A few weeks ago, I posted details on Instagram about how many calories rucking burns. People were fascinated to learn just how powerful rucking can be. But they had a lot of follow-up questions.

I wanted to address all those questions, but Instagram limits the number of words you can include in a post. And I, being overly analytical and long-winded, have trouble staying within those constraints.

I decided to answer everyone’s questions in this newsletter, where there are no word limits or editors telling me I’ve given readers way too much information and that I should probably cut the word count by 50 percent. Welcome to the rucking deep dive.

Before we begin, know that you’ll find the most thorough argument for why all humans should ruck (along with a lot of other information about the things that humans were made to experience) in my book, The Comfort Crisis. Both the print and audio versions are a steal right now, thanks to Prime day (more on that below). If someone forwarded you this email and you enjoy it, you can sign up for my newsletter here.

Thanks, and keep on reading and rucking.

Should women ruck?

Short answer: Yes, yes, and yes.

Long answer: I didn’t expect this question, but here we are. Here are three stellar reasons why women should ruck (I could have listed more):

1. It’s weight training for people who don’t like the weight room
​The US government says everyone should do at least 150 weekly minutes of endurance activity and strength train twice a week. Only 19 percent of women hit those recommendations while 26 percent of men do. Why the difference? Women and men do endurance exercise at about the same rate, but women are far less likely to strength train.

There are a variety of reasons for this. One example that comes to mind: Many weight rooms are filled with creepy, sweaty dudes. And who wants to exercise around that?

Rucking combines endurance and strength. It allows women to meet those guidelines and get stronger without setting foot in a weight room.

This is critical because scientists are just now realizing that not having enough muscle can be far more dangerous for women than an unhealthy scale weight. A recent study of 50,000 Canadian women, for example, found those most at risk of death registered a “healthy” BMI but had the lowest levels of lean muscle. (A couple of years ago I wrote a deep dive about this subject for Women’s Health. Email me if you’re interested and I can send you a PDF of the story.)

2. Rucking strengthens bones
​Everyone starts losing bone density around age 30. But women after menopause begin losing it at a rapid and dangerous rate. This is why bone fractures are one of the biggest health threats to women. Aging women in the US are two, five, and eight times more likely to break a bone than they are to have a heart attack, get breast cancer, or have a stroke, respectively. If you break an arm, it’s an annoyance that’ll heal. But if you break a hip, you’re essentially screwed. About 50 percent of people over age 65 who break their hip are dead within six months.

The best way to stop and even reverse bone loss—according to Dr. Robert Wermers, a bone disease specialist with the Mayo Clinic—is to do “aerobic walking where you’re bearing weight.” I.e., rucking. One study found that aging women who trained with a weight vest didn’t lose bone while those who trained without a weight vest saw a loss in bone density. The scientists say the earlier in life you start rucking the better you’ll be.

3. Women are damn good at carrying
​As I told Jason and Emily of GORUCK on their Glorious Professionals podcast (listen here), “what we were built to do can inform a lot of what we should do today.” Humans were built to carry (for more on that, read The Comfort Crisis).

Historical data suggests that women did significantly more carrying than men. There’s a lot of old anthropological research backing this idea, but one of my favorite studies focuses on the women of the Seri hunter-gatherer tribe on Tiburon Island in the Gulf of California. In 1895, WJ McGee, who ran the Bureau of American Ethnology, traveled to the island to study the tribe. He observed that the women would frequently make a 15-mile round trip excursion from the beach up into the mountains—through a gnarly landscape of mesquite, cactus, and agave. They’d fetch water and “rapid walk” it back to camp in heavy, awkward clay jugs. He stated that the women of the tribe were “notable burden bearers.”

I told you all that because paleo fitness and diet books tend to picture “man” or “men” as the super-fit hunter. And they use that imagery to persuade modern men to exercise. But the reality is that hunter-gatherer women seemed to have worked physically harder and longer than the men (and you still see this phenomenon in exercise studies today … women consistently go harder in interval workouts).

So next time you’re rucking and you think it sucks, just remember the women of the Seri tribe, the “notable burden bearers,” and remind yourself that you were made for this shit.

What about injuries?

Short Answer: Rucking seems to be a lot safer than running and mildly safer than lifting.

Long Answer: There’s a bunch of research supporting the “short answer” above. Let’s focus on two examples.

