Physical activity level of kindergarten staff working with toddlers and older children in Norway
Abstract
BACKGROUND:
Research suggests that one-third of Norwegian adults satisfy national health recommendations for physical activity, but little knowledge exists regarding activity levels in different occupations.
OBJECTIVES:
This study investigates the level at which kindergarten staff fulfil these health recommendations, and examines differences in physical activity levels of staff working mainly with toddlers (1–3 years) and older children (4–6 years). The study also investigates physical activity level during working time and leisure time.
METHODS:
Physical activity levels among 43 kindergarten staff members were measured utilizing accelerometers and questionnaires.
RESULTS:
The results demonstrate that 86% of kindergarten staff satisfy the health recommendations for physical activity. Moreover, kindergarten staff working with older children were significantly more physically active than staff working with toddlers.
CONCLUSIONS:
Physical activity level during working time was found to be of major significance for fulfilling the health recommendations among kindergarten staff working with toddlers.
1Introduction
Physical activity constitutes an important factor in preventing early death, cardiovascular disease, high blood pressure, obesity and being overweight, Type 2 diabetes, and some types of cancer [1]. A long-term follow-up study of 3050 twins from the Finnish Twin Cohort has shown that midlife, moderately vigorous physical activity is associated with better cognition at old age [2]. Physical activity also has a positive effect on physical fitness [3]. An individual’s physical fitness is of importance for the ability to carry out day-to-day functions, and physical fitness is therefore critical for people’s ability to function. Rothmore and Gray [4] found a link between work ability and a range of physical and psychosocial risk factors, which if addressed, may improve the longevity of the workforce. Furthermore, physical activity during work, f. ex. lifting, walking or running, may promote good health. Work in kindergarten provides good opportunities for physical activity during the working day. This is in contrast to occupational groups sitting much of their working day [5]. Miller and Brown [6] found high sitting times among Australian workers are important because it has been estimated that each 2-hr increment in sitting time at work is associated with a 5% and 7% increase in obesity and Type 2 diabetes. The demographic characteristics of the sample included scientists, management staff, office and laboratory workers, as well as cleaners and administrative staff. The clear association between increasing sitting time, occupation and lower daily step counts among this sample of working adults, suggests that those whose daily work involves long hours of sitting should be the focus of efforts to promote physical activity both within and outside the workplace. In Norway in 2014, the national guideline for adults was at least 21.4 min of moderate and/or vigorous activity (MVPA) per day [7]. A Norwegian study showed that 35% of women and 28% of men in the 20–64 age group satisfied these health recommendations for daily physical activity [1]. However, little is currently known about the activity levels of different vocational groups –including kindergarten staff. In Norway, research in this area is particularly scarce: a study by Hoel and Øen [8] demonstrated that carpenters had a daily MVPA of 38 min, while the corresponding number for academics was 29 min. Due to the physically demanding work of kindergarten staff, they arguably have a comparatively higher MVPA relative to more sedentary occupational groups such as office workers; and a large proportion of kindergarten staff fulfil the health recommendations of 150 min of MVPA per week, or 21.4 min daily. Kindergarten staff need to lift and carry, walk around the area in the kindergarten to observe children, and attend excursions or participate physical active play. Staff working with toddlers will also typically lift and carry them. Moreover, helping the children in different situations, such as finding toys, assisting in undressing or dressing them, or helping them if conflicts arise, all involve constant movement. Older children, on the other hand, uses large areas when they play, such as in chasing and catching games in outdoor areas. In addition, in kindergarten, more free play may be observed as the children age [9]. Working with older children may therefore necessitate more movement from staff, who move to where the play is, participate in games, and play and go on more trips in the neighbourhood.
Working with older children may necessitate more movement from staff, and this may due the high MVPA compared with the Norwegian study showing that 35% of women and 28% of men in the 20–64 age group satisfied these health recommendations for daily physical activity [1]. Increased physical activity due to work is supported by international research. For example, a study of 55 construction workers showed that 73% of them achieved international health recommendations for physical activity through their work, while 31% satisfied these health recommendations by means of physical activity outside of work [10]. Similarly, Lagestad and Kippe [11] found that 73% of kindergarten staff in their study fulfilled the health recommendations for physical activity through their work; and Ekler, Nagyvaradi, Kiss-Geosits and Csanyi [12] reported that 81% of teachers in their study complied with the international health recommendations for physical activity through their work. These studies indicate that the workplace may constitute a significant arena for physical activity.
