Volume 91, Issue 2, February (2004), pp. 235-243 © The Author 2004
doi:10.1079/BJN20031033

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The use of uniaxial accelerometry for the assessment of physical-activity-related energy expenditure: a validation study against whole-body indirect calorimetry

Hideaki Kumahara^1,2, Yves Schutz¹, Makoto Ayabe², Mayumi Yoshioka³, Yutaka Yoshitake⁴, Munehiro Shindo⁵, Kojiro Ishii², Hiroaki Tanaka^5
1Institute of Physiology, Faculty of Medicine, University of Lausanne, Lausanne, Switzerland
²Laboratory of Human Performance and Fitness, Graduate School of Education, Hokkaido University, Sapporo, Hokkaido, Japan
³Molecular Endocrinology and Oncology Research Center, Laval University Medical Center and Laval University, Quebec, Canada
⁴Department for Interdisciplinary Studies of Lifelong Sport and Physical Activity, National Institute of Fitness and Sports in Kanoya, Kanoya, Kagoshima, Japan
⁵Laboratory of Exercise Physiology, Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan

 (Received 4 July 2003–Revised 19 September 2003–Accepted 27 September 2003)

Assessing the total energy expenditure (TEE) and the levels of physical activity in free-living conditions with non-invasive techniques remains a challenge. The purpose of the present study was to investigate the accuracy of a new uniaxial accelerometer for assessing TEE and physical-activity-related energy expenditure (PAEE) over a 24 h period in a respiratory chamber, and to establish activity levels based on the accelerometry ranges corresponding to the operationally defined metabolic equivalent (MET) categories. In study 1, measurement of the 24 h energy expenditure of seventy-nine Japanese subjects (40 (sd 12) years old) was performed in a large respiratory chamber. During the measurements, the subjects wore a uniaxial accelerometer (Lifecorder; Suzuken Co. Ltd, Nagoya, Japan) on their belt. Two moderate walking exercises of 30 min each were performed on a horizontal treadmill. In study 2, ten male subjects walked at six different speeds and ran at three different speeds on a treadmill for 4 min, with the same accelerometer. O₂ consumption was measured during the last minute of each stage and was expressed in MET. The measured TEE was 8447 (sd 1337) kJ/d. The accelerometer significantly underestimated TEE and PAEE (91·9 (sd 5·4) and 92·7 (sd 17·8) % chamber value respectively); however, there was a significant correlation between the two values (r 0·928 and 0·564 respectively; P<0·001). There was a strong correlation between the activity levels and the measured MET while walking (r² 0·93; P<0·001). Although TEE and PAEE were systematically underestimated during the 24 h period, the accelerometer assessed energy expenditure well during both the exercise period and the non-structured activities. Individual calibration factors may help to improve the accuracy of TEE estimation, but the average calibration factor for the group is probably sufficient for epidemiological research. This method is also important for assessing the diurnal profile of physical activity.

Keywords:
Accelerometer, Daily energy expenditure, Physical activity, Respiration chamber

Abbreviations:
EE, energy expenditure, MET, metabolic equivalent, PAEE, physical-activity-related energy expenditure, PAEE_Acc, physical-activity-related energy expenditure estimated by the accelerometer, PAEE_Acc-excl.TEF, physical-activity-related energy expenditure estimated by the accelerometer excluding thermic effect of food, PAEE_Chamber, physical-activity-related energy expenditure measured by the respiratory chamber, PAEE_{Chamber-excl.TEF}, physical-activity-related energy expenditure measured by the respiratory chamber excluding thermic effect of food, SEE, standard error of the estimate, TEE, total energy expenditure, TEE_Acc, total energy expenditure estimated by an accelerometer, TEE_Chamber, total energy expenditure measured by the chamber, TEF, thermic effect of food