Active IQ Level 3 Diploma in Personal Training (sample manual)

Section 4: Using nutrients to fuel activity
Unit 2
POINT OF
INTEREST
Aerobic activities include:
• Jogging.
• Distance running.
• Distance cycling.
• Distance swimming.
• Exercise to music.
• Distance rowing.
• Brisk walking.
• Skiing.
Aerobic activities
During aerobic activities (low-intensity, longer-duration) the
demand for energy is slower. ATP is produced using oxygen,
so this type of exercise can be kept up for longer. Fats can
also be used to produce energy for aerobic activities as
they can only be broken down with oxygen present. The
body has a larger store of fat than carbohydrate.
Most sports and activities involve a mixture of both
anaerobic and aerobic exercise, e.g. football, hockey and
rugby contain short bursts of strenuous activity (sprints,
kicks, throws) interspersed with longer periods of less
strenuous activity (jogging, walking).
Fuel
Creatine
phosphate
Muscle
glycogen
Liver glycogen +
blood glucose
Maximal
short bursts
High
intensity
intermittent
Intensity of exercise
High
intensity
150 min
Low intensity
Great. Very great. Moderate. Moderate. Moderate. Negligible.
Slight. Moderate. Moderate. Very great. Very great. Negligible.
Negligible. Slight. Slight. Moderategreat.
Great-very
great.
Slight.
Fat Negligible. Slight. Negligible. Negligible. Slight. Slight.
Energy to start exercise
Table 4.2 Depletion of fuel for different types of exercise
At the start of exercise, energy is produced without oxygen. As the heart and lungs work harder, carbohydrates and
fats can be broken down. If the exercise becomes aerobic in nature, more oxygen is delivered around the body and
fats start to be broken down into fatty acids, taken to muscle cells and used as energy. For the first 5-15 minutes
(depending on fitness level) carbohydrate (glycogen) is used for fuel. As time goes on, the use of carbohydrate
lessens and more fat is utilised for energy.
Fatigue
The fitter the individual is, the longer it takes to fatigue or run out of glycogen. After three or more hours of exercise,
fatigue is caused by the depletion of glycogen in the muscles and liver, as well as low blood glucose levels.
The principles of nutrition and their application to exercise and health
No matter what type of exercise is completed, or how fit the
individual is, the body will always need glycogen. The amount
of glycogen in the muscles (and liver) before exercise is
crucial, as the size of a person’s store dictates how long they
will be able to exercise for before fatiguing. The message is
‘always start with a full glycogen store’.
A diet rich in carbohydrates ensures high glycogen stores.
The amount of glycogen in the muscles dictates how hard
and for how long an athlete can exercise. If the individual eats
a high-carbohydrate diet prior to training and competitions,
their stores will be full.
• Low glycogen levels would only allow for low-intensity
exercise and cause early fatigue.
• High glycogen levels mean an athlete can train harder
and longer.
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