Welcome to StarNet's online chat with Dr. David Raichlen about the links between exercise and happiness. If you attended the lecture, or wanted to and couldn't, you may have questions. Ask away.
Hi everyone. Thanks very much for attending the chat and I'm looking forward to answering your questions.
40 years of injury free running is a great accomplishment! Your question is an interesting one. That part of the lecture really began a discussion about how evolution can overcome these kinds of problems (with mental rewards).
But your injury question is a hot topic in paleoanthropology. There is a school of thought that suggests we ran a bit differently than many of us do today. This leads to the barefoot running debates which I'd be happy to talk about if you have questions on that topic.
Great question! The data are pretty clear that any form of aerobic exercise that leads to moderate intensities produces a positive change in mood. Many people have trouble running, but there are so many options to get your heart rate up that choosing a comfortable form of exercise can have a large impact on the way you feel.
It's become quite a complicated story. At least the data are conflicting at this point. My advice is always that if things are working well, and you are injury free, there is no reason to change. But, there are data that suggest running with a mid-foot strike (compared to the usual heel strike that most runners use) can reduce impact forces which may have an effect on injury rates. The jury is still out...
Surely someone has a question?
Yes, there are many techniques that folks have used to shift their form. One of the easiest ways to do this is to use a metronome set at a high rate (~180 beats per minute) and use that to control your step rate (match your footstrikes to the beats). At that high of a step rate, you will have to mid foot strike. Barefoot running achieves the same effect because landing on your heel when barefoot is painful, and you will quickly learn to land on your mid foot. But, as you said, it is not for everyone, and folks should start very slowly if they are interested in trying it out.
That's a great question. We've been working with a group of hunter-gatherers in Tanzania, and have found that both men and women forage at moderate intensities. Women forage mostly for tubers and berries in this group, but they walk at a high speed and they carry large loads back to camp. So even with a strong division of labor, both males and females must exercise at a moderate intensity to get their food.
The safety issue is important. There are few sidewalks where I live, so I tend to go to the running paths in town when possible. Places like Reid Park and the Rillito path are safe and well lit. You don't have to worry as much about traffic on those routes.
Right now I am working on two projects. The first explores the effects of exercise on brain aging. We've begun examining how exercise in mid- and late-life affects changes in brain structure and function and how exercise can influence diseases like Alzheimer's.
A second project looks at inactivity instead of activity. I talked a bit about how we evolved to rest during the lecture, but there's an interesting story in there. While we evolved to rest, we did not evolve to sit in chairs all day. So we're exploring how and why sitting creates so many health problems for humans.
It's actually not as hard as you'd think. Most animals instinctively run when the treadmill starts going. The hard part is trying to get an animal to walk. The higher the speed, the easier it is.
Well, resting, for our ancestors and for living hinter gatherers, is truly important. You need to save energy when you're not out foraging. So they definitely take it easy when they're not out looking for food.
Doesn't anyone want to exercise their fingers and ask a question?
In terms of improving your mood, most studies show that any aerobic exercise will work. The most important thing to do is find the one you like. Soccer could work, but depending on how you play, you may be moving into very high intensities at times. One other point that I did not discuss in the lecture is that there can be social aspects to these improvements in mood. So if you exercise in groups, that can increase your enjoyment and help you stick with an exercise program.
The key with any kind of exercise is that you find something you can do consistently. For folks with joint problems, low impact exercise can still get your heart rate up and improve your mood, and will also be beneficial for your cardiovascular system.
That's a great question. You are very right that the search for the roots of the runner's high has led to a bit of active ingredient work. There are several neurotransmitter systems responsible for rewards and many times they work together. For example, endorphins and endocannabinoids can work in concert and enhance the effects of each neurotransmitter. So, I think of this study, and this work, as the beginning, rather than the final answer on the topic. We are having discussions about how to explore other neurotransmitter systems in humans and other taxa and hope to continue this work to shed more light on the complexity of the system involved in these exercise-induced mood changes.
I don't know much about the effects of meditation on the serotonin system, but I believe there are some interesting intersections between exercise and meditation. In fact, there may be ways where your thought processes during exercise mimic thought processes during mindfulness meditation so I wouldn't be surprised if there's an interesting story there.
Thanks for your question! That's the basic problem we face, as a society. There is little incentive to get out the door and move our bodies, which has created many of the health problems we face to day. I think we can start to address this by encouraging more exercise as parts of daily life. Making it easier to walk or bike for commutes, or creating walking paths around businesses so people can have walking meetings. If more people experience the mood changing effects of exercise, then we know that will lead them to stick with an exercise program. So finding ways to get people to the point where they'll feel those effects is really our challenge.
That's a very important question. Pace is definitely dependent on your level of fitness. Our data suggest that exercise at 70-80% of your maximum heart rate are best at eliciting the mood response. For someone with a low level of fitness, that might happen while walking. For a very fit running, it may be at a reasonably high pace. But in general, for runners, it is likely the pace you naturally fall into for a regular, every-day run.
We would like to expand the sample. When we look at how different species evolved, in terms of their endurance athletic prowess, we tend to classify them into two groups (distance runners vs. non-distance runners). These groupings are based on evidence from their skeleton and physiology that suggests they are adapted for long distance running (or not). So, there are many animals that, while active, do not have adaptations for long distance exercise. We would love to look at other animals in that same group (non-runners) although they can be difficult to work with. They include critters like opossums, racoons, etc.
The first step is always the toughest. When I am dragging a little, I do two things. First, I ask myself when was the last time I regretted going out for a run. I know that once I get out there, I'll be happy I did. Then I tell myself I'll just go for a few minutes and if I'm still tired, I'll turn around (I never do). So, the key is taking the first few steps. And yes, accumulating those short bouts of exercise can increase your aerobic fitness and can increase your mood. A very active area of research these days, but the data look pretty clear at this point.
Fantastic question and comment. I fully agree with you that increasing mass transit use has an important impact on physical activity. I think comparisons in health and fitness between matched communities with and without these transit systems would be a great place to start. Hmmm...I am now thinking there is a community we all know that is about to get a mass transit system. Maybe there's a project there...
Thanks so much! Very glad you enjoyed the talk.
An important question. Tough to know how evolution will proceed because there is no clear goal other than improving our ability to reproduce. So, as long as it does not cost us in terms of reproductive success to get this effect, then there may not be selection to remove it. But, I truly hope we don't have to learn the answer to that question.
Well, I'm not much of an expert on nutrition, but from anecdotal and personal experience, once you get over about an hour, taking on calories can be helpful. And, on the advice of MDs, there is evidence that taking on food will help keep your GI system active which is important during extended bouts of exercise.
Yes, I think there has been work on play and neurotransmitter systems, although none that I know of looking into endocannabinoids specifically. Behaviors that are important for our survival can lead to a linkage between a reward system and that activity, so play and exploration could certainly do the trick for ferrets.
That's the idea. Our prediction is that just as selection shaped the bodies of some species to support distance running, selection may have linked these reward systems with running to improve their performance and keep them going for long distances.
Thanks so much for all your great questions. I hope you enjoyed the chat!
Thanks for joining our chat. Dan Russell will talk at 6:30 Wednesday evening and we will chat with him on this forum at noon a week from today.