Study one​
Researchers at the University of Pittsburgh tracked 451 soldiers in the 101st Airborne. Over a year, the group had 133 injuries. Twenty-eight of those injuries came from exercise. Here’s how the data broke down:

Rucking: 3 injuries
Lifting: 7 injuries
Running: 18 injuries

In other words, soldiers were 6 times more likely to get injured running and about 2.3 times more likely to get injured lifting.

Study two
​Researchers followed 800 soldiers going through Special Forces Assessment and Selection. It’s the 20-ish day hell soldiers go through to see if they can become Special Forces operators.

So you had 800 dudes rucking nonstop with ~50 pounds for days on end. And this was all at the highest intensities across the gnarliest of terrains.

When the scientists looked at the data, they discovered that rucking caused 36 injuries. The most common injuries were sprains, tendonitis, or non-specific pain.

I think this study puts the risk of rucking in context for the average person. Here we had 800 soldiers wearing relatively heavy rucks and going absolutely bonkers for days on end. And just 4.5 percent of them got injured.

This is why I feel rather confident telling you that it’s safe for you to do the same activity with less weight, at a less insane pace, for a few hours a week in your neighborhood or on a trail.

Of note: The researchers tracked the injury rates of other activities the soldiers did during Assessment and Selection, like running and obstacle courses. When the researchers broke the data down by injuries per hour (essentially a way to figure out a person’s true risk of getting injured during an activity), rucking had the lowest injury rate. Running and the obstacle course resulted in two and four times as many injuries, respectively.

Of course, the risk of injury while rucking depends on how heavy your ruck is. Which leads me to …

How much weight should I ruck with?

Short answer: For everyday rucking for health and fitness, men should generally stick to between 25 and 45 pounds, while women might want to hang out in the 15 to 35-pound zone.

Long answer: I’m going to pull directly from The Comfort Crisis, which is a book you should buy if you haven’t already 🙂

Prehistoric cave art depicts warriors heading into tribal battles with crude shields and spears. Together these items could weigh between 10 and 20 pounds. Thousands of years ago Greek Hoplites, Roman Legions, and Byzantine infantrymen all marched with 30 pounds of gear. Fighters in all regiments around the world until the mid-1800s carried between 20 and 35 pounds.

Then British Soldiers in the Crimean War began carrying 65 pounds. Loads crept successively higher in World Wars One and Two, and in Korea and Vietnam. By the wars in Iraq and Afghanistan, the average soldier was marching with about 100 pounds.

In the aftermath of the Crimean War, British scientists investigated the impacts of a soldier’s load on his ability to fight war. Any infantryman, they found, could move quickly and safely marching with 50 pounds. About 150 years later, in the 2000s, three different studies from US Army, Marines, and Navy all confirmed the finding. Fifty pounds is the heaviest load that allows soldiers to fight like hell, become physically bulletproof, and forge elite strength and endurance.

In other words, stay under 50 pounds. That’s a quick and easy guideline. But it’s obviously not super nuanced. For example, rucking with 50 pounds is experienced differently by someone who weighs 110 pounds versus someone who weighs 220 pounds.

In 1950, Colonel S.L.A. Marshall did a shit ton of research and concluded that 1/3 of bodyweight or less is also a pretty solid metric. It’s particularly helpful if you weigh less than 150 pounds and are searching for a safe but heavy weight.

Because most people are rucking for general health and fitness, I think anywhere from 15 to 50 pounds is ideal. The calorie burn data suggests that there isn’t as much of a calorie burn benefit going over 50lbs as you would think. (A nerdy way to put that: The relationship between pack weight and calorie burn isn’t necessarily linear…there’s a point of diminishing returns.)

Ok, but I’m just starting to ruck. Where do I start?

Short answer: 15 to 25ish pounds.

Long answer: In 2010, a team of military researchers wondered how they could optimize ruck training for military recruits. They wanted to come up with some general pointers the military could use to get new, doughy kids into fighting shape but also not push them so hard they got injured or totally burned out.

After spending a bunch of time, effort, and money reading all the research, the scientists developed a set of guidelines that were … basically common sense. They found that rucking newbies should:

• Ruck often enough that their body can get better at rucking (at least once a week)
• Not ruck so often that they don’t have time to recover (don’t do three tough days in a row)
• Not go too heavy too soon
• Progress by increasing either the load or distance, but not both at once.
• Do other stuff that makes them fit.

Rucking is inherently uncomfortable. It wouldn’t work if it were easy. But you want to start with a weight that allows you to hit the sweet spot where you’re uncomfortable but walking normally. I.e., The weight shouldn’t be so heavy that you’re super hunched over.

