Cognitive performance of military men and women during prolonged load carriage

Background: This study evaluated cognitive workload in soldiers undertaking a long duration march wearing different loads.

Methods: Military Participants (n=12 men and n=10 women) performed four 3-hour loaded marches (12.25km at 4.9km·h-1) wearing either 21kg, 26kg, 33kg or 43kg. Accuracy and response times were measured whilst marching using verbal working memory n-back test (0, 1, 2 and 3) and two bespoke Go/No Go tests (visual / auditory) to assess inhibition of a pre-potent response.

Results: The physical demands of the march increased with load and march duration but remained at moderate intensity. N-back accuracy ranged from 74 to 98% in men and 62 to 98% in women. Reduced accuracy was observed as load and time increased. Accuracy during the visual Go/No Go also reduced with load, accuracy ranged from 69 to 89% in men and 65 to 90% in women. No differences due to load or time were observed during completion of the auditory Go/No Go task; accuracy ranged from 93 to 97% in men and 77 to 95% in women. A number of participants were unable to complete the march due to discomfort. Women reported increased discomfort, which may have contributed to the greater reductions in accuracy observed.

Conclusion: These data provide further evidence that cognitive performance of military personnel can be affected during long duration loaded marching. Women reported increased discomfort from equipment, which may make them more susceptible to declines in cognitive performance. These findings highlight important considerations for equipment procurement.