How Important is Rucking for SFAS?

 How Important Is Rucking for SFAS?

This is an updated rewrite of the very first article I ever posted to Reddit. This is in essence my villain origin story. Before this I was just a “reply guy”, and I spent my time arguing with dumb people about stuff they were making up. It was all rumors, conjecture, and false anecdotes. At any rate, one particular dumb person who had just been to selection was actively promoting the idea that rucking wasn’t very important and you didn’t even have to rain rucking during your prep.  I responded in my customary calm and collected manner.

I’m obviously joking. I called him an idiot, because what he was saying was pure idiocy. But he was adamant. He wanted data, not opinion. Fair request. So did what I do. I pulled together a little micro-research paper. Here's the data, broken into the two questions that actually matter: how important is rucking to getting selected, and how important is it in your train-up.

Rucking is the most important performance measure in SFAS. To be clear, land navigation is the most failed event, but land nav is just rucking, but cross-country. Ergo, rucking is king. But this conclusion isn’t my opinion, it’s been repeatedly documented.  And it’s been documented across 30 years of SFAS history. Three independent studies, starting all the way back to 1990, just 2 years after SFAS was established, through 2010 (what many observers note as a time of some turmoil), and through the final 2019 study, all land on the same conclusion: physical performance, and rucking specifically, is the single strongest predictor of who gets selected. I haven't seen a study that contradicts this. Rucking is king, and it isn't close.

Rucking and Your Train-Up

Knowing rucking decides selection is one thing. Knowing how to train rucking is another, and this is where most candidates waste time. Mountain Tactical Institute ran a two-part research series on this exact question: Ruck Deep Dive, Study 1 identifies which physical attributes correlate with baseline rucking ability, size, relative strength, and aerobic capacity all show up as predictive. Ruck Deep Dive, Study 2 tests what actually improves ruck performance over a 6-week training block. The answer is progressive, field-based load carriage, not just running more miles.

The finding holds up in older research too. A 1987 study by Kraemer et al. tested strength training against aerobic-only training on ruck time and found the aerobic-only group showed almost no improvement. Strength combined with aerobic work is what moves the needle, a finding replicated in a follow-up Kraemer study on female soldiers in 2001. So you need to ruck, you need to strength train, and you need some foundational endurance work. All of my advice, even though I didn’t know the research, has been consistent with this. I’ve gotten much more precise. How precise? Read on…

That Was Then, This Is Now

If you find the original thread you see a back and forth in the comments. More arguing about how the data wasn’t correct, rucking is bad for your knees, I know lots of guys who didn’t ruck to prep. Utter nonsense. You will also find more than few instances where I recommend the old legacy SWCS/THOR3 training plans. Obvious nonsense, but only obvious now and this time it was my nonsense. I hadn’t really done the full research on this part yet and what I knew was that the direction leaned towards “progressive, field-based training with real load”. This is what the legacy plans programmed, so I thought they were good.

It wasn’t for some time that I really looked at the data. There are mountains of research on this topic. And it’s overwhelmingly clear that the best way to build ruck performance is field based progressive load carriage, usually 2-3 times a week, focused on short intense sessions. The legacy plans had the field based progressive load carriage part right, but they completely missed the 2-3 times a week focused on short intense session part, and that’s the part that addresses injury mitigation, programming, and balancing the rucking with all of the other domains you need to address, like weight training. Many of the legacy plans have almost no weight training.

That’s when I started deep diving the rucking literature. I penned my first draft of Ruck Up Or Shut Up, I built the analytical framework for Shut Up And Ruck, and then I never stopped researching and writing. I cite a dozen high-quality sources in my rucking performance research, but there are hundreds of similar studies. Not even one that I’ve found contradicts anything that informs my writing. It is some of the most unambiguous research out there. It’s a case of “the more you learn, the more you know how much more you need to learn”, but the lessons are all the same.

New Research: Rucking Performance and Long-Term Durability

And now we have another study to add to the pile. In October 2026, researchers published a two-year longitudinal study involving 792 soldiers enrolled in SFAS. They evaluated candidates’ physical performance, sleep, nutrition, and other health-related characteristics, then tracked medical encounters and military retention over the following two years. The findings were particularly interesting for anyone who still thinks rucking isn’t important.

Slower road-march performance was associated with increased subsequent musculoskeletal injury risk. Specifically, for every one standard deviation increase in road-march completion time, the adjusted odds of cumulative musculoskeletal injury increased approximately 33%. Read that again. We’re no longer talking exclusively about whether rucking performance predicts selection. We’re looking at a relationship between rucking performance and longer-term health outcomes in an actual SFAS population.

Now, before someone gets excited and concludes that rucking faster prevents injuries, that’s not what the study demonstrated. This was observational research. It identified an association, not causation. The researchers also followed candidates for two years, regardless of selection outcome, so these weren’t necessarily injuries sustained at SFAS.

But consider the broader picture. Across decades of research, road-march performance has repeatedly emerged as an important predictor of selection outcomes. Now we have additional evidence that slower road-march performance is associated with subsequent injury risk. That doesn’t make rucking some magical injury-prevention exercise. It suggests that road-march performance may tell us something meaningful about a candidate’s broader physical readiness and durability.

And that’s exactly why I don’t treat rucking as an isolated event that you simply need to survive. It’s a performance domain that needs to be developed deliberately, progressively, and alongside strength, endurance, nutrition, and recovery. The same study found associations involving resistance training, dietary protein, and sleep quality. That’s another reminder that the objective isn’t simply to ruck more. It’s to build a better-prepared tactical athlete. Train rucking correctly to perform well at SFAS, and beyond. Rucking performance matters at selection. And the new evidence suggests it may tell us something about the candidate beyond selection, too.

What This Doesn't Cover

This is a simplified picture of what SFAS actually assesses. We’re just talking rucking. It’s critical…the most critical. But it’s just one domain. You still need to be smart, resilient, a decent communicator, emotionally steady, and of good character. Those traits matter and they're genuinely hard to train, partly because there's no clean benchmark for them the way there is for a ruck time. For posterity, you should aim for 12-13 minute miles, with 55 pounds, pretty much indefinitely. If you can do that, you’ll be in a strong performance position for SFAS. Now you just need to work the other 100 things.

Good luck.