First, conventional cardio has been found to deteriorate muscle tissue when performed for long periods of time. Along with all your hard-earned muscle, it’ll decrease your testosterone levels, too. A recent study in the American Journal of Physiology found that, worse yet, steady-state cardio decreases a muscle’s ability to absorb glucose after training by immobilizing the glucose transporter (also known as GLUT4) transport system, which is absolutely critical to achieving a full, dry look onstage after refueling with carbs. Finally, cardio also limits hypertrophy by shutting down the mammalian target of rapamycin (mTOR) pathway—one of the primary regulators of muscle growth. With the mTOR pathway shut down, you’ll burn as much muscle as fat during your contest preparation.
Despite all this, however, it’s possible to derive massive benefits from your cardio work while simultaneously avoiding all the aforementioned disasters. In fact, it’s even possible to make cardio anabolic, provided you perform it the right way, at the right time, supported by the right nutritional supplementation.
The “right” type of cardio for your pre-contest prep work is high-intensity interval training (HIIT). Defined, HIIT is prescribed as a series of bursts of all-out, high-output cardio activity followed by rest periods. Years ago, this type of training was known as fartlek (“speed play” in Swedish), but like everything else in the fitness industry these days, it’s been polished up and trotted out as new—with a fancy name and an acronym to go with it. The main idea is still the same, though, and we’ve come a long way in our ability to integrate it into solid programming at the correct time with appropriate levels of volume, intensity, and duration.
There’s plenty of research to support this. In diametric opposition to the results you’ll get from steady-state cardio, HIIT has been shown in recent work published in the Journal of Strength and Conditioning Research to actually increase testosterone levels in addition to increasing GLUT4 concentration. It also increases 24-hour mitochondrial biogenesis (the formation of new energy-producing mitochondria in cells—I’ll explain why this is important in a moment). This process typically shuts down the mTOR pathway during steady-state cardio, but research shows that this doesn’t happen during HIIT. Finally, HIIT triggers an increase in the concentration of myofibrillar nuclei, which is important because muscular hypertrophy depends on increases of nuclei concentration and the content of muscle fibers.
Timing Is Everything
Again, along with the type of cardio you do, it’s the timing of when you do it that’s important for fat burning. Fortunately, if you commit to HIIT as your primary form of contest-prep cardio, there are several ways you can enhance the process to turbo-charge your fat-loss potential.
First, schedule your training so you’ll be completing your HIIT workouts up to an hour prior to your resistance training. Numerous studies have shown that this combination, timed properly, can amplify mitochondrial biogenesis and research in the Journal of Applied Physiology found that this combo also turns on the powerful mTOR-pathway of growth instead of shutting it off.
And when it comes to the type of resistance training you’re undertaking in concert with HIIT, volume is key: Research shows that higher-rep, strength-endurance training is the most effective way to compliment your same-day HIIT sessions.
The idea here is to cycle your training. Blast out four weeks of HIIT, followed by four weeks without it—and there’s a twist to this. For the weeks when you’re not engaging in your HIIT training, your focus will strictly be on hypertrophy. You’re looking for the mitochondrial biogenesis and increase in nuclei effect here. The greater the nuclei density, the larger you can make a muscle fiber. Trouble is, the only way to increase the number of intracellular nuclei is to perform strength-endurance training—which will actually make the muscle smaller. In other words, to get more nuclei to get bigger, you first have to train to make the muscle smaller. Ironic, right?
The Growth Spark
At the end of a strength-endurance cycle, you’ll have an increased number of cellular nuclei. When you start a pure hypertrophy cycle, this will enable you to get bigger than is possible before the cycle. You may lose some mitochondrial density—what makes muscles oxidative—but it takes time to actually lose the mitochondria. What you’re essentially doing when you cycle your HIIT on and off is alternating between periods of increasing your potential to get bigger (your four-week HIIT cycle) and fulfilling that potential by actually getting bigger (your four-week hypertrophy cycle). There exist infinite permutations of HIIT, but for anabolic cardio, the idea is to go all-out (as close as you can take yourself to 100% power output) for 30 seconds, followed by four minutes of rest, for four to six cycles. Do this three times each week, for four weeks. A great way to get this job done is to use a spin bike (the stripped-down version in your gym’s aerobics room, and not the type found in the cardio area). Instead of increasing your speed and revolutions per minute, however, crank up the resistance on the spin bike and increase your rate of force production. With this lower cadence, you’ll get a greater surge of testosterone, likely because it simulates the effects of resistance training.
The Leucine Effect
The final component to your HIIT programming is the timing of your nutritional supplementation. If you’ve read any of my previous columns, you know I’m a major advocate of adding leucine to your supplement regimen. In this case, I’d recommend taking at least 5 grams before your HIIT sessions. A study in the American Journal of Clinical Nutrition showed that taking leucine-enriched amino acids before a bout of aerobic exercise can increase post-exertion protein synthesis by up to 33%.