The physical activity level of kindergarten staff may differ depending on whether they are working with toddlers or older children [11], and a study by Lagestad and Kippe [11] investigated whether physical activity during working hours contributed to physical activity that satisfied the health recommendations. However, they did not consider in detail whether variations exist in activity level between those who work with toddlers and those who work with older children. Working with older children may require more movement and physical activity for staff, as they have to follow children where their play activity takes them, and participate in play and trips in the neighbourhood with increasingly mobile children. It may also be argued that physically active adults will be good role models for children, by encouraging a physically active lifestyle [13]. One study identified that the preschool staff emphasized the role of being a facilitator and supporter [14]. Furthermore, it seems to be a general agreement among several researchers [14, 15] that positive adult encouragement is especially important when preschool staff participate in children’s physical activity. These findings also support the view of Sørensen [16], who suggests that preschool staff should engage in physical activity with children, whereby physical activity is expressed verbally as fun rather than a duty. The preschool educator is responsible for providing activities that give the children positive mastering experiences. Positive adult encouragement might increase children’s physical activity through perceived sporting competence [15]. A systematic overview of studies of children’s activity levels published between 1986 and 2007, shows that children’s physical activity levels increase with age [17].
This study will attempt to answer the following three research questions:
1. What proportion of kindergarten staff comply with the Norwegian national health recommendations for physical activity?
2. To what extent do differences exist between staff working with toddlers and staff working with older children regarding activity levels and compliance with the national health recommendations for physical activity?
3. To what extent do working hours and leisure time contribute to physical activity among staff working with toddlers and staff working with older children, respectively?
The rationale for selecting kindergarten staff to this study was to provide new knowledge to our expert area as researcher team, and to the kindergarten themselves.
2Methods
2.1Sample
Participating kindergartens were selected from a list of all 19 kindergartens in the municipality of Levanger in central Norway. Kindergarten staff members were excluded if they did not work full-time in the seven kindergartens participating in this study. Seven kindergarten were considered as sufficient if everyone accepted to participate - a decision that was supported by the large effect size in the analyses. All 46 kindergarten staff members that had full-time employment were invited to participate, and all accepted. These staff members were informed about the purpose and the procedures of voluntary participation in the study, and all agreed to participate. One participant forgot to attach the accelerometer, one forgot to fill in the questionnaire, one participant became ill during the week that the testing was performed. Thus, 43 participants answered the questionnaire and provided valid accelerometer data. The sample comprised two men and 41 women; aged: 41.6±10.2 years. Seventeen trained as preschool teachers (university college education), 12 trained as child-care and youth workers (upper secondary school education), 14 had no training in child-care services, and four had completed lower secondary school only. Twelve participants worked in farm and/or nature and open-air kindergartens; eight worked in music kindergartens; and 23 worked in kindergartens without any particular profile. Management at each kindergarten consented for the study to be conducted at their respective sites. The participants were fully informed about the protocol before participating in this study, and agreed to participate. Ethics approval to use the data and conduct the study was given by the Norwegian Social Science Data Services (NSD).
2.2Measures
The Actigraph GT1M accelerometer was used to measure physical activity levels among kindergarten staff in the municipality of Levanger in central Norway. The Actigraph GT1M is valid and reliable tested for testing physical activity levels among adults [18]. Accelerometers detect intensity, frequency and duration of adults’ physical activity [18], and filter other noises that are not normal human movement [19]. Furthermore, accelerometers decrease subjectivity of physical activity measurement [20] and eliminate bias such as social desirability and recall problems [21]. Moreover, validated accelerometers may be the most promising method to capture physical activity in free-living situations [18, 22], because direct observation is imprecise in identifying intensities and level of energy expenditure during physical activity [23].
