Building the Combat Chassis
Rucking alone won't build your Combat Chassis
As a young Recon Marine, I heard an instructor refer to his body as the Combat Chassis. He was talking about developing well-rounded fitness.
It doesn’t matter how smart you are, or how well you can shoot or solve problems, if you can’t get to the point of friction, ready and able to fight.
I love rucking. It’s honest work. It’s great for you. It’s also repetitive as hell.
If all you do is walk under load, you’ll get better at walking under load, but you will also eventually develop tight hips, low back pain, and a lack of upper body strength.
Here is a caveat. Some of you have told me that you have just started rucking. If me telling you to do more shit is going to make you say ‘fuck it’ and quit, don’t. A rucking-only plan 3-5 days per week can help you drop Lbs, get outside and get some sunshine on your pasty-ass arms, and make you mentally tougher. Just know that once you get mentally tougher, you need to think about adding in some strength training.
You need strength work that covers what rucking doesn’t.
What Rucking is great at:
1) Locomotion / gait (the big one)
Walking under load: repetitive hip/knee/ankle cycling
Stride mechanics + rhythm: coordination, efficiency, pacing
2) Single-leg endurance
Every step is a mini single-leg stance:
Glutes + adductors (pelvis control)
Quads and calves (shock absorption + push-off)
Foot intrinsics (all the little foot muscles) / tibialis anterior (especially on uneven terrain)
3) Trunk “anti-movement” (core stability)
Mostly isometric:
Anti-extension (not letting the low back dump forward)
Anti-rotation / anti-lateral flexion (keeping ribcage stacked while one leg is on the ground) This is core stability, not core strength through range.
4) Posture + upper back isometrics
Spinal erectors working to resist flexion
Traps/rhomboids/serratus are doing endurance work to hold the shoulder girdle position
Depending on your ruck fit, you get some scapular depression and have to work to avoid hunching.
5) Elastic tissue and “durability.”
Tendons/ligaments adapt to time under tension
Skin/feet, connective tissue, and tolerance to repetitive impact (especially downhill)
And, as we know, you dig the well of mental toughness.
Movement patterns rucking mostly skips
1) True hinge strength
You get some posterior chain endurance, but you’re not training:
heavy hip extension (deadlift/RDL-level stimulus)
glutes/hamstrings through large ranges under meaningful load
2) Squat pattern (especially deep knee flexion)
Rucking is usually a shallow-range knee bend.
No meaningful deep squat strength
Limited quad strength development beyond endurance
3) Push patterns
Little to no horizontal push (push-up/bench)
Little to no vertical push (overhead press)
4) Pull patterns
No real vertical pulling (pull-ups)
No real horizontal pulling (rows)
Upper back endurance ≠ pulling strength.
5) Rotation / twisting power
Your core resists rotation while rucking, but you’re not training:
controlled rotation (like chops/throws)
rotational strength or power
6) Lateral / multi-directional movement
Rucking is mostly sagittal plane.
Minimal side-to-side change of direction, cutting, shuffling, and agility.
7) Power / speed
Unless you’re doing sprints/hills aggressively:
minimal explosive output (jumps, cleans, throws)
limited rate-of-force development
This doesn’t mean that you need to start doing ‘two-a-days’.
We can start addressing missed movement patterns by adding 2 strength sessions per week to a rucking program of 3-4 days per week with minimal equipment.
To get started, do this 2x/week, 25–35 min. You can use your ruck for weight. Adding some resistance bands and kettlebells/dumbbells would be great, but not required.
Session A (hinge + pull emphasis)
1) Backpack Romanian Deadlift – 4×8–12
Go slow. Focus on your hamstrings. Keep your spine neutral.
2) Row variation – 4×8–15
Options:
Band row (anchor in door)
“Table row” / towel row on a sturdy surface
One-arm backpack row
3) Split squat OR step-up – 3×8–12/side
Wear your ruck if possible.
4) Push-ups – 3×AMRAP (stop 1–2 reps shy of failure)
Progress by elevating feet or adding pack weight.
5) Side plank – 3×30–60s/side
Session B (squat + push emphasis)
1) Rear-foot elevated split squat OR goblet squat (ruck held in front) – 4×6–10
Go deeper than your ruck stride.
2) Push (pick one) – 4×6–15
Pike push-ups (vertical-ish)
Feet-elevated push-ups
Band overhead press
3) Pull (different angle than A) – 4×10–20
Band face pulls / pull-aparts
Band lat pulldown (door anchor)
Another row variation
4) Hinge accessory – 3×12–20
Hip hinge good-morning with ruck
Hip thrust/glute bridge with ruck
5) Carry OR anti-rotation – 3 rounds
Suitcase carry 30–60s/side (ruck in one hand)
orPallof press with band 10–15/side
Progression rule: when you hit the top of the rep range on all sets, add weight to the ruck (or add a set).
Where to fit it in with 3–4 rucks/week
Example week:
Mon: Easy/medium ruck (heavy)
Tue: Strength A
Wed: Ruck (focus on fast / high)
Thu: Off or short easy ruck + 10 min prehab
Fri: Strength B
Sat: Long ruck (Far)
Sun: Off / walk / mobility
Rules:
Start lighter that you think you should
Add reps first. Then add weight.
If you’re crippled for 4 days, you did too much. Dial it back.
This isn’t bodybuilding. This is body armor.
RTFU Rule: If your training only makes you tired, it’s entertainment. Build strength that supports durability and longevity.
If you don’t already have a strength training program:
Do this for 6 weeks. If you can’t commit to 2×/week for 20 minutes, stop pretending you’re “serious” about that long 2026 ruck goal.
Until next week, Ruck The Fuck Up,
John
Life is hard. Be harder.
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Do you recommend going directly from one exercise to another and do "rounds" or take breaks and finish all sets of the first exercise before switching to the next?