Exercise physiology diet & nutrition - PowerPoint Presentation

Slide1

Exercise physiologydiet & nutrition

2.1.2 Energy Balance & Optimal Weight

Learning Objective:

To understand optimal

weight for performance

including

energy

balance, energy

intake and expenditure.Slide2

Energy Balance

The food we eat is the energy supply for our body to work.

How

many calories (kcal) we need per day is dependent on our level of activity, age,

height and

weight.

If the amount of energy we consume in our diet is equal to the energy we expend through our daily tasks and activity, body weight will remain constant.

ENERGY INTAKE = ENERGY EXPENDITURE

 CONSTANT BODY WEIGHT

Energy IntakeSlide3

Kilojoules, kilocalories and calories

No need to make notes on this, it’s just for your interest:

K

ilojoules

, kilocalories and calories can cause confusion.

A calorie is the amount of energy needed to heat one gram of water by one degree

celcius

.

A kilocalorie is technically 1000 calories but the two terms have come to be used interchangeably and therefore effectively mean the same thing.

A kilojoule is just another unit of measurement for energy.

1 kilocalorie = 4.2 kilojoules.

You don’t need to know any of this, I just thought it was interesting.Slide4

Positive Energy Balance

If an individual has an energy intake (from their diet) greater than their energy expenditure (from the activity level), they will have a “positive” energy balance.

They will essentially have unused energy left over at the end of the day.

ENERGY INTAKE

>

ENERGY EXPENDITURE



INCREASED

BODY WEIGHT

Excess carbohydrates from food is stored as glycogen for later use.

Once glycogen stores are filled, remaining carbohydrates and excess fat intake are stored as fat around major organs, underneath the skin and in skeletal muscle. Slide5

Negative Energy Balance

Individuals looking to control their body weight (possibly after a period of weight gain) will need to shift the energy balance so that energy output is greater than energy intake.

ENERGY

INTAKE <

ENERGY EXPENDITURE



DECREASED

BODY WEIGHT

This is most successful through a combination of decreased intake from food and increased expenditure from physical activity. Slide6

Basal Metabolic Rate

BMR is the minimum amount of energy required to keep our body functioning.

The Harris-Benedict Equation (below) is used to estimate BMR using height (cm), weight (kg), and age (years),

men:

kcal/day

=

(13.75 x

Wt

) + (5 x

Ht) - (6.76 x Age) + 66women

: kcal/day = (9.56 x Wt) + (1.85 x Ht) - (4.68 x Age) + 655TASK: Calculate your estimated Basal Metabolic Rate!

REMEMBER: This is only the amount needed to maintain basic bodily functions! Any activity above resting would require additional energy intake to maintain the energy balance.Slide7

Basal Metabolic Rate + Activity Level

Once you have your BMR you can estimate your required energy intake using the following calculations.Slide8

Calorie Intake

Recommended daily calorie intake (for the general population) is 2000kcal for females and 2500kcal for males.

We would need to reduce our kcal intake by 500kcal a day to lose between 0.5 a 1kg a week.

Diet and physical activity are the key components to weight loss or gain.

Which type of physical activity is best for weight loss?

Long duration, low intensity exercise will burn fat.

Strength training will not burn fat directly but the increased BMR as a result of greater muscle mass will lead to fat being used more when at rest.

Diet v Exercise for weight lossSlide9

Energy UsageSlide10

ELT

Note the food you eat over the course of the day tomorrow.

To begin with this can be noted in the notes on your phone

etc

(something easily accessible for you to update throughout the day).

Then

, go to

NHS calorie counter

and use the search tool to complete a table of your energy intake throughout the day.

Bigger meals will have to be broken down into their ingredients. For example spaghetti

bolognese into spaghetti, minced beef, tomatoes, onions etc.

FOOD

PORTION

KCAL

MUESLI

100G

355

MILK

1 CUP

135Slide11

Body Fat

This is example data for body fat percentages of trained and untrained individuals in different age groups.Slide12

Visual representation of body fat percentagesSlide13

Is food X fattening?

Could you become fat on a diet of foods which contained 0% fat?

All foods have the potential to be fattening.

If you take in more energy than you need then the excess energy will eventually be stored as fat.Slide14

Optimal Body Weight

Place activities along the spectrum as a representation of the optimal weight to be successful in that sport.

Low body weight

High body weight

Rugby Football High jump Gymnastics Boxing

Sumo wrestling Netball Tennis HockeySlide15

Individuals have to first reach optimal weight and then try to maintain it. To reach optimal weight for their sport some individuals might need to lose weight.

This is achieved by a Negative Energy Balance…

Energy intake <

E

nergy expenditure

Others might have to gain weight to reach optimal weight for their sport.

This is achieved by a

Positive

Energy Balance…

Energy intake > Energy expenditureOnce optimal weight has been reached, it is maintained by a neutral energy balance…Energy intake = Energy expenditure

Nutrition Gareth BaleSlide16

Using a team game as an example, explain why two positions may have different optimal weights

. (4)

Points need to be linked to reasons:

For example:

In Rugby forwards need to be heavier

than backs

to allow more force production in

the scrum

Backs need to be lighter in

weight therefore than a forward, to be able to sprint at faster speeds.Points need to be linked to the explanation.

Allow any two suitable examples from one team game to support points – they must be two contrasting examples.