There’s a growing trend towards shorter, more intense workouts – for good reason. There’s research showing that shorter, intense workouts burn more fat than working out at a moderate intensity for a longer period of time, for example, running on a treadmill at a steady pace for 30 minutes or more. That’s because high-intensity workouts have a “metabolic” effect. That’s why you’ll hear these workouts referred to as metabolic training or metabolic workouts.
What Exactly is a Metabolic Workout?
Metabolic training can take a variety of forms. High-intensity interval training, a type of training that alternates period of maximal work with recovery periods, is a form of metabolic training, but so is a kettlebell workout and circuit training that alternates strength-training with short periods of cardio. Metabolic training can take a variety of forms. Some of my DVDs that utilize this fat burning principle are: After Burn, Cardio Supersets, HiiT, Tabatacise, CrossFire and To The Max.
What makes metabolic training so special? It helps your body adapt to using anaerobic energy pathways. There are three primary energy pathways your body uses during exercise. When you do a short sprint or do a power exercise that lasts 10 seconds or less, your body gets ATP to fuel muscle movement from the creatine phosphate pathway. When a powerlifter lifts a weight, he or she is using primarily the creatine phosphate pathway.
For exercise that lasts longer than this, in the range of 1 to 4 minutes, the primary energy pathway your muscles use for fuel is an anaerobic pathway called the glycolytic system. This pathway can operate in the absence of oxygen but it fatigues your muscles rapidly. This system primary burns carbohydrates to produce ATP and, due to the fact that it operates under anaerobic conditions, lactate builds up. As a result, your blood becomes more acidic and you start to feel tired. That’s why you can only do very high-intensity exercise for short periods of time. Your body needs time to flush out some of the lactate and your blood pH needs to normalize somewhat so you can do it again.
For longer duration exercise, your body uses oxygen to generate ATP, the energy currency your muscles need for movement. This is the system your body primarily uses when you do moderate-intensity exercise. It’s this system that’s operating maximally when you take a long, slow run, cycle on an exercise bike or do another exercise at a relatively comfortable intensity. This energy system uses fat as fuel, and most people have plenty of that to fuel their workouts! This energy system can fuel a steady-state workout for hours.
Keep in mind that all of these energy systems operate together to some degree when you work out, but the primary energy system you tap into during moderate-intensity, steady-state exercise is aerobic, using oxygen, and fueled mostly by fat. During high-intensity exercise, fuel usage switches mostly to anaerobic pathways that burn carbohydrates and can only be sustained for short periods of time.
Metabolic Training Taps into Anaerobic Pathways
With metabolic workouts, you challenge your body and force it to use anaerobic pathways. Why is this important? You train your body to better handle the build-up of lactate and blood pH changes that occur with intense exercise. As a result, it adapts and is able to recover more quickly. That means you can do high-intensity exercise longer before becoming fatigued. Ask a long-distance runner to do a few sprints and you’ll see how quickly they gasp for air and drop to the ground. Their anaerobic energy systems aren’t as highly trained as a sprinter who works out at a high intensity.
The other advantage of forcing your body to use anaerobic pathways is it creates an after-burn effect. When you work your body hard enough, significant amounts of lactate builds up, your core body temperature heats up and a variety of physiological changes take place that prolongs the time it takes to recover. That means your metabolism is higher for hours after a workout as your body has to work harder to return to its pre-workout state. Plus, periods of intense exercise increases levels of hormones like testosterone and growth hormone that boost fat-burning. That additional calorie burn is partially what makes metabolic workouts more effective for fat loss even when they’re shorter in duration.
Metabolic Conditioning: There Are a Number of Ways to Do It
High-intensity interval training is one form of metabolic training. With this type of workout, you push your body into the anaerobic zone, let it partially recover and repeat until your workout is complete. Metabolic circuits combine resistance training with cardio. Here you would do a resistance exercise, preferably using large muscles groups, followed by a segment of cardio. Alternate back and forth without resting between exercises. The key is to move quickly from exercise to exercise with no rest in between.
This is the most efficient way to train when you’re limited for time since you get cardiovascular and resistance training benefits, mostly muscle endurance since you won’t be able to use heavy weight. Intense strength-training sessions using large muscle groups and compound movements with minimal rest between sets is also a form of metabolic training since it creates an after-burn effect.
Are Metabolic Workouts Really Better?
In a study published in the journal Metabolism, researchers compared the benefits of a high-intensity interval training program with a moderate-intensity endurance training program. Participants who did high-intensity interval training experienced greater fat losses even though they burned fewer total calories WHILE working out. You might expect that these participants burned more calories after they stopped than those that did moderate-intensity exercise due to the after-burn effect.
Are Metabolic Workouts for You?
With metabolic workouts, you can work your entire body in a short period of time and boost the amount of fat you burn for hours afterward. It’s time expedient and never boring because you’re always changing the pace or type of exercises you’re doing. Metabolic workouts are challenging so you’ll need more recovery time between them.
Several metabolic workouts a week are all you need to get the benefits. By scheduling them into your regular workouts, you’ll get variety, reduce boredom and challenge your body in a different way. Adding variety will keep your workout from becoming stale and help you avoid a plateau.
References:
Metabolism. 1994. Jul; 43(7): 814-8.
Exercise Physiology. Fifth edition. McArdle, Katch, and Katch. (2002)
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