Rucking: The Loaded Walk That Turns Zone 2 Into Strength Work
Put weight on your back and a walk stops being a walk.
Operators have a cardio problem that has nothing to do with motivation. The easy aerobic work that builds the base, zone 2, takes time, and time is the one resource the business never gives back. Running costs joints. Cycling costs a bike and a route. The gym costs a drive.
Rucking solves most of that with a pack. It turns a walk you can take anywhere, including on a call, into a session that reaches zone 2 heart rate and loads the legs, back and core at the same time. The military has studied it for a century because soldiers have no choice about carrying weight. Operators can borrow the findings without the blisters.
This article covers what rucking is, what the load-carriage research actually says, why it fits an operator's week, how to start, an eight-week progression, the gear that matters, and the mistakes that end most people's rucking in month two. Education, not medical advice: if you have back, neck, hip or knee problems, a heart condition, or are pregnant, talk to your doctor before loading a pack.
What rucking is
Harvard Health defines it in one line: rucking is "walking while wearing a weighted vest or backpack." The word comes from the rucksack. The practice comes from infantry, where it is called a road march and is a graded test, not a wellness trend.
The appeal is in what the load does to an ordinary walk. In Harvard Health's words, it "amps up your walking intensity," and the pay-offs it lists are the ones an operator would pick: muscle strength and bone density, the heart's pumping ability, lung capacity, calorie expenditure, and core strength through the abdominal and back muscles.
The same page gives the honest cost. Weight on the body "can also strain joints and muscles, which can lead to injuries." People with neck or back pain are told to avoid it, and pregnant readers are told not to wear a weighted vest at all. Rucking is a loaded exercise. Treat it like one.
What the load-carriage research says
The deepest literature on walking under load is military, and the best single entry point is a 2004 review in Military Medicine, "Soldier load carriage: historical, physiological, biomechanical, and medical aspects." Several of its findings transfer directly.
Load has climbed, and bodies have not. "Before the 18th century, foot soldiers seldom carried more than 15 kg while on the march, but loads have progressively risen since then." Fifteen kilograms is a useful ceiling to keep in mind when a fitness brand suggests more.
Where the weight sits decides what it costs. The review's finding is that "locating the load center of mass as close as possible to the body center of mass results in the lowest energy cost and tends to keep the body in an upright position similar to unloaded walking." The opposite is expensive: "each kilogram added to the foot increases energy expenditure 7% to 10%; each kilogram added to the thigh increases energy expenditure 4%." Heavy boots are a poor substitute for a pack.
Hip belts are not optional. "Hip belts on rucksacks should be used whenever possible as they reduce pressure on the shoulders and increase comfort."
The cost rises with everything you would expect. "The energy cost of walking with backpack loads increases progressively with increases in weight carried, body mass, walking speed, or grade; type of terrain also influences energy cost." Load, speed and hills are three separate dials. Turn one at a time.
Training works, and it is not only walking. "Physical training that includes aerobic exercise, resistance training targeted at specific muscle groups, and regular road marching can considerably improve road marching speed and efficiency." The people who get good at carrying weight also lift.
The injuries are predictable. "Common injuries associated with prolonged load carriage include foot blisters, stress fractures, back strains, metatarsalgia, rucksack palsy, and knee pain." Every item on that list is a dose problem: too much load, too fast, for too long. The review's own remedy is the operator's progression plan in one sentence: "lightening loads, improving load distribution, optimizing load-carriage equipment, and taking preventive action to reduce the incidence of injury."
Two smaller studies put numbers on the metabolic side. In a treadmill study of nine volunteers carrying 25.6 kg, the oxygen cost of loaded walking "was significantly (P < 0.001) higher than that associated with unloaded walking at all downhill gradients tested." The same study found that a pack distributing weight between front and back of the trunk averaged 5% lower oxygen consumption than a back-only pack across the protocol, which is the hip-belt principle again: bring the load toward your centre.
And in a study of twelve soldiers walking at altitude with loads of 10.7, 21.4 and 30 kg, "Marked increases in almost all physiological parameters were observed with increasing load, altitude, and speed." The authors' recommendation for those soldiers was to "carry not more than 32% of their body weight." That is a ceiling set for acclimatised infantry on a mountain. It is quoted here so you know where the top of the scale sits, not as a target.
One caution on the research as a whole: the military studies use fit young soldiers, fixed treadmill speeds and loads most operators should never approach. Borrow the principles, not the numbers.