For the average active person, 15 to 25ish pounds is a good starting point. But gauge how you feel. If you weigh 100 pounds and 15 pounds feels way too heavy, go lighter. If you’re some CrossFit maniac and 25 pounds feels way too light, go heavier.

Should I ever go above 50 pounds? And how should I do that?

Short answer: Rucking with heavier loads can be useful for certain people. For example, military members and backcountry hunters. Rucking above 50 pounds is probably best done on a treadmill or Stairmaster.

Long answer: In Alaska, I rucked with 80 pounds on my back most days for a month straight. During the pack out, I had to ruck more than five miles and all uphill with over 100 pounds on my back.

In training to go up there, I had a bit of a conundrum. Based on all the research, I knew that training with super heavy loads can be a bit risky. But I also knew it would probably be smart to get used to having a soul-crushing weight on my back.

I consulted some research and smart people and came up with a plan. When I trained with over 50 pounds, I’d do it on a treadmill or Stairmaster. I’d fill my ruck with anywhere from 60 to 90 pounds. Then I’d set a treadmill to its highest incline (15%) and walk anywhere from 2.5 to 4 miles an hour for as long as I felt like (usually 45ish minutes).

In general, I view indoor training (i.e. gyms) as sterile, boring, controlled environments that allow me to safely “get ready” to do cool shit outside. A lot of the risk from rucking with over 50 pounds comes from the inherently unpredictable nature of the outdoors. I’m willing to accept risk on the mission in Alaska, but not in training for it.

The treadmill or Stairmaster gave me a totally predictable, forgiving surface. I didn’t have to worry about gnarly terrain that could lead me to roll an ankle or blow out a knee (80 pounds on your back can tip any stumble into a fracture.)

I don’t think heavy gym rucking is necessary unless you have something coming up where you’ll be forced to ruck with 70 or more pounds. It still takes a toll.

My shoulders ache when I ruck. What should I do?

Short answer: Ruck more and try wearing your ruck around the house to strengthen your shoulders.

Long answer: I ran this past my great friend Dr. Doug Kechijian, DPT. He’s a former Special Forces soldier (which means he’s done a lot of rucking) who now owns Resilient Performance Physical Therapy.

He put it to me this way: “Rucking isn’t comfortable. Shoulder discomfort while rucking is kind of normal. It obviously sucks more the heavier the weight is,” he said. “To get over it, I fidget with shoulder straps constantly. Or, if I have a hip belt, I’ll at times take almost all the tension off my shoulders and let almost all the weight ride on the hip belt.”

Another tactic is to intersperse your day with short “rucks” at home. When people ruck, they usually go 30 to 90 minutes, which is a long time for your shoulders to be weighed down if they aren’t used to it. So try wearing your ruck at home for short stints throughout the day. Start with 5-to-15-minute increments. Wear your ruck as you clean the house, wash dishes, whatever. This will help your shoulders accumulate more time under the ruck, which can strengthen them without the aches. (P.S. I usually wear my ruck when I clean up around the house … it sneaks in a workout!)

Should I use a hip belt?

Short answer: They help, especially when the weight feels heavy.

Long answer: When I was in Alaska, my 80-pound pack was essentially my conjoined fraternal twin. I’d go for 15ish minutes with the weight riding mostly on the shoulder straps. Eventually, those shoulder straps would feel like they were trying to slice me lengthwise into thirds. So I’d pull the hip belt tight and loosen the shoulder straps, so the weight was riding nearly entirely on my hips. After another 15 minutes, my lower body muscles would begin to feel like they were being burned off my body. So then I’d do something in between, where the weight was equally distributed between the belt and shoulder straps.

The beauty of the hip belt is that it allows you to shift the load around to different muscle groups so no one group gets tired enough to slow you down.

A couple of people have asked where the hip belt should be. “On your hips” was my first thought. 🙂

Backpackers say your hip belt should be up high, resting at the very top of your hip bones. This backpacking ideology, naturally, has trickled into the rucking circles. But the thing about backpackers is that they tend to be dorks about having the lightest pack possible. Out on the Appalachian Trail, for example, backpackers shoot for a pack that is no heavier than 30 pounds. I’ve even heard of ultralight backpackers cutting half the handle off of their toothbrush just to save an ounce. Dorks! 🙂

Us ruckers embrace the weight. Our rucks are heavy for the sake of being heavy. This is why backpacking rules don’t apply to rucking. I emailed back and forth with Jason at GORUCK on this (he did a ton of very heavy rucking as a Green Beret). We both came to the same basic conclusion. Here’s what I wrote him:

“My experience in Alaska and doing some heavier rucks is this: I don’t overthink the belt placement. I just cinch it where it feels most natural at any given time (which is predicated on where it was until I got too damn tired of it there). Heavy rucking sucks. I use the belt and straps in whatever way makes it suck less. Frequent transitions in belt and load placement seem to help that. I don’t think there’s one ‘magic spot.’”

