Ulf Ekelund

International physical activity questionnaire : 12-country reliability and validity

BACKGROUNDnPhysical inactivity is a global concern, but diverse physical activity measures in use prevent international comparisons. The International Physical Activity Questionnaire (IPAQ) was developed as an instrument for cross-national monitoring of physical activity and inactivity.nnnMETHODSnBetween 1997 and 1998, an International Consensus Group developed four long and four short forms of the IPAQ instruments (administered by telephone interview or self-administration, with two alternate reference periods, either the last 7 d or a usual week of recalled physical activity). During 2000, 14 centers from 12 countries collected reliability and/or validity data on at least two of the eight IPAQ instruments. Test-retest repeatability was assessed within the same week. Concurrent (inter-method) validity was assessed at the same administration, and criterion IPAQ validity was assessed against the CSA (now MTI) accelerometer. Spearmans correlation coefficients are reported, based on the total reported physical activity.nnnRESULTSnOverall, the IPAQ questionnaires produced repeatable data (Spearmans rho clustered around 0.8), with comparable data from short and long forms. Criterion validity had a median rho of about 0.30, which was comparable to most other self-report validation studies. The usual week and last 7 d reference periods performed similarly, and the reliability of telephone administration was similar to the self-administered mode.nnnCONCLUSIONSnThe IPAQ instruments have acceptable measurement properties, at least as good as other established self-reports. Considering the diverse samples in this study, IPAQ has reasonable measurement properties for monitoring population levels of physical activity among 18- to 65-yr-old adults in diverse settings. The short IPAQ form last 7 d recall is recommended for national monitoring and the long form for research requiring more detailed assessment.

Assessment of physical activity in youth

Despite much progress with physical activity assessment, the limitations concerning the accurate measurement of physical activity are often amplified in young people due to the cognitive, physiological, and biomechanical changes that occur during natural growth as well as a more intermittent pattern of habitual physical activity in youth compared with adults. This mini-review describes and compares methods to assess habitual physical activity in youth and discusses main issues regarding the use and interpretation of data collected with these techniques. Self-report instruments and movement sensing are currently the most frequently used methods for the assessment of physical activity in epidemiological research; others include heart rate monitoring and multisensor systems. Habitual energy expenditure can be estimated from these input measures with varying degree of uncertainty. Nonlinear modeling techniques, using accelerometry perhaps in combination with physiological parameters like heart rate or temperature, have the greatest potential for increasing the prediction accuracy of habitual physical activity energy expenditure. Although multisensor systems may be more accurate, this must be balanced against feasibility, a balance that shifts with technological and scientific advances and should be considered at the beginning of every new study.

The association of intensity and overall level of physical activity energy expenditure with a marker of insulin resistance

Aims/hypothesisPhysical activity is important in preventing insulin resistance, but it is unclear which dimension of activity confers this benefit. We examined the association of overall level and intensity of physical activity with fasting insulin level, a marker of insulin resistance.MethodsThis was a cross-sectional analysis of the Medical Research Council Ely population-based cohort study (2000–2002). Physical activity energy expenditure (PAEE) in kJ kg−1 min−1 was measured by heart rate monitoring with individual calibration over a period of 4xa0days. The percentage of time spent above 1.5, 1.75 and 2 times resting heart rate (RHR) represented all light-to-vigorous, moderate-to-vigorous and vigorous activity, respectively.ResultsData from a total of 643 non-diabetic individuals (319 men, 324 women) aged 50 to 75xa0years were analysed. In multivariate linear regression analyses, adjusting for age, sex and body fat percentage, PAEE was significantly associated with fasting insulin (pmol/l) (βu2009=u2009−0.875, pu2009=u20090.006). Time (% of total) spent above 1.75u2009×u2009RHR and also time spent above 2u2009×u2009RHR were both significantly associated with fasting insulin (βu2009=u2009−0.0109, pu2009=u20090.007 and βu2009=u2009−0.0365, pu2009=u20090.001 respectively), after adjusting for PAEE, age, sex and body fat percentage. Time spent above 1.5u2009×u2009RHR was not significantly associated with fasting insulin in a similar model (βu2009=u2009−0.0026, pu2009=u20090.137).Conclusions/interpretationThe association between PAEE and fasting insulin level, a marker of insulin resistance, may be attributable to the time spent in moderate-to-vigorous and vigorous activity, but not to time spent in light-intensity physical activity.

Energy expenditure assessed by heart rate and doubly labeled water in young athletes.

PURPOSEnTo compare total energy expenditure (TEE) estimated by the FLEX heart rate (HR) method with that measured by the doubly labeled water (DLW) technique in young speed skaters. We hypothesized that the accuracy of FLEX HR-estimated TEE would be affected by a) the definition of the FLEX HR and b) the type of training regimen.nnnMETHODSnEight young athletes (mean age 18.2 +/- 1.3 yr) underwent measurements during two 10-d training periods: an off-season period with voluntary training (predominantly running) and a preseason period mainly focused on skating technique training. TEE was measured simultaneously by the DLW and FLEX HR methods. FLEX HR1 was defined as the mean of the HRs during all resting calibration activities and the lowest HR during exercising calibration activities. FLEX HR2 was defined as the mean of the highest HR during resting activities and the lowest HR during exercising.nnnRESULTSnANOVA showed that FLEX HR1 was significantly lower than FLEX HR2 (mean of both periods; 77 +/- 5 vs 84 +/- 6 beats.min(-1); P = 0.004). TEE values obtained by DLW were 16.8 +/- 3.8 and 16.9 +/- 2.9 MJ.d(-1) in the two periods, respectively. TEE values calculated from FLEX HR1 were 17.8 +/- 3.6 and 17.4 +/- 2.6 MJ.d(-1), and those from FLEX HR2 17.1 +/- 3.1 and 17.0 +/- 2.7 MJ.d-1, respectively. No significant period (P = 0.83) or method (P = 0.44) effect on TEE was observed.nnnCONCLUSIONnFLEX HR-estimated TEE was not affected by the definition of the FLEX HR or by the type of training regimen as compared with TEE measured by the DLW method in young athletes.

