Foods

ENERGY OUTPUT

 There are two components to your energy requirements:  Basal metabolic rate (BMR) which takes care of energy required for body processes at rest and physical activity.  Your energy needs vary with your age, body size, BMR, physical activity and gender.  Excess or unused energy (Calories) can be stored as body fat.

 

Total Energy Requirement = BMR (kcal/kJ) + physical activity (kcal/kJ)

 

Physical Activity is an important part of your lifestyle.  Regular activity can:

• help control your weight
• reduce your body fat
• firm up your muscles
• improve your digestion
• improve your circulation and give you a healthier heart
• provide an opportunity to meet people
• regulate your appetite
• provide a release for emotional stress

Two Types of Energy Systems:  Aerobic and Anaerobic

During physical activity your body relies on one or both of its energy systems.  Aerobic activity refers to progressive, regular (low intensity) muscularactivity carried out over an extended period of time.  It usually involves a large portion of the body.  During this period of time the muscles rely on the presence of oxygen from respiration (breathing) to run the energy system.  Examples of aerobic activities are walking, hiking, jogging, cycling, rowing, swimming,and cross country skiing

Anaerobic activity is very intense muscular activity (sprinting, lifting heavy objects).  The energy demands of the muscles are greater than can be met by respiration alone. Under these circumstances, the muscles obtain the extra energy they need from anaerobic processes and incur an oxygen debt and an accumulation of lactic acid (in the muscles and liver).  When the intense activity is over, you continue to breath hard for some time and continue to supply the liver with large quantities of oxygen to reconvert the lactic acid into muscle glycogen (a storage form of energy).

During participation in many different sports your body uses a combination of the two energy systems (aerobic and anaerobic), i.e. soccer, tennis, basketball:  where the intensity of the activity alternates between high and low.

Extra Energy Needs

The need for energy from food increases in proportion to the increased energy expenditure.  The size and weight of the individual, the type of activity and the frequency, intensity and duration of the activity are the major factors in determining the extra energy needs.

Sports requiring a single effort, like diving or golf, require high energy expenditure only if carried out intensively for long periods.

Sports such as soccer, marathon running and swimming which involve endurance, high intensity and hours of training require high energy expenditure.

USING PHYSICAL ACTIVITY TO CONTROL OR ALTER YOUR WEIGHT

An increase in physical activity can help you change your energy balance and help you lose body fat.   If you wish to gain weight, regular, but not excessive exercise is still necessary as it will help you maintain a normal appetite and ensure that the weight gain is muscle tissue, not just fat.

The following variables in physical activity are related to the number of calories burned:

1. Duration - the length of time and distance traveled
2. Intensity - percentage of maximum heart rate

The number of calories burned is more closely related to an activity’s duration than to its intensity.  For example, a one hour light walk burns more calories than a 20 min brisk walk.  Also the Calories burned during a 2 km walk and 2 km run are identical because the distance traveled is the same. 

Prolonged activity at low to moderate intensity (65% of maximum heart rate) is preferable to the same amount of work at higher intensity. Increase duration gradually, before you increase intensity.  This is an effective method of burning calories when the goal is weight loss or weight control

Approximate Energy costs of Various Activities

 

ACTIVITY	CALORIES/MIN	KILOJOULES/MIN
cycling, fast	11.1	46.2
cycling, slow	4.5	18.9
Dancing	5.0	21.0
Gardening	5.5	23.1
grocery shopping	3.5	14.7
house cleaning	2.0	8.4
Laundry	3.0	12.6
rowing, 51 strokes per minute	4.1	17.2
rowing, 87 strokes per minute	7.0	29.4
rowing, 97 stokes per minute	11.2	47.0
Sitting	0.3	1.1
skiing, cross country	20.0	84.0
skiing, downhill	12.0	50.4
snow shoveling	7.0	29.4
Standing	0.4	1.4
Sweeping	1.7	6.9
Swimming	11.0	46.2
walking, brisk	6.0	25.2
walking, light	3.0	1

Janice has started walking 20 minutes a day to increase her physical activity and lose weight.  Should she first try to walk faster for 20 minutes or walk 30 minutes a day at the same speed?    Answer:  30 mins a day, then faster

Julie cycles after school every day for about 30 mins.  She was losing weight up until a week ago but has now stabilized.  To continue to increase her physical activity without increasing the time spent cycling what should she do?   Answer:  Cycle faster, for 30 mins

THE CAR ANALOGY

Three guys are driving to Banff.  One is driving a mid sized car, a Chevrolet, the second is driving a small car - a Toyota Tercel and the third is driving a full sized model, a Lincoln.

1.  What do the cars use for energy to get there?  ____________

2.  Which car will use the most energy? ____________

Why? 

The Smith’s own a Jeep Cherokee.  Mrs. Smith drives the jeep to work (10 km), Jeremy Smith drives to his friend’s house (2 km) and Mr. Smith drives the jeep on road trips (300 km).

3.  For which trip will the Jeep require the most energy?  ____________

Why?

Diane, Jennifer and Susan are all 17 years old.  Diane is small framed, Sue is medium framed and Linda is full framed.  They all have a similar daily schedule.

4.  Where do these girls get their energy?  ___________

5.  Which girl will use the most energy in a day?  ___________

Why?

Jim, Brad and Arthur are all 24 years old.  Jim is a professional hockey player, Brad is a stay-at-home dad with 2 small children and Arthur is a computer operator who spends most of his day working at his computer.

6.  Where do these guys get their energy?  ___________

7.  Which guy uses the most energy?  _________

Why?

8.  What are the two major factors (from above) that determine the amount of energy we

 need from food?

Other factors that influence energy needs are:  gender, age and BMR (basal metabolic rate).

Now try these:

		Who needs more energy?	What factors?
8.	Jane is 12.  Her sister is 20.
9.	Sandy likes to read and watch T.V and Alice enjoys swimming and dancing.
10.	Emma and Robert are twins.
11.	Mary and Lori are both 18 and play on the same soccer team.  Mary weighs 135 lbs and Lori weighs 115 lbs.
12.	Jared and Connor are both 12 years old.  Jared plays hockey and Connor loves video games.