Why Hunters Should Do Long Duration Zone 2 Training

Zone 2 training is exceedingly popular right now thanks to folks such as Peter Attia championing it. But the truth is, Zone 2 work has been a pivotal part of athletic development and endurance training plans for a long, long damn time. Back in the day, it was just called cardiac output training. Folks like Joel Jamieson, Mark McLaughlin, and Bill Hartman – who adopted it from Soviet exercise physiologists – popularized it among coaches and trainers here in the States. And for good reason – it is the foundation of all other conditioning because builds the structural elements of your aerobic system.

But why is it so important for hunters – especially those that hunt on mountains and head into the backcountry? Also, why is it so important for us to do long-duration Zone 2 sessions that last up to 90 minutes, sometimes more?

I’ll lay all of that out for you, starting with what Zone 2 does for your body.

What is Zone 2 and What Does it Actually Do?

What is Zone 2?

Zone 2 is the intensity zone just below your aerobic threshold. That means you’re still predominantly using aerobic energy pathways to contract your muscles. The only definitive way to know if you’re training in Zone 2 is to measure your blood lactate as you exercise. You’re in Zone 2 when your blood lactate is between .17 mmols and .2 mmols. Now, it’s impractical for most people to stick themselves and measure their blood lactate during each training session, so we work off of approximated percentages based on max heart rate tests or calculations. Zones based on percentages are tricky because different folks use different schools of thought and calculate the zones differently. I’ve seen folks say that Zone 2 starts anywhere from 55% to 65% of max heart rate, and ends anywhere from 75% to 80% of max heart rate. Most systems, however, agree that for most people it’s between 65% and 75% of heart rate max. 

So, let’s say your max heart rate, based on the equation 211 - .64(age) is 189. Your Zone 2 is roughly between 123 bpm and 142 bpm. If you’re a bit fitter and have done a lot of aerobic training, you can likely bump that up by 5 - 10 beats per minute.

You mostly burn fat for fuel in Zone 2, but at the upper end of the range, there is some contribution from carbs. Since that’s the case, Zone 2 training improves your aerobic efficiency, making your body better at utilizing fat for fuel while sparing carbohydrates for way more intense efforts. This is a good thing for day-to-day stamina on a hunt lasting a week or longer. If you deplete your carbs on day one, well, you’re going to have a bad time starting on day two.

What does Zone 2 Do for You?

Zone 2 training builds the structural elements of your aerobic system. Let’s start with the heart. The main adaptation at the heart is eccentric ventricular hypertrophy – specifically of the left ventricle. This happens because blood pools in the left ventricle as it returns to the heart, stretching it. As a result, the heart is trained to handle a lot of blood coming back to the heart and it pumps out more blood with each beat, improving what’s called stroke volume. This improves cardiac output, or the amount of blood the heart pumps out each minute. (Hence why it’s been called cardiac output training.)

The capillaries are at the other end of the cardiovascular system. These are the smallest blood vessels in your body. They transfer oxygen and nutrients to your muscles and recover metabolic waste products to take away from the muscles. Zone 2 training increases capillary density, giving your body more surface area for transferring oxygen and nutrients and removing waste products. The adaptations at the heart and in the capillaries coincide to reduce blood pressure.

Next up is mitochondrial density. You remember mitochondria from the Magic School Bus when Ms. Frizzle and the gang taught you that the mitochondria are the powerhouse of the cell. That’s true. But mitochondria also clear lactate, which helps to reduce fatigue during intense exercise. Fewer, or shittier, mitochondria, and you get tired a lot faster. Zone 2 training increases the amount of mitochondria in your muscle cells, especially your Type I, slow-twitch muscle cells.

Then there’s the effect on your nervous system.

Consistent Zone 2 training decreases sympathetic tone and increases parasympathetic tone because there is a strong tie between cardiac function and vagal nerve activity. The vagal nerve runs the show on the parasympathetic side of your autonomic nervous system. So, what does this mean for you? That consistent Zone 2 training chills you out, lowers your heart rate, improves a lot of other automatic functions in the body, and helps your nervous system shift into recovery mode much faster after exercise.

Those are the main points about what Zone 2 is and what it does for you. Let’s move on to why we promote long Zone 2 sessions.

Why Long Zone 2 Sessions?

When I say long Zone 2 sessions, I mean longer than an hour and more like 90 minutes. Just wanted to get that definition out of the way before we got into the meat of this section. We’ll start with practicality.

