these CrossFit workouts both meet the mark.
Similar to the HR responses, V•
O2 increased
immediately during the first round of both workouts
and increased slightly with subsequent rounds
(Figure 2). Researchers found that V•
O2 averaged 80
percent of V•
O2max during both CrossFit workouts,
indicating that the subjects were exercising
well above their anaerobic thresholds. This is at
the higher end of industry recommendations of
maintaining 40 percent to 85 percent of V•
O2max to
improve cardio endurance.
The vigorous intensity of a CrossFit workout was
further illustrated by participants’ blood lactate
values, which averaged 15.9 mmol/L for men and
12.4 mmol/L for women, both of which are well
above the normal lactate threshold of 4 mmol/L.
Across the board, subjects’ RPE values for both
workouts were rated as “hard” (Figure 3) and
the RPEs during Donkey Kong (workout 1) were
markedly higher than those for Fran (workout 2).
THE BOTTOM LINE
CrossFit works. For those who already do CrossFit
regularly, this is surely no news flash. Based on the
high intensity of the workouts tested, researchers
conclude that CrossFit does a really good job of
helping exercisers improve their aerobic fitness, while
burning a fair number of calories in the process.
And, like other high-intensity interval-training (HIIT)
workouts, one can expect greater increases in aerobic
capacity than what is seen with traditional aerobic
training, which is typically performed well below an
individual’s anaerobic threshold.
Working out more intensely for shorter periods
means that exercisers can likely get good results
with CrossFit while spending less time exercising,
says Babiash. “The two workouts were completed in
fewer than 12 minutes, not including the warm-up
and cool-down. Yet, despite this short duration,
subjects still burned an average of 115.8 calories,”
she says. “Seeing the benefits in such a short
amount of time is encouraging, especially if you
have a busy lifestyle.”
Porcari agrees, but also notes that a pretty
big asterisk should accompany all of his team’s
findings. “You look at the intensity of CrossFit
and it’s off the charts,” he says. “This is not the
workout for a 45-year-old person with multiple
cardiovascular risk factors. People absolutely need
to be properly screened before beginning CrossFit.”
Beyond being potentially risky for heart-attack
prone, would-be exercisers, Porcari warns that the
competitive nature and emphasis on completing
CrossFit exercises as quickly as possible may well
be a recipe for injury for some exercisers.
“The thing we’ve seen with a lot of these
workouts is you go flat-out as fast as you can, but
then your form falls apart. You really need to be
technically correct with a lot of these exercises or
else you’re going to get hurt,” says Porcari. “And