Rhonda: So on the athletic side, I have a question for you. In "The 4-Hour Body," you talk about the minimal effective dose. You mention high intensity interval training and how you can get long lasting effects with less effort, basically. At first I was like, "Hmm . . . " and then you went on to talk about biomarkers and studies that have shown high intensity interval training increases mitochondrial biogenesis as much if not more than, let's say, like an hour and a half or something of cardio. And then you went on to the brain. That was my real concern. I was like, "Well, fine, if you're going to get the same amount of muscle mass or more by doing this, but what about the brain benefits?" Because I'm interested in staving off Alzheimer's. Like I mentioned, I've got an increased risk. So exercise has been shown to people with ApoE4 allele are much, much less likely to get Alzheimer's if they exercise, the more intensely the better. Part of that is your BDNF, your increasing neurotrophic factors that are growing your neurons because you need to repair a lot of that damage that's going on in the brain. So I'm interested in whether or not you are still engaging in high intensity interval training and what, if anything, you measure to know that minimal effective dose is working. Tim: Yeah. That's a good question. So I am coming off of and rehabbing some very serious leg, knee and ankle injuries that inflicted on myself doing the crazy parkour episode for my TV show. So I'm not doing a lot of interval training that would be recognizable as, let's just call it tabata training or some type of sprint training because it's too high impact. So I have concluded yes I am still practicing the minimal or minimum effective dose in a lot of facets of exercise. I think that most people do as much as possible, not as little as is needed. You can land somewhere in the middle. But the higher the level of athletics, generally speaking, the more coaches work on holding their athletes back and not pushing their athletes. I think this is a very poorly understood idea. But at the highest level, pushing the athletes is not the problem. With some team sports it's different, like even in the NFL. But if we're talking about, say, track and field, the coaches spend more time pulling their athletes back. So in my case, for instance, most people go to the gym one hour a day, five days a week if they're trying to change body composition would get better results by doing two or three sets of kettlebell swings per weeks. I've seen this hundreds of thousands of times in readers already. For me, with mental performance, and there's the book "Spark" that talks about a lot of this stuff and like you said, the brain drive neurotrophic factors and so on, from a subjective standpoint, I've seen as good results if not better results in terms of cognitive performance from resistance training of almost any type when compared to, say, steady state or even higher intensity interval training that could be thought of as cardio, like sprinting or cycling or what not. Mechanistically, I don't have specific before and after biomarkers that I'm tracking. But I am looking at, say, pages per day output, quality of writing, which can get very subjective. But I think that as these studies hopefully get funded, we will see that resistance training, if you think about it, weight training is very effective cardio. Rhonda: Yes, if you push it. Tim: Either way. If you're using, and Doug McGuff has talked about this quite a bit, if you're utilizing musculature to move your body through space, particularly with resistance, your heart has to work really hard generally to supply all the necessary nutrients and so on to get that job done. So I think that on top of that, if you're looking to prevent age-related cognitive end physical decline, one of the key correlates with all the bad stuff is sarcopenia, so loss of muscle mass, to which I would say targeted resistance training, much more effective bang for the book in not only preventing lean muscle tissue loss but increasing muscle gain than say most types of internal training, even if you're temporarily spiking certain hormones. But that's also because I hate doing endurance work. Rhonda: Yeah. Tim: I really hate doing metabolic conditioning. I find it miserable. I usually avoid it. But I do think if you were to just do two, three sets. I really focus these days personally in my exercise regimen on high intensity very brief duration or very, very long duration, typically walks, like two to four hour walks. I have a bar bell approach. So it's kind of like my investing approach. But my physical training approach is very barbell-oriented. So it's either like these sprint-like demands, which could be, say, overhead squats are really fantastic for a whole host of reasons for preventing a lot of the physical maladies that plague people as they get older and then long two to four hour walks. Rhonda: Awesome. Tim: Humans have made a lot of evolutionary tradeoffs to be able to walk long distances. So I feel like maybe that's something we need to do more of. We've made so many compromises to be able to walk long distances. I find quality of life suggestively assessed a lot higher when you're doing long, steady-state walking. Rhonda: And it's also the meditative aspect of it. That's something that you get from walking long distances. Tim: For sure.