Can a Marine march all day carrying a heavy load still perform basic mission requirements effectively?

The Load Carriage Study tested more than two dozen Marines over a period of several months. Each Marine was tested over three days, carrying a different load each day, and performing a series of mental tasks projected on a screen in front of them. Day 1 - for baseline testing, march at two miles per hour for two one-hour periods carrying no weight. Day 2 - carry 98 pounds of equipment during the march. Day 3 - increase the load to 135 pounds.

While marching, changes in physiological conditions were checked and recorded, eye-tracking equipment monitored where on the screen they were looking, and mental condition was assessed when performing the tasks.

Tasks included:

• Identify hostile versus non-hostile targets in an urban environment
• Memorize and recall items in a photograph of random objects
• Memorize and recall a series of common orders
• Memorize and recall mission-critical map directions