Rhonda: What about the high intensity resistance training or resistance intensity training?

Dr. Gibala: It goes a different way. You know, some people call it functional training, but certainly there's high intensity resistance training. You know, I think it can still count. You know, for a lot of resistance training, just because the intensities are so high, you know, we're talking about now very high force efforts that last less than a second sometimes.

By its definition, it's interval training. We just never really think about that. But so I think certainly bodyweight style type interval training or what used to be traditional calisthenics and that, that can play a role here. So I think, again, using this generic term interval training, I think we can have more aerobic style interval training or resistance style interval training.

And again, bodyweight style interval training would sort of be the classic one to me that is interval resistance training. And I think it can have tremendous benefit. You know, it's often a sort of a middle ground. You're not going to see the gains in strength that you would see with traditional heavy weightlifting exercise, and you're not necessarily going to see the gains in fitness that you would have with a traditional well-structured aerobic training program, but you can get a lot of both right in the middle.

You know, especially if, you know, we're talking air squats, burpees, sets, pushups, where you also keep recovery periods relatively short. You know, you engage in that for 10 to 20 minutes, you can keep your maximum, your heart rate up to about 80% of maximum, but you've done a lot of resistance style training that's increasing functional strength as well. I think it's a tremendous way for people to train.

Rhonda: It sounds like a lot of CrossFit kind of things.

Dr. Gibala: Yeah, absolutely. You know, now maybe not necessarily as intense as some of these programs that you see, but absolutely that style of functional training, whatever you want to call it or label it, can be extremely beneficial, I think. And in a time-efficient way, you get strength gains and some aerobic conditioning as well.

Rhonda: Can you get any muscle mass gains, even strength gains from high-intensity interval training? Let's say if you're on a stationary bike and you're cranking the resistance up.

Dr. Gibala: Yeah, so that one really depends where your starting level is, right? And so if you're already relatively fit and healthy, then the general belief is that you're not going to see massive changes in muscle protein synthesis or changes in fiber size or anything like that, even with fairly intensive sprinting. Now if you're someone just starting out, you think of a very deconditioned elderly individual who is going to get on the bike and do some moderate pushes there, you know, so we're not talking all-out sprint training, they could see some improvements in protein synthesis.

You know, and again, are we talking mitochondrial, myofibrillar, but I think traditional muscle protein synthesis where we're seeing an increase in fiber size and that, if your baseline is very, very low, then I think even aerobic-style interval training can be beneficial there. But otherwise, you know, once you get to a certain level, it's not a hypertrophy stimulus, generally speaking.

Rhonda: Yeah, okay. Because I crank my resistance up really high on my peloton and I'm standing and doing it, you know, like I'm like, this has to be something on my quads and...

Dr. Gibala: Well, you know, you look at Tour de France cyclists, right? Like I mean, they're amazingly muscled, now they're very, very lean as well, right?

How much of that is...that was covered in a layer of fat, how much muscle would there be there? But you know, I think it's not nothing, but you know, you can get much greater gains in protein synthesis with some more traditional squat exercise and things like that with a lot, lot less volume of work.

Rhonda: Can you just lift? I mean, like, can you, you know, like, let's say you're doing more of a resistance training, like higher intensity resistance training circuit or like you were talking about. Can you just get by with just doing that? I mean...

Dr. Gibala: Yeah, again, right, compared to what? But you know, so like, I don't...only doing heavy resistance training as traditionally practiced, I think you're definitely leaving something on the table in terms of cardiorespiratory fitness and health benefits and all of that.

I think it's a really good question of, you know, again, if it's that person like we talked about, the classic individual, you know, type A, limited time, still engaged in real life with responsibilities, family, job, things like that, and they have an hour a week to train, if they only did high-intensity functional training, calisthenics-style, bodyweight-style exercise, I could see a lot of value in that, right, in terms of aerobic conditioning and gains in strength.

You know, coming back to what we've talked about earlier, you know, if it's four sessions a week they can do, maybe two of those are high-intensity functional training or bodyweight-style training and two or more interval training for aerobic conditioning on a bike, on an elliptical, things like that. You know, if you only have three, I'm not sure how I would divvy those up, but still getting some variation in ideally, but yeah, I have a lot of time for high-intensity functional training.