The accelerometer was placed at the participant’s right hip, as recommended by Ainsworth, Cahalin, Buman and Ross [24], and the participants were required to wear it daily except during sleep, showering or other water-based activities. Each participant wore an accelerometer for one full week from Monday to Sunday night in accordance with procedures for accelerometer measurements of adults in Norway [1]. This method has been tested for validity and reliability in measuring physical activity levels and satisfying the health recommendations [1]. Such a strategy makes it possible to compare the physical activity levels of kindergarten staff MVPA and counts per minute (CPM) with the health recommendations and other population groups. The accelerometer produce a variable (counts) that translates into physiologically interpretable variables. Counts are aggregated post-filtered raw accelerometer data that are calculated over 1-minute epochs [25]. Hansen et al. [1] recommend 2019 counts per minute as the limit to MVPA. The kindergarten staff also filled in a questionnaire, which included questions about how much they worked with toddlers and older children. The questionnaire included was pilot-tested before the kindergarten staff answered the questions.
2.3Procedures
Participants were instructed on how to place the accelerometer correctly on the right hip and were told to wear it throughout the day, except when sleeping, showering, or swimming. The accelerometer registered data at 5-s intervals. After the 7 d, the accelerometers were collected from the kindergartens where the participants worked. The data were downloaded into the Actilife program. In accordance with the test protocol [1] 600 min of activity were required for the day to be considered valid, and periods of more than 60 min without activity were omitted. The participants needed at least three valid days of activity to be included in the study. Only workdays were included in the analysis. The limit value for MVPA was defined as more than 2019 counts per minute in accordance with Norwegian population studies [1].
2.4Statistical analysis
The sample sizes were satisfactory in relation to a two-group comparison using t-tests, and t-test was appropriate to examine the research question [25], and the Shapiro-Wilk test showed the assumption of normality was met (p > 0.05). Three kindergarten staff members worked an equal amount of time with toddlers and older children, and were thus excluded from the analysis of between-group differences in physical activity. The results are presented as mean measurements, standard deviations (SD), and distribution according to percentage. An independent t-test was applied to highlight differences in MVPA and CPM relating to kindergarten staff who worked mostly with either toddlers or older children. A paired t-test was performed to identify the differences between kindergarten staff activity levels during leisure time and working hours. Chi-square tests were utilized to discern any differences between kindergarten staff members who worked mostly with either toddlers or older children, concerning the proportion who satisfied the health recommendations. The results are presented as proportions (%), mean values, and standard deviations. The effect size was evaluated using η2 (Eta partial squared), where 0.01–0.06 indicates a small effect, 0.06–0.14 indicates a medium effect, and > 0.14 indicates a large effect [26]. The boundary for significance was set at p < 0.05. The statistical analysis was carried out using SPSS software, version 23.0 (SPSS, Inc., Chicago, IL).
3Results
The questionnaire data revealed that 26 of the staff worked all of the time or most of the time with toddlers (0–3 years) and 15 staff members worked all of the time or most of the time with older children (4–6 years). No significant differences were found in the ages of the kindergarten staff regarding who worked with toddlers or older children.
The kindergarten staff spent 44.8 min (SD = 20.5) daily on activities with moderate to vigorous intensity, achieving 364.2 CPM (SD = 114.1). This standard deviation indicates a large variation in the number of minutes of MVPA among kindergarten staff; 95% spent between 24.3 min and 65.3 min with such intensity daily. Variation in the CPM is also high among kindergarten staff. 86% of the kindergarten staff had an activity level that satisfied the health recommendations for daily physical activity (21.4 MVPA). Kindergarten staff working mostly with older children had significantly higher CPM (428) than those who worked with toddlers (324; t = – 3.2, p = 0.002, η2 = 0.20). Kindergarten staff working mostly with older children also spent significantly more time in MVPA (55 min daily) than those who worked with toddlers (38 min daily; t = – 3.0, p = 0.004, η2 = 0.18). Kindergarten staff who mostly worked with older children complied more with the health recommendations for physical activity, than staff working with toddlers (93% versus 80%). However, this difference was not statistically significant (χ2 =1.2, p = 0.273). In other words, there was no difference in the proportion of kindergarten staff who met the recommendations for PA, based on the age groups of the children they worked with.
