What to expect this week:

It’s rare for a species to have the ability to grasp, let alone the ability to carry heavy loads - let alone to carry those heavy loads for long distances. We are one of those species.

We’ve devised tools, like backpacks, to load our bodies with even more weight than our hands alone can hold. In the past, this was essential because we were nomadic. We had to carry our all of resources because we had no place to store them. Today, doing the same thing can be a great form of exercise.

Mainly inspired by military conditioning, people are adopting rucking as a form of physical activity. Rucking is simply putting on a weighted vest or loaded backpack and taking that thing for a long walk. It’s this beautiful form of resistance training combined with endurance - working both your musculoskeletal and cardiovascular systems.

This week’s video is on this unique capacity for humans to carry, especially over long distances, and how it can be implemented in the modern world to improve our fitness.

House Keeping:

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  1. A summary of my philosophy on exercise that’s grounded in my research into human exercise and my experience training Brazilian Jiu-Jitsu.

  2. A 7-day exercise protocol consisting of the main forms of physical activity which I would deem to be non-negotiables - aerobic, anaerobic, resistance training, and play.

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Rucking: Why Carrying is Important and How it Makes Us Unique

Our hands are arguably our most useful tools. The food we cook, the technology we use, and the vehicles we drive all depend on our ability to grasp and manipulate the world around us. Most other primates have hands with opposable thumbs that can grab things like branches and sticks, but we can grip with precision. It’s primarily our fine motor skills that separate our hands from those of our primate relatives. 

That being said, our gross motor skills also differ from those of monkeys and apes. Whereas their arboreal environments call for hanging and swinging, our terrestrial environments call for carrying. 

An often overlooked aspect of human evolution is our ability to carry. Like walking, it is such a subconscious thing we do in our everyday lives, that we often take it for granted. Carrying our phones and groceries takes such little brain power, but is so valuable. We’ve even built tools to help us carry things independently of our freed hands.

Let’s take a look at the role that carrying played in human evolution, and how this unique power can be used today to improve our health and fitness.

Human Carrying is Unique

The origins of carrying are far more ancient than you may have known. The first primates came into existence around 55 million years ago and it’s believed that by this point infants were being carried by their parents [1]. 

Like modern-day primates, these infants would likely cling onto their mother’s back or stomach as they roamed the forest. Presumably, both mother and child developed adaptations to improve the energetic efficiency of carrying and being carried. One could make the argument, then, that the origin of resistance training is marked by this 55 million-year-old tradition.

Fast forward to today and we see that the trait for carrying infants has been conserved in all primate lineages [2]. However, beginning around 4 million years ago, there was an evolutionary shift in human infants, which had downstream effects on carrying.

Human infants are vastly more altricial. This means that human mothers give birth to less mature babies who take longer to become independent. Just compare a baby deer walking immediately out of the womb to a baby human who can’t walk for the first 15 months of their life. A human’s child is relatively meek compared to that of a chimpanzee, requiring more attention and care from their parents.  

Why humans? Because our bigger brains need more time to mature. Giving birth to live young, a mother would be hard-pressed to push out an infant with a skull that’s big enough to support an adult-sized human brain. Humans solved this problem by giving birth to less mature babies whose brains were smaller and less developed, leaving a greater percentage of that maturation period outside of the womb, post-natally The result is an infant who requires being carried for a longer period and a mother (or father) who has the strength and endurance to do so.

Walking on two feet also affected our carrying abilities. One study comparing the upright posture of the Homo lineage to the more bent posture of our predecessors (like the australopithecines) suggests that ours is more energetically efficient for carrying [3].

This shift to bipedalism freed our hands, allowing us to carry infants in various new ways.

One obvious difference between humans and other primates is that we can hold infants directly in our arms without obstructing our locomotion too much. Another is that we use those hands to construct tools for carrying our infants. Ethnographic studies of traditional cultures show that people create satchels to carry infants on their fronts, sides, and backs [4]. With the help of our hands and a hint of inventiveness, we became the primate version of a kangaroo. 

