Table 2 Variable groups and its candidate variables after stage I selection using stepwise regression seperately for each group (n = 49).

From: Prediction of activity-related energy expenditure under free-living conditions using accelerometer-derived physical activity

Variable group

Candidate variables for stage I selection step

Offered to the model (groupwise)

Selected by the model (significant)

Accelerometrya

(Separate analysis)

VM countsa

ADP

FFMADP, FMADP, FM%ADP

FFMADP

BIA

FFMBIA, FMBIA, FM%BIA

FFMBIA

Anthropometry

Height, weight, body mass index, waist circumference, hip circumference, waist-to-hip ratio, arm circumference

height

QUAPb

Time in occupation, MET-h in occupation, time in domestic work, MET-h in domestic work, time in bicycling, MET-h in bicycling, time in locomotion, time in walking, time in sportsb

Time in locomotion

IPAQ

Time in vigorous PA, time in moderate PA, time in walking activity, total time in moderate and vigorous PA, total time in moderate PA and walking activity, total time in moderate and vigorous PA and walking

Total time in moderate PA and walking activity

Sitting (from QUAP & IPAQ)

Time spent sitting (IPAQ), time spent sitting (QUAP), time spent sitting on weekdays (QUAP), time spent sitting on weekend (QUAP)

Time spent sitting (QUAP)

Sleeping (from QUAP & IPAQ)

Time spent sleeping incl. napping (IPAQ), time spent sleeping incl. napping (QUAP), time spent sleeping excl. napping (QUAP)

None

Nutrition 1

Energy intake, fat intake, relative fat intake, carbohydrate intake, relative carbohydrate intake, protein intake, relative protein intake

Energy intake

Nutrition 2c

Carbohydrate intake, fat intake, relative fat intake, relative carbohydrate intake, protein intake, relative protein intake

Carbohydrate intake

Circulatory parameters

Systolic blood pressure, diastolic blood pressure, resting heart rate

Resting heart rate

Physical fitness

Handgrip strength

Handgrip strength

Demography

Age, sex

Sex

Metabolism

Fasting respiratory quotient

None

Socioeconomic

School education, professional qualification, occupation

None

Lifestyle

Smoking status, pack years of smoking, frequency of alcohol consumption, alcohol intake

None

Other

Season of examination

None

  1. In each group all candidate variables were offered to select significant variables for AEE prediction by stepwise selection regression using p-value limits of 0.05 for the corresponding partial F-statistic for including and retaining variables in the model.
  2. aIn the accelerometry group, of 15 candidate variables the single parameter VM counts was selected because it explained the highest proportion of variance in AEE (33.8%, similar to Axis 1 counts 34.0%) using linear regression, was frequently used in previous studies13, and revealed higher correlations in similar designed studies with higher sample sizes24.
  3. bIn addition, we tested the following combined variables that were calculated as sum of the single variables: total time in locomotion, bicycling, walking, and sports; total time in locomotion, bicycling, walking, sports, and domestic work; total time in locomotion, bicycling, walking, sports, domestic work, and occupation.
  4. cWe considered two groups for nutrition: the second group does not include energy intake, as this variable is directly related to the aggregated intake of the macronutrients (carbohydrate, protein, and fat).
  5. ADP air-displacement plethysmography, BIA bioelectrical impedance analysis, FFM fat-free mass, FM fat mass, IPAQ International Physical Activity Questionnaire, MET metabolic equivalent of task, PA physical activity, QUAP Questionnaire on Physical Activity on previous 12 months, VM vector magnitude.
Back to article page