Exercise and Weight Loss, Part 3: Interval Training


Interval Training and Weight Loss

by Devin Sarno, NSCA-CPT

Exercise comes in a number of different forms and so far we've covered cardiovascular and strength training exercises as a form of training for weight loss. Next in our discussion is interval training. Interval training is unique in that it can be meshed with other modes of training. It has become increasingly popular in the 21st century and is more or less the “go-to” method in a lot of gyms all over the country. But what made is so popular and how does it relate to weight loss?

By definition, interval raining is when your workout consists of alternating periods of high-intensity exercise with low-intensity recovery periods. You can apply the interval principle to so many different exercise modes including sprinting, jogging, biking, rowing, and resistance training. One benefit of interval training is the ability to maximize the amount of high-intensity exercise you can complete. By building in rest periods rather than trying to continually work at maximum capacity you will be able to recover throughout your exercise and give yourself an opportunity to spend more time collectively working at or near your maximum intensity. The reason behind adding rests is if you try to work near maximum capacity for too long of a time, you will hit a point of exhaustion of all your energy stores and can no longer continue to produce energy fast enough to replace what was expended. At that point, your workout is essentially done. That is why when you are doing cardiovascular or aerobic training you work at a sub-maximal, maintainable pace. So it makes sense that individuals looking to lose weight tend to use the interval training method since weight loss is simply about burning calories and the more time spent working near your maximum capacity leads to more calories burned!

As stated before, you can apply interval training to a number of different exercise modes. If you are doing a more aerobic based workout, you can alternate between running a mile and walking a quarter mile. This will allow for you to keep a faster pace for your mile than if you just tried to run two miles straight. The same applies to anaerobic exercise like sprints. You can do ten 100 yard sprints with a 60 second rest in between so that you can stay a lot closer to your max effort pace than if you sprinted 100 yards and turned around and sprinted right back 10 times. The same can also be used in your weight training to up the intensity. For example, you could perform a loaded barbell back squat for 5 minutes and squat for an interval of 30 seconds with 30 seconds of rest in between. This would increase your heart rate while simultaneously strengthening your leg muscles and burning more calories.

Utilizing intervals allows for you to spend more cumulative time working at or near your maximum intensity. It also gives your muscles and lungs some time to recover in between your “high intensity” bouts, allowing for less of a drop off in max intensity. This means you will burn more calories because when you spend more time working at high intensities with a higher heart rate, the metabolic demand for energy production is greater. As a result of your metabolism needing to work harder, the overall caloric need and caloric expenditure is greater. Given that interval training is also inherently anaerobic, you also receive the benefits of the EPOC effect we discussed during the previous article on weight loss and traditional weight training, allowing you to burn more calories even after the completion of your workout.

Some might say that interval training is the best of both worlds. While this may hold some truth, going out and doing this every single day when you are trying to lose weight probably won’t be good for the overall longevity of your weight loss journey. Given that you should be working at such a high intensity during an interval training session, it is taxing on the body. If you try to do it every day, you are not giving your body enough time to recover from the tough session the day before so the chances of burn out or even potential injury are high from the constant high stress on the muscles and joints. Without proper recovery time, the physical and mental fatigue will continue to compound so it is suggested to limit your interval training to 2-4 days per week while mixing in other modes of exercise such as cardiovascular exercise, traditional weight training, flexibility training, or a recovery day. Additionally, if you are new to exercise, your heart hasn't experienced high intensity work so it might be best to begin with other training modes we've discussed so as to allow you to lay the cardiovascular and strength foundation.

There are undeniable benefits to interval training but it should be “handled with care” so as to avoid burnout. It could certainly be argued that as far as exercise is concerned, this type of training is where you will get the most bang for your buck. While we know there are other more important factors to weight loss such as sleep and nutrition, when you look at exercise in regards to weight loss, interval training may help get you closer to your goal than any other exercise mode. This is due to the extremely high calorie burn, contributing to your overall calorie deficit you need to lose weight. However, it should absolutely not be the only form of training you utilize. Training variation and proper recovery are going to help keep you healthy and fit while you lose weight.