Tag Archives: interval training

Female sprinter | The Paleo Diet

So with the New Year upon us, diet and exercise resolutions typically feature prominently in many people’s lives.  However, in most cases, these resolutions fail fairly quickly and; in many cases, they have already been broken.  Despite the well-recognized beneficial impact of regular exercise on numerous health parameters, exercise participation and adherence in the general population remains poor1 – ‘lack of time’ being one of the most commonly cited reasons why individuals fail at committing to a regular exercise program2.  Consequently, it would be prudent to examine effective exercise programs that do not require a significant time commitment.

Last year, I wrote an article here that covered some of the science behind supra-maximal interval training (SIT), a mode of exercise that creates physiological benefits with a minimal time investment. And; so, if you think the title of this piece sounds too good to be true, I advise you to go and read or re-read that article so that the protocol I’m about to describe to you is more believable; as well as, understand that it does indeed have scientific backing and makes physiological sense. So the purpose of this article is to simply provide the reader with an easy to implement effective exercise protocol that requires an incredibly small investment of time.

When I lecture about SIT, I describe an activity that helps my audience understand why intensity, not duration, is the key ingredient to improving one’s fitness.  I ask the audience to close their eyes and imagine they are standing at the base of the stairs inside a football stadium. I, then, ask them to imagine ascending the stairs as fast as they can while I describe to them the many varied speeds that would be witnessed despite everyone putting forth the same relative effort.  I also describe what everyone would be typically feeling at 15, 30, 45 and finally 60 seconds when I shout stop. I, then, ask them to compare the heaving breathing and the feeling of lactic acid in their lungs and muscles that they would be experiencing to what they would experience following an hour-long walk or slow jog.  Then a simple question:  which of these two training modalities do they think is going to stress them more to cause a physiological change to their cardiorespiratory and metabolic fitness?  Common sense leads everyone to consistently choose the all-out sprint as the method that they think would lead to a greater physiological change.  After then quantifying the number of steps attained, I state that everyone is done training for the day and; since they will inevitably feel some effects from that all-out effort, they will have a day’s rest before returning to the stadium for their second all-out stair-climb on day three.  I tell them we are going to continue doing this for 30 sprints, which will equate to two months of training requiring just 3½ minutes per week! To clarify this time commitment, it would take two weeks to complete seven “every other day” 60-second sprints, hence 3½ minutes per week.  And, finally, the ultimate question, “does anyone doubt, that on the 30th sprint, you will be able to attain significantly more steps than you did back on day one?”  Intuitively, people understand that they would be able to do more steps on their last sprint compared to their first.  And if this happens, by definition one is now fitter since a greater amount of work has been accomplished in a given amount of time.  So you can indeed improve your fitness in just 3½ minutes per week when the training effort is maximal or close to maximal.

You can test this out for yourself, and so here’s your challenge for the New Year:  While continuing with your current level of activity, add just 3½ minutes per week of all-out sprinting and see for yourself what this can accomplish.  I will offer different options for you on how to accomplish adding in these “sprints”; but, first let me describe what I recently did to prove my point.  Since improvement is always harder when one is already very fit, I reduced my own training to the lowest possible quantity, given that conditioning people is part of what I do for a living and am; therefore, constantly on my feet; as well as, demonstrating exercises throughout the day.  However, eliminating my own training for a few months led to a significant decrease in my maximal 60-second sprint speed, on a treadmill set to a 15% incline, from about 9.0 mph to around 7.0 mph.  I, then, embarked on an exercise protocol that involved sprinting on a treadmill, set at a 15% incline, for just 60-seconds, every other day, beginning at 7.0 mph, a speed previously established as a maximal or at least close to maximal effort.  If the 60-second sprint was successfully completed, the subsequent sprint was done at a speed 0.1 mph greater than the preceding sprint, equivalent to running an additional 2.68 meters in 60-seconds.  If the 60-second sprint was not successfully completed, the speed was not increased for the next sprint until it was successfully completed.  The protocol was conducted for five weeks such that a total of 18 sprints were completed.  Table 1. shows the speed (mph), time completed (s), meters attained, increase in meters from the first sprint, and percent improvement from the first sprint for each of the 18 sprints, and Figure 1. graphically displays the additional meters attained from the first sprint.


