How To Build RELENTLESS ENDURANCE for Selection

Intro

If you’re just rucking and running for cardio, you’re missing the keys to developing what I call relentless endurance.  

Relentless endurance is the ability not just to crush your timed events, but to transition seamlessly from one to the next, with rapid recovery, impressive performance, and an unending engine.

In this article, I’m sharing the blueprint and methodology I use with my athletes to develop relentless endurance, along with sample weeks of training at the end.  

What Is Relentless Endurance?

When we compare athlete performance, we often talk in terms of a candidate’s best 5-mile run, 12-mile ruck, or how many pull-ups they hit.  

But that’s not what selection tests for. Depending on the branch, you’re looking at several weeks or a multi-month crucible that stacks fatigue, exposes weaknesses, and then expects you to perform.  

So, you can understand how having a great timed 5-mile or 12-mile ruck is great. But that performance is just a snapshot of your peak endurance in your best state. What matters more is how you perform when fatigued.

So ‘Relentless Endurance‘ and ‘Peak Endurance’ are two concepts and terms I will use in this article.

Peak Endurance is what drop jaws with single feats of performance-like running a 30-minute 5-mile. 

Whereas Relentless Endurance is running 7:30-minute miles. Then grinding through a brutal leg and overhead circuit. Then rucking with 65 pounds while carrying 45-pound dumbbells in hand. And after all that, coming back and grinding out sub 8-minute miles.

Peak Endurance VS Relentless Endurance

Before I share how to develop relentless endurance, I want you to look at this chart.

You can see how someone who trains for peak endurance will crush the competition on fresh legs.   And without the right training, you will have a  massive  dropoff when fatigue sets in. Whereas someone who trains for relentless endurance has minimal drop off in performance.

This concept of relentless endurance explains the anecdote of the cross country runner who comes out first on the timed events but then crashes and burns after he’s tested in other areas.

Pillars to Relentless Endurance

Now, let’s dive into the 3 pillars to developing relentless endurance.

Pillar 1: Exceed the Standards

Pillar 1 is exceeding the endurance standards in your peaked state. Because no matter how conditioned you are, you will not get faster with fatigue. In other words, in order to hit a 35-minute 5 miles on fatigued legs, you need to be running 7-minute miles on fresh legs first. And the higher your peak, the greater potential for relentless endurance you will have.

And beyond that, we have hard data on peak performance being predictive of success.

This SFAS study from 2019 shows that candidates in the top quarter of run times had a selection rate over 50%, while the slowest had 21% or less chances of getting selected.  

And the same is true for rucking, except the difference was even greater. With the bottom quarter of ruckers having a 5% selection rate and the top quarter having a 67% selection rate.

Why Should You Care About “Relentless Endurance”?

You might wonder, why talk about relentless endurance when the data on peak performance is so clear, and you can just focus on that?

Well, there’s two reasons:

1. There’s no test or data on what I would call “relentless endurance”

All that we have are the peak endurance tests. But, if they tested 5-mile runs after max push ups, a max set of 225lb squats, and a heavy ruck carry – I suspect that the fatigued 5 mile time would be a greater predictor of success. But because they didn’t, all we have to go off of is peak endurance scores.

2. Selection is a crucible – your cumulative performance is more important than a snapshot.

Nobody actually cares about how well you perform on day 1 if your performance bleeds every day and hour from that point on. Hyperfixating on those peaked, fresh numbers can become a problem.

Even with athletes I work with, they can get hyperfixated on numbers and have goals to be top 5 across the board. And while maximizing performance is my top priority as a coach, we also need to be realistic. If you are a guy who has to work really hard to be a middle-of-the-pack runner. You shouldn’t let running a 37-minute 5-mile instead of 35 deter you from shipping.

Remember, selection is about the cadre testing your performance and your grit – all to identify the best candidates for the job. It’s not as objective as a 100m dash at the Olympics. So, in those final months leading up to selection, I’d rather prioritize relentless endurance to ensure you recover quickly and perform across all events over fine-tuning your fresh 5-mile pace.

How Fast Should You Be?

So, pillar 1, relentless endurance, is about exceeding the standards, but what are the standards you should strive for before pivoting your training?

For your 2-mile run, most guys should strive for <13:20, and on your 5-mile run, under 38 minutes.

Both of these numbers are very achievable, even for you big guys, or those who have a tougher time running. Anything slower than these run times, and you’re cutting it close. Remember, the benefit of a higher peak is that you can have a rough day and still make the cut.

For rucking, I want to see you hitting 8 miles with a 60lb ruck at a low intensity heart rate, doing 16:00 minute miles or faster. That will put you pretty comfortably at < 14-minute miles when you pick up the pace.

