The Effect of High Intensity Interval vs Moderate Continuous Endurance Exercise Training on Program Adherence
Phase: NA
Conditions: Physical Activity, Fat Burn
Sponsor: Western University, Canada

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The effect of high intensity interval vs moderate continuous endurance exercise training 
on program adherence  
 
Introduction & Background  
For optimal health, current Canadian physical activity guidelines recommend 150 minutes of 
moderate intensity or 75 minutes of vigorous-intensity endurance exercise training per week. 
Yet many Canadians fail to meet these recommendations apparently due to lack of time. 
Recently, several studies observed that very brief, repeated exercise bouts at high intensity 
promote similar health and exercise performance benefits as those found with moderate 
endurance training of much longer duration. For example, MacPherson and colleagues (2011) 
has compared brief, sprint vs much longer continuous endurance exercise training and found 
similar improvements for endurance capacity and exercise performance. Similarly, Gillen et 
al. (2014) found three 20 second bouts of high interval training at an all-out effort intensity 
elicited similar physiological benefits as to 50 minutes of moderate endurance training. 
Further, another recent study found short, repeated bursts of high-intensity training over 12 
weeks had similar health benefits as 50 minutes of moderate endurance training (Gillen et al., 
2016).  The current study will follow a similar exercise training protocol as Gillen et al. 
(2016) however, importantly, will control exercise time (20 minutes in both groups) because 
it is assumed that the shorter duration in the high intensity groups of previous studies may 
contribute to greater program adherence rates. 
 
Research Objectives 
1. To determine whether high-intensity interval training (HIIT) group experience a 
greater program adherence than moderate continuous endurance exercise training 
(MCEET) group when matched for time commitment of 20 minutes 
2. To assess whether HIIT group results in greater improvements in fat loss and 
endurance capacity than MCEET group  
 
Research Hypothesis  
The study hypothesizes that HIIT group will result in greater program adherence than 
MCEET. Also, HIIT group will result in greater improvements in fat loss and endurance 
capacity vs. MCEET group.  
 
Methods  
40 healthy adults aged 19 to 35 years (20 men, 20 women) will participate in the study. 
Participants will be recruited from Western University and its surrounding community via 
university poster. Interested participants will be asked to come to the Exercise Nutrition 
Research Laboratory (Room 2235 3M Centre) for a face-to-face interview with the 
investigator and to complete Get Active Questionnaire (GAQ) that includes medical history 
for pre-screening eligibility. Inclusion criteria include healthy participants between the ages 
of 19 to 35 years who engage in physical activity less than three times per week. They must 
be able to run a mile, have an access to the gym as well as smart phones (such as Android, 
Cat phone, Google Nexus, Samsung Galaxy, iPhone, Microsoft Lumia, myTouch or Phablets) 
and can access to Apps (such as MyFitnessPal, Rise Up, Calorific, My Diet Coach, Yazio, 
On The Regimen, See How You Eat, Lost It, MyNetDiary or MyPlate). Exclusion criteria 
include diabetic, pregnant, individuals with a history of fainting, low and high blood pressure, 
heart disease, respiratory disease, migraines, heartburn, smokers, engage in physical activity 

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more than two times per week and answering YES to any questions from page 1 of GAQ. 
Eligible participants will be provided with the written informed consent. 
 
Once completed, all participants will complete body composition testing via air displacement 
plethysmography (Bod Pod) pre and post intervention (week 0 and 6). Following Bod Pod 
measurements, participants will run a practice mile run for familiarity and will run again for 
measurement purposes before and after the exercise intervention to assess their endurance 
capacity. Time will be measured by a stopwatch. Participants will be match-paired based on 
their endurance capacity to either HIIT or MCEET group for five weeks. They will fill out 
two validated questionnaires, physical activity enjoyment scale (PACES) and exercise 
adherence rating scale (EARS) after the 6th, 9th and 15th session to assess their program 
adherence. They will be instructed not to engage in any either exercise program during the 
study period.  
 