Sprint Table with Caption (2)


Sprint Graph with Caption (2)


As both Table 1. and Figure 1. demonstrate, over the course of just five weeks, sprinting all-out for 60 seconds every other day, resulted in an improvement of 32.18 meters (105.58 feet) from the first sprint, a 17.14 percent improvement.  Note that not every sprint was successfully completed on the first attempt at the increased speed.  When you are working at a maximal effort, there are many factors that influence performance, mental fortitude probably playing the largest role.  But even when the sprint isn’t successfully completed, your system is still being significantly challenged and a training effect is still occurring.  Consequently, over time, you will see an increase in performance albeit with a few peaks and valleys along the way.

Now, while this protocol will help you improve your fitness, I’m not suggesting that adding a few more sprints to your work-out is not going to help you more.  In fact, you might be thinking, if I’m going to make the effort to get to the gym, I might as well do a couple more sprints while I’m there!  So, of course, you can do more; but, be careful how much SIT you do, as it is easy to over-train.  Research has already shown that SIT for 8 minutes per week for just 2 weeks can both double endurance capacity3; as well as, substantially improve insulin action4 , so doing significantly more than that likely isn’t necessary for most people.  Additional exercise time could be better spent in other modes of exercise to improve strength and mobility for example.  Since I began my interest in SIT back in the mid 1990s, the research has always suggested a similar quantity to that used in the above referenced research.  As a consequence, I have used with my clients and recommended in lectures, a 12-minute per week protocol that has proven very successful.  This 12-minute per week protocol involves completing four, 60-second sprints, separated by a 4-minute recovery, three days per week.  The three days also need to be separated by at least one days rest in order for the body to adapt and recover.  Consequently, a Monday, Wednesday, Friday timetable works well for many people.  It is important not to shorten the 4-minute recovery because if you do, you will not be able to maintain the power output attained in the first “all-out” effort interval.  In fact, 4 minutes is a minimal recovery timeframe and you can certainly take more recovery with no detriment to the training.  In fact, I have often stated that having a very long recovery (e.g., an hour or more) is better because you will ultimately be able to increase your power output by having more recovery. It is not about “keeping your heart-rate up” during the work-out, the 60-second sprint itself is challenging enough.  Now obviously having an hour recovery is not the most time-efficient if you’re doing this work-out at the gym; however, if you have access to a modality at home or work, this approach can work very well.  For example, many people have a tall enough staircase at their workplace which works well for SIT as the impact is low while the intensity can easily become maximal.

I have conveyed this message to thousands of fellow health-care professionals in my capacity as a lecturer for the Titleist Performance Institute, who, in-turn, have passed this on to their clients, and I have yet to hear that the protocol hasn’t significantly improved anyone’s health and performance.  A year after one such lecture, a physical therapist approached me at another seminar to thank me for the recommendation.  He worked at a hospital and used the staircase in his building to run four, 60-second sprints throughout the day on a Monday, Wednesday, and Friday. A great benefit to spacing the sprints throughout the day is that you do not really perspire in just 60-seconds and; so, with a long recovery, you do not need to be changing into work-out clothes – avoid high-heals; but, other than that, your pretty much good to go in your usual work attire.  The physical therapist went on to tell me that he corralled a group of his co-workers to commit to the program along with him and; in doing, so was able to lose over 50 lbs. over the course of the year!  Pretty good for just 12 minutes per week!

There are many different modalities that can be used for SIT; but, for those where balance, mobility or joint issues come into play, the upright stationary bike is probably the best alternative.  It also works well for everyone else, too.  However, unlike for most treadmills, where the speed is pre-determined, upright stationary bikes set a resistance and the speed is dictated by the user.  As a consequence, the speed is quicker at the beginning and slows quickly as fatigue develops with time; hence, 60 seconds feels like an eternity. So if you choose to use an upright stationary bike, set the resistance to as high as you can handle and complete the time prescription in 30-second increments rather than 60.

