If you ever want to be anything other than a show pony at some point you’re going to have to do some type of training to develop your work capacity. Work capacity can be a fuzzy catch all term for many things. It combines aerobic endurance, muscular endurance, and is the sort of thing pictured when people talk about Hell Week during BUDS.

Everyone gets all tangled up over trying to define the terms, as if there is any appreciable difference to cardio or conditioning. Both require you to have an elevated heart rate and both teach you to work for extended periods of time. And truthfully, there is no one exercise that is builds work capacity that is exclusively one or the other.

Cardio comes from the Greek word kardia, for heart. For lack of a better definition anything that makes your heart work harder is going to be cardio work. Sure, in some minds cardio is what you do on an empty stomach to try to lose some fat. It is mind-numbing and boring to many and people are worried about losing their hard earned muscle.

Cardio has copped a bad rap over the last twenty years in response to the jogging craze of the 70s. Even worse, with a rise in popularity of fitness classes we saw the rise and fall of the lycra-clad, big-haired aerobics craze – something no self-respecting man would ever do in lieu of bench press. But there’s nothing wrong with making your heart bigger and stronger and you don’t need to wear pastel lycra to improve your conditioning.

You may think that if anything that gets your heart rate up can count as cardio training that you will be fine just doing high rep squats. Well, no. Just like you can have concentric and eccentric muscle contractions when doing curls and presses, your heart can have the same training adaptations.

It makes sense that the hearts of endurance athletes and strength athletes differ, just like their physiques do. In endurance training, the athlete’s heart must pump large quantities of oxygen to the working muscles for extended periods of time. To cope with this the main chamber of the heart, the left ventricle, gets both larger and slightly thicker.

However, in strength-trained athletes, there isn’t the need to pump such large quantities of blood. In stead the heart is subjected to higher blood pressures, and in response the left ventricle thickens up, and can actually even reduce the internal diameter of the heart. What that means is even though you’re spending time performing exercises that raise your heart rate instead of seeing a fitness benefit you’re effectively reducing your possible horsepower, just like trading down from a V8 to a 4-cylinder car. Perhaps the reason why you huff and puff walking up a flight of stairs has little to do with the bulking cycle you’ve been on and everything to do with your heart struggling to pump blood to all the muscle you’ve got?

When it comes to conditioning there is a very clear hierarchy. Like it or not some exercises are just more effective. In tier one are the classics – running, swimming, cycling, rowing, cross-country skiing, and the versa climber. Tier two includes kayaking, boxing, and kettlebell snatches. It’s not until you get to tier three that you find the exercises most try to use for conditioning – skipping rope, circuit training and kettlebell swings.

The reason why circuit training is in tier three comes down to one factor – blood flow. When a muscle is tensed beyond 50% all blood flow is stopped. That means that less oxygen is being used by the working muscles because less is being provided. And when it comes to getting that adaptation to the heart that helps it grow it’s all about the need for high levels of oxygenated blood to be pumped to the muscles.

This is one of the big disconnects when it comes to conditioning work – your goal is to end up with higher levels of work capacity. While circuits may help to develop high levels of strength endurance they do little to boost the ability of your heart to pump large quantities of blood. Further, because of the low loads used they do little to develop muscular strength. Frankly, if you’re looking for ways to improve functional horsepower there is a far better way.

There’s a saying in sports performance that “if it fires together it wires together”. That means if you really want a way to get real world conditioning, the kind that helps you not just out work your opposition, but crush their heads like a grape, you need a combination of heavy lifting and tier one conditioning.

Pat O Shea in his book Quantum Strength and Power Training first talked about interval Weight Training, or IWTs. The basic setup goes like this:

• Perform a full body athletic movement such as the power clean, power snatch, or snatch pull for 8 – 12 reps. Immediately following the strength movement move to a cardiac conditioning effort for 2 – 4 minutes and work at 90 – 95% of your MHR. After completing this round, rest for two minutes and begin again, performing three total rounds.
• Following the three rounds take a five-minute complete rest. Let’s face it – you’ve earned it by now, but you’re only 30% done.
• Following the five-minute rest repeat the format first used, again using a whole body strength movement, but this time use a grinding type movement such as the front squat. Perform three total rounds again and take another well-earned five-minute break after.
• The final stage is a bodyweight circuit using exercises performed at high pace, with minimal rest for 6 – 12 reps each. Rest no longer than one minute between circuits. Complete 3 – 5 complete circuits.

