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Archived Comments for: Objectively measured physical activity in two-year-old children – levels, patterns and correlates

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  1. Response to Johansson et al., (2015)

    Jill Hnatiuk, University of Western Sydney

    2 July 2015

    We read with interest the paper by Johansson and colleagues [1] on objectively assessed physical activity in two-year old children. Given the scarcity of work in this field, it is always pleasing to see the expansion of evidence. However, there were a number of issues with this manuscript that we would like to bring to the attention of readers.


    We had concerns about some of the methodology employed in the study, similar to the issues raised by Costa and colleagues [2] in response to a previously published manuscript [3]. While methodological procedures in this age group are still being developed, some considerable limitations were evident in the present study which may impact the results obtained. This includes the inclusion of sleep as sedentary time during the day and the lack of acknowledgement of the impact of excluding particular times of the day (early morning/late evening) on prevalence estimates in the discussion section.


    A number of conclusions drawn from the data in the discussion were not appropriate. Strong statements were made regarding endogenous factors (e.g., genetic and epigenetic variations) regulating physical activity and sedentary behaviour in early childhood despite only a few correlates examined in the study. Further research is required in this area before such assertions can be made.


    In addition, the authors failed to acknowledge existing evidence in the field with the paper intimating that this work was the first of its kind. The field is currently far more progressed than what is alluded to throughout the manuscript. There is a growing body of evidence on preschool children, including systematic reviews on prevalence and correlates of physical activity [4-6] and several manuscripts published on the toddler age group [7-11]; many of which were largely omitted from the introduction section.


    In order to help successfully progress the field forward we have raised these points so as to provide a more balanced view of the state of the evidence in this age group at this time.


    Dr Jill Hnatiuk1 & Associate Professor Kylie Hesketh2

    1School of Science & Health, University of Western Sydney, Australia

    2Centre for Physical Activity & Nutrition Research, Deakin University, Australia



    1. Johansson E, Hagstromer M, Svensson V, Ek A, Forssen M, Nero H et al. Objectively measured physical activity in two-year-old children - levels, patterns and correlates. Int J Behav Nutr Phys Act. 2015;12(1):3.

    2. Costa S, Cameron N, Clemes SA. Deriving and evaluating new accelerometer cut-points in young children – a comment on Johansson et al. (2014). Pediatr Obes. 2015;10(1):74-6. doi:10.1111/ijpo.256.

    3. Johansson E, Ekelund U, Nero H, Marcus C, Hagströmer M. Calibration and cross‐validation of a wrist‐worn Actigraph in young preschoolers. Pediatr Obes. 2014;10(1):1-6.

    4. Hinkley T, Crawford D, Salmon J, Okely AD, Hesketh K. Preschool Children and Physical Activity: A Review of Correlates. Am J Prev Med. 2008;34(5):435-41. doi:DOI: 10.1016/j.amepre.2008.02.001.

    5. De Craemer M, De Decker E, De Bourdeaudhuij I, Vereecken C, Deforche B, Manios Y et al. Correlates of energy balance-related behaviours in preschool children: a systematic review. Obes Rev. 2012;13:13-28. doi:10.1111/j.1467-789X.2011.00941.x.

    6. Hnatiuk J, Salmon J, Hinkley T, Okely A, Trost SG. A review of preschool children's physical activity and sedentary time using objective measures. Am J Prev Med. 2014;47(4):487-97.

    7. Manios Y. Design and descriptive results of the "Growth, Exercise and Nutrition Epidemiological Study In preSchoolers": The GENESIS Study. BMC Public Health. 2006;6:32-9. doi:10.1186/1471-2458-6-32.

    8. Gubbels JS, Kremers SPJ, van Kann DHH, Stafleu A, Candel MJJM, Dagnelie PC et al. Interaction between physical environment, social environment, and child characteristics in determining physical activity at child care. Health Psychol. 2011;30(1):84-90. doi:10.1037/a0021586.

    9. Hnatiuk J, Ridgers ND, Salmon J, Campbell K, McCallum Z, Hesketh K. Physical Activity Levels and Patterns of 19-Month-Old Children. Med Sci Sports Exerc. 2012;44(9):1715-20.

    10. Cardon G, Van Cauwenberghe E, De Bourdeaudhuij I. What do we know about physical activity in infants and toddlers: A review of the literature and future research directions. Science and Sports. 2011. doi:10.1016/j.scispo.2011.01.005.

    11. Xu H, Wen LM, Rissel C. Associations of maternal influences with outdoor play and screen time of two‐year‐olds: Findings from the Healthy Beginnings Trial. J Paediatr Child Health. 2014;50(9):680-6.

    Competing interests

    None declared