I’m sure on Planet X there is a television station live streaming cardio machines at Globo Gyms across the United States. This program provides endless elation to our extraterrestrial friends. Not only is it hard to understand why people would subject themselves to 30-45-60-90 minute low intensity cardio sessions for the pure boredom, but they are doing it unnecessarily and out of ignorance to boot!
This misunderstanding comes from the partially true fact that cardio performed at 60% of your max heart rate (210 minus age times .6) puts you in a “fat burning zone”; exercise that eats away at fat stores. Any work done above this heart rate burns carbohydrate stores. Based on this fact alone, long sustained cardio seems like not too bad of an idea. The Aliens assume we know this and show us some sympathy between chuckles. However, there are more factors to consider such as efficiency, calories and the after affect of cardio.
High intensity training is exercise performed in the range of a max effort, down to about 70% of your max heart rate for bouts of 15 seconds to one minute, respectively. The more intense the effort, the shorter amount of time it can be sustained. These kind of efforts require a rest period, making them interval training— a set amount or work time to a set amount of rest time. High intensity training is fueled primarily by carbohydrate stores, secondarily using fat stores.
Aliens are super efficient. If they had any fat to burn, they would want to burn the most fat in the shortest amount of time. So even though you are primarily burning fat in low intensity training, it takes longer because you are burning calories faster with high intensity. Would you rather Elliptical (yes, the verb) for an hour burning 100 calories, 85 coming from fat, or do sprints intervals for 30 minutes burning 500 calories, 150 coming from fat?
Maybe the answer is no. You’d rather Elliptical because you hate working hard or you love watching daytime TV. That is fine but you are missing out on the after affect of high intensity training. Here are a few of those benefits as outlined in Thinner Leaner Stronger by Michael Matthews:
- Increased resting metabolic rate for more than 24 hours after exercise
- Improved insulin sensitivity in the muscles
- Higher levels of fat oxidation in the muscles
- Significant spikes in growth hormone levels (which aid in fat loss) and catecholamine levels (chemical in your body produced to directly induce fat mobilization)
- Post-exercise appetite suppression
Both modes of training have their place, especially in performance sports. However, I do HIIT when I am training for my sport of Obstacle Racing (three+ mile obstacle races) and right now while training for a figure competition. One is for a performance sport (an endurance sport at that) and one is a competition solely based on physique and I primarily use HIIT to train for both. When it comes to efficiency and function, high intensity interval training takes the cake (and burns it off, too).