So, in closing, don’t give up on a new year’s exercise resolution because you can’t commit to a plan that requires an amount of significant time.  Hopefully, you’ve seen that a little exercise can go a long way when implemented with an all-out effort.  And if you do fail with your New Year’s resolution, don’t give up for the long term; realize that you can get right back on track any time with a minimal amount of time required.


[1]Hallal PC, Andersen LB, Bull FC, et al. Global physical activity levels: surveillance progress, pitfalls, and prospects. Lancet 2012; 380(9838): 247-57.

[2]Korkiakangas EE, Alahuhta MA, Laitinen JH. Barriers to regular exercise among adults at high risk or diagnosed with type 2 diabetes: a systematic review. Health Promot Int 2009; 24(4): 416-27.

[3]Burgomaster KA, Hughes SC, Heigenhauser GJF, Bradwell SN, Gibala MJ. Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans. Journal of Applied Physiology 98: 1985-1990, 2005.

[4]Babraj JA, Vollaard NB, Keast C, Guppy FM, Cottrell, Timmons JA. Extremely short duration high intensity interval training substantially improves insulin action in young healthy males. BMC Endocr. Disord. 2009 Jan 28; 9:3.


Interval Training: Stop with the Tabatas and Do Some Gibalas! | The Paleo Diet

Sprinting would obviously have been a necessary requirement for Paleolithic hunter-gatherers, both for the procurement of food and to avoid becoming food! Those who want to argue against that statement with the “persistence hunting” position, I will address that in a future post. Regardless, let’s fast forward to modern day and address a topic pertinent to my initial statement. To say that “Tabatas” have become an extremely popular interval training protocol in the fitness industry would be an understatement. When I wrote a position paper1 back in 2008 on the benefits of sprint interval training, the research conducted by Izumi Tabata et al. was obviously referenced as it added to the body of evidence that supports the benefits of high-intensity intermittent (interval) training (HIIT). However, the interpretation of this protocol in the fitness industry has often been misunderstood, and even when done correctly, I would argue that, for most individuals, it is not the most effective approach to interval training. After all, the protocol tested was simply one that was first introduced by a head coach of the Japanese National Speed Skating Team, Kouichi Irisawa; a protocol one would assume worked well for certain athletes based upon the duration of their events. Further, most good coaches use training methods that are often experimentations that change with time, as more successful protocols take shape. Along these same lines, I believe most people could improve their investment of time by not using the Tabata protocol for their interval training; but rather, use a different approach.

For the uninformed, in 1996, Tabata et al. published the findings of a study comparing moderate-intensity endurance training (MIET – 70% VO2 max for 60 minutes, 5 days per week) with HIIT (170% VO2 max for 20 seconds x 7-8 with 10 seconds recovery, 5 days per week) on a cycle ergometer.2 The study found that HIIT improved maximal oxygen uptake slightly more than MIET; but, also improved the anaerobic capacity by 28% while the MIET had no effect on the anaerobic capacity. So, essentially, a “two for one” in terms of improving metabolic capacities for the HIIT protocol.

While the results of the study were important for the comparison of MIET to HIIT, other interval training protocols have demonstrated similar and; in some cases, even greater benefits with a decreased investment of time.3, 4, 5, 6 These latter studies support what I have witnessed clinically over nearly 20 years, which is, that intensity, not duration, is the key ingredient for beneficial physiological change. The intensity of the HIIT protocol examined in the Tabata study was 170% VO2 max, which, while correctly being labeled supramaximal (above 100% VO2 max) and certainly “high-intensity,” is nowhere near a maximal sprint effort given that humans are capable of intensities around 250%. The power output sustained for a maximal effort for the duration of the exercise time of the Tabata HIIT protocol (140 seconds to 160 seconds), is very different to the power output sustained for a maximal effort for an “all-out” sprint lasting, say, 30 seconds. If 170% VO2 max was all one had to escape a predator in primitive times (or today for that matter), it is pretty much a guarantee that you are going to be out of the gene pool in short order! 100% VO2 max represents the power output attained when one reaches maximal oxygen consumption during a graded exercise stress test. Any human starting out at that equivalent intensity would not find it anywhere near a maximal effort for a short “all-out” sprint.