Why rucking fits an operator's week
The case rests on three things rucking does at once that nothing else in a founder's schedule does.
It reaches zone 2 at a walk. Zone 2 is the easy aerobic intensity where you can still speak in sentences, and it is the base layer of the zone 2 training protocol for entrepreneurs. Most people cannot reach it by walking unloaded on flat ground. Add weight and the heart rate climbs into the band without the joint cost of running. The heart rate zones guide shows how to calculate the band for your age and resting heart rate; check it on your first few rucks and adjust load until you sit in it.
It is strength work your calendar will accept. The load trains the posterior chain, the trunk and the feet while the heart does aerobic work. It is not a substitute for lifting, and the military review is explicit that resistance training is part of getting good at carrying. But on a week when the lift gets cut, the ruck keeps a strength stimulus alive.
It travels and it talks. A pack and a pair of shoes go in any suitcase. A conference city, a hotel loop, a client's industrial estate: all of them are routes. Phone calls work at zone 2 by definition, since you can still hold a conversation. The travel workout protocol treats the loaded walk as the default session away from home for exactly this reason.
There is a Stoic point in here too. The Stoics trained voluntary hardship as a discipline: carry a little more than necessary, on purpose, so that necessity has less to teach you later. A pack is the most literal version of that practice available to a modern operator. Thirty minutes under load every few days is a rehearsal for every heavier week the business will send.
How to start
The starting load is the decision that determines whether you are still rucking in three months. Harvard Health's guidance is the right one and it is quoted here rather than invented: "Most people can try a weighted vest, however. If you do, stick to a version that's about 10% of your body weight, at least for starters." For an 80 kg operator that is 8 kg. For a 60 kg operator, 6 kg. It will feel too light on the first walk. That is correct.
- Load the pack with something dense and stable. Water bottles, a wrapped weight plate, bagged sand or rice. Pack it high and close to the spine, per the military finding on centre of mass, and pad anything with an edge.
- Weigh it. Bathroom scale, pack on and off, subtract. Guessing is how 10% becomes 18%.
- Walk 30 minutes on flat, familiar ground. Normal walking pace. The only job of the first week is to learn where the straps rub and how your feet feel at minute 25.
- Check heart rate at the midpoint. If you are under your zone 2 band, pick up the pace before you add weight. If you are above it, slow down. Speed is the cheapest dial.
- Finish with ten minutes of unloaded walking. Take the pack off, keep moving, let the back settle.
The eight-week progression
This is the Apex recommendation for a healthy adult starting from a base of regular walking, built from the research principle that load, speed and grade are separate dials and only one moves at a time. It is not a study protocol. Hold any week an extra week if your feet, knees or back complain.
| Week | Sessions | Duration | Load | Terrain and pace |
|---|---|---|---|---|
| 1 | 2 | 30 min | 10% bodyweight | Flat, normal pace |
| 2 | 2 | 40 min | 10% | Flat, normal pace |
| 3 | 3 | 40 min | 10% | Flat, brisk pace into zone 2 |
| 4 | 3 | 45 min | 10% | Add gentle hills, normal pace |
| 5 | 3 | 45 min | 12 to 13% | Flat, brisk |
| 6 | 3 | 50 min | 12 to 13% | Mixed terrain |
| 7 | 3 | 60 min | 12 to 13% | One session with sustained hills |
| 8 | 2 plus one long | 45 min, plus one 75 to 90 min | 15% | Flat for the long one |
After week eight, most operators have found their maintenance dose: two or three rucks a week at 10 to 15% of bodyweight, 45 to 60 minutes, one of them long. Going heavier than that is a choice to train a different quality, and it brings the injury list from the military review closer. If the goal is aerobic base and durable strength for a long working life, the zone 2 and longevity article explains why volume at easy intensity beats load for that purpose.
Gear that matters, and gear that does not
The pack. It needs a hip belt that actually bears weight, a sternum strap, and a frame or back panel stiff enough to keep a plate from folding into your spine. The research is unambiguous that the belt reduces shoulder pressure, and that the load should ride high and close. A purpose-built rucking pack does this well. A sturdy hiking daypack does it adequately. A soft school bag does not.
Footwear. Blisters and metatarsalgia head the injury list, and both are footwear problems before they are training problems. Use shoes you already walk long distances in, with room in the toe box, and wool or synthetic socks rather than cotton. Remember the energy finding: each kilogram on the foot costs 7 to 10% more energy, so heavy boots make the session harder without making it better.
