HICT, or High Intensity Continuous Training, is cardio for meatheads. When most people hear the word "aerobic," they think of running, rucking, or maybe dystopian rows of people hamstering away on cardio machines while watching TV.
Unlike those methods, HICT is different and unique. It's both high intensity and high volume. It also uses two of the body's three energy systems, making it a perfect metabolic conditioning tool for the lifter.
The body produces – or, more accurately, converts – energy through three primary systems. They're all working to some extent at all times, but the degree to which they work depends on the intensity and duration of the activity.
1. Alactic or ATP-PCr
This is the predominant energy system used during relatively short bursts of intense output. It's the most powerful system, but it's also the most short-lived. It can only provide energy for about 10-12 seconds before it's depleted and other systems begin to step in.
As an example, a 40-yard dash is heavily dependent on the power of your alactic energy system. The system also fuels other short burst activities like swinging a golf club or baseball bat.
2. Lactic or Anaerobic
During sustained, high-intensity activity such as a sprint, the anaerobic energy system starts to take over just as the alactic system fades out. This system breaks down carbs in the absence of oxygen to produce energy. This system is also powerful but is usually depleted after 60-90 seconds of maximal work. Activities that rely on this system include a 200-400 meter run or sustained bursts of effort in soccer, tennis, or boxing.
3. Aerobic or Oxidative
Any activity lasting longer than 90 seconds will begin to rely predominantly on the aerobic system. This system isn't as powerful as the other two, but can go for hours as it uses both sugars and fats to produce energy. Metabolically healthy people are able to rely predominantly on fat metabolism for aerobic energy at lower intensities or at rest, but this fat-to-carb ratio skews more and more toward carbs as intensity increases.
This is especially true at or near maximal intensities, when the only available substrate for aerobic metabolism is carbohydrate. This system supports activities like long-distance swimming or running and also drives the recovery of the other energy systems in between intense efforts. The more efficient your aerobic system, the more effectively your alactic and anaerobic energy systems can bounce back for repeated bouts of high-intensity efforts.
It's important to train each energy system in some fashion as they all work together. If one is neglected, the others can't do their job as well and you'll have vulnerabilities in your performance and recovery.
A well-rounded program that addresses each system creates a more efficient body that performs better, recovers better, and makes better progress in every physical activity it attempts.
This method is unique because it's both high intensity and high volume. It's also a means of training two different energy systems at once: the alactic and the aerobic systems. This is also what makes it so effective.
The "high-intensity" aspect of the method is based on the resistance/force output level of each repetition rather than more traditional high-intensity intervals that typically involve reps of sustained activity such as sprints or high-rep circuits.
In this sense, "intermittent" may be a more accurate word than "continuous" because in practice, HICT means that you're doing a steady rhythm of 1-3 powerful reps every few seconds with a little bit of rest in between each set.
Most traditional interval methods involve sustained speed and power, which means you only have a limited amount of time before you lose intensity and have to slow down. With HICT you're in less of a hurry, but you're using high resistance on each rep.
HICT works by using a high number of very short sets. Most of the time, this means 1-3 reps per set, but you can do sets of 5 with fast movements like kettlebell swings. As you progress through your time block, you can drop to sets of 3, 2, or even 1.
You'll do a set of 1-3 (or 5), take a short rest, and repeat. The pacing depends a bit on the movement. With something like push-ups or kettlebell swings, it's easiest to follow a timer so that you're doing one set every 15-20 seconds. With something like step-ups or a spin bike with the resistance cranked up, it'll be more of a steady stop-and-go rhythm. Rest as needed, but only as little as needed.
This is what it should look like (using kettlebell swings as an example):
- Set One: 5 kettlebell swings
- Rest: 15-20 seconds
- Set Two: 5 kettlebell swings
- Rest: 15-20 seconds
- Set Three: 5 kettlebell swings
- Rest: 15-20 seconds
Continue for anywhere from 5 to 20 total minutes. Rest 5 minutes and repeat for 2-6 total sets per workout, depending on how long each set is and your conditioning level.
The idea is to use a big movement that can be done sustainably for a long period of time. My favorite exercises to use are weighted step-ups, goblet squats, push-ups, kettlebell swings, and ring rows. Upper body movements can be especially grueling, so keep the blocks of time shorter for these exercises.
HICT Kettlebell Swings
You may feel some lactic acid building. A brief flash of lactic acid burn is okay, but make sure to rest long enough for that to clear before the next set. You don't want to push your intensity so high that the sets become anaerobic.
Rather, the goal is to put out a short burst of power via your alactic energy system, then recover enough to do it again, over and over. Your aerobic energy system is driving your recovery while your alactic system kicks in for each set to generate the quick bursts of effort.
A few key guidelines:
- Keep your heart rate below 150, or in zone 3 or below. You should be able to breathe through your nose the whole time.
- Use maximum resistance, maximal effort.
- Work in low-rep sets, typically 1-3 reps at a time.
Other great options are tire/sled drags, spin/airdyne bikes, Versaclimber, or climbing up a steep hill.
HICT will improve the work capacity of your fast twitch muscle fibers, along with being a good way to simultaneously develop your aerobic system. Remember, you'll be working high volume and high resistance but at a slow pace.
Your fast twitch fibers will be forced to work, but you can maintain the workload for much longer than traditional cardio bursts because of the slow pace. This means that you'll be able to maintain higher intensity for more total volume, recover better, and be able to do it again.
In other words, you'll become more powerful and efficient in your workouts or athletic endeavors.