I’ll be honest and say that after you’ve earnestly done one of these workouts you’ll never think of a few mindless laps of farmer walks and prowler work as conditioning ever again.

Things to keep in mind:

• Don’t substitute small exercises for big ones. Lat pull downs aren’t a replacement for power cleans.
• While the loads should be relatively light – O Shea recommends 70% of your 3RM – don’t skimp. The strength component must tax the muscles so you learn to display strength as well as high levels of conditioning.
•  90 – 95% of Max Heart Rate is hard. Like collapse on the ground hard afterwards. If you don’t despise these workouts you’re just not doing them hard enough.
•  If you think running for two minutes will make you skinny then stick to the big guy options – the Airdyne, rower, and ski erg – although a two-minute incline run on a treadmill is the hardest option you could do.
• If using a heart rate monitor don’t expect to see your heart rate at 90%+ for the first thirty seconds. It takes about that long for it to really jump. Instead expect to see it peak right near end of your effort.

Bonus points – if you’ve spent some time already addressing your fitness and know that while strong you suffer with endurance work, then use slightly longer intervals of 3 – 4 minutes. Three-minute efforts, in particular, are heavily used in training methods designed to peak VO2max abilities – that is the kind of training that gets you comfortable with being uncomfortable and increases your top end fitness dramatically.

More is not more when it comes to IWTs. A single session each week done following the full format is enough to see great improvements in real-world conditioning, and see you ready to kick some serious ass when needed. Trying to do multiple IWTs in a week will see you burnt out very quickly.

Try this IWT once a week for four weeks before taking a break:

First round:

Power clean x 8 – 12 reps

Row 2 minutes.

Rest 2 minutes.

Repeat for three rounds total.

Rest five minutes before beginning round two.

Second round:

Back squat x 8 – 12 reps

Airdyne 2 minutes.

Rest 2 minutes.

Repeat for three rounds total.

Rest five minutes before beginning round three.

Third round:

Mountain climbers x 10

Push-ups x 10

Burpees x 10

Squats x 10

Box jumps x 10 (jump up and step down).

Rest one minute.

Repeat for five rounds total. Crawl into a corner and curse my name.

Your goals for this workout each week should be as follows:

Record the distances rowed on each interval. At the end of the four weeks you should cover 10% more total distance than you did in the first week. A good starting goal is 550m per two minutes. That means you should break 600m per interval in the final week.

Record total calories on each round for the Airdyne. Each Airdyne model records calories burned slightly differently. On the newer AD6s we expect to see 40 calories or better for two minutes, while on the older AD4s and the Stair Master Air Bike we see roughly double that. In either case, just like with the rowing, your goal is to add 10% over the four weeks.

What you’ll see to begin with:

If you’re really out of shape you’ll notice a tremendous drop off in the number of reps you can get with the strength exercise as well as how far you can go on each tier one effort. Over time, as you become fitter and better adapted, you’ll see that all your efforts stay very close to one another. At my gym we expect to see less than a 10% drop in performance from one interval to the next.

When choosing your weights don’t pick a weight that you can just get 8 reps with for the first set. That’s too heavy and the likelihood is that you’ll then get only 5 – 7 reps in the second and third sets. Instead pick a weight that you are confident you can get 10 reps with and try to get at least 8 reps each set. If your three rounds see you hitting 12 reps each time add some weight for next week.

Don’t be scared of conditioning. You won’t lose muscle. In fact, as you get better conditioned and your heart gets stronger you’ll find all sorts of other benefits such as faster recovery between sets of your regular workouts as well as increased recovery between workouts too. A strong, healthy heart is the most important muscle in the body.