Other Flashcards
What is the impact factor?
measure of the frequency with which the average article in a journal has been cited in a particular year
What does the IF indicate?
relative importance of a journal within its field; journals with higher impact factor values = status of being more important/carry more prestige in their fields, than those with lower values.
IF gradient?
IF
1 = 70%
3 = good
10 = excellent
Disadv of IF?
IF tends to be used for analysing the quality of articles. When calculating IF, self citation is also counted. Unfair to compare across fields
Hydration FFM, density FM, Density FFM?
Hydration FFM = 0.75
Density FM = 0.9
Density FFM = 1.10
Density = (formula)?
Weight/volume
Limitations of 2-comp model?
● Assumption that density of FFM = 1.100 g /cm3
● Assumption that hydration of FFM = 73%
Definition of physical activity?
any bodily movement produced by the contraction of skeletal muscles resulting in caloric expenditure above a basal level
Def of exercise?
subset of physical activity that is planned, structured and repetitive, and has as a final or intermediate objective the improvement or maintenance of physical fitness
What can imaging techniques measure?
- Body fat distribution
- Muscle tissue
- Ectopic fat
3d techniques: ultrasound, how does it work?
send sound waves into the body which are reflected at interfaces between tissues
● Return time of the waves tells us of the depth of the reflecting surface
CT vs MRI: difference?
X-ray vs magnetic
How do you go from fluid volume to lean mass (BIA)?
volume of conductive fluid > regression models > Impedance index > adjustment for hydration lean tissue > lean mass
What are normal body fat % of men and women?
Normal body fat woman = 20-30%
Normal body fat man = 14-24%
MRI vs CT: which is better to measure ectopic fat? Why?
MRI, can measure spectrum, quantify size of fat peak and measure fat accumulation
With CT: X-ray absorbed by tissue, depends on type of tissue. Liver with lot of fat, difference in absorption of x-ray (attenuation). More/less attenuation = fat level
Are MRI and CT expensive?
Yes, very
What aspects could affect the correlation between PA record and true PA?
Physical activity:
- Difficult to recognize all kinds of activity, such as standing or household activities
- Forgetting to add exercises (Recall errors)
- Within an exercise, differences in activity may occur which are not captured
- Using inappropriate MET scores
- Long time frame affects compliance
- Socially desirable answers
Low correlation FFQ on vit c intake and blood level vit C bc?
FFQ = habitual intake (last month - 3 months)
Blood level = actual intake (very recent)
> vitamin C intake fluctuates from day to day.
Recovery markers are influenced by metabolism
not bio-availability
What biomarkers are influenced by bioavailability?
Concentration biomarkers
How to measure isotopic enrichment?
MS (mass spectr)
What if you need to be sure what people are eating?
- Observe what they eat
- Collect duplicates
- Provide what they eat
How can DLW be improved?
estimating VO2
Accelerometer counts in..
METs
Characteristics of measurement of nutrient in blood?
- Values depend on pharmacokinetics
- time dependent
- concentration
- often very tightly controlled (indirect relatoin intake)
Example of homeostatic control in plasma?
Sodium in plasma
Calcium in serum
Plasma nutrient level depends on..
Intake: pharmacokinetics (bioavailability, half-life, frequency consumption)
Body needs: homeostatic control
Time-dependent
How does the goldberg cut-off work?
Calculate average EI/BMR (which should be > 1.35 in a sedentary population
and > 1.55 in an active population). If it is under these values = underreporting
What is a plethysmograph?
an instrument for measuring changes in volume within an organ or whole body
serum homocysteine is a biomarker for..
folate status, not intake
n = (Zα * CVw/D0)2 is used to estimate the number of days that is needed for a dietary assessment in a certain study. If the between-person variation of intake increases, the number of days according to this formula do/ do not increase ?
Dissect the formula
Do not increase. n = Z alfa (1.96)
* Cvw = (sd/mean)
/ D0 = defined error (e.g.10%)
What is on the X- and Y-axis of the bland-altman graph?
X-axis: average of method A (reference) and B (new method)
Y-axis: Method B (new method) minus Method A (reference)
4-comp model to describe FM + FFM?
body mass, body volume, total body water and bone mass
Potassium bromide isotope: best way to assess TBW?
No
