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High-Intensity Intervals May Be Single Best Exercise
30 Seconds More Effective than 3 Minutes
(Reader Response Below)
New York Times health and fitness writer Gretchen Reynolds challenged exercise scientists to help her pick "The Single Best Exercise.” The results are ably reported in her Phys Ed column on The Times’ Well blog (April 15, 2011). After much fascinating back and forth, she concluded that sprinting up stairs, a power version of intervals, “just might be the single best exercise of all.”
Shortly after Reynolds’ article appeared, researchers from the University of Nebraska (Lincoln and Omaha) published their study of optimal interval duration and intensity for athletic performance in the Journal of Strength and Conditioning Research (May 2011).
The two explorations, taken together, are a boon for anyone interested in getting the most bang for their exercise buck.
Let’s start with some take away points from Reynolds’ quest.
Single Best Exercise
As you might imagine, there were almost as many opinions as there were experts. “Trying to choose a single best exercise,” McMaster University (Canada) kinesiology chairman Martin Gibala told Reynolds, is “like trying to condense the entire field [of exercise science].” Urged on by Reynolds, Gibala suggested—and then rejected—a venerable calisthenics movement, the burpee, in which you drop to the ground, kick your feet out behind you, pull your feet back in and leap as high as you can. “It builds muscles. It builds endurance…But it’s hard to imagine most people enjoying or sticking with it for long.”
“Sticking with an exercise is key,” Gretchen Reynolds wrote. An exercise is of little value if people won’t do it on a regular basis. “The one indisputable aspect of the single best exercise is that it be sustainable,” Reynolds wisely concluded.
The next suggestion, by Michael Joyner, MD, a leading researcher in the field of endurance exercise at the Mayo Clinic in Rochester, Minnesota, clearly met the test of sustainability. “I personally think brisk walking is far and away the best single exercise,” he told Reynolds.
You’ll find numerous articles on this website affirming the value of walking. It’s a mainstay of healthy living. Almost everyone enjoys doing it. Even Rush Limbaugh walks—on the golf course. But there’s a problem.
“Let’s face it,” Reynolds writes, “walking holds little appeal—or physiological benefit—for anyone who already exercises.” It’s not challenging enough for aggressive trainers. Remember, we’re looking for a stand-alone, single best, exercise.
“I nominate the squat,” Stuart Philips, PhD, an expert on the effects of resistance training at McMaster University. (He’s a familiar name on this website, as is his colleague Dr. Gibala.) The squat “activates the body’s biggest muscles, those in the buttocks, back and legs,” he told Reynolds. It’s particularly good for combating sarcopenia, the debilitating loss of muscle mass that typically accompanies advancing age. “Each of us is experiencing sarcopenia right this minute,” he told Reynolds. “We just don’t realize it.” Walking and other endurance exercises, he added, do little to slow the condition.
While most physiologists believe that only endurance-exercise can raise oxygen uptake capacity, Philips told Reynolds that several small experiments have shown that weight training, by itself, effectively increased cardiovascular fitness. “I used to run marathons” he told Reynolds. Now he mostly weight trains, “and I’m in better shape.”
Reynolds, however, was still not satisfied that she had found the single best exercise. “There’s something undignified and boring about a squat only routine,” she opined. “And the science supporting weight training as an all-purpose exercise approach, while provocative, remains inconclusive. Is there a single activity that has proved to be, at once, more strenuous than walking while building power like squats?”
Professor Gibala takes up the challenge. “I think, actually, that you can make a strong case for HIT.” (When weight trainers use the term HIT, they mean high intensity strength training, as advocated by Arthur Jones, Mike Mentzer, and others. For exercise physiologists, however, HIT refers to high-intensity interval training. Not surprisingly, the two forms of exercise have much in common; they both call for short bouts of intense exercise.)
“As studied in Gibala’s lab, [HIT] involves grunting through a series of short, strenuous intervals on specialized stationary bicycles, known as Wingate ergometers,” Reynolds explains. “In his first experiments, riders completed 30 seconds of cycling at the highest intensity the riders could stand. After resting for four minutes, the volunteers repeated the intervals several times, for a total of two or three minutes of extremely intense exercise. After two weeks, the HIT riders, with less than 20 minutes of hard effort behind them, had increased their aerobic capacity as much as riders who had pedaled [at a steady pace] for more than 10 hours.” (For more details on Gibala’s first interval studies, see our article Sprints Build Endurance! http://www.cbass.com/Sprintendurance.htm )
Gibala last month published a new study on HIT, Reynolds reports. “In this modified version, you sprint for 60 seconds at a pace that feels unpleasant but sustainable, followed by 60 seconds of pedaling easy, then another 60-second sprint and recovery, 10 times in all.” (See our article Sub-max Intervals Everyone Can Use http://www.cbass.com/SubMaxIntervals.htm )
Importantly, Gibala explained to Reynolds that HIT can be adapted to almost any sport, as long as you adequately push yourself. Moreover, people seem to like HIT better than other forms of strenuous exercise.
