Week 4: Assessment of Physique and body composition

Question 1

What is the role of understanding physique and body composition in sport?

Answer 1

To measure the changes in an athlete, protect the player’s health and provide the appropriate nutrition and training programme

Question 2

What are some of the problems regarding the body composition in weight category sport?

Answer 2

Short and long term weight loss issues

Question 3

Name some of the reference techniques used for assessing body composition

Answer 3

Cadaver Dissection
Imaging techniques
Multi-compartment models

Question 4

Name some of the lab techniques for assessing body composition

Answer 4

DXA, Densitometry (under water and bod pod), 3D scan, ultrasound

Question 5

Name some of the Field techniques for assessing body composition

Answer 5

Anthopometry, Bioelectrical Impedance analysis, and BMI, waist circumference, waist/hip ratio

Question 6

Explain the DXA technique

Answer 6

Dual-energy x-ray absorptiometry.
It quantifies region of fat, bone, and lean body mass using very low doses of X-ray at 2 energies.

The differentials in attenuation of the 2 energy determines the bone mineral content and the soft tissue composition.

Also assesses deep bone mineral content

Used to assess osteoporosis

Question 7

What are some of the strengths and limitation of the DXA

Answer 7

Advantage: Not much radiation and it can scan the whole body

Disadvantages:
1. Only 2 tissue compartments can be measured therefore soft tissue compartments (lean body mass and fat) can only be measured in areas without bone compartments.

2. There is an assumption that hydration of fat-free mass stays constant at 73%
3. Participants that are too large or tall may not be able to fit on the table
4. Not suitable for regular use as there is still some dose of X-ray

Question 8

Explain the MRI

Answer 8

This provides imaging of soft-tissue in a cross-sectional region.

Question 9

What are the disadvantages if the MRI?

Answer 9

The high expense, amount of resource needed, radiation, and the fact that it can only collect cross-sectional data doesn’t provide information about other parts of the body. There is also a need for profesionals to assess data.

Question 10

Explain the Ultrasound methods

Answer 10

Allows for a measurement of tissue depth at a give site on the body.

Question 11

Limitation of the Ultrasound method

Answer 11

Need for a reasonable amount of skill to be able to interpret ultrasound data. No standardised protocol for it.

Question 12

Explain the advantages and disadvantages of Ultrasound in a box

Answer 12

Disadvantages: No standardisation regards to the measurement site, costly

Advantages: no discomfort

Question 13

Explain Water Densitometry and it’s limitations

Answer 13

A procedure where the participant is weighed underwater and measure the change in body mass underwater.

The participant is dunked into water and asked to stay completely still and exhale as much as they can to release as much air as possible.

Limitation: error with prediction of other body air like in the intestines. Expensive and a lot of equipment. Assumption that density is known and constant for FFM and FM

Question 14

Explain the bod pod and its Advantage and limitations.

Answer 14

Measures body volume by the change in pressure (in bod pod and out.

Pros: Easy and very well tolerated

Cons: Hair in the body creates unwanted artifacts for trapped air. The environment in where this technique is conducted must be controlled (shut windows so that no change in pressure is experienced). It could be uncomfortable for the participants, assumption that density is known and constant for FFM and FM

Question 15

Explain 3D scanning and its advantages and limitations

Answer 15

It scans the body and creates a 3D avatar based on an existing human.

Pros: big potential which could be used to track change in muscle mass

Cons: Takes measurement of body volumes and when converting in %body fat which relies on assumptions

Question 16

Explain the Bioelectrical Impedance Analysis. Its limitations

Answer 16

Volume of fat and lean body mass is estimated by measuring the resistance from an applied electric current flowing through the body. (Lean tissue: more water which is less resistance, Fat tissue: Less water which is more resistance)

Limitations:
Assumption that the body is composed of cylinders, uniform in shape, length, cross-sectional area and with constant conductivity
Total body weight is estimated and used to calculate fat-free mass with the assumption that 73% of bodys fat-free mass is water

Question 17

What factors affect the Bioelectrical Impedance analysis and what are the pre-requisits?

Answer 17

Affected by: gender, age, core temperature, room temperature, body positioning, height and mass, Fluid balance, Glycogen stores, proportionality

Pre-requisits:
No food for >4hrs
No exercise for >24 hours
NO alcohol for >48 hours
Pretest within <30 mins
No diuretic medications
Standardised timing for female subjects

Question 18

Explain surface Anthropometry and its assumptions

Answer 18

Measures the skin fold using calipers to measure adipose tissue. Must be assessed by professionals to get an accurate representation

Assumptions:

• Fat is evenly distributed across the whole body for the individual
• Skin layer is neglected or assumed constant
• the regression is applicable for the same population
• a compressed double skinfold and adipose is equivalent to an uncompressed single layer of adipose
• Adipose compresses in a predictable manner
• # SF sites represents remaining subcutaneous adipose tissue