He agreed—“100 pounds is 100 pounds … it’s terrible,” he wrote—and added that placing the belt lower on the hips seems to be better for him and other SF guys he’s talked to because it allows you to breath better. Seconded … I didn’t have the belt up by my belly button much in Alaska.

More on calorie burn…

Short answer: Rucking burns about two to three times as many calories as walking.

Long answer: This post gives some general graphs and metrics. The number of calories you burn while rucking rises or falls based on a variety of factors like the weight in the ruck, the terrain, etc.

Calorie burn, however, is just a way to measure work. And if a person is measuring work in calories (and not time or distance, which are performance metrics) it suggests to me that the person wants to change how their body looks.

Looking “better” (as we define it in modern society) requires two things: Fat loss and muscle growth or preservation.

Rucking is better for fat loss compared to lifting because it burns about two to three times more calories than lifting. And it’s better for muscle growth and preservation compared to running because it’s actively working your muscles with weight. This stimulates muscle growth or, at least, tells your body to not get rid of muscle.

In other words, rucking helps you avoid the sometimes doughy, excess bulk from lifting as well as that skinny-fat look that running can sometimes render. Consider a study on backcountry hunters. Over 12 days, a group of backcountry hunters/ruckers lost a lot of fat, preserved muscle, and saw fitness and health markers rise. Here are the numbers:

Body Fat: Down 14%
Muscle Mass: Up 0.1%
VO2 Max: Up 8.4%
Bad Cholesterol: Down 28.7%

That said, I think it’s more important in the long term to think about the health implications of rucking and body type. So…

Some info on body type and health…

Short Answer: Rucking creates a body type that is harder to kill. This applies to both men and women, but for different reasons.

Long answer: When I asked Jason from GORUCK about what kind of body type rucking builds, he said: “We call it super medium,” he said. “Just think of Special Forces soldiers. We can’t be too thin, but we also can’t be too muscular. Rucking corrects for body type. Have too much fat or muscle? It’ll lean you out. Too skinny? You’ll get stronger and put on some muscle.”

Women often need a little more muscle than they have (which we covered above). But men often have the opposite problem. Men often try to build extra muscle just for the sake of it—they often think that more muscle = healthier. But that isn’t always the case.

I started thinking about this more after spending a week with my good friend Trevor Kashey. To say that Trevor is smart is like saying Lebron James is good at basketball. The kid’s a genius—graduated college at 18, got a Ph.D. in biochemistry at 23, did cancer research, and now owns Trevor Kashey Nutrition, where he’s helped people (many of them dire cases) lose a collective 200,000+ pounds and win Olympic gold medals. Yes, Trevor appears in The Comfort Crisis. Yes, his wisdom in the book may change how you think about nutrition forever.

Anyways, I was talking to Trevor about muscle and he was explaining to me why more isn’t always better. He told me to think about intraspecies variation. “If you compare two healthy, full-grown animals of the same species, the smaller one will probably have a longer life span,” Kashey said. “Think of a Great Dane versus a Chihuahua—the Chihuahua lives more than twice as long on average. And there are a number of reasons for that. Like oxidative damage, inflammation, organ stress, joint stress, etc. This is why BMI is so important.”

He continued. “Lots of fit but very muscle-bound men will be like, ‘BMI is irrelevant, because it puts me in the overweight category, and look at me, I’m not overweight, I’m just super jacked!’,” he said. “But I take the position that huge amounts of muscle mass causes different and probably worse strain on your organs compared to an equal amount of fat. The difference between being overweight with lean mass versus overweight with fat mass is what organs get stressed out and fail first. Huge amounts of muscle mass means ton of vascular strain, which means more stress on your heart. Huge amounts of fat means tons of visceral fat which leads to liver, and pancreatic issues. So let’s say you have a bodybuilder and a couch potato who are both in the ‘obese’ category according to BMI. Both are going to die younger than necessary, but the bodybuilder will have a heart attack and the couch potato will get diabetic nephropathy…and probably a heart attack.”

