Recap of last weeks lecture on food labelling…

Nutrition for Sports Performance Energy Production: Introduction to Energy Systems and Metabolism

Objectives of session…. –Identify the importance of energy metabolism to the body –Distinguish the difference between BMR and TMR –Ascertain where energy for exercise is derived from –Identify which energy sources will be used for different exercise durations and intensities of exercise

Task Why do you think that it is important we understand the energy demands used in different sports – why is this relevant for sport nutrition?

Importance of understanding energy metabolism for sports nutrition Know what to eat/drink: CHO, Fat, Protein Know how much to eat Know when to eat: –Training phase –Pre-competition –Competition –Post-competition –Off-season This will help us create and use energy optimally!

Energy Why do we need energy? –To maintain body functions – to breath, keep the heart beating, keep warm etc. –For active movement, such as muscle contraction –For growth and repair How do we measure energy? –Joules or calories

Energy Metabolism ‘The total intake of food must be sufficient to supply enough energy to keep cells alive, their systems working and to meet the demands of any activity that the body undertakes’

Metabolic Rates Basal Metabolic Rate (BMR)= body’s basic cost of living. The average adult for instance will use around 4.6 kj (1.1 Kcal) every minute Total Metabolic Rate (TMR) = sum of BMR costs plus all the energy required to carry out daily activities

Metabolic Rates Discuss the following statement: ‘Energy requirements of an individual vary according to age, size, metabolic rate, gender, environment, lifestyle.’

Energy production and storage How is energy produced? –By a substance called ATP (Adenosine Tri-Phosphate). The body produces ATP from the breakdown of carbohydrates, fats and proteins. ATP is often referred to as the “energy currency”. What happens to your energy store when you exercise? –The body only stores a small amount of ATP at any one time, when you start exercising, your energy demand increases and the supply of ATP is used up within seconds. The body must then breakdown more fuel (or food) to produce more ATP.

Fuel for Exercise Where can we obtain fuel for exercise from? –Carbohydrate (16 kj / 4 kcal) –Fat (37 kj / 9 kcal) –Protein (17 kj / 4 kcal) –Alcohol (23 kj / 7 kcal)

Fuel for exercise The amount of each fuel that your muscles use during exercise depends on the following: a)Type, duration and intensity of exercise b)Fitness level and training programme c)Diet and nutritional status.

Fuel For Exercise The fuel blend used for a short sprint differs from that used for a long, slow jog. In other words, a different ‘blend’ of CHO & Fat. Fuel blend also changes as exercise continues: the combination used at the start will be different from that at the end.

Task Split into groups of 3 and complete the following: Identify what fuel’s would be used for a game of football, and the proportions of each Explain what food groups you would therefore eat and why Explain how level of fitness affects fuel usage Feedback to the group

Carbohydrate In what form is carbohydrate stored in the body? –Glycogen, stored in the liver and muscles. Glycogen is first released from the muscles to produce energy, then when these stores are depleted glycogen is released from the liver. –There is enough glycogen stored in your body to last approximately one day if you were unable to eat.

Fat Oxidation There is 60x as much energy stored as fat than CHO in the body. However, much more oxygen is required to metabolise this fat making it a relatively slow source of energy. As long as the demand for oxygen does not exceed the amount inhaled, the body will try to preserve muscle glycogen and use fat stores Eg. Comfortable walking

Energy Stores The body’s energy stores are the link between diet + performance -----> The amount of glycogen stored in muscles before an event is one of the most important limiting factors in performance. When these stores run out you will have to slow down ‘hitting the wall’.

Hitting the wall…. Long distance runners or other endurance athletes will train to put this off as long as possible.

Which Energy System for Which Sport? It is difficult to classify sports as either aerobic or anaerobic as the vast majority of them use both systems (apart from the extremes such as 100m or marathon). -Even a marathon runner will use anaerobic system at the start of the race, when tackling a hilly course, or when attempting a sprint finish! -Team sports tend to be a combination of short, high intensity bursts with periods of lower intensity exercise in between.

Task: Complete the following table… Exercise Intensity Exercise Duration Fuel Used Maximal SprintShort Low to moderate Moderate (up to 2 hours) SevereProlonged (eg. Cycling)

Exercise Intensity Exercise Duration Fuel Used Maximal SprintShortCarbohydrate Low to moderate Moderate (up to 2 hours) Carbohydrate and fat equally SevereProlonged (eg. Cycling) Less Carbohydrtae, more fat

Summary Vital importance to get appropriate and correct nutrition for sporting performance Fuel for exercise dependent on: –Type, duration, intensity of exercise –Fitness level and training programme –Diet and nutritional status Fuel from fat and CHO

Further study… Research into a successful sportsperson’s diet. You could cover the following: –What they eat –When they eat –How this relates to the specific energy requirements of the sport they play –What % of CHO – Fat they utilise