Achieving transient hypofrontality generally requires exercising at one’s “ventilatory threshold”—the point at which breathing becomes labored, corresponding to about 80 percent of the exerciser’s maximum heart rate—for forty minutes or more. It’s a daunting summit to scale, but when it is reached, observes Kathryn Schulz, another writer-runner, it can “provoke a kind of Cartesian collapse”: mind and body melding together in what she calls a “glorious collusion.”