Total daily energy expenditure and pattern of physical activity measured by minute-by-minute heart rate monitoring in 14-15 year old Swedish adolescents

Objective: To assess total daily energy expenditure (TDEE) and patterns of physical activity among Swedish male and female adolescents and to relate the amount and intensity of physical activity to existing recommendations (energy expenditure equal to or above 12.4u2005kJ/kg/day or accumulation of 30u2005min/day in moderate physical activity equal to 4.5 times sedentary energy expenditure or more).Design: TDEE, physical activity level (PAL=TDEE/BMR), energy expenditure (EE) and time spent in different intensities of physical activity were assessed by using minute-by-minute heart rate monitoring in combination with laboratory measured sedentary energy expenditure (SEE) and peak oxygen uptake.Setting: Department of Physical Education and Health, Örebro University, and Department of Clinical Physiology, Örebro Medical Centre Hospital, Sweden.Subjects: Eighty-two 14–15u2005y old adolescents (42 boys, 40 girls) from the city of Örebro, randomly selected through a two-stage sampling procedure.Results: TDEE was 12.8u2005MJ/day and 10.0u2005MJ/day for boys and girls respectively (P<0.001) and PAL was 1.74 and 1.67 (NS). Forty-four percent and 47%, respectively, of TDEE referred to EE in physical activity, of which 70% for both genders referred to light physical activity (corresponding to <4.5 times SEE). Eleven boys and 14 girls had an EE lower than 12.4u2005kJ/kg/day and/or did not accumulate 30u2005min/day in physical activity ≥4.5 SEE. Those (n=20) with the highest PAL values (>2.01 and 1.81, respectively) spent 149u2005min/day at a ≥4.5 SEE intensity level compared to 40u2005min/day for those (n=30) with the lowest PAL values (<1.55 and 1.45, respectively).Conclusions: Swedish adolescent boys and girls are similarly physically active. The major amount of time devoted to physical activity refers to light physical activity. At least thirty percent of adolescents seem not to achieve appropriate levels of physical activity considered to be beneficial for health.Sponsorship: Örebro County Council, The Public Health Committee of Stockholm County Council, Sweducation Foundation.European Journal of Clinical Nutrition (2000) 54, 195–202

Estimation of free-living energy expenditure by heart rate and movement sensing: A doubly-labelled water study

Background Accurate assessment of energy expenditure (EE) is important for the study of energy balance and metabolic disorders. Combined heart rate (HR) and acceleration (ACC) sensing may increase precision of physical activity EE (PAEE) which is the most variable component of total EE (TEE). Objective To evaluate estimates of EE using ACC and HR data with or without individual calibration against doubly-labelled water (DLW) estimates of EE. Design 23 women and 23 men (22–55 yrs, 48–104 kg, 8–46%body fat) underwent 45-min resting EE (REE) measurement and completed a 20-min treadmill test, an 8-min step test, and a 3-min walk test for individual calibration. ACC and HR were monitored and TEE measured over 14 days using DLW. Diet-induced thermogenesis (DIT) was calculated from food-frequency questionnaire. PAEE (TEE ÷ REE ÷ DIT) and TEE were compared to estimates from ACC and HR using bias, root mean square error (RMSE), and correlation statistics. Results Mean(SD) measured PAEE and TEE were 66(25) kJ·day-1·kg-1, and 12(2.6) MJ·day-1, respectively. Estimated PAEE from ACC was 54(15) kJ·day-1·kg-1 (p<0.001), with RMSE 24 kJ·day-1·kg-1 and correlation r = 0.52. PAEE estimated from HR and ACC+HR with treadmill calibration were 67(42) and 69(25) kJ·day-1·kg-1 (bias non-significant), with RMSE 34 and 20 kJ·day-1·kg-1 and correlations r = 0.58 and r = 0.67, respectively. Similar results were obtained with step-calibrated and walk-calibrated models, whereas non-calibrated models were less precise (RMSE: 37 and 24 kJ·day-1·kg-1, r = 0.40 and r = 0.55). TEE models also had high validity, with biases <5%, and correlations r = 0.71 (ACC), r = 0.66–0.76 (HR), and r = 0.76–0.83 (ACC+HR). Conclusions Both accelerometry and heart rate may be used to estimate EE in adult European men and women, with improved precision if combined and if heart rate is individually calibrated.

Heart rate as an indicator of the intensity of physical activity in human adolescents.

Abstract. The aims of this study were, in a group of adolescents, firstly to identify the absolute heart rates (HR) and the percentages of maximal heart rates (HRmax) corresponding to 40%, 60% and 80% of peak oxygen uptake (

Total daily energy expenditure and patterns of physical activity in adolescents assessed by two different methods

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