannot be absorbed efficiently. This is particularly relevant during prolonged exercise, when athletes may attempt to consume carbohydrate and fluid while blood flow and mechanical movement place additional demands on the gastrointestinal system.

Hydration is not a fixed number for every athlete

The textbook covers water requirements and fluid balance without establishing a single fluid volume appropriate for every athlete. Environmental conditions, sweat losses, exercise duration and individual physiology all affect practical requirements. That makes individualized assessment more defensible than treating one number as universally applicable.

How does nutrition influence training adaptation?

One of the notable additions to the second edition was a chapter on nutrition and training adaptations, including discussion of overtraining. Training is not only an energy-consuming event; it is also a stimulus that produces physiological change during subsequent recovery.

Nutrition interacts with this process by influencing substrate availability, recovery and the materials available for tissue remodeling. This does not mean more energy or more nutrients always produce better adaptation. It means nutritional status is one part of the environment in which adaptation occurs.

Energy availability connects diet with recovery

Athletes need enough dietary energy to support training as well as normal physiological functions. The book's inclusion of energy, body composition, weight management and eating disorders highlights the tension that can arise when performance goals encourage athletes to manipulate body mass while maintaining demanding training schedules.

The 2010 text predates some of today's terminology and research frameworks around low energy availability. Its chapters should therefore be read in their historical context rather than assumed to contain every concept or recommendation used in current sports nutrition practice.

What Do Vitamins, Minerals and Supplements Contribute?

Vitamins and minerals participate in many physiological processes, including energy metabolism, oxygen transport, tissue maintenance and immune function. The book provides a dedicated grounding in micronutrients rather than presenting them as optional additions to macronutrient planning.

It also addresses nutritional supplements and explicitly aims to help readers distinguish evidence from unsupported claims. That distinction remains important because the existence of a plausible biological mechanism does not automatically demonstrate a meaningful improvement in athletic performance.

Supplements should not replace nutritional foundations

The book places supplements after foundational chapters on energy, macronutrients, hydration, vitamins and minerals. Structurally, this reinforces a useful principle: supplements are one part of sport nutrition rather than its starting point.

The textbook does not establish a universal supplement list for athletes. Specific supplement decisions depend on evidence of effectiveness, appropriate dosing, safety and relevant sport regulations.

Immune function is linked with overall nutritional status

The second edition includes updated material on exercise, nutrition and immune function. Later work by Gleeson similarly emphasizes adequate energy, carbohydrate, protein and micronutrient intake as part of maintaining normal immune function in athletes, while noting limited evidence for many individual immune-targeted supplements.

Table 2. Questions the Book Helps Readers Ask About Nutrition Strategies

Question	Why it matters
What is the exercise demand?	Intensity and duration influence fuel use and nutritional priorities.
Is energy intake adequate?	Training, recovery and normal physiological functions all require energy.
Are carbohydrate needs matched to the session?	Carbohydrate availability can matter for sustained or high-intensity work.
Is protein supporting recovery and adaptation?	Amino acids contribute to tissue turnover and training responses.
Are fluid losses being considered?	Sweat loss and environmental conditions influence hydration needs.
Is a supplement supported by evidence?	Marketing claims and plausible mechanisms are not the same as demonstrated benefit.

Practical takeaway: Sport nutrition is not one performance food or one ideal diet. It is the matching of energy, nutrients and fluids to the physiological demands of training, competition and recovery.

How Should the 2010 book be used today?

The second edition remains a useful snapshot of the scientific foundations taught in sport nutrition around 2010. Its value lies in the integrated treatment of metabolism, nutrient function, digestion, hydration, training and recovery. The second edition was published by Human Kinetics and covers 16 major topics.

At the same time, sport nutrition is an active research field. Recommendations and terminology have continued to develop since publication. Readers using the book for current professional practice should therefore distinguish durable physiological principles from recommendations that may have been updated by later consensus statements or research.

