Even with these low impact options, sprinting is
widely neglected by all levels of exercisers. We
generally are comfortable tackling the low level
cardio and strength training components of PBF,
but seem intimidated by the concept of sprinting.
This could be due to injury risk from doing high-
impact options, or the prevailing mentality that
more is better—an hour of Chronic Cardio three
days a week must be better than an occasional
10-minute max effort, right?
As I said in the opening of this book, I love shortcuts.
My entire training regimen revolves around finding
shortcuts to better fitness by maximizing efficiency
in the gym, on the track, at the beach, in a hotel
room, or wherever else I’m exercising. I’m not sell-
ing myself short, and I’m not losing out on any of the
benefits; I’m training smarter and more effectively
than ever. The sprint is the ultimate exercise hack.
By definition, it’s brief. It has to be, because once
you start slowing down—once your power output
begins to wane—you have ceased to sprint.
So how does sprinting work so well in such a short
amount of time? Why is it important to maintain
maximum speed by sacrificing work volume? And
aren’t you missing out on “aerobic endurance” by
focusing on short sprints?
Let’s answer that by first reviewing our muscle
fiber types. There are two primary muscle fiber
varieties: fast twitch and slow twitch. Fast twitch
fibers regulate powerful, explosive movements—
stuff like Lifting Heavy Things and Sprinting Once
in a While—while slow twitch fibers are better
for endurance training—long distance aerobic or
cardio activities. Outdated Conventional Wisdom
says that one must train the slow twitch fibers
through endurance exercise to increase actual
endurance. On the surface, this seems somewhat
reasonable, right? It seems to jibe with the Primal
philosophy on functional fitness (improve your
ability to perform real world, natural movements
by training those exact same real world, natural
movements when you work out), and it doesn’t
sound outlandish to imagine that endurance work
improves aerobic endurance, while sprint work
improves sprinting. Once again, Conventional
Wisdom has led us astray.Sprint Once in a While cont’d 61