Habitual Physical Activity in Children and Adolescents during School and Free Days OLIVIER GAVARRY, MAGALI GIACOMONI, THIERRY BERNARD, MARC SEYMAT, and GUY FALGAIRETTE Unite ´ d’Ergonomie Sportive et Performance, Universite ´ de Toulon et du Var, La Garde, FRANCE ABSTRACT GAVARRY, O., M. GIACOMONI, T. BERNARD, M. SEYMAT, and G. FALGAIRETTE. Habitual Physical Activity in Children and Adolescents during School and Free Days. Med. Sci. Sports Exerc., Vol. 35, No. 3, pp. 525–531 2003. Purpose: The purpose of this study was to analyze habitual physical activity (HPA) of boys and girls from primary school to high school. Methods: One hundred eighty-two schoolchildren and teenagers (6 –20 yr) were studied at primary school (PS, N = 64), junior high school (JHS, N = 67), and senior high school (SHS, N = 51). HR was continuously monitored during the whole week to assess HPA during school days and free days. Total physical activity (TPA), low physical activity (LPA), moderate physical activity (MPA), and vigorous physical activity (VPA) were evaluated from the time spent each day above 50%HR reserve (HRR), below 50%HRR, between 50% and 70%HRR, and above 70%HRR, respectively. Results: During school days, TPA decreased by 69% in male subjects (P  0.05) and by 36% in female subjects (P = 0.058) from PS to SHS. In contrast, TPA did not vary significantly during free days (male subjects, PS: 62  37 min·d -1 , SHS: 63  67 min·d -1 ; female subjects, PS: 75  59 min·d -1 , SHS: 62  44 min·d -1 ). Gender differences were only observed during school days at PS for TPA (male subjects: 121  37 min·d -1 vs female subjects: 92  44 min·d -1 , P  0.05) and VPA (male subjects: 38  21 min·d -1 vs female subjects: 18  12 min·d -1 , P  0.05). Male and female subjects were more inactive during free days than during school days at PS (P  0.05). No effect of the type of day and gender was observed for all indices of HPA at high schools. Conclusions: Our results highlight the importance of taking into account the type of day (school day vs free day) in the analysis of children and adolescents’ HPA. Key Words: HEART RATE MONITORING, SCHOOLCHILDREN, TEENAGERS, SCHOOLING I n our urban community, the rapid evolution in the way of life has induced some sociocultural changes affecting the level of habitual physical activity (HPA). The in- crease in the prevalence of cardiovascular diseases, obesity, hypertension, diabetes, osteoporosis, and stress is partly linked to the reduction in physical activity. Epidemiologists have been interested in assessing HPA not only in adults but also in children. An objective measure of physical activity is necessary in understanding the amount of exercise recom- mended for reducing harmful risk to health. Many methods have been used to estimate HPA such as the assessment of movement (pedometry and accelerometry techniques), the measurement of physiological responses (respiratory gas exchange, isotope dilution technique, and HR monitoring), and the analysis of behavior (observation, diary, question- naire, and interview). Criteria for reliability and validity as well as advantages and disadvantages of using these meth- ods have been reviewed elsewhere (17). In cross-sectional studies involving wide age span, the use of reliable methods for assessing physical activity is needed, as ability of children to recall activity may vary across ages. HR monitoring using short-range radio telem- etry has been described as an effective tool for field re- search. This method, used to determine daily energy expen- diture (16), has been generally applied to calculate the time during which a subject was considered physically active (2,3,9,10,13,25,28). Studies using HR monitoring have reported a decrease in HPA during childhood and adolescence (13,22,26). How- ever, in such studies, identifying the ages when greatest decline in HPA appears remains difficult in both male and female subjects. As stated by Sallis (22), such evaluation “may be useful in targeting interventions to critical periods of life.” Comparison of HPA between boys and girls has lead to conflicting results in the literature. Some studies have reported that boys were more active than girls (2,9,10,14,32), whereas others did not find any gender dif- ferences (21,25). A major limitation of studies using HR monitoring is that they were based on a single day assess- ment and certainly did not reflect children’s HPA. The duration of HR monitoring has questionable validity in HPA determination. In this regard, Durant et al. (5) have demon- strated that 4 d of HR monitoring were necessary to obtain a reliability coefficient of 0.80. Similar findings were re- ported in children by Trost et al. (31) using uniaxial accel- erometer monitoring, but for adolescents the duration was longer (8 d). Taylor and Sallis (30) examined the determinants of physical activity in children and proposed several recom- mendations for future research. One of them was to take into account the different settings where children engage in Address for correspondence: Olivier Gavarry, U.F.R. S.T.A.P.S., Univer- site ´ de Toulon et du Var, Avenue de L’Universite ´, B.P. 132, 83 957 La Garde Cedex France; E-mail: gavarry@univ-tln.fr. Submitted for publication October 2000. Accepted for publication October 2002. 0195-9131/03/3503-0525/$3.00/0 MEDICINE & SCIENCE IN SPORTS & EXERCISE ® Copyright © 2003 by the American College of Sports Medicine DOI: 10.1249/01.MSS.0000053655.45022.C5 525