Heart Rate, Burn, and Grit: What a Ruck March Study Reveals About Walking with Weight

Heart Rate, Burn, and Grit: What a Ruck March Study Reveals About Walking with Weight

Rucking is often described as the perfect minimalist workout: just walking, but with weight. But what actually happens to your body when you load up your ruck pack and hit the trail?

A recent study out of the University of North Georgia set out to answer that exact question. And while it focused on ROTC cadets, the findings have implications for anyone interested in getting fitter, stronger, or just more efficient with their time outdoors.

Turns out, adding weight doesn’t just make things harder–it changes your entire physiological response. Heart rate, calorie expenditure, perceived effort–it all shifts. We read the study and broke it down, so you don’t have to. Here’s what they found, and what it means for you:

 

The Study: Loaded vs. Unloaded Ruck Marches

Researchers tracked 9 physically trained cadets as they completed two identical 6-mile ruck marches. One with a 43-lb load (ruck pack + gear), and one unloaded, with no additional weight. 

Both marches followed the exact same hilly outdoor course, and cadets were free to self-pace. During each test, they wore high-tech fitness monitors to track heart rate, cadence, smoothness, and more.


The Big Question: What Does Carrying Weight Actually Do?

The goal was to compare how the body responds when carrying weight vs. not–without changing the route, terrain, or level of fitness in the participant.

What they found: load changes everything.

Let’s break it down.


Key Findings: 6 Major Differences with Weight

When comparing those cadets rucking vs those carrying no load, researchers found 6 major differences, including time to finish, heart rate, calories burned, walking cadence, perceived effort, and running form/smoothness.


  1. Differences in Time

Researchers found that cadets took approximately 20% longer to complete the loaded march (an average time of 1 hour 15 min) compared to the unloaded one (around 56 minutes). Additionally, only 2 of 9 cadets hit the gold-standard goal of finishing the loaded ruck march (LRM) in under 70 minutes.


  1. Heart Rate Differences

The cadets who performed the LRM (loaded ruck march) had an average heart rate of 181 bpm during the march (90.5% of the max). The max heart rate during the LRM (loaded ruck march) was nearly 197 bpm. These heart rates mirror what’s seen in elite endurance athletes–which shows just how taxing a loaded ruck really is.


  1. Calories burned

Adding weight to the march led to a 45% increase in energy expenditure. In other words, the same 6-mile distance burned significantly more calories with a ruck.


  1. Differences in Cadence (Steps per Minute)

Cadets participating in the LRM (loaded ruck march) had a cadence of around 135 steps per minute. On the other hand, cadets participating in the unloaded ruck march (or ULRM) had a cadence of 157 steps per minute. That’s a 16% drop in cadence, likely caused by the need to preserve energy and keep the load more stable throughout the ruck.


  1. Perceived Effort (RPE) Differences

Cadets who participated in the LRM (loaded ruck march) rated the loaded march as significantly harder than a regular ULRM (unloaded ruck march). RPE scores jumped from an average of 11.8 to 15 out of 20–meaning it shifted from “light” to “hard” exertion in the opinions of the cadets, just by simply adding weight.


  1. Differences in Running Form and Smoothness

Surprisingly, cadence dropped among the cadets performing the LRM (loaded ruck march). But, interestingly enough, smoothness didn’t suffer. In fact, the loaded march showed less jerkiness, likely due to greater core muscle engagement to keep the load steady. 


So, What Does All This Mean?

Adding weight–just like wearing a ruck–triggers real, measurable changes:

  • Heart rate goes up
  • Calorie burn increases
  • Your body works harder–even at a slower pace

Even though the march was the exact same course and distance between the two groups, the weighted version forced cadets to dig deeper. Their bodies responded with higher cardiovascular strain and a noticeable bump in perceived difficulty.

That means more adaptation. More stress = more growth in the long run.

 

Why This Matters (Even if You’re Not in ROTC)

This study focused on cadets, but the lessons apply to anyone looking to get stronger or burn more calories without sprinting or lifting heavy in a gym.

It confirms what ruckers already feel: 

Add weight, and your body has to work harder–even if the movement is simple.

That’s great news if you’re:

  • Short on time
  • Looking for a low-impact but high-effort workout
  • Trying to build endurance, strength, or fat-burning potential outdoors

It also helps explain why rucking feels so productive–because it is!

 

Final Thoughts: The Case for a Simple Load

This study may not have had a huge sample size (only 9 cadets), but the trends were very clear and consistent. Walking with weight changes the physiological game in ways that align with elite endurance efforts–without ever needing to run.

And the best of all? It’s 100% scalable.

You don’t need 43 pounds on your back to start seeing–and feeling–the benefits. Even 10-20 lbs can increase your heart rate and calorie burn while staying joint-friendly.

So, if you’re already walking… why not add some weight and maximize the efficiency of your workout?