Percentage Change in Reaction Time Can Predict Respiratory Quotient during Light Weight Schoolbag Carriage

Abstract

While structured physical activity improves cardio-pulmonary parameters and Reaction Time (RT), heavy weight schoolbag carriage is detrimental. Schoolbag carriage may have either consequence. The purpose of this study is to explore the consequences of heavy and light weighing schoolbags on cardio-pulmonary parameters and RT. Healthy male participants (10-15 years) carrying schoolbags- 0%, 4%, 8%, 12%, 16% load of bodyweight walked (20-minutes) for 5 times each. For each of the 30 participants, during walks, COSMED k4b2 measured heart rate (HR), respiratory quotient (R), total energy expenditure (EEtot) and number of steps taken. Ruler-drop-test marked RT before and after each walk. RT improved after walking with schoolbags weighing 0%, 4% of bodyweight. RT didn’t improve for 8%, 12% carriage, worsened for 16% load carriage. HR and EEtot showed proportionality (r=0.24, p<0.05), R correlated positively to percentage change in RT (r=0.24, p<0.05) and inversely to number of steps taken (r=-0.40, p<0.01). Percentage change in RT could significantly predict R (R=1.223+0.028(Percentage RT change)). Respiratory quotient can predict whether or not reaction time worsens for 20-minutes schoolbag carriage as per Receiver Operating Characteristic (ROC) curve (Area Under Curve (AUC)=0.668, 95% confidence interval: 0.558-0.779, p<0.01). Carrying light-weight schoolbags (4% of bodyweight) for 20-minutes is beneficial, but heavy-backpack carriage effectuates adverse cardio-pulmonary response and higher RT.