2444: The Pros and Cons of High Intensity Interval Training HIIT on Muscle building & Weight Loss

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[00:01:10] And I'm Dr. Neal, your host of the show. Hey there welcome back to another special Friday edition of Optimal Health Daily where I answer your questions. On the other days I read health and fitness blogs to you kind of like an ongoing audiobook.

[00:01:25] Now once a month, usually on the first Q&A episode of the month, I like to share a little bit about my background and my credentials. I only do this so you can better understand where my perspectives come from.

[00:01:36] And given this is the first Q&A of the month, it's time I share this with you. Now while I've always been obsessed with Batman, I wasn't always interested in nutrition, exercise, health and wellness. Basically all the stuff I talk about on this podcast, I really wasn't interested

[00:01:54] in until later in life. Being diagnosed with a chronic disease at the age of 19 definitely changed my life's purpose. It was then I decided to focus my attention on helping others so that no one else had to experience a chronic disease diagnosis like I did.

[00:02:11] But in order to do that, I wanted to be sure I had some credibility. This isn't meant to be a humble brag but instead gain your trust. I received both my master's and doctoral degrees in public health.

[00:02:23] And to make sure I covered all of my bases, I also became a registered dietitian nutritionist, a certified health education specialist, and a certified exercise physiologist through the American College of Sports Medicine. I've been teaching in higher education for over 15 years now and I'm currently faculty

[00:02:41] within the California State University System. I have published peer reviewed studies, I've presented at national and international conferences. I've been interviewed by over 70 different media outlets for my expertise on basically all these things I discuss on this podcast.

[00:02:57] So all of this to say that when I provide my commentary after each episode and answer the questions you send in, I hope you feel as though it's coming from a place of truth. My only intention is to help you feel your best.

[00:03:11] Alright, let's finally hear today's question and start optimizing your life. Today's question came via email. Manny writes, Hello Dr. Neal, I'm a huge fan of the Optimal Health Daily podcast. Thank you for all that you do to keep us informed.

[00:03:30] I have a question regarding high intensity interval training and boot camp style workouts. Can you share with us any data on whether or not these types of workouts are beneficial for muscle building or weight loss? I've heard mixed things about these styles of workouts.

[00:03:47] There are some that simply love high intensity interval training style workouts because they're efficient and effective for muscle building and weight loss. Then there are others that claim high intensity interval training style workouts are not good for your body since they can lead to inflammation

[00:04:03] and an overproduction of cortisol, negating the benefits and preventing muscle building or weight loss. Thank you so much. Thank you for your kind words Manny and for being a regular listener of the show and thank you for taking the time to send in your question.

[00:04:19] Now I'll start at the beginning and talk about what high intensity interval training means. Then I'll move on to answering your specific questions. So first, what is high intensity interval training which is often abbreviated HIT. Well let's first think more about traditional cardiovascular exercises.

[00:04:39] Think walking, cycling, rowing, running, swimming and so on. Usually these exercises are performed rhythmically and at the same intensity during the workout. For example, many of us will walk or run at the same pace for the entire workout

[00:04:58] like we might set the treadmill to three and a half miles per hour and keep that speed for 30 minutes and then we're done. High intensity interval training or HIT involves repeated bouts of high intensity exercise with some lighter intensity or some rest periods thrown in between.

[00:05:19] An example of high intensity interval training would be walking for five minutes at three and a half miles per hour. Then once those five minutes are up, run for one minute since running is a higher intensity activity. After that one minute of running, you go back to walking.

[00:05:40] Maybe you walk for another five minutes and then run for another minute. Then you repeat that cycle as many times as you want. High intensity interval training can also be used with resistance training not just with cardio. For example, you could perform 10 push-ups, rest for one minute,

[00:05:58] then perform 10 more, rest for another minute and perform 10 squats. Rest for a minute, you get the idea. And we can get really fancy and mix and match cardiovascular exercise with resistance training and incorporate high intensity interval training. So you could perform 10 push-ups, rest, then run for one minute,

[00:06:22] rest, then perform another 10 push-ups, rest, then run for another minute, and so on. Now is high intensity interval training safe? The American College of Sports Medicine, considered by many to be the authority in all things exercise, does not consider high intensity interval training safe

[00:06:42] for those they consider high risk. Those would include individuals with pre-existing conditions like cardiovascular disease or diabetes. Those that would also be identified as high risk would include those that experience cardiovascular related symptoms when they exercise. So like they're exercising and they experience chest pain