When sprinting “all-out,” most individuals are going to start slowing down within seconds; but, could probably still hold a decent percentage of their maximum power output for anywhere between 20-60 seconds, depending on their level of conditioning, and, in particular, their ability to handle the lactic acid production associated with supramaximal exercise. Considering the short duration of supramaximal activity, it generates a relatively large volume of excess post-exercise oxygen consumption (EPOC), partly due to the lactic acid production. Research has shown a significantly larger EPOC is generated for a 45 second “all-out” sprint compared to a 30 second “all-out” sprint, and a significantly larger EPOC is generated for a 60 second “all-out” sprint compared to a 45 second “all-out” sprint.7 However, a 90-second “all-out” sprint did not generate a larger EPOC than a 60 second “all-out” sprint. The reason for this is that lactic acid production typically reaches its peak at around 60 seconds of supramaximal exercise, which, in turn, inhibits muscular contraction and thereby decreases the production of further large quantities of lactic acid.  Anyone can easily experience this for him or herself. There simply is not a human on the planet that can maintain close to maximal power output without a precipitous drop-off at around 60 seconds. If you find otherwise, immediately contact your country’s Olympic Committee as I can assure you that you will be in high demand! So, 60 seconds is essentially a maximal and optimal duration to engage in supramaximal activity. Perhaps selective pressure with respect to our ancestral survival played a part in this physiological reality.

Now, back to the Tabata protocol. There are two ways in which individuals in the fitness community are misinterpreting this methodology. First, and perhaps somewhat ridiculously, are those individuals and classes that label their work-outs as “Tabatas” because they simply exercise for 20 seconds (at relatively low intensities), rest for 10 seconds, and then repeat the same for seven to eight intervals, and then, in some cases, even repeat again for an hour long workout. Anyone engaging in this approach is as far away from supramaximal interval training as one can get. The second misinterpretation comes from those that are completing the seven to eight 20 second intervals as “all-out” efforts.  With this approach, based upon the previous discussion about 60 seconds being a maximal duration for “all-out” exercise, any intervals past the first three 20 second sprints are essentially a waste of time. The only way someone can complete seven to eight 20-second intervals with only a 10-second recovery is to back down from an “all-out” sprint, to an intensity similar to that tested in the Tabata study. Doing this certainly has its merits for athletic endeavors that last for 140 seconds to 160 seconds; however, for the average individual and most athletes, I would argue that the protocol researched by the group headed by Martin Gibala from the Department of Kinesiology at McMaster University in Hamilton, Ontario, Canada, is a much more effective approach to interval training.

This protocol, as first described by Burgomaster et al.,3 involves completing “all-out” 30-second sprints (also on a cycle ergometer) with a 4 minute recovery between exercise bouts. The number of sprints increased from 4 during the first two sessions, to 5 in the third and fourth sessions, and 6 in the last two sessions. The total time commitment was 17–26 minutes per session, involving only 2–3 minutes of sprint exercise. Exercise sessions were completed every two to three days such that 16 minutes of exercise was completed in a two-week time period.  The results of this protocol showed a doubling of the participants’ endurance capacity! So these benefits occurred over a two-week period using just 16 minutes of sprinting. Further studies using this same protocol have been shown to substantially improve insulin action in young sedentary subjects, a much-needed outcome in this world full of metabolic syndrome.4 This demonstrates that quality not quantity causes physiological change for the better and, in many cases, the Tabata protocol in the fitness industry has become a methodology that has moved away from quality toward quantity. Further research has now shown that intense bouts as short as 6-20 seconds can have a tremendous benefit on physiological health, emphasizing, again, that intensity, not duration, is the key element to beneficial change.5,6 I have also found clinically, that these very short bouts of intense activity are better adhered to while still providing tremendous improvements in health and performance.