Use foundational physiology and current guidance together

Concepts such as fuel metabolism, digestion, energy balance and the physiological roles of nutrients provide a foundation for understanding newer sports nutrition guidance. These principles help explain how dietary strategies influence energy availability, exercise performance and recovery under different training conditions. However, scientific recommendations continue to evolve as new research clarifies individual nutritional requirements and the effectiveness of specific interventions. Current decisions about exact intake targets, supplement use or clinical nutrition should therefore be evaluated against contemporary evidence and, where appropriate, individualized by qualified professionals.

Avoid turning general principles into universal prescriptions

The book is designed to explain the science behind recommendations, not to prove that one diet works for every sport and athlete. Differences in body size, training volume, event duration, environmental conditions, gastrointestinal tolerance, goals and health status can all change practical needs.

That is the central strength of a physiology-based approach: it encourages readers to ask why a strategy might work, under what conditions it applies and what evidence supports it before translating a general recommendation into an athlete's plan.

Practical takeaway: General principles should not be treated as universal prescriptions because athletes’ needs vary with sport, training load, environment, goals and individual tolerance. A physiology-based approach helps determine why a strategy may work, when it applies and whether the evidence supports using it in an individual athlete’s plan.

Frequently asked questions

What is sport nutrition?

Sport nutrition applies nutrition and exercise physiology to the demands of training, competition and recovery. In Jeukendrup and Gleeson's framework, it includes energy metabolism, macronutrients, micronutrients, hydration, digestion, supplements and body composition. The aim is to understand how nutritional choices interact with exercise rather than to prescribe one universal athlete diet.

Why is carbohydrate important for athletic performance?

Carbohydrate can supply working muscle with fuel at rates that are especially important during sustained or high-intensity exercise. Muscle and liver glycogen provide stored carbohydrate, while carbohydrate consumed during prolonged exercise can also contribute. The amount and timing needed depend on the exercise demands and the athlete's tolerance.

Do athletes need more protein than non-athletes?

Exercise increases the importance of protein for tissue turnover, recovery and training adaptation, but there is no single intake target appropriate for every athlete. Needs can vary with training type, total energy intake and individual goals. Exact current targets should therefore be based on contemporary guidance rather than treated as a universal prescription.

How important is hydration during exercise?

Fluid balance is a core topic in the book because exercise can produce substantial sweat losses. Practical requirements vary with duration, environment, clothing, exercise intensity and individual sweat rate. A single fixed drinking volume is therefore not supported as an appropriate recommendation for every athlete and every session.

Sources

Jeukendrup, A. E., and Gleeson, M. (2010). Sport Nutrition: An Introduction to Energy Production and Performance. 2nd ed. Human Kinetics. ISBN 978-0-7360-7962-4.
Jeukendrup, A. E. (2008). Carbohydrate feeding during exercise. European Journal of Sport Science, 8(2), 77–86.
Gleeson, M. (2016). Immunological aspects of sport nutrition. Immunology and Cell Biology, 94(2), 117–123.
Indiana University Libraries. Sport nutrition: an introduction to energy production and performance. Catalogue record for the 2nd edition.
Masaryk University. Sport nutrition: an introduction to energy production and performance. Publication record, 2010.
Open Library. Sport nutrition: an introduction to energy production and performance, 2nd edition. Bibliographic and contents record.
WorldCat. Sport nutrition: an introduction to energy production and performance. 2nd edition bibliographic record.
Jeukendrup, A. E., and Burke, L. M. (2010). Exercise Performance. In Nutrition and Metabolism, Second Edition.

Sophie Bennett — author

Sophie writes the health and nutrition explainers. Her editorial focus includes nutrients, dietary patterns, energy metabolism, hydration, supplements, sports nutrition and the interpretation of health research for general readers. She approaches health conten...

This article is for general information and is not medical advice. It was reviewed for accuracy by a qualified clinician; decisions about your health should be made with your own doctor.