From The Desk Of Clarence Bass
The debate in public health is not about the efficacy and time efficiency of these protocols. It is whether outside of the controlled laboratory setting will the vast majority of the population that is physically inactive ever perform HIIT, SIT or a version of either with bodyweight exercises? The common belief is that the protocols are too hard, most people will find them very aversive to perform, and virtually no one will continue to perform any of these protocols. There is also the belief that performance of these protocols will result in numerous adverse events, e.g., a cardiac event, but that has not been the case with proper screening and initial supervision. Richard Winett, PhD, Heilig Meyers Professor of Psychology (Master Trainer, October, 2017)
The Psychology of Interval Training—What Works for Body & Mind
I first started studying, experimenting with, and writing about high intensity interval training (HIIT) 20 years ago (in 1997) when my friend Richard Winett, a lifetime fitness trainer and professor of psychology at Virginia Tech, alerted me to the work of Izumi Tabata and his colleagues at the National Institute of Fitness and Sports in Tokyo, Japan. Tabata et al compared the effects of moderate-intensity endurance and high-intensity intermittent training on V02max. They reported that speed skaters doing seven to eight sets of 20 seconds all out, with a 10 second rest between each bout, increased V02max at one of the highest rates ever recorded. A total of two minutes of all-out effort was shown to produce the same or better results than two hours of traditional endurance training.
That came to be known as the “Tabata protocol.” Dick and I were among the first to try it in this country.
As Winett wrote in the October, 2017, issue of Master Trainer, he actually enjoyed the challenge, “but it absolutely put me down for the count.” It never really caught on among fitness trainers, because it was just too darn hard to do on a regular basis. Few people—especially fitness trainers—are willing to keep doing a protocol that puts them down for the count.
After a few years, I moved on to sub-max intervals, where only the last few reps are all-out. Two weeks of this protocol were shown to improve insulin sensitivity by about 35% and increased muscle mitochondria content by about 35%. Muscle glucose transport capacity increased by about 260%. (These markers were selected because they are typically found to be depressed in sedentary individuals.) All of those benefits, from two weeks of training, and only a few minutes of it taxing!
It worked because people are willing to go all-out when the finish line is in sight.
After a time I tired of this as well. Ten total reps, as called for in this protocol, were boring and unpleasant. The finish line was too far off to keep me motivated.
I eventually moved on to sprint interval training (SIT), which is what I’m doing now. After a two minute warm-up, I do 2 to 4 all-out 20 or 30 second reps, with 90 to 120 seconds of recovery between sprints. Total time is 8 to 10 minutes, including 2 minutes of cooldown.
Interestingly, my experience is much like that found in a series of studies on the psychology of interval training and what works for most people.
Psychological Response to Intervals
As so often happens, Dick Winett called my attention to a huge study assessing the cognitive and emotional response to different high intensity interval protocols, a new endeavor with most of the research conducted in the last five years. Matthew J. Stork and a team including Martin J. Gibala (who is largely responsible for introducing intervals to fitness trainers) identified and examined 42 published articles involving 1258 participants from various active/inactive and healthy/unhealthy populations. Of the many different protocols, 69% were HIIT, 27% were SIT, and 4% used bodyweight exercises. While the report goes on for 30 pages of fine print, whether interval exercise is a viable alternative to tradition exercise is a resounding “YES.”
“Post-exercise assessments indicate that overall, enjoyment of, and preferences for interval exercise are equal or greater than for continuous exercise,” Stork et al concluded. “The emerging data support the viability of interval exercise as an alternative to continuous exercise.”
Winett wrote in his newsletter that interval training seemed to give people “confidence” in their ability to perform exercise. “This may be because there is a hard work part and then a relief part that may provide more control and enough relief to perform the next hard work part,” he explained.
Makes sense doesn’t it? In steady state exercise there is no relief, it’s a long steady grind. Frankly, I have never had much stomach for continuous exercise. I need variation to hold my interest. I look forward to doing sprint intervals, especially on different devices to spread the stress over my entire body. (See below for a study of “all-extremity” exercise on the Schwinn Airdyne.)
(You can read the Stork study online, in the June 1, 2017, Health Psychology Review.)
Let’s move on to the continuing search for protocols that build cardiovascular fitness and other desirable health outcomes with fewer and shorter sprints. More bang—physically and emotionally—for the buck.
Fewer and Shorter Sprints.
UK authors Niels B. J. Vollaard and Richard S. Metcalfe wrote recently that research should focus on finding effective protocols with fewer and shorter sprints. (Sports Medicine, online, April 8, 2017)
They say that the most commonly used SIT protocol (4-6 all-out 30 second cycle sprints, with 4 minute recovery, up to 30 minutes total) is longer and more demanding than necessary to achieve the desired benefits.
“Shorter/easier protocols [as little as two 10-20s sprints] have the potential to remove many of the common barriers to exercise in the general population,” they write. “We propose that there is a need for a fundamental change in focus in SIT research…towards establishing acceptable and effective protocols that involve minimal sprint duration and repetitions.”
