Body Composition: Physical Activity's Impact on Body Fat %, Slides of Physical Education and Motor Learning

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Body Composition

What is body composition?

 The ratio of lean body mass to body fat

 Generally this is a topic many physical

educators try to avoid

 Although “exact” figures for % fat may

not be necessary, it is important for

students to understand the relationship

of physical activity to body comp

Definitions of Overweight:

(Based on ht /wt tables)

 Moderately Overweight

 20% over desirable body weight

 Severely overweight

 40% over desirable body weight

Burton, Foster, Hirsch, and Van Itallie, Health implications of obesity: An NIH consensus development conference. Int J. Obesity, 9, 155-169, 1985.

Problem: Ht/Wt tables do

not take muscles mass

into account

Obesity

 120 percent of ideal body weight or

greater

Overweight and Obesity:

New Mexico

 24% of New Mexico high-school

students are overweight or at risk of

becoming overweight. (NM YRRS,

 22% of low-income children between 2

and 5 years of age in New Mexico are

overweight or at risk of becoming

overweight. (CDC PedNSS, 2002)

Obesity Trends* Among U.S. Adults

BRFSS, 1990

No Data <10% 10%–14%

(BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person)*

Obesity Trends* Among U.S. Adults

BRFSS, 2001

No Data <10% 10%–14% 15%–19% 20%–24% ≥25%

(BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person)*

Obesity Trends* Among U.S. Adults

BRFSS, 2004

No Data <10% 10%–14% 15%–19% 20%–24% ≥25%

(BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person)*

Relate to other HR

components

 MS & E: muscles cells burn more calories at

rest than fat calories

 Aerobic: raise BMR and burns calories; more

effective than MS & E training

 Flexibility: less prone to injury when doing

aerobic activity and strength and endurance

training

 Aerobics + resistance= best management

Body Composition

Assessment

Skinfold Technique

Subcutaneous

Fat

Skinfold

Thickness

Skin

Skin

Subcutaneous Fat

Layers of subcutaneous

fat are measured at

different sites of body

to estimate total body

fat levels

Benefits of Skinfold Technique

 Fairly accurate

 Easy to perform

 Inexpensive

 Skinfold Sites for Children: tricep & calf

 Not as “invasive” as adult sites

BMI

 BMI = weight in pounds

Ht in inches x ht in inches x 703

Advantages:

1. Takes little class time

Disadvantage:

1. BMI is age and gender specific
2. Over-simplifies body composition

BMI Chart for children

Underweight: BMI-for-age < 5th percentile

Less than 18.

Normal: BMI-for-age 5th percentile to < 85th percentile

At risk of overweight: BMI-for-age 85th percentile to

< 95th percentile

Overweight: BMI-for-age > 95th percentile