Long Sessions Make It Easier to Get in the Volume

Aerobic base building requires sufficient time and training volume in Zone 2. While you can get a training benefit from any time training in Zone 2, provided it’s not overly mixed with high-intensity intervals, it takes hours per week in Zone 2 to build an aerobic base. If you’re totally new to aerobic base building, two hours per week can make a dramatic difference. But for most folks, it’s best to aim for three to four hours per week during aerobic base building. One, 90-minute session gets you about halfway there. That’s pretty neat.

It’s important to maintain your Zone 2 training adaptations after the aerobic base-building phase. That’s right, you can’t just stop doing it and expect to keep getting the benefit. You have to maintain it. A 90-minute plus session over the weekend and a shorter duration session during the week is enough volume to help most folks maintain their aerobic base.

Resembles What We Do While Hunting

While hunting, especially during spot and stalk, upland, and still hunting, we spend most of the day moving at low- to moderate intensity. So, doing that in preparation for hunting season seems like a real dang good idea. You can’t just do short training sessions all the time and expect your body to efficiently produce energy all day when you’re out hunting. You must train it to produce energy all day. Long Zone 2 sessions do that.

As we get into our pre-season program, we prescribe sessions that last up to 3 hours. That looks a whole lot like hiking while keeping an eye on your heart rate. It’s a double-whammy. It’s specific to the tasks we do while hunting, and you maintain, or improve, your aerobic fitness the whole way up to hunting season.

Longer Time in the Zone Accentuates the Adaptations

You learned about the adaptations to Zone 2 training and what they do for you in the previous section. Staying in the zone for longer, continuous durations accentuates those adaptations. It’s more time for the muscle of your left ventricle to stretch in response to blood coming back into the heart. It’s more time for your body to build the pathways that use fat efficiently as fuel. It’s more time to stimulate your slow-twitch muscle fibers and build mitochondria. 

Yes, these adaptations happen during shorter sessions – improving cardiac output for example – but longer, continuous time in the zone helps to maximize how your body utilizes fat for fuel while sparing carbs. The longer, continuous duration also helps to maximize slow-twitch muscle fiber development and mitochondrial development.

More continuous time in the zone means better adaptations.

Now, please don’t read this as shorter sessions are worthless. They most certainly are not. Use what time you have and you will still get a training benefit. But, longer sessions will drastically improve your fitness.

Hunting as a Frame for Understanding

Now, think about all of this through the frame of hunting. Let’s use a week-long elk hunt as an example. You’ll be underfed, underslept, and moving a whole lot. 

Since you’ll be underfed, it’s super important that your aerobic lypolytic (fat-burning) pathway is well-developed. Otherwise, you’ll burn through the carbs in your muscles and in your liver relatively quickly without the ability to replenish them. No bueno.

You’ll be underslept, meaning that it’ll be tougher to regulate your emotions. Aerobic training improves emotional regulation while keeping you toward the parasympathetic side of your autonomic nervous system.

You’ll be moving a lot. The better your ability to move below aerobic threshold, the better your endurance and your stamina. 

How about we view it through the lens of an upland hunter chukar hunting their way across the west or just chukar hunting a day or two per week throughout the season?

You’re going up and down hills all day. The best way to keep that from costing you too much is to have serious aerobic efficiency so you don’t jump up into higher heart rate zones as soon as you start marching uphill.

You have to handle your dogs and make good decisions about shooting. Talk about needing the emotional benefits that come from aerobic training. (Yes, I understand some folks are just naturally cool as a cucumber. But that ain’t everyone.)

You’ll need the ability to recover between hunts. Without enough Zone 2 training, especially long duration, your recovery will lag.

In both instances, it’s important to maintain balance toward the parasympathetic side of your autonomic nervous system so you recover between hunts.

What Should You Do?

If you’re not doing any conditioning at all, start by doing a couple of 45-minute Zone 2 sessions per week. Walk those up to 60 or 75 minutes during the course of a month. Then, start adding in a 90-minute session on the weekend while continuing with a couple of shorter sessions during the week.

If you’ve been conditioning, and doing Zone 2 training, but just not doing longer sessions. Start adding a longer session on the weekend, working up to 90 to 120 minutes.

We’re currently doing 75- to 90-minute weekend sessions in Backcountry Ready and our DIY programming. But we’ll progress up to multiple-hour sessions as we get into summer.

And if you want certainty about your hunting fitness, and you want to save the mental space for other aspects of hunt prep, turn it over to us. Shoot an email to humanpredatorpackmule@gmail.com and we’ll get your conditioning dialed in so you’re the first guy up the hill this hunting season.