For more details—the authors list 11 studies with shorter and/or fewer sprints than the classic protocol—this article is open access and can be read online without charge.
My view is that you can overdo it both ways, too long and too short. I do fewer and shorter intervals, but I come at the body different ways: the Ski Erg, the rower, and the Airdyne.
The next study examines the effectiveness of non-weight-bearing arms and legs exercise on the Schwinn Airdyne, a stationary cycle with push-pull arm action.
All-Extremity HIIT, But Not MICT, Improves Aerobic Fitness, Heart Function, and Insulin Resistance
Researchers at the University of Florida at Gainesville compared the effectiveness of HIIT and moderate intensity continuous training (MICT) using the Schwinn Airdyne.
Fifty-one healthy adults (average age 65) were randomly divided into three groups: HIIT (4x4 minutes at 90% of HR peak), MICT (32 min at 70% of HR peak), and sedentary controls. Exercise protocols were designed to burn the same number of calories.
It was a knock out for HIIT.
All-extremity HIIT, but not MICT, improved aerobic fitness, ejection fraction, and insulin resistance. After 8 weeks, aerobic fitness and ejection fraction improved by 11% and 4% respectively in the HIIT group, with no change in the MICT or control groups. Insulin resistance decreased only in HIIT, by 26%.
Hwang et al confirmed the feasibility and safety of HIIT for older adults who need to avoid weight-bearing activities due to musculoskeletal and balance problems. They also found that exercise adherence in the HIIT group surpassed most, if not all, previously reported studies.
I would go further and predict that adherence would have be even better if they had taken the advice of Vollaard and Metcalfe and used fewer and shorter work periods. Four minutes is a long time to maintain a 90% heart rate—for people of any age. Their subjects would have been more enthusiastic about doing work periods of one minute or less—and would have very likely shown even better results.
I would also emphasize the advantages of all-extremity exercise, which were enumerated by Dr. Len Schwartz in his Heavyhands book, published in 1982. His basic contention was that four limbs are better than two for expending calories and burning fat, and that you can continue exercising longer at the same intensity than you can using only the legs. It seems that we are only now catching up with the good doctor (a psychiatrist) on the benefits of training arms and legs together.
The Schwinn Airdyne, shown here, was our first arm and leg fitness trainer. Once again, we learned about it from Dick Winett, early in our friendship. The faster you pedal and push and pull the more resistance it provides. This is our third Airdyne; we've never tired of using it. Photo by Laszlo Bencze
The Hwang study is reported in the September, 2016, Experimental Gerontology. You’ll find the abstract online, but will have to pay to read the entire study.
We’ll end with a study suggesting that light to moderate continuous exercise still has a place in a program for total fitness.
All-Extremity MICT, But Not HIIT, Improves Arterial Stiffness
“Just when it appeared that if we are performing HIIT or SIT, there is no need for any moderate intensity training, or physical activity outside of training,” Dick Winett wrote in Master Trainer, “another study from the same Hwang group was published that focused on a different, and quite important variable, arterial stiffness.”
The only difference in this and the earlier study is that the target is central arterial stiffness, as shown by pulse wave velocity. If pulse wave velocity is fast, that means you have stiff arteries. If the pulse wave travels slowly—because the artery absorbs part of the pulse wave—that means you have soft, elastic arteries. Stiff arteries cause high blood pressure and increase the risk of heart attack and stroke.
They found that 8 weeks of moderate intensity continuous training (70% heart rate peak) improved arterial stiffness by about 30%. Arterial stiffness, however, remained unchanged after HIIT (4 x 4 minute at 90% HR maximum]. Again, the Schwinn Airdyne was used by both groups.
Confused? You are not alone.
Here's where we stand, according to the researchers.
“Our findings have important implications for aerobic exercise prescription in older adults,” the researcher concluded. “[They] are in accordance with previous reports on the effect of moderate-intensity brisk walking on arterial compliance in sedentary middle-age men and older men and women.”
Yes, but there's more.
“It is not clear why arterial stiffness improved in response to all-extremity MICT but not HIIT,” the researchers wrote in discussing their findings. As expected, aerobic fitness improved more in response to HIIT than MICT.
“To the best of our knowledge, there are no published data on the effect of HIIT on arterial stiffness in older adults,” they continued. “However, in young and middle age patients with hypertension and women at high familial risk for hypertension, HIIT but not MICT resulted in significantly improved pulse wave velocity.” (Emphasis added)
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Until we know more, the safe course would be to include brisk walking in your total fitness plan. That’s a good idea in any event, because it speeds recovery from high intensity workouts. It also keeps the blood flowing to the brain and makes us more productive.
(I termed this "barbell aerobics" in my book Challenge Yourself; for details, see http://www.cbass.com/barbellAerobics2.htm )
Carol and I walk every day in our neighborhood and once a week in the foothills above our home.
December 1, 2017
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