The Airborne Shuffle, Why Faster Isn't Always Better When Rucking with a Heavy Pack

Alastair Hunt
15 hours ago
4 min read

If you've ever tried jogging with a heavy backpack, you've probably noticed your gait change instinctively into something shuffling and awkward. In the military, this movement has a name: the Airborne Shuffle. It's described as a slow jog with short, shuffled steps and less vertical lift of the feet than a normal jog. Soldiers sometimes adopt it when they need to move quickly under load but can't sustain a full run.

Researchers at Middle Tennessee State University wanted to find out whether this shuffle is actually a smart way to move quickly under load, or whether it costs more than it saves.

What the Study Did

Twenty male Army ROTC cadets walked and shuffled on a treadmill at three speeds (2.5, 3.0, and 3.5 mph) while carrying a combined load of 65 lbs, made up of a weighted vest simulating body armour and a fully packed rucksack.

Researchers measured oxygen consumption, heart rate, respiratory exchange ratio (RER, a marker of fuel use), and stride length for each gait at each speed. Testing was conducted on separate days to prevent fatigue from skewing results, and the order of conditions was randomised to reduce bias.

What They Found

At every speed tested, the airborne shuffle was significantly more demanding than standard walking. Oxygen consumption, heart rate, and RER were all measurably higher during the shuffle. Stride length was shorter too, meaning cadets took more steps to cover the same distance. These differences were statistically robust and consistent across all three speeds, suggesting the pattern holds regardless of how fast you're moving within this range.

The researchers identified two likely culprits for the increased physiological cost.

First, shorter strides tend to increase aerobic demand. There is an optimal stride length for any given speed, and departing significantly from it in either direction costs extra energy.
Second, video analysis suggested the shuffle also involved greater vertical displacement, meaning more up-and-down bounce with each step.

Both factors together drive up the physiological cost considerably. Research on runners confirms this: those who run with exaggerated vertical bounce consistently show higher oxygen uptake than those who move more horizontally efficiently.

The RER findings are particularly telling. RER is a ratio that reflects which fuel the body is primarily burning. An RER approaching 1.0 indicates the body is leaning heavily on carbohydrates rather than fat. Since carbohydrate stores (glycogen) are limited, burning through them quickly brings on fatigue sooner. The shuffle produced consistently higher RER values at all speeds, and the gap was most pronounced at 3.5 mph, where walking produced an RER of 0.87 compared to 0.93 during the shuffle.

Over a long march, that difference in fuel burning could meaningfully shorten how long a person can keep going before hitting the wall.

Interestingly, cadets didn't always perceive the shuffle as harder, despite the measurable physiological cost. This perception gap is worth noting: physical effort isn't always a reliable guide to actual energy expenditure. You can feel like you're coping while your body is quietly burning through reserves faster than you realise.

The study does have limitations worth acknowledging. The sample was small, exclusively male, and restricted to trained military cadets, so results may not translate directly to all populations. The speeds tested were also relatively modest, and it remains unclear how the findings would change at higher paces.

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

Most of us aren't marching in full combat kit, but the core lesson applies directly to anyone who rucks, hikes, or carries a loaded pack. If you want to go faster, prioritise maintaining a steady, longer stride rather than shuffling your steps. Bouncing upward and shortening your stride both waste energy that you'll need later.

When covering long distances under load, walking with good posture and an efficient stride consistently outperforms a hurried shuffle. Pace yourself deliberately, move smoothly, and resist the temptation to speed up in a way that costs you far more than the time you gain. Save energy early, and you'll have more left when it counts most.

How do you like to increase pace during a ruck or tab? I find that the airborne shuffle keeps my legs fresh over longer distances, using different muscles than striding out the distance. And I also have my fueling and hydration dialled-in for longer, harder events - to support the increased effort.

Wherever you are: train safe and enjoy the process!

Alastair

LinkedIn, Community, Articles and More

Related resources & research

The study in question...

Brenes AN, Caputo JL, Clark C, Wehrly LE, Coons JM. Comparisons of the airborne shuffle to standard walking while torso loaded. J Strength Cond Res. 2015 Jun;29(6):1622-6. doi: 10.1519/JSC.0000000000000801. PMID: 26010797.

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.

Orr R, Pope R, Lopes TJA, Leyk D, Blacker S, Bustillo-Aguirre BS, Knapik JJ. Soldier Load Carriage, Injuries, Rehabilitation and Physical Conditioning: An International Approach. Int J Environ Res Public Health. 2021 Apr 11;18(8):4010. doi: 10.3390/ijerph18084010. PMID: 33920426; PMCID: PMC8069713.

Godhe M, Helge T, Mattsson CM, Ekblom Ö, Ekblom B. Physiological Factors of Importance for Load Carriage in Experienced and Inexperienced Men and Women. Mil Med. 2020 Aug 14;185(7-8):e1168-e1174. doi: 10.1093/milmed/usaa050. PMID: 32248224.

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.