Obesity in lung transplant recipients: the role of daily physical activity, food intake, resting energy expenditure

Body composition: Body mass index and fat-free mass

Weight and fat-free mass will be measured by a Bioelectrical Impedance Analysis

(bodystat 1500). The high correlation coefficient (r = 0.974), small bias and

standard estimation of error of a Bioelectrical Impedance Analysis, makes it

able to predict fat-free mass in pre- and post transplant patients.



Daily physical activity, performance based

Daily physical activity was assessed on a performance basis by the Digiwalker

SW-200 (Yamax; Tokyo, Japan). This pedometer has proved to accurately detect

steps taken, as an indication of volume of daily physical activity. It has also

shown evidence of reliability and convergent and discriminative validity. In

this study patients are instructed to wear the pedometer during ten days (until

going to bed), and to record the number of steps per day. The number of minutes

that they are swimming, doing fitness or cycling will be reported in a diary

and will be converted into steps. Steps/day including the converted steps will

be expressed as step equivalents. The last seven out of ten daily-records will

be used for further processing.



Daily physical activity, questionnaire based

Daily physical activity was assessed in self-reported fashion with the Short

QUestionnaire to ASsess Health-enhancing physical activity (SQUASH). This

questionnaire is designed to give an indication of the habitual activity level,

and has shown to be a fairly reliable and reasonably valid questionnaire (r =

0.36-0.74). It was expressed in MET/min (MET: ratio of exercise metabolic rate

to resting metabolic rate) and total minutes a week.



Food intake

Food intake will be estimated by a dietitian using an extensive food anamnesis.



Resting Metabolic Rate

Resting metabolic rate (RMR) will be measured using the ventilated-hood

technique. Criteria for a valid RMR are: a minimum of 15 minutes of steady

state, the participants should not have eaten food 4 hours before the

measurement, testing will be in the morning. RMR will be measured for 15-20

minutes.

Fatigue

Fatigue based on daily activities in household, body care and social activities

will be measured with the Dutch Exertion Fatigue Scale (DEFS). The DEFS

contains nine questions, which have to answered on a five-point score ranging

from 0 (no) to 4 (yes). A low score on the DEFS represents a low score on

fatigue of daily activities (reliability: Cronbach*s alpha 0.91).



Lower body strength

Lower body strength is assessed using the sit-to-stand test. Lower body

strength plays an important role in every-day-activities. This test involves

counting the number of times, within 30 seconds, that the patient can come to a

full stand from a seated position without using his arms. The 30-second

sit-to-stand test has been shown to be reliable (test-retest correlation r =

0.80) and has been validated against the gold standard measure for lower-body

strength, the leg-press test. According to Rikli and Jones, intraclass

reliability is r = 0.89 (test-retest) and criterion validity related to leg

press is r = 0.77 (test-retest).