Figure 1 shows the number of minutes of daily MVPA during working hours and leisure time among staff working mostly with toddlers and staff working mostly with older children. There was no difference in the number of minutes of time spent in MVPA during working hours between staff working mostly with older children and staff working mostly with toddlers (t = –1.4, p = 0.171, η2 = 0.04). However, kindergarten staff working mostly with older children spent more time in MVPA during leisure time, compared to those who worked with toddlers (t = –3.0, p = 0.005, η2 = 0.19). There were no significant differences in time spent in MVPA during working hours and leisure time among staff working mostly with older children (t = 0.89, p = 0.389, η2 = 0.07). However, staff working mostly with toddlers spent more time in MVPA during working hours than during leisure time (t = 4.10, p = 0.001 η2 = 0.44).
Fig. 1
Mean minutes of daily MVPA during working hours and leisure time among staff working mostly with toddlers and staff working mostly with older children. *Difference in the mean number of minutes of MVPA during leisure between staff working with toddlers and staff working with older children.
4Discussion
4.1Physical activity levels of kindergarten staff
The results demonstrate that 86% of the kindergarten staff met the health recommendations of 21.4 min of daily physical activity with moderate and/or vigorous intensity. This is higher than other Norwegian women and Norwegian men. According to a population study of Norwegians [1], 34% of Norwegian women and 28% of Norwegian men in the 20–64 age group satisfied these recommendations. 95% of the kindergarten staff in our study were between 30 and 50 years of age, with a mean age of 41.2 years. Data from the Directorate of Health, which are based on a nationwide study of 3267 persons, showed that just under 30% of Norwegian women aged in their 30 s and slightly more than 30% of women aged in their 40 s met the health recommendations for physical activity [3]. A higher proportion of female participants in our study satisfied the health recommendations for physical activity than Norwegian women in general.
Our study found that the kindergarten staff had a mean MVPA of 44.8 minutes per day that was higher than that reported in a previous study of Norwegian adults [28]. That study found that the mean time spent on MVPA in the 20–64 age group was 34.3 min for women and 36.5 min for men. The kindergarten staff in our study had a higher CPM of 364.2, compared to the CPM for Norwegians in the 20–64 age group (345 for women and 349 for men). The kindergarten staff in the municipality of Levanger, Norway in our study had a higher physical activity level, when compared with the findings of other studies of women and men in Norway and Sweden [28, 29].
If we compare the findings from our study with other occupations that also comprise elements of demanding physical work, kindergarten staff in the municipality of Levanger in our study have similar physical activity level as carpenters [8] and construction workers [10]. A study by Hoel and Øren [8] determined that carpenters and academics had 439 and 332 CPM in a working day, respectively. This shows that the number of counts (364) that kindergarten staff have is higher than academics and much lower than carpenters. One study showed that healthcare workers in hospitals had a mean MVPA of 23.57 min –an activity level substantially lower that of the kindergarten staff in our study [30]. This is a somewhat surprising finding because kindergarten staff and healthcare workers have similarly physically demanding jobs. However, the authors [30] argued that walking in a patient care unit (which can be argued to be a major physical activity among these health-care workers) is probably not sustained for one minute, which is necessary to be categorized as moderate physical activity by the accelerometer. On the other hand, kindergarten staff take field trips with children and often help children in different situations where they play. This may entail physical activity that lasts for epochs of more than one minute, and may explain the differences in activity levels among kindergarten staff and healthcare workers.
This may indicate that working in a kindergarten, and in other jobs that demand physical activity contributes to satisfying the health recommendations for physical activity. Incidental physical activity throughout the workday reduces sedentary time and increases total physical activity. A relevant question is whether there may be differences in this occupation category depending on whether the staff are working with toddlers or older children.
