Backpack load limit recommendation for middle school students based on physiological and psychophysical measurements

Area of Science:

• Biomechanics and Ergonomics
• Pediatric Health and Safety

Background:

• Student backpack loads are a growing concern for child safety and well-being.
• Previous research has not definitively established safe backpack weight limits for adolescents.

Purpose of the Study:

• To determine an acceptable backpack load limit for middle school students.
• To investigate the effects of backpack load on physiological and biomechanical markers.

Main Methods:

• Utilized electromyography (EMG), posture analysis, heart rate monitoring, and perceived exertion/pain ratings.
• Subjects (n=20, ages 11-14) carried incremental backpack loads (0-20% body mass) during stationary and walking trials.
• Assessed physiological and biomechanical responses at each 5% body mass increment.

Main Results:

• Trunk flexion angle and Borg-CR10 ratings significantly increased between 10% and 15% body mass during walking.
• No significant differences were observed in these metrics between 0% and 10% body mass.
• These findings suggest a potential load limit around 10% body mass.

Conclusions:

• A backpack load limit of 10% body mass is recommended for middle school students.
• This limit is supported by biomechanical and subjective measures indicating increased strain beyond this threshold.
• Further research can refine guidelines for safe student backpack carriage.