THE 7-WEEK
ADD-YEARS-
TO-YOUR-
LIFE INTERVAL
WORKOUT
PLAN
Lower your “Fitness Age”
with just two interval
workouts a week.
BY MICHAEL RODIO
ou’re a 35-year-old
desk jockey with
the heart of a
60-something couch
potato? Join the club,
Jack. But there’s hope for you:
Wisløff has created a seven-week
program that primes your heart for a
better fitness age — and burns plenty
of fat — in just minutes of sweat.
It’s all built around Wisløff’s
lab-tested “4x4 interval training”
workout: four minutes of high-
intensity exercise, followed by three
minutes of active recovery, repeated
four times. The core concept is to
blast your heart to 85–95% of its
maximum rate—not quite all out but
intense enough that you’ll be able to
say only a few four-letter words by
the end. Then you’ll downshift to a
three-minute active-recovery phase
at 70% capacity—still moving, but
moderately enough to catch your
breath and scrub lactic acid from
your muscles.
The best part? You can do any
kind of exercise you want —
swimming, cycling, rowing, and
running are popular, but anything
will work, as long as you’re pushing
your heart to the limit. With just
two of these 4x4 workouts a week,
Wisløff’s lab has made progress with
everyone from untrained slobs to
elite athletes. After the fourth round,
you should feel like you could have
done another round.Y