4.2Differences in physical activity levels between staff working with toddlers and older children
The results reveal that the kindergarten staff who worked mostly with older children spent more time in MVPA during a full day, compared to those who worked mostly with toddlers. Furthermore, kindergarten staff who worked mostly with older children also had substantially more CPM (433 counts) than those who worked mostly with toddlers (321 counts). Figure 1 shows that no difference existed in terms of minutes with MVPA during working hours between those who worked with older children and those who worked with toddlers. However, kindergarten staff who mainly worked with older children had more minutes with MVPA during their leisure time than those who worked with toddlers. More kindergarten staff members who worked with older children satisfied the recommendations for daily physical activity compared to staff working with toddlers, even if this difference was not significant. As previously mentioned, kindergarten staff working with older children may have to follow the children where play activity takes them, and also take part in play and field trips in the neighbourhood with increasingly mobile children. Moreover, toddlers tend to sleep more than older children. Thus, it is reasonable to assert that kindergarten staff working with older children have a higher physical activity level during work. This assumption is supported by the findings of Tucker [17] and Reilly et al. [31], that children’s physical activity levels increased with age. Three- and five-year-olds had, on average, 818 CPM measured by accelerometer [31]. The three-year-olds spent only two per cent of this time in MVPA, while the five-year-olds spent four per cent of the total time in MVPA. Children aged between 29 and 52 months had a CPM of 667 when playing outside [31]. In comparison, Brasholt et al. [32], found higher physical activity levels among children aged 62-months (877 + /- 233 counts/min).
The absence of large differences in the number of minutes with MVPA during working hours for those who work with older children and those who work with toddlers may be because physical activity is achieved through different physically demanding situations with the children. For example, toddlers typically engage in social actions in which the purpose is to establish contact with other children [32]. The youngest children also tended to use large objects to crawl into, get on top of, and move around in.
4.3The importance of working time in relation to physical activity level
Extant research has indicated that physical activity during working hours in physically demanding jobs has great importance for an employee’s total physical activity and compliance with health recommendations for physical activity [10, 11]. One study found that physical activity during working hours contributes 65% of total minutes with moderate physical intensity and 29% of total minutes of vigorous intensity physical activity in the course of one day; whereas, physical activity during leisure time contributes 35% of the total minutes with moderate physical intensity and 71% of physical activity with vigorous intensity [10]. Therefore, evidence exists that the workplace may constitute an important arena for satisfying the recommendations for physical activity. 73% of construction workers satisfied the recommendations for physical activity through their work, while 31% fulfilled the recommendations through activities in their leisure time [10]. An other study found that 73% of kindergarten staff met the physical activity recommendations through their work; whereas, 57% did so through activities during leisure time [11]. A study by Ekler et al. [12] showed that 81% of teachers in their study achieved the recommended level through their day-to-day work.
An interesting finding in our study is that kindergarten staff working mainly with older children spent more time in MVPA during their leisure time, compared to those who worked with toddlers. Further studies are needed to investigate whether those who are most physically active in their leisure time also choose to work with older children, as older children are likely to require more physically active kindergarten staff. Staff who worked with toddlers only fulfilled half of their activity recommendations during their time off. This indicates that the focus on more physical activity in leisure time for those who work with toddlers will be important, as this group has insufficient physical activity in relation to the recommendations. Therefore, physical activity when working with children in kindergarten is essential for the contribution it provides to total physical activity in a day.
5Conclusion
The current study found that 86% of kindergarten staff met the health recommendations for daily physical activity, and that kindergarten staff working with older children spent more time in MVPA during a whole day, compared to those who worked with toddlers. There was no difference in the total time spent in MVPA during working hours, between staff working with older children and staff working with toddlers. Staff working with older children spent more time in MVPA in their leisure time. However, staff working with older children spent more time in MVPA in their leisure time, and a greater percentage of these staff met the recommendation for daily physical activity, compared to those working with toddlers. On the other hand, staff working with toddlers had a significantly higher activity level during working hours than at other times of the day and, for this group, physical activity during working hours was essential for fulfilling the recommendations for physical activity.