“A study published last month found that when a group of recreational runners practiced HIT on the track, they enjoyed the workout more than a second group of runners who jogged continuously for 50 minutes,” Reynolds relates. “The HIT runners, the authors suspect, were less bored.”
“The only glaring inadequacy of HIT is that it builds muscular strength less effectively than, say, the squat,” Reynolds writes, still not satisfied.
Gibala again rose to the challenge. “Sprinting up stairs is a power workout and interval session simultaneously.”
“Meaning,” Reynolds conceded, “that running up stairs just might be the single best exercise of all.”
With that thought provoking background (thank you, Gretchen Reynolds), we’re primed for the Nebraska University study on optimal interval duration and intensity for athletic performance. (The study was led by Jorge M. Zuniga, Human Performance Laboratory, University of Nebraska Lincoln, and Vidya S. Hanumanthu, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha.)
How Hard and How Long?
That’s what athletes and their coaches what to know. How hard and how long should my intervals be? This study is designed to help answer that question.
Zuniga, Hanumanthu, and colleagues measured physiological responses during interval training with different intensities and duration of exercise. The major finding was that short intervals (30 seconds work and rest) and sub-maximum power output (90%) allow the athlete to complete longer interval sessions with greater metabolic demand and lower blood lactate concentrations than longer intervals (3 minutes work and rest). The shorter intervals maximized power output.
Exercise scientists generally agree that the major advantage of interval training is that it allows the athlete to do a greater volume of high-intensity exercise with lower blood lactate concentrations. In short, intervals allow you to do more work in less time than steady state exercise. Short intervals (30-30) at 90% intensity appear to maximize the benefits. The Nebraska study is an important breakthrough.
The researchers arrived at that conclusion by testing 12 recreationally competitive male (average age 26.2) and female (average age 27.6) triathletes. The subjects performed four interval sessions on a cycle ergometer varying in intensity (90 and 100% of maximum power output) and duration (30 seconds and 3 minutes). The responses measured were mean oxygen uptake, total oxygen uptake, heart rate, blood lactate concentration, perceived rate of exertion, total time completed, and total time at or above 95% of maximum oxygen uptake. (Wow! I can't think of another important variable. Can you?)
Here are the results as detailed in the report:
“This study revealed that interval training using 30-second duration intervals (30-30 seconds) allowed the athlete to perform a longer session, with a higher total and mean oxygen uptake, heart rate, and lower blood lactate concentration than 3-minute duration. Similarly, submaximal exertion at 90% of maximum power output also allows performing longer sessions with a higher total oxygen uptake than 100% intensity. The results…suggested that to increase the total time at high intensity of exercise and total oxygen uptake of a single exercise session performed by the athlete, interval protocols of short duration (for example, 30 seconds) and submaximal intensities (for example, 90%) should be selected.”
The searchers do not claim that 30 seconds at 90% effort is the best possible protocol. They simply say that their study “may provide useful information for coaches in designing interval training programs for athletes.”
This study tested the outer limits of normal practice. “Short intervals of 30-30 seconds and long intervals of 3-3 minutes are the two most common extremes in interval training durations used by endurance athletes,” the researchers wrote in introducing their study.
In general, it seems that short work/rest periods are better than long work/rest periods. Twenty seconds or one minute intervals—or anywhere in between—are likely to be similarly effective. That’s good because few would want to do the same workout all the time. A varied approach is likely to be most effective, especially over the long term. Throwing in some longer intervals is probably a good idea from time to time.
To reinforce these findings, let’s look are some specific responses to the long and short intervals. In some cases, the difference in response is quite remarkable. In a few parameters there is little difference.
The most pronounced differences were in total oxygen uptake, total exercise time, and total time at or above 95% of maximum oxygen uptake. Note that these three responses, taken together, indicate work time at high-intensity—the principle gauge of interval training benefit.
Total oxygen uptake for 30-30 at 90% was 78.8 on average compared to 41.5 for 3-3 minutes at 100%, a difference of almost 90%. Total time completed was 25.5 minutes compared to 13.9 minutes, a difference of 83%. And total time at or above 95% of maximum oxygen uptake was 6.4 minutes compared to 4.6 minutes, a difference of 39%. If total time at high intensity and total oxygen uptake are the critical factors, as they seem to be, then short intervals are demonstrably better than long intervals.
Significantly, blood lactate concentration was 32% lower for 30-30 at 90% than for 3-3 minutes at 100%, 7.5 for the short intervals compared to 9.9 for long intervals. That, of course, means less lactic acid to shut down muscles and shorten high-intensity exercise time.
