The Science and Application of

HIIT Training
Bryce Hastings, MPhil Jinger S Gottschall, PhD

Head of Research Associate Professor Kinesiology

Les Mills International
 WHY
GLOBAL HEALTH IS SUFFERING
DUE TO LACK OF ACTIVITY AND OPTIMAL
EXERCISE PRESCRIPTIONS
 WHY
PHYSICAL ACTIVITY AND FITNESS
CAN REDUCE THE RISK OF DISEASE AND
IMPROVE SATISFACTION WITH DAILY LIFE
AMERICAN COLLEGE OF SPORTS MEDICINE EXERCISE GUIDELINES

WHY
Moderate
DURATION FREQUENCY EXERCISES FREQUENCY DURATION FREQUENCY

30 - 50 MIN 3 - 4 DAYS/WEEK 8 - 10 2 DAYS/WEEK 60 MIN 1 DAY/WEEK

OR

Vigorous
DURATION FREQUENCY

20 - 60 MIN 3 DAYS/WEEK
 WHY
THERE IS AN OBVIOUS GAP IN THE
CURRENT LITERATURE WITH RESPECT
TO INTENSITY IN REDUCING DISEASE
AND ENHANCING FITNESS
WHAT

HOW
Definition:
Repeated bouts of short to moderate duration
exercise completed at an intensity that is greater
than the anaerobic threshold (Laursen & Jenkins

WHO
2002).

Efforts interspersed with brief periods of partial

recovery, either low to moderate intensity activity or
passive rest.
Purpose:
To perform significantly more total exercise time at a
higher intensity than can be achieved using a
continuous, steady state exercise (SSE) protocol.

WHO
Therefore, HIIE is considered a time-efficient training
strategy to induce rapid adaptations in skeletal
muscle and exercise performance that are
comparable to traditional continuous endurance
training (Gibala et al. 2006)
 WHY
LES MILLS vs LES MILLS GRIT PLYO

BODYATTACK BODYCOMBAT BODYSTEP RPM LES MILLS GRIT PLYO

WHAT
WHO
HOW
WHEN/WHAT/HOW?
RPM & SPRINT

HOW
 GET FIT WITH HIIT

PROTOCOL RESULTS

WHO
ADHERENCE INJURY

SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY

Gottschall, et al. 2014

 PROTOCOL

GROUP GROUP

FIT HIIT
CONTROL (N=42) EXPERIEMENT (N=42)

WHO
3 2 1 2 2 2 1
 RESULTS

WHO
VO2 BODY FAT TRIGLYCERIDE

6.4% 2.0% 16.9%

blood sample
blood sample

HDL (mg/dL) TRI (mg/dL)

WHO
FIT 0.3 -3.3

GRIT 2.3 -16.9

difference 2.0 -13.6

body composition

WHO
strength
strength

leg (kg) back (kg)

WHO
FIT 4.5 6.5

GRIT 12.1 16.3

difference 7.6 9.8

fitness
fitness

VO2 (ml/kg/min)
FIT 0.7

WHO
GRIT 6.4
difference 5.7
INJURY

WHO
 ADHERENCE

SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY

WHO
compliance rate was

less than 30 workouts missed for the 84

participants in 2772 sessions
PARTICIPANTS RATED THE TRAINING

WHO
SESSIONS AS A POSTIVE EXPERIENCE
SATISFACTION WITH CHALLENGING INTENSITY
fitness

VO2 (ml/kg/min)
FIT 0.5

WHO
SPRINT 4.1
difference 3.6
fitness

leg (kg)

FIT 0.3

WHO
SPRINT 9.1
difference 8.8
WHEN

HOW
AMERICAN COLLEGE OF SPORTS MEDICINE EXERCISE GUIDELINES

Moderate
DURATION FREQUENCY EXERCISES FREQUENCY DURATION FREQUENCY

30 - 50 3 - 4 MIN DAYS/WEEK 8 - 10 2 DAYS/WEEK 60 MIN 1 DAY/WEEK

HOW
OR

Vigorous
DURATION FREQUENCY

20 - 60 MIN 3 DAYS/WEEK
 While these minimum guidelines are
maximum 90-100%
clearly described, there are currently no
maximum guidelines, particularly with
respect to high-intensity time and
frequency, for the prevention of
overtraining or functional overreaching.

mins = OR

HOW
??? per wk
 BACKGROUND Overtraining syndrome (OTS) and functional overreaching (OR) are results
of a combination between excessive load and inadequate recovery, which
lead to symptoms related to stress and decrements in performance.

SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY

HOW
Insufficient evidence is available to determine whether a dose-response
relationship exists between the quantity of high intensity interval training
and functional overreaching for active adults.

Cadegiani and Kater, 2017; PAG Advisory Committee, 2018

BACKGROUND: Cortisol is a stress hormone produced in the adrenal
gland (above kidney). It can help control blood sugar levels, regulate
metabolism, reduce inflammation, and assist with memory formulation.

early am late am early pm late pm

+ Short term elevation of cortisol with high intensity exercise can

be beneficial to help the body repair, adapt, and grow stronger.

HOW
- Long term elevation of cortisol with too much high intensity
exercise can cause fatigue, joint pain, and mood disturbance.
 #1 #2

cortisol ug/dL
A B C A B C

Healthy response to a high intensity protocol

#1 with cortisol measured before exercise, after
exercise, and after recovery.

HOW
Unhealthy response with elevated resting
#2 cortisol and reduced elevation after exercise
indicating greater lifestyle stress or overtraining.
HYPOTHESIS There is an optimal time per week of high intensity (90-100% maximum
heart rate) training that will lead to greater variation in the production of
stress hormones and reduced self-reporting of stress related feelings.

maximum 90-100%

+ mins = OR

HOW
??? per wk
METHODS: participant characteristics

years 35 kg
35.19 + 9.52 68.64 + 12.84

28 7

HOW
hours meter
9.01 + 2.52 1.68 + 0.09
METHODS: Three weeks of typical training

Polar A370, H10

SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY

5 maximum90-100%
maximum 90-100%

hard
4 hard 80-90%
80-90%

moderate
3 moderate 70-80%
70-80%

light
2 light 60-70%
60-70%

kcal total time

macro mood quality

HOW
MyFitnessPal POMS 40 Polar A370
METHODS: Two-bout, high intensity protocol with saliva collections

0900 1000 1100 1200 1300 1400 1500 1600 1700

A B C D E F

HOW
HIIT HIIT
RESULTS: The greatest hormonal response was measured in the
participants who completed 30-40 minutes of high intensity training per
week.
* indicates a significant difference from 30-40 min above 90%; p < 0.05
CORTISOL
less than 25 min between 30-40 min greater than 45 min
0.70

0.60
cortisol ug/dL

0.50

0.40
*
0.30
*

HOW
0.20 * *
0.10
*

0.00
A B C D E F

saliva collection points

RESULTS: The greatest hormonal response was measured in the
participants who completed 30-40 minutes of high intensity training per
week.
CORT E-D
0.80

0.60

0.40
cortisol ug/dL

0.20

0.00

HOW
-0.20

-0.40

-0.60
0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00

average minutes per week 90-100% HRmax

RESULTS: Sleep quality was greatest for the participants who completed
30-40 minutes of high intensity training per week.

Sleep Quality
5

4.5

3.5

2.5

HOW
2

1.5

1
0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00

average minutes per week 90-100% HRmax

RESULTS: Total Mood Disturbance was minimal in the participants who
completed 30-40 minutes of high intensity training per week.

Total Mood Disturbance

120

110

100

90

80

HOW
70

60
0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00

average minutes per week 90-100% HRmax

RESULTS: Moderate negative correlation (R = -0.404, p < 0.05) between
baseline cortisol and kilocalorie balance; greater cortisol when in energy
deficit.
baseline CORTISOL
1.400

1.200

1.000
cortisol ug/dL

0.800

0.600

0.400

0.200

0.000
0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30

kcal in / kcal out

CONCLUSION Our data demonstrate that 30-40 minutes of high-intensity (90-100%
maximum heart rate) training per week is a suggested range of
cumulative time in order to prevent symptoms related to overreaching.

maximum 90-100%

maximum
+ mins = fitness &

HOW
wellness
30-40 per wk
INTENSITY AWARENESS

5 - 9%

WHEN/WHAT/HOW?
EXERCISE PRESCRIPTION

2 2-3 2-3 1

WHEN/WHAT/HOW?