With the advent of bipedalism, our hands were freed from locomotion, and we could use them to carry children. With the advent of technology, our hands were further freed from carrying children, allowing us to do so while simultaneously hunting and gathering.

A Nomadic Species

For most of our history, we lacked permanent shelter. Before developing the practices necessary for settling in one geographic area, such as plant and animal domestication, early humans migrated from location to location. Groups of hunter-gatherers roamed the natural landscape in search of food and water. Because of these nomadic lifestyles, we couldn’t accumulate large quantities of items. We had no place to store them. We were limited only to what we could carry on our person.

Importantly, what we chose to carry were only the essentials. Any extra nonessential weight would have been unnecessarily energy-consuming. This would have put people in evolutionarily disadvantageous positions. What we did carry, in addition to the aforementioned infants, were things like tools, food, and resources such as stone and firewood. 

For example:

Looking at the archaeological evidence of the Oldowan stone tool culture (which dates to roughly 2 million years ago) elucidates how people were carrying their raw materials for more than 10km [5]. Some later stone tool technologies were carried up to 40km away from their source material [6].

Nomadic hunter-gatherers would have had camps, where they gathered for limited amounts of time. They would spend the day hunting game and foraging for plant foods to then bring back to camp and cook over the fire. Much research has gone into the adaptations humans evolved in order to hunt prey for long distances, but it is just as important to carry what you caught back to camp! 

One thing that’s beautiful about the internet is that you no longer need to read an anthropologist’s lengthy 300-page dissertation to see examples of this. There is a surprising amount of YouTube videos that document the lifestyles of people like the Hadza, including their hunting strategies. In this video, you can see multiple Hadza men returning to camp after a 2-hour hunt, carrying an antelope, some monkeys, and all of their hunting equipment. Some of this is attached to their body using satchels and ropes, while they are simply holding some equipment in their hands.

Carrying was clearly one of the staple forms of physical activity performed by humans throughout our evolution. It enhanced our survival.

From Infants to Infantry

Despite having access to supermarkets, many people in the modern world still opt to hunt for the bulk of their meat. They will go on long voyages in places like Alaska or Montana, to track down an elk and put an arrow through one of its vitals. Modern hunters certainly have more advanced technology compared to what humans had in the past, such as high-power compound bows and long-distance rifles, but they still have to lug their equipment through some very rugged terrain. And, they still have to carry the carcass of their catch after a successful hunt.

A study published in 2021 looked at the metabolic biomarkers of several individuals (four men and three women), who participated in an Alaska backcountry expeditionary hunt [7]. The researchers measured things like their body weight, fat mass, muscle mass, and cholesterol before and after the hunt. They found improvements in all metrics. After the 8-12 day hunt, participants:

• Weighed less

• Had less body fat, but maintained muscle mass

• Had less bad cholesterol, but maintained good cholesterol

A key component of the study was that these participants were carrying all of their provisions in a backpack consistently across the 8-12 days.

No wonder why militaries around the world institute a ruck march as part of their habitual exercise protocol. A ruck march, or rucking, is when troops carry a load similar in weight to that which they would carry in battle for long distances. To prepare for the hyper-competitive environments of war, soldiers need to be in great physical condition. Rucking is a supreme tool to achieve optimal fitness while practicing something practical. 

Another study, this time looking specifically at United States Army cadets, compared the physiological differences between a loaded and an unloaded 6-mile ruck march (i.e., with and without weight) [8]. The loaded ruck took longer to complete, resulted in higher average and max heart rates, and burned about 400 more calories than the unloaded ruck. Needless to say, it was more physically demanding to complete the 6-mile march while carrying an extra 40 lbs.