Moreover, I found a common objection to this methodology is that unfit and elderly individuals should not engage in this type of supramaximal activity due to the inherent dangers of engaging in such intense activity. With extensive experience in this field, I have never had a situation where an unfit individual or an elderly individual has had a problem with engaging in this kind of supramaximal activity. In fact, I would argue that it is beneficial to engage in this type of exercise in a controlled environment; rather than leave it to the reality of life where external pressures may demand an effort above which one is physiologically not trained to handle.  Interestingly, an increased QT dispersion (QTd) – a marker of myocardial electrical instability that predicts ventricular arrhythmias and sudden cardiac death – has been shown to be decreased with short-term supramaximal exercise.8 This supports the notion that short-term supramaximal exercise is an appropriate approach for anyone to improving one’s physiological health.

In closing, unless you have an athletic event lasting between 140 seconds to 160 seconds, skip the Tabatas and engage in Gibalas or some other shorter interval training protocol that produces better results with a smaller investment of time.  And don’t overdo the quantity of “all-out” sprints – eight to twelve minutes per week is sufficient to reap the benefits without the risks associated with overtraining.

Dr. Mark J. Smith

Dr. Mark J. Smith | The Paleo DietDr. Mark J. Smith graduated from Loughborough University of Technology, England, with a Bachelor of Science in PE & Sports Science and then obtained his teaching certificate in PE & Mathematics. As a top-level rugby player, he then moved to the United States and played for the Boston Rugby Club while searching the American college system for an opportunity to commence his Master’s degree. That search led him to Colorado State University where Dr. Smith completed his Masters degree in Exercise and Sport Science, with a specialization in Exercise Physiology. He continued his studies in the Department of Physiology, where he obtained his Doctorate. His research focused on the prevention of atherosclerosis (the build up of plaque in arteries that leads to cardiovascular disease); in particular, using low-dose aspirin and antioxidant supplementation. Read more…


1. Smith MJ. Sprint Interval Training – “It’s a HIIT! A research paper discussing the superior health and performance benefits of high-intensity intermittent exercise over low-to moderate-intensity continuous exercise. 2008 //docsmith.org/SIT-HIITbyMJS-1411.pdf

2. Tabata I, Nishimura K, Kouzaki M, Hirai Y, Ogita F, Miyachi M, Yamamoto K. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Med Sci Sports Exerc. 1996 Oct; 28(10): 1327-30

3. Burgomaster KA, Hughes SC, Heigenhauser GJ, Bradwell SN and Gibala MJ. Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans. Journal of Applied Physiology 2005 98:1985-1990

4. Babraj JA, Vollaard NB, Keast C, Guppy FM, Cottrell G, Timmons JA. Extremely short duration high intensity interval training substantially improves insulin action in young healthy males. BMC Endocrine Disorders 2009 Jan 28; 9: 3.

5. Adamson S, Lorimer R, Cobley JN, Lloyd R, Babraj J. High Intensity Training Improves Health and Physical Function in Middle Aged Adults. Biology 2014 3: 333-344.

6. Metcalfe RS, Babraj JA, Fawkner SG, Vollaard NB. Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. Eur J Appl Physiol.2012 Jul; 112(7):2767-75.

7. Withers RT, Van der Ploeg G, Finn JP. Oxygen deficits incurred during 45, 60, 75 and 90‐s maximal cycling on an air‐braked ergometer. Eur. J. Appl. Physiol. 1993; 67(2): 185‐91.

8. Drigny J , Gremeaux V, Guiraud T, Gayda M, Juneau M, Nigam A. Long-term high-intensity interval training associated with lifestyle modifications improves QT dispersion parameters in metabolic syndrome patients. Ann Phys Rehabil Med. 2013 Jul; 56(5):356-70.

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