بررسي پاسخ هاي ضربان قلب، اكسيژن مصرفي (vo2) و هزينه انرژي دانش آموزان هنگام حمل كوله پشتي هاي مدرسه اي

The examine of heart rate, V02 and energy expenditure responses of students carrying school backpacks

The purpose of this study was to examine of heart rate, V02 and energy expenditure responses to carrying school backpacks in students aged 12-13 years. The fifteen boysʹ students (mean height of 164.7 ± 1.8 em and mean weight of 55 ± 1.6 kg) volunteered to participate in this study. All subjects carried backpacks of 0, 8, 10.5 and 13 % of their own body weights, randomly in different days on treadmill at 3.9 km.hʹ for 15 min. Heart rate (HR), energy expenditure (EE) and oxygen consumption (VO,) of subjects were measured by Gas Analyzer System, in each of carriage test, in 3 positions: rest, exercise (15 min walking) and recovery (3 min after walking). The results indicated that EE and VO, during and 3 min after carrying backpacks equal to 10.5 & 13 % body weight were significantly higher than in 8 % body weight load condition (p ~ 0.000). Also, these parameters, 3 min after carrying 8 % body weight backpack, were recovered to near to rest levels(p > 0.05), but, 3 min after carrying backpacks of 10.5 & 13 % body weight were significantly higher than rest basal levels(p ~ 0.000). There were no significant differences between 0 and 8 % body weight load conditions, in both, during and 3 min after load carriage in these variables (p > 0.05). Thus, a load equal to 8% body weight can be recommended as optimal backpack weight for carrying by adolescent students.