Which Comes First, Cardio or Weights_ - Alex Hutchinson [99]
Endorphins are produced by virtually any vigorous physical activity, as confirmed by the fact that even the solo rowing sessions in Cohen’s study enhanced pain threshold to some degree. But group work appears to enhance the effect dramatically—and there’s plenty of evidence that exercise classes meet that description. In a series of studies stretching back more than a decade, University of Saskatchewan professor Kevin Spink has found those who feel a greater sense of “groupness” and cohesion within an exercise class are more punctual, have better attendance, and even work harder.
Of course, not all collections of individuals qualify as a group. Spink and other researchers have identified factors that make some crowds “groupier” than others, such as the existence of group norms. For example, the shift in the past decade from sign-up exercise classes to drop-in classes has made it more difficult to build cohesion in these groups. Still, it appears that the most important factor is what’s in your head, even for drop-in classes. “As long as I perceive the people I’m exercising with as a group, my adherence is way better,” Spink says.
There is an important caveat regarding individual preferences. About a third of people enjoy exercising in groups; another third prefer exercising alone, while the remaining third are indifferent, Spink notes. For those who are happy exercising alone, there’s no reason to join a group. For everyone else, exercising with partners or in groups has all sorts of benefits that have nothing to do with neuroscience, from the simple act of committing to meet someone to the pleasures of gossiping during a workout. But the endorphin findings help explain how exercise is transformed from a chore to a lifelong habit, and indeed a pleasure, for some people—and suggest one way of getting there.
What are the effects of exercise on the brain?
The theme of much of the research described in this chapter is how much influence your brain has on the way you exercise. But it works the other way around too: the exercise you do has wide-ranging effects on your brain, with the power to alter mood, memory, and even the structure of the brain itself. Over the long term, there’s not much doubt that exercise makes you smarter. Studies in rodents have shown that physical activity makes brains develop denser and more complex connections between neurons and stimulates the growth of new brain cells. These effects are especially important during adolescence and early adulthood, when your central nervous system is developing rapidly and taking the shape it will maintain, more or less, for the rest of your life.
A massive Swedish study published in 2009 combed through the records of 1.2 million 18-year-olds who had taken compulsory military screening exams between 1950 and 1976. The first finding was that aerobic fitness, but not muscular strength, was associated with greater intelligence. But it wasn’t just being fit that helped—getting fit also offered a major boost. Those who had gained the most aerobic fitness from 15 to 18, as assessed from their high school phys ed marks, scored far better on the cognitive tests than those who had lost fitness. Since 268,496 of the subjects were brothers, the researchers were also able to determine that the links between aerobic fitness and intelligence were primarily due to environmental factors like exercise, rather than genetic factors.
The fact that aerobic exercise improves intelligence but strength training doesn’t may come as a surprise. Researchers believe that many of exercise’s neural benefits relate to whole-body effects such as increased blood flow: getting your heart pumping in a cardio workout carries more blood, along with helpful growth factors, to your brain. A 2009 study by University of North Carolina researchers used magnetic resonance angiograms to