Poles. Optional. In a treadmill study with a 15 kg pack on moderate inclines, hiking poles did not change heart rate, oxygen consumption or calories, but perceived exertion "was significantly lower (P < 0.05) with hiking poles." If hills feel harder than your heart rate says they should, poles are a legitimate tool. Flat urban rucking does not need them.
What you can skip. Weighted vests marketed at prices that imply a technology. Apps. Anything that promises the walk will "feel like running." The point of rucking is that it does not feel like running. A pack, a scale and a heart rate reading are the whole kit.
The mistakes that end rucking in month two
- Starting at the weight you think you deserve. The lifter's instinct is to load the pack like a bar. The 10% figure exists because the tissue that fails under load, feet, shins and lower back, adapts slower than the heart does. Your cardio will be bored for a month. Let it.
- Moving two dials at once. Heavier and hillier in the same week is how knee pain arrives. Load, speed, grade: one change per week.
- Letting the pack ride low. A sagging load pulls you into a forward lean and moves the weight away from your centre of mass, which the research shows costs more energy and changes posture. Cinch the belt, shorten the straps, pack high.
- Treating it as the whole programme. The military review lists resistance training alongside road marching. Keep lifting. The ruck is the base and the bridge, not the pyramid.
- Ignoring a hot spot. A blister forming at minute 20 is information. Stop, tape it, shorten the session. The soldiers in the literature did not have that option. You do.
Frequently asked questions
What is rucking?
Rucking is walking while wearing a weighted backpack or vest. The name comes from the military rucksack and the practice from infantry road marches. The added load raises the intensity of an ordinary walk so that it reaches an aerobic training heart rate while also working the legs, back, core and feet, which is why it has become a popular strength and cardio session for people who prefer walking to running.
How much weight should I start rucking with?
Harvard Health advises sticking to about 10% of your body weight to begin with. For an 80 kg person that is 8 kg; for 60 kg, 6 kg. It will feel light on the first walk, which is the point: feet, shins and lower back adapt more slowly than the heart. Weigh the loaded pack on a scale rather than guessing, and hold 10% for at least four weeks.
Is rucking good cardio?
Yes, at the easy aerobic end. Load raises walking heart rate into the zone 2 band that most people cannot reach walking unloaded on flat ground, and research shows the energy cost of walking rises progressively with the weight carried, body mass, speed and grade. It will not replace high-intensity intervals, but it builds aerobic base with far less joint stress than running.
Is rucking bad for your back or knees?
It can be, if the dose is wrong. A review of soldier load carriage lists back strains, knee pain, stress fractures, blisters and metatarsalgia as the common injuries of prolonged carrying, and Harvard Health warns that weighted walking can strain joints and muscles. People with existing neck or back pain are advised to avoid it, and pregnant people should not wear a weighted vest. Start light, progress one variable at a time, and use a hip belt.
Where should the weight sit in a rucking pack?
High and close to your spine. The load-carriage research finds that placing the load's centre of mass as close as possible to the body's centre of mass produces the lowest energy cost and keeps posture closest to normal walking, and that hip belts should be used whenever possible to take pressure off the shoulders. Weight on the feet is the most expensive place to carry it: 7 to 10% more energy per kilogram.
How often should you ruck?
Two to three sessions a week is a sensible maintenance dose for a healthy adult, 45 to 60 minutes each, with one longer session once you have built up over about eight weeks. Keep at least one strength session in the week as well, since the research on load carriage shows that resistance training improves carrying performance alongside the walking itself.
Carry a little more, on purpose
Rucking is unglamorous, which is why it works for operators. It needs no venue, no partner, no perfect weather and no mood. It converts the one form of exercise everyone already does into a session that builds the aerobic base and the structural strength a long career runs on, and it does it while you take the call you were going to take anyway.
The research adds nothing mystical. Keep the load near your centre. Use the belt. Progress one dial at a time. Respect the feet. Lift as well. Do that for eight weeks and the pack becomes what the Stoics meant by voluntary hardship: a small weight chosen now so that the large ones land on a body that is ready.
If you want rucking inside a daily structure rather than bolted onto a busy week, the free 5-Day Stoic Operator Challenge installs the training block, the Stoic review and the operating rhythm in five days. Day one's walk can be the first one with weight on your back.