6Limitations and strengths
The major strength of the present study is that it is based on objective measurements of physical activity, which decreases subjectivity [20], and eliminates bias, such as social desirability and recall problems [21]. Furthermore, the utilization of accelerometers is based on high-quality standard procedures, validated and reliability-tested for researching physical activity levels for adults. Despite the small sample size, the effect size was large [27], which indicates real differences between the groups, and not just random variations. Furthermore, the sample sizes are not equal for the two groups of kindergarten staff working with toddlers and older children. However, the sample size in the two groups reflect the natural distribution regarding work with toddlers and older children in Norwegian kindergartens. Working in a kindergarten necessitates a high degree of walking, lifting, carrying, and physical activity together with children. Further research should shed light on how high physical activity levels among kindergarten staff, combined with ergonomic measures, increased knowledge and weight training, may have an effect on staff sickness absenteeism. It is also necessary to obtain additional knowledge about how the physical activity level of kindergarten staff influences children’s physical activity levels. These studies should also include larger sample sizes than that in the present study.
Conflict of interest
The authors declare no conflict of interests.
Acknowledgments
KK contributed to the design, and writing the introduction, discussion, and conclusion. PL contributed to the design, and writing the introduction, methods, discussion, and conclusion.
References
[1] | Hansen BH , Kolle E , Andersen SA . Fysisk aktivitetsnivå blant voksne og eldre i Norge. Oppdaterte analyser basert på nye nasjonale anbefalinger i 2014 [Physical activity among adults and elderly in Norway. Updated analyses based on national recommendations in 2014]. Oslo: Directorate of Health; 2014: Report 05, IS-2183. |
[2] | Iso-Markku P , Waller K , Vuoksimaa E , Heikkilä K , Rinne J , Kaprio J , Kujala UM . Midlife physical activity and cognition later in life: a prospective twin study. J Alzheimers Dis. (2016) ;54: (4):1303–17. |
[3] | Directorate of Health. Fysisk form blant voksne og eldre i Norge. Resultater fra en kartlegging i 2009–2010 [Physical fitness among adults and elderly in Norway. Results from an examination in 2009-2010]. Oslo: Directorate of Health; 2010: Report 10, IS-1816. |
[4] | Rothmore P , Gray J . Using the work ability to identify workplace hazards. Work. (2019) ;62: (2):251–9. |
[5] | Castillo-Retamal M , Hinckson EA . Measuring physical activity and sedentary behaviour at work: a review. Work. (2011) ;40: :345–57.) Miller and Brown. ... |
[6] | Miller R , Brown W . Steps and sitting in a working population. International Journal of Behavioral Medicine. (2004) ;11: (4):219–224. |
[7] | Andersen S , Meltzer HM . Anbefalinger om kosthold, ernæring og fysisk aktivitet [Recommendations for diets, nutrition and physical activity]. Oslo: Norwegian Directorate of Health; 2014: Report IS 2170. |
[8] | Hoel KA , Øren TS . Fysisk aktivitet hjå akademikarar og tømrarar i Sogndal målt med akselerometer [Physical activity in academics and carpenters in Sogndal measured using an accelerometer]. [Bachelor paper, 11 November 2014] Downloaded from http://brage.bibsys.no/xmlui/handle/11250/149891?show=full (2013). |
[9] | Osnes H , Skaug HN , Kaarby KM . Kropp, bevegelse og helse i barnehagen [Body, movement and health in day-care institutions]. Oslo: Universitetsforlaget; 2015. |
[10] | Arias OE , Caban-Martinez AJ , Umukoro PE , Okechukwu CA , Dennerlein JT . Physical activity levels at work and outside of work among commercial construction workers. JOEM. (2015) ;57: :73–8. |
[11] | Lagestad P , Kippe K . Physical activity levels at work and leisure among kindergarten workers. Sci. J Pub. Health. (2016) ;4: :147–54. |
