[Giselle]: I think when we're teasing apart these different types of exercise, I think one of the questions that come up is we care about these different types of exercise because we do believe that there are certain circumstances where the brain may play a more active role, meaning it's driving some circuit-specific effect. And what I mean by that is this whole idea, for example, if I'm more engaged in what I'm doing, if I'm more top-down cognitively involved in my process of movement through space and learning something, that I may be activating certain circuits, right? And that activation of circuitry by virtue of using it harder may itself drive some of these benefits, right?

[Rhonda]: Can you give me an example of that type of physical activity?

[Giselle]: Right. So, for example, let's say something that would be more skillful, right? So where I'm actually having to get better at it, it's actually quite challenging. For example, I live in Southern California, so surfing, as an example, where I'm not only considering obviously how I'm balancing on the board, but I'm watching the waves, I'm thinking about my speed, getting up on the board, my weight distribution. So there's a lot of different things I'm thinking about as I'm trying to get better on that. I fall off and I do it again and getting through a lot of different practices. So it's a lot of practice, repetition, learning, feedback where I'm really thinking hard about what I'm doing. So that as a skill versus, for example, a stationary bike, right? Where I'm just moving, you know, just moving my legs, trying to get up to a certain speed, but maybe not having to think about balance as much, these sorts of things.

[Rhonda]: What would be an example for someone, for example, that has Parkinson's disease, they probably aren't going to be out surfing?

[Giselle]: So, an example, in other words. So tai chi or yoga, as an example, right? And boxing as an example.

[Rhonda]: So non-contact exercise?

[Giselle]: Right. But also even a physical, you know, many of the physical therapists, what they'll do, as an example, is just even gait and balance practice, making it harder. Anytime you're making something harder, more challenging, whether it's through balance, whether it's through weight change, through dynamic balance, working harder with dynamic bounce, speed, you get the speed up, you have to make them more accurate, all those sorts of things is going to make it harder for you. So the idea would be getting out of your comfort zone, problem-solving how to get more accurate, how to get that speed up, how to become more dynamic on that task. And as I said, that can be done even with a physical therapist working on gait and balance, right? That itself is going to be more skillful over time.

[Rhonda]: So the skillful exercise that you're describing, it seems really independent of talking about something else which would be the intensity of your exercise, the vigorousness, like that's another aspect. What you're talking about specifically has to do...I mean, you're getting some physical activity, but it's a very specific type of activity where you're focusing on something, you're getting that feedback of learning, and, you know, you're basically engaging your brain a lot more than just like...

[Giselle]: Right. And I think fundamentally, you're sort of getting at the two kind of discussions that are going on with exercise. Actually, there's other discussions with muscle resistance and those sorts of things. But I think fundamentally, some of the questions that are coming up are intensity in the context of learning. Someone is learning. More about motor learning, right? Which definitely requires lots of practice and challenge to get good, right? Like tennis as an example, right? And the other type of intensity was the heart rate, getting your heart rate up, feeling your heart pounding in your chest, and sweating. That's also intense. So they can both be very intense, but for different reasons, right? So one more from the aspect of learning and practice and problem-solving to get better at something from a physical point of view. So things can be very physically challenging to learn, you know, like skateboarding, or tai chi, or yoga.

And Parkinson's disease, the bottom line is their gait isn't normal. The balance is not normal. We're starting all over again. So this is not normal walking, right? And this is not normal dynamic balance. They have impairments in that. So we can start at that level where we're concentrating on getting their balance better, the walking stride better, the posture better. All those things are what we call more normal, automatic gait. That's practice to them, to get it good and to make it harder.