How to Start Rucking

In the modern era, exercise fads rapidly come in and out of existence. In one sense, this dilutes the pool of potential workouts one can implement. In another sense, this acts as a filter, allowing the legitimately effective forms of exercise to persist. We can even think of this in a Darwinian sense. Exercise consists of different variants, and those that are more effective are more likely to out-compete the others. 

Resistance training in the form of carrying weight is by no means a fad. It is millions of years old, originated as a physical activity for survival, and persists today as a reliable form of exercise.

Michael Easter, bestselling author of The Comfort Crisis and Scarcity Brain is a huge proponent of incorporating rucks into one’s exercise regimen. As a health and performance journalist, Easter has done a deep dive into the evolutionary origins of carrying and concurs that it is a.) a defining feature of Homo sapiens and b.) a favorable way to combat the sedentary lifestyles of today and improve one’s overall fitness.

Easter’s research has led him to these general guidelines for people just getting into rucking:

• Ruck often enough that your body can get better at rucking (at least once a week)

• Do not ruck so often that you don’t have time to recover (don’t do three tough days in a row)

• Do not go too heavy too soon

• Progress by increasing either the load or distance, but not both at once.

The beauty of carrying is in its simplicity. Some companies make backpacks and vests specialized for rucking, but at the beginning, all you need is a general backpack and something to put in it. Starting with a lighter weight (e.g., 20 lbs) and slowly increasing that weight week after week will surely do the trick. Your initial weight will depend on your personal body weight and fitness levels, of course.

In all honesty, you don’t even need a backpack. You can get even more primitive by picking something up with your hands, holding it, and just start walking. In modern exercise terminology, this is called a farmer’s walk, but it could equally be called a hunter-gatherer’s walk. Often done with kettlebells, dumbbells, or larger specialized handles, anything of sufficient weight that you can grab with your hands will work. 

Both forms of carrying will work your body in important ways, improving your cardiovascular health, muscle strength and endurance, and core stability.

Let’s not take our free hands and carrying abilities for granted. It’s part of what makes humans unique. Even Darwin himself understood the importance of our hands in defining our species. He said [9]:

By combining our adaptations to endurance, carrying, and making tools for carrying, could rucking be the most human form of exercise? 

References:

[1] Rose, K. D. 2005. “The earliest primates.” Evolutionary Anthropology: Issues, News, and Reviews 3(5):159–173.

[2] Jolly A. 1972. The evolution of primate behavior. In: Simons EL, Pilbeam D (eds) The MacMillan series of physical anthropology. MacMillan, New York

[3] Wang, W. and Crompton, R. 2004. “The role of load-carrying in the evolution of modern body proportions.” Journal of Anatomy 204(5):417-30.

[4] Wall-Scheffler, C., et al. 2015. “Human Footprint Variation while Performing Load Bearing Tasks.” PLOS ONE 10(3):e0118619.

[5] Braun, D., et al. 2008. “Oldowan behavior and raw material transport: perspectives from the Kanjera Formation.” Journal of Archaeological Science 35(8):2329-2345

[6] Isaac GLI. 1977. Olorgesailie. Chicago, IL: University of Chicago Press.

[7] Coker M., et al. 2020. “Alaska backcountry expeditionary hunting promotes rapid improvements in metabolic biomarkers in healthy males and females.” Physiological Reports 9(1):e14682.

[8] Walsh, D., et al. 2020. “Physiological Differences of US Army Cadets during a Loaded and Unloaded 6-Mile Ruck March.” Journal of Exercise Physiology 23(1):79-86.

[9] Darwin, C. 1871. The Descent of Man, and Selection in Relation to Sex. John Murray: London.

Fit Fuel Song Suggestion

The Fit Fuel song suggestions are hand-picked by yours truly to elicit the motivation (and possibly aggression) needed to initiate or persist through a grueling workout. They consist of heavy, brutal guitar riffs and gruesomely guttural vocals. Additionally, I timestamp what I believe to be the best riff of the song - one that will kick your nervous system into overdrive when approaching a personal record (PR).