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A Case Against Cardio, Part 27

I’m mostly joking with the title. Though, considering how much I’ve written on this topic [1] since starting this blog way back in 2006, it’s probably not too far off. And it’s not just me. Endurance training has been getting the snot beaten out of it in recent years. A variety of media outlets, TED talks [2], other blogs, observational research and clinical trials have all sounded the alarm about the dangers of excessive chronic cardio [3].

A new string of studies [4] has found evidence of higher arterial plaque levels in the most active endurance athletes. This is becoming a trend. While endurance athletes tend to have more of the calcified kind of plaque, which is more stable and theoretically less prone to dangerous ruptures than less-calcified plaque, it remains worrying. I’ve spoken in the past about the proclivity toward heart problems found in endurance athletes [3]. I know many former peers with atherosclerosis, cardiac arrhythmias, and other heart troubles.

As disconcerting as that is, that’s not what today’s post is about.

Today, I’m asking, “What’s the point?”

The whole “this thing will kill you” tactic is helpful from time to time, but more effective is the utility argument: what works better? What gets you fitter, faster, stronger, and sexier?

In recent years, researchers have been running direct head-to-head comparisons between traditional endurance training and more intense forms of exercise, like strength training or sprint interval training. They almost always end badly for cardio. How badly?

Let’s find out:

A recent review [5] asked an important question: what’s better for altering body composition—resistance training alone, endurance training alone, or endurance training with resistance training?

Resistance training won, leading to greater fat loss and retention of lean muscle mass. Furthermore, RT alone was better at reducing fasting insulin levels and improving blood lipids.

The only way the authors were able to find endurance training helpful was by including high intensity interval training in the endurance category. Their overall conclusion was that the “focus of treatment” for people interested in losing body fat should be on producing a large metabolic stress via intense strength training and/or interval training.

This jibes with other recent papers:

Endurance training burns more belly fat [6] when you incorporate strength training.

In obese teens, strength training alone reduced body fat more [7] than endurance training or combined endurance/strength training.

In women with PCOS, both strength training and interval training [8] reduce body fat and improve insulin resistance without affecting body weight, which indicates gains in lean muscle mass. In another study [9], women with PCOS who engaged in standard moderate cardio improved endothelial function but lost no body fat.

It’s surprising, isn’t it? You’d assume that although strength training is definitely great for health, fitness, and body composition, adding in some endurance work could only improve those metrics even more. Sometimes, that’s true [10], but in the majority of studies, this just isn’t the case. Strength training or interval training alone are generally superior.

How about “unhealthy” people with conditions like heart failure or diabetes? Aren’t they too fragile to endure resistance training or high intensity intervals? Wouldn’t an hourlong jog be a better, safer use of their time?

In September [11], patients with heart failure (with preserved injection fraction [12]) were placed on one of two exercise modalities: continuous medium-intensity cardio (30 minutes at 70% maxHR) or high-intensity interval training (4×4 minutes at 85-90% maxHR; 3 minutes rest). HIIT resulted in numerous improvements to arterial function and ventricular volume. The HIIT group even improved their cardiovascular fitness, with VO2max going up. The cardio group saw no improvements at all.

Other studies [13] have found that endurance training can improve VO2max in heart failure patients but has little effect on markers of endothelial function or arterial stiffness.

Recently, researchers compared [14] the effects of endurance training to either resistance training or HIIT on microvascular function in type 2 diabetes [15]. Microvascular function refers to the system of tiny, precious little capillaries delivering blood and nutrients to individual cells and tissues. Poor microvascular function predicts future cardiovascular problems [16], so it’s really important. They found that the training modalities which employed the most amount of muscle tissue produced the biggest improvements. As most traditional endurance training localizes muscle recruitment, while HIIT and strength training tend to target the entire body, that’s a roundabout way of saying strength training and HIIT trounced endurance training.

Other diabetes researchers examining this exact issue are quick to say [17] that “more exercise is not better” and that it’s all in how you exercise. You can’t just do something that gets you winded and hope you’re destroying your glucose intolerance, insulin resistance, and normalizing your glucose levels. You have to train the glucose sinks—the actual muscles that will be accepting (or rejecting) the glucose. And the absolute best way is to move those muscles, particularly vigorously. Jogging through your neighborhood or cycling for three hours just doesn’t cover all your bases like a full-body strength workout [18] or a CrossFit WOD [19].

We’re not the fragile snowflakes we think we are. We can tolerate intense exercise. We cannot tolerate avoiding intense exercise. Dress for the job you want. Train for the intensity you want your body to endure and thrive in.

Plus, we’re all busy. Everyone’s working. Very few single income families exist these days. And if we want to be able to have it all—perform well at work, maintain relationships at home, procure and prepare good food, enjoy much-deserved leisure time—smart, efficient exercise has to be a part of our routine.

This might be even more relevant for my female readers. In many respects, you have it harder. You often take on more domestic responsibilities while still working, and yet the conventional wisdom is that you mustn’t lift too many weights or damage your delicate bodies with intense intervals. You’re warned about “getting all bulky.” You want “tone, not muscle.” And so you end up taking hour long pilates classes or doing 45-minute light aerobics sessions, when you could just as easily—and to greater effect—lift something heavy [20] for 10-15 minutes or go sprint up a hill [21] or do a quick bodyweight circuit [22].

What’s the point of hard-core endurance training? If you’re competing, professionally or on an amateur level, I get it. The drive to push your past its limits and beat the other guys is powerful and difficult to ignore. There’s something to be said for satisfying that part of human nature. There are probably benefits to seeing your enemies driven before you and hearing the lamentations of their women, particularly psychological ones.

If you’re getting paid to run marathons [23] or compete in triathlons, keep doing it. You’ve got the justification you need to tax your body and perform what probably amounts to a suboptimal training regimen. Just be sure to get out while you can still walk [24] and move well.

I don’t hate cardio (I might have loved it, in a manner of speaking, a bit too much, in fact). In the context of a movement-nutritious lifestyle—lots of walking [25], strength training [26], occasional sprinting [27], physical play [28]—some cardio can be beneficial. It simply doesn’t work as well as we’ve been told it does. There are just better ways most of us can and should be spending our training time.

All that said, endurance training can enhance your health, and there are better ways to do it. Stay tuned for Primal Endurance, where I’ll lay out a whole new paradigm for endurance training.

Now let’s hear from you: have you experienced middling or nonexistent improvements from straight up endurance training? Does this gel with your experiences?

Thanks for reading, everyone.

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