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 (12.25 km at 4.9 km/hour) wearing either 21 kg, 26 kg, 33 kg or 43 kg. During the march, accuracy and response time were measured using the 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 test 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 test 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. Reports of discomfort were more frequent in women, 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 discomfort from equipment more frequently than men, which may make them more susceptible to declines in cognitive performance. These findings highlight important considerations for equipment procurement.

Building a transdisciplinary expert consensus on the cognitive drivers of performance under pressure: An international multi-panel Delphi study

Introduction

The ability to perform optimally under pressure is critical across many occupations, including the military, first responders, and competitive sport. Despite recognition that such performance depends on a range of cognitive factors, how common these factors are across performance domains remains unclear. The current study sought to integrate existing knowledge in the performance field in the form of a transdisciplinary expert consensus on the cognitive mechanisms that underlie performance under pressure.

Methods

International experts were recruited from four performance domains [(i) Defense; (ii) Competitive Sport; (iii) Civilian High-stakes; and (iv) Performance Neuroscience]. Experts rated constructs from the Research Domain Criteria (RDoC) framework (and several expert-suggested constructs) across successive rounds, until all constructs reached consensus for inclusion or were eliminated. Finally, included constructs were ranked for their relative importance.

Results

Sixty-eight experts completed the first Delphi round, with 94% of experts retained by the end of the Delphi process. The following 10 constructs reached consensus across all four panels (in order of overall ranking): (1) Attention; (2) Cognitive Control-Performance Monitoring; (3) Arousal and Regulatory Systems-Arousal; (4) Cognitive Control-Goal Selection, Updating, Representation, and Maintenance; (5) Cognitive Control-Response Selection and Inhibition/Suppression; (6) Working memory-Flexible Updating; (7) Working memory-Active Maintenance; (8) Perception and Understanding of Self-Self-knowledge; (9) Working memory-Interference Control, and (10) Expert-suggested-Shifting.

Discussion

Our results identify a set of transdisciplinary neuroscience-informed constructs, validated through expert consensus. This expert consensus is critical to standardizing cognitive assessment and informing mechanism-targeted interventions in the broader field of human performance optimization.

Testing the Effects of 3D Multiple Object Tracking Training on Near, Mid and Far Transfer

Cognitive training (CT) aims to develop domain general mental abilities to support functions like decision making, multitasking, and performance under pressure. Research to date has indicated that CT likely aids performance on lab-based cognitive tests, but there has been little demonstration of transfer to tasks representative of real-world high performance environments. This study aimed to assess transfer from a CT intervention to near and mid-level transfer tasks, plus a far transfer test representative of real-world multitasking in a military environment. 84 participants were randomized to four independent training groups, using NeuroTracker, a CT task based on 3D object tracking. There was no evidence for near transfer (to another object tracking task) or for far transfer to a route monitoring task designed to replicate real-world multitasking. There may, however, have been some improvement in working memory performance as a result of training. These findings raise further questions about whether domain general CT will transfer to real-world performance. Effective uses of CT may require more task specific training targeting mid-level transfer effects.

Caffeine effects on physical and cognitive performance during sustained operations

PURPOSE

This study examined caffeine (CAF) effects on physical performance and vigilance during 4 d and 3 nights of sustained operations in Special Forces personnel.

METHODS

There were 20 soldiers (28.6 +/- 4.7 yr, 177.6 +/- 7.5 cm, 81.2 +/- 8.0 kg) who were divided equally into placebo (PLAC) and CAF groups. A 4-km run that included three obstacles (OBST) was completed each morning with the performance on Day 2 representing control (CON) after familiarization on Day 1 and an 8-h sleep. From 01:30 to 06:15 of Days 3-5, soldiers performed two 2-h vigilance (VIG) sessions in the field. PLAC or 200 mg of CAF was administered at 21:45 of Days 2-4 and at 01:00, 03:45, and approximately 07:00 on Days 3-5. The run commenced within 30 min of the final dose. Soldiers were provided a 4-h sleep period from 13:30-17:30 during Days 3 and 4.

RESULTS

VIC during Days 3-5 was greater for CAF vs. PLAC and not different from CON. Total run time was faster for CAF (29.7 +/- 2.0 min) compared with PLAC (30.7 +/- 2.9 min) on Day 3 due to faster completion of OBST (8.7 +/- 0.7 min vs. 9.2 +/- 1.0 min for CAF and PLAC, respectively). Thereafter, run times decreased for both groups on Days 4 and 5 compared with CON due primarily to an increased pace between OBST.

CONCLUSIONS

it was concluded that CAF maintained both vigilance and physical performance during sustained operations that require periods of overnight wakefulness and restricted opportunities for daytime sleep.