Quick caveat: these are general guidelines. In all my articles, I try to help the most people possible with general information, but the reality is I would treat someone who is 5’7 and 150lbs very differently from someone who is 6’6 and 240. If we’re working 1 on 1, I’ll be able to do a full analysis and give my recommendations, training, and reasoning behind it.

But otherwise, make a call based on what you’re comfortable with and make sure you’re referencing the data I’ve shared in this video and others on performance and selection rates.

Pillar 2: Fatigued Endurance Efforts

The second pillar to developing relentless endurance is training endurance under fatigue.

Essentially, practicing the skill of performing on tired legs or a pumped upper body will allow you to perform better than if you don’t practice than someone who doesn’t practice it. 

I recommend incorporating a few of these strategies from day one of your training. However, there are a few downsides, so I’ll share a few examples first, and then outline when you should and shouldn’t use them.

Strategy 1: Intervals after leg training

Strategy 1 is performing short-distance intervals after leg training

For most of my athletes, I program hard running intervals immediately after our heavy, lower-body or full-body session of the week. The benefit is that not only are these workouts insanely challenging physically and mentally because your legs are pumped with blood and you’re running at near max effort, but you’ll also realize that after 4 – 6 weeks you’ve been physically and mentally sharpened. And when it comes time for the final kick in your PST or ACFT, you will know what it feels like to push hard on spent legs.

The other benefit is that by consolidating our most high-stress sessions on the same day, that leaves more time for recovery later in the week.

Example Workout:

Strategy 2: Non-Impact Cardio after Strength/Metcons

A second example is adding zone 2 finishers to your strength or metabolic conditioning sessions.

This acclimates your body to the rough transition so many of us have felt where your whole body is pumped and then you need to slow your breathing and transition to moving your body at a low intensity – as little as 20 – 45minutes of easy rucking, swimming, or stationary bike is a great addition after your lift.

 
Example Workout:

Strategy 3: Calisthenics Before Zone 2 Cardio

Strategy 3 involves redistributing some of the calisthenics volume you had throughout your training week and strategically placing it either at the beginning or throughout a long, zone 2 endurance session.

Now, the downsides to pre-fatiguing your training are that it can detract from the purpose of the endurance session which follows. For instance, if your goal is to practice max speed 400m repeats, it doesn’t make sense to do that session after training legs.

But, if you’re comfortable running slower 400m repeats at 1.5 or 2-mile goal pace (and making them more challenging than they would be fresh), you can still hit that session after legs. 

When I incorporate endurance training under fatigue, it is highly targeted to the athlete’s needs. You don’t want all your endurance work done in a fatigued state – that’s not how you build peak endurance most effectively. But if you never train it under fatigue, you’re missing out on developing that key skill, which is critical for selection.

Pillar 3: Functional Metabolic Conditioning 

Pillar 3 is functional metabolic conditioning, which, in a more specific fashion than pre-fatigued efforts, trains your body’s ability to move from event to event and maintain a high work rate.

The problem with most metabolic conditioning sessions I see, though, is that they don’t serve a purpose.  

Here’s a sample functional metcon with a focus on grip:

You’ll go from exercise to exercise with your 65lb ruck on to add fatigue as you move from carries to walks

The metabolic conditioning you do should be tailored to your selection course.  

For instance, for Army athletes, I often focus on three main areas:

1. Grip Focus (Farmer Carry, Pull Ups, Hangs)
2. Overhead Emphasis (OH Press, Front Rack Carry, OH Walk)
3. Leg and Core Stamina (Goblet Squat, Lunges, DB RDL)

It varies based on whether someone’s training for BUD/S, SFAS, or A&S.

And when it comes to incorporating these workouts, I’d wait until you’ve reached pillar 1s target times.

And from there, start incorporating them once per week, or potentially twice as you reach closer to your ship or selection date.

Bonus Tip

My bonus tip for this article is to do your relentless endurance work, but watch your recovery. Once you do them, you’ll see these sessions are intense. Intervals after legs and metabolic conditioning sessions will push you to 100%, even adding zone 2 finishers to your calisthenics or lifts will add fatigue.

But, every session cannot and should not be 100%. Progress will stall, and you’ll burn out. Make sure you have 1 to 2 days of low-intensity work and at least 1 rest day per week. It’s what I do for my athletes and what I recommend for everyone.

Conclusion

If you’re not training for relentless endurance, you’re leaving performance on the table. Anyone can run fast fresh. That’s the ACFT, but it’s not selection. Selection is about how you move when your legs are shot, your grip’s gone, and your heart rate won’t come down.

Relentless endurance is what lets you transition from max-effort runs to heavy carries and grinder circuits without falling off. So, make sure you’re incorporating this kind of training into your routine. Your future self will thank you.

If you’d like to work with me 1 on 1, the application link is here.