During school hours, adolescents spent large amounts of time sitting (≈70%). Although breaking up sitting time using height-adjustable desks have shown positive effects on classroom energy expenditure (EE) among children, however, the impact on adolescents’ health has not yet been reported. The aim of this study was to investigate the effects of height-adjustable desks into classroom, accompanied by messages encouraging breaking-up sitting on adolescents’ body mass index (BMI), waist circumference (WC), EE, and musculoskeletal discomfort.
This quasi-experimental pilot study equipped one classroom in a secondary school with 27 height-adjustable desks and posters displaying information about the impact of break-up sitting on health and how often to break-up sitting while in class. Intervention teachers assisted to a professional development session. Participants included 55 adolescents and their teachers who used the intervention classroom at least 2-5 times/week and 50 adolescents and their teachers who used traditional classrooms. All measurements were taken at three time points: baseline, at 4-weeks and at 17-weeks follow-up. EE (kcal/min) was objectively assessed using a SenseWear activity monitor (Body media, Inc., Pittsburgh). BMI and WC were assessed by trained research staff. Musculoskeletal discomfort was self-reported. Hierarchical linear and multilevel logistic regression mixed models were used to examine intervention effects. All models were adjusted for baseline values, sex and age.
EE was significantly higher at 4-weeks and 17-weeks (29.4 and 37.7 kcal/lesson, respectively), BMI was higher at 4-weeks (0.34 kg/m2), and WC was lower at 4-weeks and 17-weeks (-3.53 and -2.64 cm, respectively) in the intervention compared to the comparison group. No intervention effect was found for musculoskeletal discomfort.
The introduction of height-adjustable desks and supportive prompts in a secondary-school classroom had a beneficial impact on EE during lessons and waist circumference at 4 and 17-weeks relative to a comparison group, and did not negatively impact perceived musculoskeletal discomfort.