GRIT: PRESCRIPTION FITNESS EXERCISE– BUT WHAT TYPE AND HOW MUCH? We all know that we should be exercising regularly. Our doctors tell us. The government tells us. Even celebrities tell us. And yet, despite the copious amounts of literature expounding the dangers of inactivity and its associated diseases, an astonishingly high number of us do not fulfill the recommended guidelines for physical fitness. And when we say ‘exercise’ – what should this entail? Will a brisk walk suffice or should we be exhausting ourselves until we are gasping for air? The guidelines themselves have proved to be unclear: In 2013 ACSM (American College of Sports Medicine) recommended that, to reduce the risk of developing cardiovascular disease (CVD), we engage in an unspecified combination of moderate-intensity and vigorous-intensity exercise 3-5 days per week. At present there is no clear prescription for engaging in exercise of vigorous intensity vs. moderate intensity; a gap in the guidelines exists.

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GRIT: PRESCRIPTION FITNESS
EXERCISE– BUT WHAT TYPE AND HOW MUCH?
We all know that we should be exercising regularly. Our doctors tell us. The government tells us. Even
celebrities tell us. And yet, despite the copious amounts of literature expounding the dangers of
inactivity and its associated diseases, an astonishingly high number of us do not fulfill the
recommended guidelines for physical fitness.
And when we say ‘exercise’ – what should this entail? Will a brisk walk suffice or should we be
exhausting ourselves until we are gasping for air? The guidelines themselves have proved to be
unclear: In 2013 ACSM (American College of Sports Medicine) recommended that, to reduce the risk
of developing cardiovascular disease (CVD), we engage in an unspecified combination of moderate-
intensity and vigorous-intensity exercise 3-5 days per week. At present there is no clear prescription
for engaging in exercise of vigorous intensity vs. moderate intensity; a gap in the guidelines exists.
HIIT AND THE FIT AND ACTIVE
Recent research has revealed that HIIT (High Intensity Interval Training) is the key to getting fitter,
faster. Several studies, conducted with sedentary adults, have provided compelling evidence that HIIT
also significantly lowers the risk of developing CVD. However, to date no studies had clarified how this
type of training affects the already fit and active. The research team at Les Mills set out to investigate
what effect HIIT would have upon a fit and active population, using the formula of the LES MILLS
GRIT™ Series – 30 minute HIIT workouts that incorporate explosive plyometric and dynamic strength
exercises.
THE TEST
Two studies were conducted at The Pennsylvania State University under the guidance of Dr Jinger
Gottschall, a professor of Kinesiology. Each lasted a duration of six weeks. One study focused on 84
active adults who were already regular participants in Les Mills’ strength and cardiovascular group
fitness classes and the other on 18 female soccer players.
 The group fitness study participants were split into two groups for comparison. Both
groups completed five hours of fitness classes per week: the first (high intensity)
protocol included two LES MILLS GRIT™ workouts per week alongside two
cardiovascular and two strength group fitness classes; the second (moderate intensity)
was comprised of three cardiovascular and two strength group fitness classes.
 The female soccer players changed their offseason conditioning: seven hours of
traditional training were replaced with four hours of traditional soccer and strength
training, plus two LES MILLS GRIT™ workouts.

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THE RESULTS
The most startling outcome of the group fitness study was that HIIT reduced CVD risk factors in an
already active population with above average health statistics. These participants showed vast
improvements in lean body mass, glucose tolerance and maximal oxygen consumption.
With respect to the soccer study, it was the first of its kind to use female athletes, and thus we can
look to the results with a focus upon HIIT for women. When asked why they exercise, the prevailing
response from most women will reference weight loss. We know that the best way to turn your body
into an efficient fat-burning machine is to develop muscle mass – with the most familiar way to
increasing your muscle mass being to lift weights. However, it’s a common fact that women often
prioritize cardiovascular exercise and neglect resistance training. This may be from a fear of ‘bulking
up’, or from a belief that cardio is the best way to lose weight. LES MILLS GRIT™ Strength incorporates
full body exercises such as clean and presses, deadlifts, dead rows, upright rows and hang cleans with
loaded bars. - The focus is on short sharp bursts of high repetition, not pushing excessive weight. The
significant changes in body composition seen in our results are the consequence of developing lean
muscle without the need for heavy weights; we can conclude that the significant improvements in
strength - demonstrated by these results - would benefit females for long term weight management.
For a fit and active population, HIIT is extremely time efficient. In the soccer study, the players
decreased their training time by two hours per week and still experienced improvements in training
status. LES MILLS GRIT™ offered variety to their training – thus potentially reducing the risk of overuse
injuries which may be sustained from traditional conditioning e.g. distance running. While this
particular investigation focused upon soccer players, the research indicates that HIIT could be applied
to a number of competitive sports - offering a real prescription for maximizing competition
performance and minimizing training time.
A PRACTICAL SOLUTION
LES MILLS GRIT™ takes HIIT out of the lab and offers a safe, evidence-based, practical application for
high-intensity exercise. One of the most important features of HIIT is that, not only can it enable
people to break through a fitness plateau, but the nature of the training is such that you won’t
plateau. For those who already have a good base level of cardiovascular fitness and strength, HIIT will
enable you to keep getting fitter. For athletes, it can reduce training time and still improve
performance on the field. The message is clear: it’s not the volume but the intensity that makes the
change. Our combined studies prove that 30 minutes of LES MILLS GRIT™ performed at the
recommended frequency of twice a week, will create significant changes in your fitness and body
composition, lower the risk factors for CVD, and smash through your fitness plateau. Finally - you’ve
got your prescription, what are you waiting for?