How Rucking Affects Mental Performance, Maintaining Awareness While Training
- Alastair Hunt
- 2 days ago
- 5 min read
Updated: 2 hours ago
Most people preparing for a long ruck focus entirely on the physical side: legs, lungs, load. Few think about what happens to their mind during hours of marching under weight. The research is clear that cognitive performance deteriorates meaningfully during prolonged load carriage, and this has real consequences for navigation, decision-making and safety.
As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies / resources at bottom of page.
The problem
Multiple studies now confirm that carrying a loaded pack while walking for extended periods degrades cognitive performance in ways that unloaded exercise does not. In one study, soldiers walked for two hours carrying a 40kg load while performing cognitive tasks measuring response inhibition and visual target detection. Performance on the inhibition task, which requires the brain to override an automatic response, declined significantly in the loaded condition compared to the unloaded condition, particularly between 45 and 65 minutes into the march. Participants carrying the load were more likely to respond incorrectly, had slower reaction times and showed a measurable shift in their decision-making threshold toward impulsive responses.
A separate study of soldiers undertaking three-hour loaded marches found the same pattern across working memory and response inhibition tasks, with accuracy declining as both load and time increased. The effects began appearing at loads as light as 21kg and worsened progressively across the march.
The mechanism behind this is well established. Exercise increases physiological arousal, which improves cognitive performance up to a moderate level. Beyond that level, as physical demand pushes harder, the brain begins to divert resources away from higher-level cognitive processes toward the motor and sensory systems needed to sustain movement. The prefrontal cortex, which governs decision-making, inhibition and working memory, is the first to be deprioritised. The result is a measurable decline in exactly the cognitive functions most needed during a long event.
Fitness level matters here. Research has found that individuals with higher aerobic capacity show smaller cognitive decrements during loaded exercise than those with lower fitness, providing yet another argument to develop aerobic fitness in general training for rucking.
The risk is highest in the later stages
Both studies found that cognitive decline under load was most pronounced in the second hour of sustained effort, and continued to accumulate over time. The risk is highest in the later stages of a long event, exactly when fatigue, heat and dehydration are also building. Attention narrows. Working memory shrinks. Reaction times slow. Decision-making becomes less reliable at precisely the moment when good decisions matter most.
Importantly, one study found that even when participants recovered some physiological capacity during a less demanding second-hour phase, their cognitive performance did not recover in parallel. Physical recovery and cognitive recovery are not the same thing. Your body may feel slightly better at a rest stop. Your brain may still be operating below its normal capacity.
A hidden contributor: Discomfort
One finding deserves particular attention. Discomfort from equipment, ill-fitting pack straps, developing blisters and pressure points, was found to directly reduce cognitive performance independently of physical fatigue. Participants managing discomfort showed worse cognitive accuracy than those who were equally tired but physically comfortable.
The mechanism is simple. Managing pain consumes mental resources. Every kilometre spent thinking about a worsening blister or a cutting shoulder strap is a kilometre with less attention available for navigation, pacing and self-monitoring.
Heat, hydration and fueling compound the problem
Three additional factors accelerate cognitive decline during a long ruck.
Rising core temperature independently impairs attention and decision-making, meaning hot and humid conditions produce a faster and earlier cognitive decline than cooler environments.
Dehydration reduces blood flow to the brain alongside the muscles, impairing concentration even before physical symptoms appear.
And the substantial energy deficit that builds during a long march, since few people can eat enough to keep pace with what they burn, leaves less fuel available for the brain precisely when mental demands are highest.
This creates an important safety distinction. Confusion or disorientation late in an event is not always simple mental fatigue. It can be an early sign of hyponatraemia, dangerously low blood sodium from overdrinking, which shares many of the same symptoms. Anyone showing confusion after consuming large volumes of fluid should be treated as a possible medical concern, not simply encouraged to push through.
Symptoms to watch for
In yourself or others on a long march, watch for: difficulty concentrating on simple tasks, slower decision-making, increased impulsivity or errors that would normally be avoided, irritability or uncharacteristic behaviour, missed turns or navigation errors, and an inability to perform basic mental tasks that would normally be effortless.
These are early signs that cognitive capacity is being compromised, often well before physical collapse becomes apparent.
If you are training for the PARAS'10, a Norwegian Foot March, or just to get fast and fit, our self-paced online course"Built to Ruck The Science and Practice of Rucking" covers everything the research tells us about load carriage training, pacing, progression, heat management, hydration, fueling and more. It is built for ruckers at every level of experience, and draws directly on the peer-reviewed military and sports science research.
What This Means for Us
Experience matters. Research found that participants with more load carriage experience showed smaller cognitive decrements than less experienced participants, likely because familiarity with discomfort and pack management frees up mental resources that novices spend on simply coping.
Beyond experience, the most effective strategy is reducing the number of active decisions required during the hardest stretch of the event. Know your route in advance. Plan your fuelling and hydration schedule so it does not require decision-making mid-march. Use heart rate rather than ongoing calculation to judge pace. Address equipment discomfort immediately rather than tolerating it. I also like to play mental exercises while rucking, identifying upcoming landmarks - where to expect them, calculating alternate route options, where the nearest services are etc etc. Anything to meaningfully stimulate the brain and support the session.
The later hours of a long ruck are not just physically demanding. They are when your mind is least equipped to handle complexity. Planning for that in advance, rather than relying on willpower in the moment, is what separates good preparation from hope.
Wherever you are: train safe and enjoy the process!
Alastair
Key Studies
Armstrong NC, Smith SJR, Risius D, Doyle D, Wardle SL, Greeves JP, House JR, Tipton M, Lomax M. Cognitive performance of military men and women during prolonged load carriage. BMJ Mil Health. 2023 Feb;169(1):37-45. doi: 10.1136/bmjmilitary-2021-002000. Epub 2022 Apr 7. PMID: 35393357; PMCID: PMC9887367.
Martin K, Périard J, Rattray B, Pyne DB. Physiological Factors Which Influence Cognitive Performance in Military Personnel. Hum Factors. 2020 Feb;62(1):93-123. doi: 10.1177/0018720819841757. Epub 2019 Apr 22. PMID: 31009241.
Eddy MD, Hasselquist L, Giles G, Hayes JF, Howe J, Rourke J, Coyne M, O'Donovan M, Batty J, Brunyé TT, Mahoney CR. The Effects of Load Carriage and Physical Fatigue on Cognitive Performance. PLoS One. 2015 Jul 8;10(7):e0130817. doi: 10.1371/journal.pone.0130817. PMID: 26154515; PMCID: PMC4496096.
Other
Oeschger R, Roos L, Wyss T, Buller MJ, Veenstra BJ, Gilgen-Ammann R. Influence of Soldiers' Cardiorespiratory Fitness on Physiological Responses and Dropouts During a Loaded Long-distance March. Mil Med. 2022 Jan 7;188(7-8):e1903–9. doi: 10.1093/milmed/usab540. Epub ahead of print. PMID: 35015894; PMCID: PMC10363014.
Faghy MA, Shei RJ, Armstrong NCD, White M, Lomax M. Physiological impact of load carriage exercise: Current understanding and future research directions. Physiol Rep. 2022 Nov;10(21):e15502. doi: 10.14814/phy2.15502. PMID: 36324291; PMCID: PMC9630762.
Hunt AP, Billing DC, Patterson MJ, Caldwell JN. Heat strain during military training activities: The dilemma of balancing force protection and operational capability. Temperature (Austin). 2016 Feb 26;3(2):307-317. doi: 10.1080/23328940.2016.1156801. PMID: 27857960; PMCID: PMC4965006.