Key Takeaway
Comprehensive review of load carriage research finds that carrying external loads alters gait biomechanics, increases metabolic demand proportionally to load, and recommends managing intensity around 45% VO2max for sustained performance.
Summary
This narrative review examined the physiological and biomechanical factors that affect load carriage performance, with a focus on military applications where soldiers routinely carry heavy equipment during training and operations.
The review synthesized evidence on how load weight, speed of movement, load placement, body armor, and environmental conditions influence energy expenditure, gait mechanics, and fatigue during loaded walking. The authors introduced the "Load-Speed Index" as a framework for understanding the interaction between carried weight and movement speed.
Key findings showed that heavier loads increase trunk and lower limb flexion, alter stride mechanics, elevate metabolic cost, and increase injury risk. The literature recommends maintaining exercise intensity at approximately 45% VO2max during prolonged load carriage to delay fatigue. These principles apply broadly to any form of loaded carrying, from military rucking to farmer's walks and everyday carrying tasks.
Methods
- Narrative review of load carriage literature
- PubMed and military research databases searched
- Studies on load weight, speed, placement, and environment included
- Physiological and biomechanical outcomes analyzed
- Load-Speed Index framework developed
Key Results
- Heavier loads increase trunk and knee flexion during gait
- Metabolic cost rises proportionally with load carried
- Load placement affects energy expenditure and balance
- ~45% VO2max recommended for sustained load carriage
- Body armor adds significant physiological burden
- Environmental heat compounds load carriage stress
Limitations
- Narrative review (not systematic)
- Primarily military-focused populations
- Most studies use backpack-style loads, not hand-held carries
- Limited data on training adaptations over time
- Few studies on female participants