[12] | Ekler J , Nagyvaradi K , Kiss-Geosits B , Csanyi T . Moderate and vigorous physical activity in the 55+teachers’ daily routine. J Hum. Sport & Exerc. (2013) ;8: :204–11. |
[13] | Bjørgen K , Svendsen B . Kindergarten practitioners’ experience of promoting children’s involvement in and enjoyment of physically active play: Does the contagion of physical energy affect physically active play? Contemporary Issues in Early Childhood. (2015) ;16: (3):257–271. |
[14] | Brown WH , Pfeiffer KA , McIver KL , Dowda M , Addy CL , Pate RR . Social and environmental factors associated with preschoolers’ nonsedentary physical activity. Child Dev. 2009a;80. |
[15] | Gubbels JS , Kremers SP , Van Kann DH , Stafleu A , Candel MJ , Dagnelie PC , et al. Interaction between physical environment, social environment, and child characteristics in determining physical activity at child care. Health Psychology. (2011) ;30: (1):84. |
[16] | Sørensen HV . Børns fysiske aktivitet i børnehaver [Young children’s physical activities in preschool]. [PhD-thesis]. Odense: University of Southern Denmark; (2012) . |
[17] | Tucker P . The physical activity levels of preschool-ages children: a systematic review. ECRQ. (2008) ;23: :547–58. |
[18] | Plasqui G , Westerterp KR . Physical activity assessment with accelerometers: an evaluation against doubly labeled water. Obesity. (2007) ;15: (10):2371–9. |
[19] | Chen KY , Bassett DR . The technology of accelerometry-based activity monitors: current and future. Med Sci Sports Exerc. (2005) ;37: (11):S490. |
[20] | Sirard JR , Pate RR . Physical activity assessment in children and adolescents. Sport Med. (2001) ;31: (6):439–54. |
[21] | Evenson KR , Catellier DJ , Gill K , Ondrak KS , McMurray RG . Calibration of two objective measures of physical activity for children. J Sports Sci. (2008) ;26: (14):1557–65. |
[22] | Van Cauwenberghe E , Labarque V , Trost S , De Bourdeaudhuij I , Cardon G , editors. Calibration and comparison of accelerometer cut-points to define physical activity intensities in preschool children. 2010; Annual exchange meeting Cambridge-Amsterdam-Gent. |
[23] | Butte NF , Wong WW , Lee JS , Adolph AL , Puyau MR , Zakeri IF . Prediction of energy expenditure and physical activity in preschoolers. Med Sci Sports Exerc. (2014) ;46: (6):1216. |
[24] | Ainsworth B , Cahalin L , Buman M , Ross R . The current state of physical activity assessment tools. Prog Cardiovasc Dis. (2015) ;57: (4):387–95. |
[25] | Kocherginsky M , Huisingh-Scheetz M , Dale W , Lauderdale DS , Waite L . Measuring Physical Activity With Hip Accelerometry Among U. S. Older Adults: How Many Days Are Enough? PloS one. (2017) ;12: (1):e0170082. doi: 10.1371/journal.pone.0170082. |
[26] | O’Donoghue P . Statistics for sport and exercise studies. An introduction. London: Routledge; (2012) . |
[27] | Cohen J . Statistical Power Analysis for the Behavioral Sciences. 2nd ed. Hillsdale. NJ: Lawrence Erlbaum Associates; (1988) . |
[28] | Hansen BH . Physical activity in adults and older people. Levels of objectively measured physical activity in a population-based sample of Norwegian adults and older people (20–85 years). Oslo: Dissertation from the Norwegian School of Sport Sciences; 2013. |
[29] | Hagstrømer M , Sjøstrøm M . Physical activity and inactivity in an adult population assessed by accelerometry. Med Sci Sports Exerc. (2007) ;39: :1502–08. |
[30] | Umukoro PE , Arias OE , Stoffel SD , Hopcia K , Sorensen G , Dennerlein JT . Physical activity at work contributes little to patient care workers’ weekly totals. JOEM. (2013) ;55: :63–8. |
[31] | Reilly JJ , Jackson DM , Montgomery C , Kelly LA , Slater C , Grant S . et al. Total energy expenditure and physical activity in young Scottish children: mixed longitudinal study. The Lancet. (2004) ;363: :211–12. |
[32] | Brasholt M , Chawes B , Kreiner-Møller E , Vahlkvist S , Sinding M , Bisgaard H . Objective assessment of levels and patterns of physical activity in preschool children. J Pediatr Res. (2013) ;74: (3):333–8. |
