33. Sex Differences

Question 1

Fat distribution in males vs. females.

Answer 1

Males:
-concentrated in the gut and back
-skinny limbs
Females:
-concentrated in hips & thighs
-fat more evenly distributed throughout body

Question 2

What is the minimal essential body fat for females?

Answer 2

12%

Question 3

What is the minimal essential body fat for males?

Answer 3

5-6%

Question 4

Define Q angle.

Answer 4

Difference between the vertical of the tibia and the lateral of the femur

Question 5

Do men or women have a larger Q angle? Significance for injury?

Answer 5

• Women

- More prone to ACL frequencies

Question 6

What is the normal ranges of % body fat for each sex?

Answer 6

• Males = 5-25%

- Females = 12-36%

Question 7

Why is there less difference between male and female world class swimming performances than between male and female running performances?

Answer 7

• Running = 10% difference in performance has to do w/ body fat
• Swimming = women have more fat –> more buoyancy
• Women maintain better trim (posture in water - rear segment is directly behind forward limbs) so women’s energy balance going forward is better

Question 8

Are there sex differences in muscle fiber type distribution and/or specific strength?

Answer 8

NO

Question 9

When during life do sex differences in muscle mass distribution develop?

Answer 9

Puberty

Question 10

Relative hypertrophy seen in men vs. women in response to equivalent weight training

Answer 10

• Testosterone level is stable –> hypertrophy is same in men and women
• Females grow muscle just fine in proportion to their initial size

Question 11

Describe the differences in endurance performances between genders, like cycling and running.

Answer 11

• Males’ best times usually range between 5-15% faster than females b/c:
• Males have greater amount of lean body mass per unit of total body weight
• Increased hemoglobin concentrations elevate arterial blood oxygen carrying capacity

Question 12

The faster male “best time” performances (10%) in endurance running are due primarily to what 2 factors?

Answer 12

• 5% is change in % of fat minimum in males

- 5% is lower [Hb] in males (Hct ~39-40 vs Hct ~44-45)

Question 13

Name 3-4 mechanisms allowing female distance runners to out-perform 99% of young adult males?

Answer 13

• A lower body fat (11-13%) than all but the leanest 20% of males
• Compensating for the lower hemoglobin level w/ an overall blood volume expansion…
• Increased capacity to pump larger blood volume (SVmax and Qmax)
• A greater ability to extract oxygen at the muscle level, based on greater capillary density, higher proportion of slow-twitch fiber, mitochondrial and oxidative enzyme content.

Question 14

What sex differences exist that affect physiologic function?

Answer 14

• Q angle
• Skeletal mass during adolescent growth spurt
• Essential fat
• Fat distribution
• Lean body mass

Question 15

Which types of athletic events would show greatest differences among genders? Least difference?

Answer 15

• Greatest differences = high jump, long jump, bench press

- Lowest differences = open water swimming