ABSTRACT
School children carrying heavy bags are a common phenomenon. The overloading of school bags has aroused the concern of communities in many countries. Reports from Europe and Asia have found that many students carry weights that are more than 10%, and in some cases even up to 20%, of their body weight (Sander, 1979; HKSCHD, 1988). However, compared with extensive studies on physiological and biomechanical responses to load carriage in adults, investigations on the influence of load carriage on growth and development in children are limited. Malhotra and Sen Gupta (1965) examined the metabolic cost to children associated with different ways of carrying schoolbags while walking. Pascoe et ale (1995) studied the kinematic impact on children's static postures and gait of walking under four different conditions: without a load; carrying a book bag weighing 17% of mean body weight in the form of a one-strap backpack; carrying the same load in a twostrap backpack; and carrying the load in a one-strap athletic bag. The one-strap backpack induced significant elevation of the strap-supporting shoulder and concomitant lateral bending of the spine. Hong et al. (1998) investigated the energy expenditure of children walking under four different load conditions-at 0%, 10%, 15%, and 20% of their body weight. The results showed that walking for 20 minutes under 15% and 20% load conditions produced significantly higher physiological strain than those measured under 0% and 10% load conditions. Recently, Hong and Brueggemann (2000) reported changes of gait patterns in tenyear-old boys carrying school bags of 0%, 10%, 15%, and 20% of their body weight while walking on a treadmill for 20 minutes. They found that the 20% load condition induced a significant increase in trunk forward lean, double support, and
stance duration, as well as decreased trunk angular motion and swing duration; and the 15% load condition induced a significant increase in trunk forward lean.
