590 likes | 688 Vues
The Biannual Fritz Duras Lecture, Dean’s Lecture Series , University of Melbourne July 27, 2010. Standing up for children's health and education: questioning the sedentary nature of classrooms. Professor Jo Salmon Centre for Physical Activity & Nutrition Research (C-PAN), Deakin University.
E N D
The Biannual Fritz Duras Lecture, Dean’s Lecture Series, University of Melbourne July 27, 2010 Standing up for children's health and education: questioning the sedentary nature of classrooms Professor Jo Salmon Centre for Physical Activity & Nutrition Research (C-PAN), Deakin University
Overview • Children’s health in Australia • Sedentary behaviour (or time spent sitting): an alternative perspective • Role of schools & teachers in reducing children’s sitting time
As the pioneer of physical education in Australia & a former physician, Professor Fritz Duras (1896 – 1965) would have some interesting thoughts about current role of schools & education in children’s health in Australia
% Australian children overweight/obese, 2007 % (CSIRO, 2008)
Childhood overweight/obesity: Worldwide trends & 2010 projections % Wang & Lobstein IJPO 2006
Trends in overweight/obesity among children in Australia: 1985-2005 Olds et al IJO 2010
Odds ratios for obesity in young adulthood Whitaker et al, 1997
8.0 Type 2 diabetes 7.0 6.0 5.0 Type 2 diabetes incidence / 100 000 population per year 8.0 4.0 7.0 3.0 Prevalence of obesity (%) Obesity 6.0 2.0 5.0 1.0 1975 1980 1985 1995 1995 Kitagawa T et al. Clin Pediatr 1998 Obesity trends & Type 2 diabetes among children in Japan
Role of energy balance behaviours 30% Health behaviours present the “greatest single domain of influence” on health in the population (McGinnis et al., Health Affairs, 2002) Genetics Social Environ -ment 15% 5% Health Medical care Health Behavior 40% 10%
Energy dense drinks & foods Physical activity Childhood Obesity & metabolic health Genetics Sedentary behaviour
Sedentary behaviour (or time spent sitting): an alternative perspective • word sedentary derives from the Latin verb sedere, meaning to sit • a distinct group of sitting/lying behaviours that involve low energy expenditure to perform (≤1.8 METs) • EG: schoolwork, reading, watching TV, computer use, car travel
Changes in children’s discretionary and non-discretionary time Homework
Median mins/day TV viewing 1949-2000 Marshall et al, 2006
Change in homework time 1981-1997, US Hrs/week Hofferth & Sandberg, 2000
GETTING OUT OF A CHAIR 4 STEPS SITTING STANDING Illustration of SB based on muscular activity Hamilton et al Diabetes 2007
Objectively-assessed sedentary time & health(Sardinha et al Diab Care 2008) HOMA-IR by stratified quartiles of time spent sedentary (Actigraph), p<0.05 between Q1 & Q4 (n=147) Adj for sex, birth weight, pubertal status, fat mass
Mod-to-Vigorous PA Patterns of sedentary time Light Intensity Sedentary (<100 counts per minute) Interruptions or breaks in sustained periods being sedentary Acknowledgement: Genevieve Healy, UQ
Mean accumulated time spent sedentary across school day (Salmon, Healy, Hume, Ridley, Timperio, Dunstan, Owen, Crawford) 48% 51% (p<0.001) • 174±46 mins/day (48% of time) mins SB & light PA : r = -0.78 SB & MVPA: r = -0.55 N=2,452 participants
Mean number sedentary breaks in school day • 33±6 breaks/day • 10-12 yo = 34 breaks/day • 5-6 yo = 31 breaks/day (p<0.001) Breaks & light PA : r = 0.37 Breaks & MVPA: r = -0.06
Associations with BMI z-score • Total sedentary time* 5-6 yo: r = -0.04 (ns) 10-12 yo: r = 0.01 (ns) • Sedentary breaks* 5-6 yo: r = -0.12 (p=0.001) 10-12 yo: r = -0.11 (p<0.001) *partial correlations adj for light & MVPA
p=0.04 p=0.01 Sedentary breaks/day & weight status AOR (light, mvpa) for each additional break 5% less likely ov/ob
Hypothetical1 EE over a 12-hour day for 2 children - both meeting PA recommendations 1PA defined > 3 METs (green line) SB defined as 1.0-1.8 METs (shaded area)
How can we intervene to reduce children’s discretionary & non-discretionary sedentary time? • What are the potential health & educational benefits?