Be harder to kill. Be super medium.

Should I ruck with a weight vest or a ruck?

Short answer: A ruck.

Long answer: Before I get all dorky, let me say this: at the end of the day, that you carry weight for distance is far more important than how you carry weight for distance.

Now for the nuance…rucks win for rucking. The reason comes down to back health. Most of us spend a significant portion of our day sitting, with our backs flexed forward. Our backs sort of get “used” to that position (and this position gets drilled into us early, thanks to school desks).

In this slightly leaned forward position, your body has to fire your back muscles even harder to hold up your torso, which can put stress on your spine. It’s one of the reasons 80 percent of us will have back pain in our lives.

A weighted ruck “pulls” your spine backward into a better position and holds up your torso. That puts less compression on your spine, strengthens neglected muscles, and can even help and prevent back pain. Weight vests don’t have this benefit.

Rucks also allow your chest to be open, so you can breathe better. This generally allows you to get more oxygen and be faster with the same weight.

I also ran this question past Jason at GORUCK. He recently started making a weight vest and has been doing a lot of testing. He pointed out that vests might be optimal if…

You’re doing a bodyweight workout​
Vests allow you to strap the weight close to your body, so it doesn’t jostle around. This might make them slightly better if you have a workout that includes rucking paired with weighted jumping, push-ups, pull-ups, etc.

You’re a military member or police officer ​
These jobs often require that you wear a vest for protection at work. As Jason put it, “Train as you fight. MURPH was originally called ‘BODY ARMOR.’ Murph did the workout in a Vest/Body Armor because that’s how he fought. If you wear body armor (at work), thank you for your service.”

So if you buy just one thing, make it a ruck. Or just buy both and be ready for any party that comes your way. Speaking of weighted running…

Should I run with my ruck on?

Short answer: Probably not.

Long answer: Running was critical to human evolution (more on that in The Comfort Crisis), but those humans were “essentially professional athletes whose livelihood required them to be physically active,” one Harvard anthropologist told me. To stay alive, early humans had to be very physically versatile. They were good at just about every physical skill, from movement to endurance to strength.

Modern people in the developed world, on the other hand, sit an average of 6 to 8 hours a day (and that stat was taken before Covid quarantines). Our inactive lifestyles give us weird muscle weaknesses, strength imbalances, and restricted movement patterns. We’re also generally very heavy people. For example, the average hunter-gatherer weighs around 125 pounds while the average American man and woman weigh 200 and 170 pounds, respectively.

So when we run, we do so with our wonky movement patterns, weaknesses, and heavy bodies. You can see how this might be problematic. Which is probably why anywhere from “27% to 70% of recreational and competitive distance runners sustain an overuse running injury during any 1-year period,” according to one massive review of the research on running and injuries.

Adding weight to running just increases a person’s injury risk further. A group of scientists at the University of Wisconsin studied this exact topic and found that running with a 20-pound weight vest was a bad idea. It led to force changes that would likely bring about runner’s knee rather quickly.

Obviously, plenty of people run a couple miles with a 20-pound vest during the annual Murph workout, and their knees don’t spontaneously combust afterward. So you’ll probably be fine if you do it now and then, but I definitely wouldn’t make it a regular part of training.

If you want or need to ruck faster, try a ruck shuffle. When I visited GORUCK HQ, Jason and I had to ruck five miles and we only had an hour and change to do so. So we moved in a “ruck shuffle.” It’s faster than a walk but slower than a run, a foot always maintaining ground contact. Think: a slightly hunched speed walk.

Does walking with my kid in a backpack kid carrier count as rucking?

Short and long answer: Yes. Plus you get bonus points because the load moves around, cries at you to ruck faster, and can even spontaneously projectile vomit on you.

Anything else I should know?

Short and long answer: You should read Tribe Book of the Month of August, The Comfort Crisis.

First, Amazon is offering Audible for $6.95 per month for the first four months. In other words, the audiobook is $6.95 right now. Here’s a link.

Second, the hardcover edition of The Comfort Crisis is included in a “buy 2 get 3” promotion. You can use this on other books, or just buy a copy for yourself and others for gifts. Link.

If you bought the book and read it, it would be awesome if you’d review it on Amazon. Reviews are HUGE for authors.

Still have questions? Stay in touch through my newsletter. 

Thanks for reading. Keep exploring the edges.

-Michael

Author, Writer, Professional