Energy Intake and Expenditure

Energy Energy is obtained from the foods we eat. Measure in calories or joules. As these are both very small they are multiplied by a 1000 and referred to as kilocalories and kilojoules.

Sources The potential fuel sources available to exercising muscles are: Fats – 1g = 9.0Kcal = 38KJ Carbohydrate – 1g = 4.0Kcal = 17KJ Protein – 1g = 4.0Kcal = 17 KJ

Protein May be used during prolonged periods of exercise and towards the latter stages of endurance events like the marathon, particularly if carbohydrate and fat stores have become depleted.

When you exercise, your muscles use energy at a rate which is directly proportional to the intensity of your activity. If this energy is not replaced as it is used up, your muscles will be unable to maintain their rate of work and the intensity of the activity will need to be reduced or stopped.

Measuring requirements Body composition – somatotypes: Ectomorph Mesomorph Endomorph Lean body mass – includes bone, muscle, water, connective tissue and organ tissue.

Percentage body fat Methods of assessing body fat include: Skinfold analysis Bioelectrical impedance analysis Hydrodensitometry

Direct and Indirect Calorimetry Energy expenditure can be assessed by direct or indirect calorimetry (measurement of heat production).

Direct Calorimetry Measures the actual amount of heat produced by the body. It uses an airtight chamber where heat produced by the subject warms water surrounding it.

Indirect Calorimetry Estimates heat production by measuring respiratory gases. The most common technique is through mouthpiece and gas analysis system, with energy consumption calculated from the amount of oxygen consumed. 1 litre of oxygen equates to approximately 4.8Kcal of energy expended.

Tasks 1 – perform an internet search of ‘body composition assessment’. Look at a range of assessment products available and take note of: Affordability Ease of application Suitability for use with athletes

2 – Investigate other measures of energy expenditure including: Doubly labelled water Motion analysers