[00:07:04] or pain in the muscles in their limbs that then goes away once they stop exercising. These would be risk factors for some type of blood vessel or heart trouble. For the longest time, researchers were afraid to push anyone

[00:07:19] with a history of chronic disease to perform high intensity interval training for fear of them having a cardiovascular event like a heart attack during exercise. But now, researchers have been studying these high risk groups and are discovering that high intensity interval training may be safe for most people,

[00:07:38] even those living with cardiovascular disease or diabetes. That does not mean though that you should automatically jump in. Before jumping right in, pun intended, and starting a high intensity interval training program yourself, it is always a good idea to double check with your doctor

[00:07:56] to be sure it's safe for you. Now, let's get back to your specific questions, Manny. What about high intensity interval training and hormones like cortisol? Cortisol is a stress hormone. And in fact, a meta-analysis found that both testosterone and cortisol

[00:08:14] do increase immediately after a single high intensity interval training session. But within 24 hours after that exercise, both testosterone and cortisol return to normal levels. So it doesn't seem like that increase in cortisol is really going to have any physiological effect.

[00:08:37] Now, what about high intensity interval training and muscle gain? A different meta-analysis tried to answer this very question. The authors of this study found that high intensity interval training does in fact help with building muscle. But let's say someone's goal is to build muscle as quickly

[00:08:56] and efficiently as possible. Then, according to other studies, performing more traditional resistance training without incorporating high intensity interval training would be better. So what do I mean when I say traditional resistance training? Let me first start with the example I gave before.

[00:09:15] I said that a high intensity interval resistance training program might look something like this. Perform 10 push-ups, rest for a minute. Then perform 10 more, rest for another minute. Then you could perform 10 squats, rest for a minute, and then continue this pattern. A resistance training workout that doesn't involve

[00:09:34] high intensity interval training would look more like this, and this would be considered more traditional resistance training. Perform 10 push-ups, rest for 2 to 3 minutes. Then perform another round of 10 push-ups or move on to squats. Rest for 2 to 3 minutes. Note that the rest period is longer.

[00:09:57] By having a longer rest period, you're going to lower the heart rate in between sets and allow the muscles to recover. In turn, this will increase the amount of power your muscles have with each round, which will then help build muscle more quickly.

[00:10:13] Now what about high intensity interval training and weight loss? Again, you're in luck, Manny, because other scientists wanted to answer this very same question too. Authors of yet another meta-analysis looked at whether those that performed high intensity interval training lost more body fat and more body weight

[00:10:33] when compared to those that performed lower intensity cardiovascular activity. After comparing the results of 149 studies performed over 12 years, the authors found that both groups, the high intensity interval training group and the lower intensity cardio group, lost about the same amount of body fat and body weight.

[00:10:56] The researcher said that the most important thing was consistency. So those that were able to stick to their prescribed workouts were most successful with body weight loss and fat loss. So finding exercises that you enjoy seems to be most important.

[00:11:13] Now are there any risks to high intensity interval training? I did mention some before, but just to say again, this type of intense activity is not meant for everyone. It is best to talk to your doctor first. In fact, for those with overweight or obesity,

[00:11:29] starting out with a high intensity workout program is not recommended. This is according to the American College of Sports Medicine. Instead, starting out with short bouts at a lower intensity and doing that most days of the week is recommended. There were also some concerns

[00:11:45] that performing high intensity interval training can make your immune system weaker. The immune system is mainly responsible for keeping us healthy, right? Some early studies found that high intensity interval training can reduce the strength of the immune system. These studies are correct. This does happen.

[00:12:04] But this decrease in the strength of the immune system is temporary. Other more recent studies have found that the immune system bounces back pretty quickly. And in fact, performing high intensity interval training regularly can make the immune system stronger over time. All right, so what's the bottom line?

[00:12:24] Where does this leave us? Basically, high intensity interval training can help build muscle and help with weight loss. But the most important thing is staying consistent. You have to stay consistent with your activity, whether it's high intensity or not. Also, high intensity interval training

[00:12:43] does not seem to lead to more cortisol production over time. Instead, it may make the immune system stronger over time. Thank you again so much for the question, Manny. Now if you want to submit a question and have it answered right here on the show,

[00:13:01] you can email a question to health at oldpodcast.com. You can also call in your question. The number is 161-ILOV-OHD. That's 1-614-568-3643. Or you can submit your audio question at oldpodcast.com slash ask. All right, that's another Q&A edition of Optimal Health Daily.

[00:13:29] Thank you so much for listening every day and all the way through. And I'll see you back here tomorrow and over the weekend where your Optimal Life awaits.