Total daily energy expenditure and pattern of physical activity measured by minute-by-minute heart rate monitoring in 14-15 year old Swedish adolescents

Objective: To assess total daily energy expenditure (TDEE) and patterns of physical activity among Swedish male and female adolescents and to relate the amount and intensity of physical activity to existing recommendations (energy expenditure equal to or above 12.4 kJ/kg/day or accumulation of 30 min/day in moderate physical activity equal to 4.5 rimes sedentary energy expenditure or more). Design: TDEE, physical activity level (PAL = TDEE/BMR), energy expenditure (EE) and time spent in different intensities of physical activity were assessed by using minute-by-minute heart rate monitoring in combination with laboratory measured sedentary energy expenditure (SEE) and peak oxygen uptake. Setting: Department of Physical Education and Health, Orebro University, and Department of Clinical Physiology, Orebro Medical Centre Hospital, Sweden. Subjects: Eighty-two 14-15 y old adolescents (42 boys, 40 girls) from the city of Orebro, randomly selected through a two-stage sampling procedure. Results: TDEE was 12.8 MJ/day and 10.0 MJ/day for boys and girls respectively (P < 0.001) and PAL was 1.74 and 1.67 (NS). Forty-four percent and 47%, respectively, of TDEE referred to EE in physical activity, of which 70% for both genders referred to light physical activity (corresponding to < 4.5 times SEE). Eleven boys and 14 girls had an EE lower than 12.3 kJ/kg/day and/or did not accumulate 30 min/day in physical activity greater than or equal to 4.5 SEE. Those (n = 20) with the highest PAL values (> 2.01 and 1.81, respectively) spent 149 min/day at a greater than or equal to 4.5 SEE intensity level compared to 40 min/day for those (n = 30) with the lowest PAL values (< 1.55 and 1.45, respectively). Conclusions: Swedish adolescent boys and girls are similarly physically active. The major amount of rime devoted to physical activity refers to light physical activity. At least thirty percent of adolescents seem not to achieve appropriate levels of physical activity considered to be beneficial for health.