Experimental study of seita-fitting

Area of Science:

• Biomechanics
• Human Physiology
• Ergonomics

Background:

• Load carriage is a common activity in military and occupational settings.
• The placement of a load (sacrum vs. lumbar) can influence biomechanical and physiological responses.
• Understanding these differences is crucial for optimizing load-carrying strategies and preventing injury.

Purpose of the Study:

• To compare the physiological and subjective responses to carrying a load on the sacrum (LOS) versus the lumbar vertebrae (LOL).
• To investigate differences in oxygen uptake, muscle activation, heart rate, cadence, and perceived exertion.

Main Methods:

• Nine male participants walked on a treadmill carrying a 40 kg load.
• Load placement was varied between the sacrum (LOS) and lumbar vertebrae (LOL).
• Oxygen uptake, electromyography (EMG) of multiple muscles, heart rate, cadence, and rated perceived exertion were measured.

Main Results:

• Lumbar load carriage (LOL) resulted in significantly higher oxygen uptake, leg muscle activity (tibial anterior, soleus, gastrocnemius), cadence, and perceived exertion compared to sacral load carriage (LOS).
• Erector spinae muscle activity was significantly lower in LOL compared to LOS.
• Sacral load carriage (LOS) led to decreased leg muscle activity, potentially offsetting increased erector spinae activity.

Conclusions:

• Sacral load carriage (LOS) is more metabolically and muscularly efficient than lumbar load carriage (LOL).
• Load placement significantly affects the distribution of muscle activity and overall physiological cost.
• Optimizing load placement can reduce the physical burden during load carriage activities.