Tremblay Interval Training Study

The purpose of this article is to take a closer look at Tremblay's way of interval training. While Dr. Tabata's interval training research and training program is very popular, Dr. Tremblay's interval training research deserves just as much publicity. I will attempt to summarize Dr. Tremblay's study the best I can since it is very detailed and technical. In 1994, Dr. Angelo Tremblay and his colleagues at the Physical Activities Sciences Laboratory, Laval University, Quebec, Canada, challenged the common belief among health professionals that low intensity, long duration exercise is the best program for fat loss. Their study compared the impact of moderate intensity steady-state exercise and high intensity interval training on fat loss.

The Subjects
The study divided 27 inactive, healthy, non-obese adults (18 to 32 years old) into two groups. One group (8 men and 9 women) did a 20 week endurance training (ET) program of continuous cycling (steady-state exercise). The other group (5 men and 5 women) did a 15 week program of mainly high intensity interval training (HIIT).

The ET Group

	Performed a 20 week ET program consisting of uninterrupted cycling (steady-state exercise) 4 to 5 times per week.
	Duration of the cycling sessions started at 30 minutes and progressively increased to 45 minutes.
	The exercise intensity began at 60% and progressively increased to 85% of maximal heart rate reserve.

The HIIT Group

	They started with twenty five 30-minute sessions of steady state exercise at 70% of maximal heart rate reserve. In addition to the steady-state exercise they performed 19 short and 16 long intervals over a period of 15 weeks.
	They progressively transitioned the exercise sessions from steady state and HIIT to HIIT only.
	Each HIIT session began with a 5-minute warm up at an intensity of 50% maximal oxygen uptake (VO2max).
	The short intervals were initially 10 sets and later 15 sets of 15 second work intervals, which were later increased to 30 second work intervals.
	The long intervals were 4 to 5 sets of 60 second work intervals, which were later increased to 90 second work intervals.
	The work intervals were separated by rest intervals that allowed the heart rate to return to 120-130 beats per minute.
	The intensity of the short work intervals was initially fixed at 60% of maximal work output in 10 seconds (this might be a typo, I think they meant 30 seconds), and that of the long work intervals corresponded to 70% of the individual maximal work output in 90 seconds.
	The intensity of the short and long work intervals was increased by 5% every 3 weeks.

The Results
The HIIT group burned twice as many calories while exercising than the ET group. This was shown by the difference in the total energy cost of the two programs. When the decrease in the sum of skinfolds was divided by calories burned, the subcutaneous fat loss was ninefold greater for the HIIT program than the ET program. In short, the HIIT group lost 9 times more fat for every calorie burned during exercise. Furthermore, the study stated that is is also possible that high intensity exercise burns more calories and fat after exercising than does moderate exercise.

Observations
There were some interesting things I noticed about the study. The rest intervals were not timed, so the length of the rest intervals was however long it took for the subjects' heart rate to return to 120-130 beats per minute after the work intervals were performed. Since the rest interval lengths were not reported in the study I am curious how long it took for the subjects' heart rate to return to 120-130 beats per minute during the rest intervals. Furthermore, the study did not state how many times per week the HIIT group trained, which I would have also liked to know.

The Tremblay study tells us that untimed rest intervals that allow enough time to bring your heart rate back down to 120-130 beats per minute are still effective for interval training. And doing interval training in this manner provides a really good breather during the rest intervals. Lastly, doing Tremblay intervals will require the use of a heart rate monitor to track the rest intervals.

References
University of Colorado Boulder: Tremblay study
Clarence Bass: Forget the Fat-Burn Zone

Tremblay Intervals Chart
Let's chart and organize the Tremblay intervals for better reference. Give them a shot for a unique interval training experience for one of your interval workouts.

HR (heart rate)
BPM (beats per minute)

Short Intervals (15 or 30 seconds)

Work Interval  &  Rest Interval                                  Sets               
15 seconds         Allow HR to return to 120-130 BPM    10-15

Work Interval  &  Rest Interval                                  Sets               
30 seconds         Allow HR to return to 120-130 BPM    10-15

Long Intervals (60 or 90 seconds)

Work Interval  &  Rest Interval                                  Sets               
60 seconds         Allow HR to return to 120-130 BPM     4-5

Work Interval  &  Rest Interval                                  Sets               
90 seconds         Allow HR to return to 120-130 BPM     4-5