People are great at making resolutions around getting in shape every new year. Then by the end of January or maybe even mid February, a lot will typically throw in the towel and start to abandon new year’s resolutions related to health and fitness, telling themselves that it’s just too much work and/or they don’t have enough time to put towards doing it “properly”. I believe that a lot of people think that in order to reach their fitness goals they need to be in the gym/track/pool daily and slogging away for long periods of time to see the results they desire. Unless you are a competitive athlete, body-builder or training for an extreme endurance event I don’t think that that is necessarily true. You can get a lot of bang for your buck if you just train smarter rather than longer.
High Intensity Interval Training workouts are a combination of high intensity bursts with low intensity/ recovery periods. Workouts that involve high intensity interval training (HIIT) can achieve similar results to just steady rate cardio in much less time. This is due to several benefits that are afforded specifically to HIIT style workouts, the most compelling being that your body is able to burn through more fat, even while expending a lower number of calories. Studies have been done to prove this very fact. Here is an excerpt from one such study from Laval University in Quebec:
“The impact of two different modes of training on body fatness and skeletal muscle metabolism was investigated in young adults who were subjected to either a 20-week endurance-training (ET) program (eight men and nine women) or a 15-week high-intensity intermittent-training (HIIT) program (five men and five women). The mean estimated total energy cost of the ET program was 120.4 MJ, whereas the corresponding value for the HIIT program was 57.9 MJ. Despite its lower energy cost, the HIIT program induced a more pronounced reduction in subcutaneous adiposity compared with the ET program. When corrected for the energy cost of training, the decrease in the sum of six subcutaneous skinfolds induced by the HIIT program was ninefold greater than by the ET program.”
This is pretty amazing when you think about it. Even though the HIIT participants had a much lower energy output (calories burned), the actual amount of body fat lost (as measured by skin folds) was nine times more than those engaging in steady state cardio exercise. In addition to body fat loss there are other benefits to HIIT style workouts:
1. An increase in your VO2 max
Your VO2 max is the absolute maximum capacity your body has during physical exertion of moving around and utilizing your oxygen. This is very important, as your VO2 max is a marker for how fit you are as a person. As your VO2 max increases, you will be able to go harder for longer periods of time during a workout.
2. EPOC production
Somewhat related to VO2 max is EPOC, or excess post exercise oxygen consumption. After a hard workout, the body needs to up your oxygen levels to compensate for the deficit it has just undergone. This process, also known as “afterburn” involves using more caloric energy when repairing the muscles and re-upping your stores of glycogen.
3. Creation of new mitochondria
Mitochondria are the energy creating powerhouses of your cells. Because they are responsible for converting macronutrients fat and carbohydrate into energy, the more of them you have, the better your body can create energy from the food you are providing it with. To make more mitochondria, the body needs to feel a need for more energy output and HIIT style training provides that need well.
4. An increase in insulin sensitivity
The way your body responds to insulin (a storage hormone) corresponds to how well you can utilize carbohydrates for energy by activating fatty acids. The less insulin sensitivity you have, the more insulin is needed for this important job. In studies, HIIT style training has been proven to increase insulin sensitivity and this is good news because that translates to easier fat loss.
5. Important hormones for metabolic advantage are elevated
So along with the insulin sensitivity piece, there are other beneficial hormone modulations that happen due to HIIT style workouts. Testosterone and growth hormone are both elevated after 10 minutes of HIIT. The levels that they reach are directly tied to the amount of intensity that is brought to the workout. The combination of Testosterone and growth hormone are a good partnership for both growing muscle and losing fat.
If you are thinking about trying HIIT style workouts I would say go for it! You don’t need any particular equipment, it can be done effectively in as little as 20 minutes per session, and you can utilize it with lots of different physical activities like weight training, running, swimming, biking, martial arts and etc…