Role of schools & teachers in reducing children’s sitting time & on educational outcomes
Lanningham-Foster et al. Changing the school environment to increase children’s PAObesity 2008 • 3 conditions: • Traditional school • Activity permissive school • Standing classroom
Mahar et alEffects of a classroom-based program on physical activity and on-task behavior. MSSE 2006
Grieco et al. Physically active academic lessons, time on task & BMI. MSSE 2009. Mean % of time on task for the inactive control condition (left) & the active condition (right) for normal weight, at risk & overweight children (n=97)
Liu et al Evaluation of a classroom-based physical activity promoting programme. Obes Rev 2008 • 10-min activity break every day during school class times Hrs/day
Erwin et al Promoting children’s health through physically active math classes. Health Promot Practice Step rate (mean ± SE)during baseline and physical activity (PA) integration math classes Step rate (mean ± SE)during baseline and physical activity (PA) integration school days
Reed et al. Impact of active lessons on fluid intelligence & academic performance. JPAH 2010 • PA integrated into core curricula (~30 mins/day, 3 days/wk, Jan-April 2008) n=155, 9yr olds • Used non-invasive fluid intelligence cognitive measures & State-mandated academic achievement tests • Children in active lessons performed better on Fluid Intelligence Test & on the Social Studies academic achievement test
Summary • Active lessons can: • lead to increased PA across the school day • lead to increased time on task/concentration • lead to better fluid intelligence scores • What about reducing overall sitting time in class? • What about increasing number of interruptions/breaks to sitting in class? • Not just school time important, family setting also key focus
Transform-Us! intervention for reducing sedentary behaviour & promoting physical activity Salmon1, Hume1, Arundell1*, Brown1*, Hesketh1, Daly2, Dunstan3, Ball1, Crawford1, Pearson1, Cerin4, Moodie1, Bagley1*, Chin A Paw5 1Deakin Uni; 2Uni Melb; 3Baker/IDI; 4Hong Kong Uni; 5Vumc Netherlands; *PhD students
Aims • Examine efficacy of 18-mth intervention targeting reductions in SB & increases in PA alone & in combination among 8-9 yr olds compared with current practice • Examine health outcomes, mediators & perform economic evaluation
Participants & design • 20 primary schools (within 50km Melbourne), ~600 children aged 8-9 yrs • All year 3 students in intervention schools will receive the intervention, those with active consent will participate in assessment • 4 groups: • SB-I reducing sedentary (sitting) time at school & home • PA-I increasing PA during school breaks & outside of school hours • SB+PA-I combination of above • C usual curriculum
SB-I: reduce sitting in class • Delivery of 9 key messages/yr • Teachers will modify the delivery of one class lesson per day (30-45 minutes) so children complete the lesson standing (eg, classroom activity stations) • On average, this will result in 150-mins less sitting per week
SB-I: interrupt sitting in class • Interrupt 90-120 min classroom teaching blocks every 30-mins with 2-min guided light-intensity activity break (eg, standing passing ball around while recalling key learning outcomes from current lesson) • Should equate to ~6 mins interrupted sitting time every 2 hrs (~ 60-minutes less sitting time per week)
SB-I: family setting • 8 postcards/yr to parents with tips & key messages for reducing SB at home (eg, effective use of rules) • Homework assignments (eg, switch off TV for weekend) • TV allowance unit
PA-I: environmental cues & prompts • access to PA equipment (recess & lunch breaks) • Line markings • Signage DID YOU KNOW IT TAKES 30 HOPS TO GET TO THE LIBRARY FROM HERE??
PA-I: key messages & active homework • Delivery of 9 key messages/yr • 8 postcards/yr to parents with tips & key messages for encouraging child’s PA at home & in neighbourhood (eg, Kinect Australia website and free Infoline) • Active homework (eg, go for a walk in your street with mum or dad & count the number of letterboxes) • YamaxDigiwalker pedometer
Pilot study • 2009, pilot study to test strategies to reduce children’s sitting time in class & at home • n=124 children, n=6 teachers, n=28 parents • Teachers delivered 2 standing lessons & interrupted sitting over 2-wks & gave 2 homework tasks designed to reduce sitting time & increase PA
Standing lessons Standing homework Walk around Australia • Talking easels Interrupted sitting class time Interrupted sitting homework • Stand & Discuss • Stand & spell/rise & read
Sedentary time in class (mins/day)**Actigraph accelerometer (sed time <100cpm)
Percent of time in sedentary, LPA, MVPA Weeks 1 & 3 during classtime Week 1 Week 3
Children’s perceptions • “When you’re standing, you might fiddle with your legs, and you don’t hear what the teachers say” (Yr 4 child) • “I would like to do more standing lessons because if you sit down for too long you get all ‘blah’ and then you don’t focus as much” (Yr 4 child)
Teachers’ perceptions • “I try to get them …to move …around a bit and stuff, but to do stuff at the standing lesson …it was great fun, it was new for them, so they really enjoyed it.” (Yr 4 teacher) • “they (parents) loved the idea behind it, of getting kids …moving around in class a bit more” (Yr 4 teacher)