I suspect that the confusion on this topic, beyond the deceptive title, is that most people have simply read the title and moved on.
Could this be too good to be true?
The Actual Study
These articles are referring to a very cool study, entitled "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."4
A small group of overweight, sedentary men were assigned to one of three groups for 12-weeks (3 times/week):
A sprint-interval group (SIT), 9 men
- Three, 20-sec 'all out' maximum cycling efforts, separated by 2 minutes of low-intensity cycling.
- 9 total minutes of exercise
- 31 total sessions
A moderate-intensity continuous training group (MICT), 10 men
- 45-minutes of continuous cycling at 70% of maximum heart rate.
- 50 total minutes of exercise
- 32 total sessions
A control group, 6 men
- No exercise
"The major novel finding from the present study was that 12 weeks of SIT in previously inactive men improved insulin sensitivity, cardiorespiratory fitness, and skeletal muscle mitochondrial content to the same extent as MICT, despite a five-fold lower exercise volume and training time commitment."4
As Good As...
In other words, both groups small similar improvements on three specific variables, but not ALL aspects of exercise.
- Insulin Sensitivity
- Cardiorespiratory Fitness
- Muscle Mitochondria Content
This research adds to our growing research evidence of how both moderate- and high-intensity exercise can improve certain health- and fitness-related outcomes.6,8,9
However, we have to be careful as to what outcomes we plug in here. Very specific outcomes were measured. In other words, we cannot just plug in any outcome we want.
"1-minute of exercise is just as good as 45-minutes of exercise for... (fill in the blank)."
9-Minutes, Not 1-Minute
Yes, the SIT group did 1-minute of 'all-out' exercise, but 9-minutes of total exercise per session (< 30-minutes per week). Still not too shabby!
In this overweight group of men, here were the approximate weight loss results after the 12 weeks.
- SIT: Lost 1.8 kg or 3.9 lbs
- MICT: Lost 1.4 kg or 3.1 lbs
- Control: Gained .2 kg or .4 lbs
Other research supports the minimal weight or fat loss that would occur with such short duration, high intensity training.1,5
The sample was really small, thus more research is needed before we start giving up on moderate-intensity exercise for high-intensity interval training.
The authors state, "While the present study and work by others highlights the efficacy of SIT for improving indices of cardiometabolic health, the potential effectiveness of interval training in its various forms and likely impact on public health remains contentious."4
Sure, some would enjoy this type of 'all out' exercise. Many, if not most, will not.
To illustrate, I tested a version of the study's protocol (see video below). It wasNOT enjoyable, at all, and I do not look forward to having to do that work out again – much less for 3 times a week for 12 weeks!
Also, I only expended 78 calories during the 9-minute protocol. I was working pretty darn hard though, and blew the estimated calories from the study out of the water. The study only found about 14 calories were expended each SIT session, on average.
Less Time = Better Adherence?
The question still remains – would the shorter exercise time outweigh the aversive, negative feelings and pain associated with the high-intensity 'all out' workout, and improve adherence? I suspect not.
In general, we know that the higher the intensity, especially past our physical functional limits, greatly increases displeasure.2 Luckily, we tend to select an adequate intensity for health improvements.
We typically fall a bit short with resistance exercise, and our research found that just letting people select their own intensity does NOT lead to greater adherence in a short, 6-week program.3
However, the more positive the responses from a single exercise session can predict how much people will actually be exercising up to 1-year later!10 Also, comfortable feelings of exertion during exercise could improve competence, which might help improve to adherence.7
So, be careful what exercise you do. If it is too hard, you might undermine your own competence and future efforts to stick with it. Start with something more pleasurable, that you like (or do not mind), especially since you will probably be doing it most days of the week.
We must consider that these workout are not suited for everyone. As the authors conclude, "While SIT is clearly a potent stimulus to elicit physiological adaptations, this type of exercise requires a very high level of motivation and is clearly not suited for everyone."4
Also, if moderate-intensity worked AND high-intensity worked, requiring 45 minutes and 10 minutes, respectively, is it possible that something in-between would work also? Future research will tell.
- Bagley, L., Slevin, M., Bradburn, S., Liu, D., Murgatroyd, C., Morrissey, G., ... & McPhee, J. S. (2016). Sex differences in the effects of 12 weeks sprint interval training on body fat mass and the rates of fatty acid oxidation and VO2max during exercise. BMJ Open Sport & Exercise Medicine, 2(1), e000056.
- Ekkekakis, P., Parfitt, G., & Petruzzello, S. J. (2011). The pleasure and displeasure people feel when they exercise at different intensities. Sports Medicine, 41(8), 641-671.
- Faries, M. D., & Lutz, R. (2016). Self-selected intensity and adherence in a campus recreation center with novice, female weight lifters: a preliminary investigation. Recreational Sports Journal, 40(1), 56-68.
- 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.
- Gibala, M. J., Little, J. P., MacDonald, M. J., & Hawley, J. A. (2012). Physiological adaptations to low‐volume, high‐intensity interval training in health and disease. The Journal of Physiology, 590(5), 1077-1084.
- Grossman, J. A. C., & Payne, E. K. (2016). A randomized comparison study regarding the impact of short-duration, high-intensity exercise and traditional exercise on anthropometric and body composition measurement changes in post-menopausal women–A pilot study. Post Reproductive Health: The Journal of The British Menopause Society, 2053369115623899.
- Parfitt, G., Olds, T., & Eston, R. (2015). A hard/heavy intensity is too much: The physiological, affective, and motivational effects (immediately and 6 months post-training) of unsupervised perceptually regulated training. Journal of Exercise Science and Fitness, 13(2), 123-130.
- Ross, L. M., Porter, R. R., & Durstine, J. L. (2016). High-intensity interval training (HIIT) for patients with chronic diseases. Journal of Sport and Health Science. In Press.
- Kilpatrick, M. W., Jung, M. E., & Little, J. P. (2014). High-intensity interval training: a review of physiological and psychological responses. ACSM's Health & Fitness Journal, 18(5), 11-16.
- Williams, D. M., Dunsiger, S., Ciccolo, J. T., Lewis, B. A., Albrecht, A. E., & Marcus, B. H. (2008). Acute affective response to a moderate-intensity exercise stimulus predicts physical activity participation 6 and 12 months later. Psychology of Sport and Exercise, 9(3), 231-245.