The first week of the exercise intervention will consist of one-on-one supervised treadmill 
training, three times per week in the lab. From week two to five, participants will follow the 
same exercise program on their own at their preferred gym three times per week in order to 
examine free-living individuals adhere to two exercise programs. Each participant will be 
matched to either HIIT or MCEET group based on their timed one-mile run. The HIIT group 
will perform six, 20-second bouts of high intensity interval exercise separated by 2 minutes 
of active recovery (walking) while the MCEET group will perform 14 minutes of continuous 
endurance exercise at 70% Maximum Heart Rate (MHR). Both exercise protocols will 
include 3 minutes of warm up and cool down at a 30% MHR, for a total of 20 minutes for 
each treatment.  
 
Ratings of perceived exertion (RPE; Borg CR-10 scale) will be recorded at the end of each 
interval for HIIT group and at 10 and 20 minutes of exercise for MCEET group on the 6th, 9th 
and 15th session. All participants will log their heart rate before, during, and immediately 
after each training session using Fitbit or a free heart rate monitor mobile App (e.g. Argos) to 
ensure safety and achievement of their targeted heart rate. Participants will also complete 
physical activity enjoyment scale (PACES) and exercise adherence rating scale (EARS) on 
the 6th, 9th and 15th session to assess their program adherence. To accommodate progression, 
training intensity will be adjusted to maintain the desired relative exercise intensity based on 
above measurements. Finally, no attempt will be made to modify the participants daily diet, 
but a 3-day food log will be collected via free mobile app (e.g. MyFitnessPal) to assess food 
intake for any change. Completed questionnaires and the recorded heart rate data saved on 
Fitbit or a mobile app will be used to confirm program adherence.  
 
All the collected data will be statistically analyzed by Sigma Plot 12.0 (Systat Software, San 
Jose, CA, USA) using a two-way analysis of variance (ANOVA), Tukey’s post hoc test, and 
a paired t-test. Significance set at p<0.05. Sample size estimates are generated with a two-
way analysis of variance (ANOVA). The primary outcome variable is the program adherence, 
with a minimum important difference of 19.6 between HIIT (103.8 ± 9.4) and MCEET (84.2 
± 19.1; Thum, Parsons, Whittle & Astorino, 2017). Based on the data from Kadam & 
Bhalerao (2010), we calculate the pooled variance (19.1), effect size f (0.8), and Cohen’s d 
(1.96) for the sample size estimation.  

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Using ANOVA, match-paired study design, a minimum of 15 participants is required for an 
alpha of 0.05 and 95% power. 34% of drop out rate (Linke, Gallo & Norman, 2011) will be 
included in addition to the minimal sample size resulting in 20 participants for each group. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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References 
 
Gillen, J. B., Martin, B. J., MacInnis, M. J., Skelly, L. E., Tarnopolsky, M. A., & Gibala, M. 
J. (2016). Twelve weeks of sprint interval training improves indices of 
cardiometabolic health similar to traditional endurance training despite a five-fold 
lower exercise volume and time commitment. PloS one, 11(4), e0154075. 
Gillen, J. B., Percival, M. E., Skelly, L. E., Martin, B. J., Tan, R. B., Tarnopolsky, M. A., & 
Gibala, M. J. (2014). Three minutes of all-out intermittent exercise per week increases 
skeletal muscle oxidative capacity and improves cardiometabolic health. PLoS 
One, 9(11), e111489. 
Kadam, P., & Bhalerao, S. (2010). Sample size calculation. International Journal of Ayurveda 
Research, 1(1), 55–57. http://doi.org/10.4103/0974-7788.59946 
Linke, S. E., Gallo, L. C., & Norman, G. J. (2011). Attrition and adherence rates of sustained 
vs. intermittent exercise interventions. Annals of Behavioral Medicine, 42(2), 197. 
Macpherson, R. E., Hazell, T. J., Olver, T. D., Paterson, D. H., & Lemon, P. W. (2011). Run 
sprint interval training improves aerobic performance but not maximal cardiac 
output. Medicine & Science in Sports & Exercise, 43(1), 115-122. 
Thum, J. S., Parsons, G., Whittle, T., & Astorino, T. A. (2017). High-Intensity Interval 
Training Elicits Higher Enjoyment than Moderate Intensity Continuous 
Exercise. PloS one, 12(1), e0166299.