Relationships between tibial accelerations and ground reaction forces during walking with load carriage

Area of Science:

• Biomechanics
• Human movement science
• Musculoskeletal health

Background:

• Peak tibial accelerations (TAs) correlate with vertical ground reaction forces (GRFs) during running, a factor in musculoskeletal injury.
• Limited research exists on GRF-TA relationships during walking, especially with added loads, a common military activity.

Purpose of the Study:

• To investigate the associations between ground reaction forces (GRFs) and tibial accelerations (TAs) in U.S. Army trainees walking with heavy loads.
• To compare these relationships to those reported for unloaded walking and running.

Main Methods:

• 649 U.S. Army trainees walked on an instrumented treadmill with an 18.1 kg pack.
• An inertial measurement unit recorded tibial accelerations (TAs) at the distal antero-medial tibia.
• Linear regression analyzed relationships between peak TAs and GRF loading rates/peak forces.

Main Results:

• The strongest correlations were between vertical loading rates and peak vertical TAs (R = 0.43–0.50).
• These relationships were weaker than those previously reported for unloaded walking and running (R > 0.7).
• Other GRF-TA relationships were trivial to small (R = 0.06–0.27).

Conclusions:

• The weaker GRF-TA relationships during loaded walking may stem from methodological variations or altered gait mechanics, such as an extended double-limb support phase.
• Understanding these biomechanical responses is crucial for mitigating injury risk in military personnel performing loaded marches.