Interestingly, there was little difference in heart rate and rating of perceived exertion. Heart rate variation was within a three percent range (167 for 3 minute intervals and 172 for 30s) and exertion rating was 15 (hard) for all 4 interval protocols. The perception of the athletes was that they were working equally hard (15 on a scale of 6 to 20) doing both long and short intervals. Physiological measures, of course, showed that they were working longer and harder when doing short intervals. More gain without more pain is good.
If you want more bang for your interval buck, short intervals seem to be the clear choice.
* * *
I haven’t had much time to experiment with 30-30 intervals, but I like it so far—more intensity with less lactic acid shutdown. I began experimenting with 30-30 intervals on the Lifecycle, because it was next in my interval rotation. (See below)
As usual, I started out with a load level that I was pretty sure I could handle. After a 2 minutes warm-up, I did 6 30-30 reps, and ended with a 2 minute cool-down. The whole workout took only 10 minutes—plenty for a trial run. I’m eager to do it again, because I know I can do better. (I did 9 30-30 reps at slightly higher intensity on the Airdyne the day before this article was posted. I expects to do 10 reps next time.)
That’s what I suggest readers do. Start out with something you can handle without too much trouble—and then work up from there.
I already know the first question I’m going to get. How do I know when I’m doing 90% of maximum power output? Don’t worry about precise measurement; start out at an intensity that makes you work hard, without maxing out on each rep. And then go from there.
Ninety percent is on the threshold of very hard. The talk test is a good way to judge intensity. At 90%, you can’t say more than a word or two without pausing for breathe. Maximum effort, 100%, you can’t talk; you're too busy breathing.
Feel your way along and you’ll be fine. If you overshoot your limit, back off and start lower next time. Don't be afraid to make mid-workout corrections.
Make a habit of success. Work hard, but don't allow yourself to fail. With a little experience, you'll know your limit. Again, don't fail.
The second question will be: How often should I do intervals? I generally do intervals twice a week, on different apparatus. I rotate the Concept 2 rower, the Airdyne and the Lifecycle. For more details on integrating high-intensity aerobics into your workout, see my books Lean For Life and Great Expectations: http://www.cbass.com/PRODUCTS.HTM
Good luck. Remember to enjoy yourself. Challenge yourself, but don’t overshoot your limits. If intervals aren’t challenging—and fun, you won’t be doing them for long. Nothing makes you want to go back for more Nordic than success.
Reader Submits "Best Exercise" Choice
10-15 second intervals of everything you can give it with as many major muscle groups involved as possible and a variable, “full recovery” rest interval (repeated 4 to 8 times) is almost certainly BEST. And I do mean BEST. Dan Williams
Hello Clarence --
I have appreciated your website -- and been inspired by your personal example -- for quite a few years now.
Read your article on single best exercise/30 vs.180 second intervals and would like to comment. First, the fundamental idea of a "single best exercise" doesn't make an awful lot of sense to me. Individual goals differ, the body has got a lot of parts, and variety keeps things more interesting, don't you think? [Yes, but a good vehicle for discussion.]
That said, I do have a favorite that seems to do more for me in less time with less risk of injury than anything I have ever done.
My wife and I (as well as a gradually increasing number of friends) like walking with Nordic trekking poles up in the deep sand at the beach here in Southern California. (The lifeguards refer to us as the "Stick People.") The sand offers lots of resistance and provides low impact. I go barefoot unless it is too hot, too cold, or too dark, in which case I wear Vibram Five-Fingers Flows (with socks) which provide a close-to-barefoot experience and keeps the sand out. The poles get the arms, shoulders, and back working, and one has complete control of just how hard one makes the upper body work. (I typically feel a workout more in the arms, shoulders, and back than in the legs.) Walking for three miles at a brisk pace several times a week is a gentle way to lay down and maintain a solid aerobic base. This, however, is not my favorite exercise.
About every 3 to 5 days I add short, high intensity sprints into the walk at about the halfway point after I am well warmed up. I do three 100 stride preparatory runs at a progressively faster pace (about 30-35 seconds each) with about 30 seconds active recovery between. Then the fun starts.
I next do a series of 4 to 6 or more short (50 strides or about 70-75 yard) sprints at 95-100% maximum effort, using the poles to drive hard with the arms and trying to obtain the fastest turnover I'm capable of generating. These sprints last no more than 12.5 to 14 seconds, so I am able to turnover at a rate between 3.5 and 4.0 steps per second. (It feels fast to me -- this is all in deep, soft sand.)
I arrived at this particular duration empirically. My goal is to go as hard as I can in order to produce maximum recruitment of Type 2b [fast-twitch] muscles fibers and to stop as soon as I feel myself starting to lose the ability to go flat out due to lactic acid build up. I am interested in developing power (strength x speed), and, frankly, I’m not worried about moving my lactate threshold anywhere.
I allow myself from one to two minutes or more of active recovery between sprints -- I'm still striding along down the beach at a fast walk. My goal for each recovery interval is to give my body however much time it needs to replenish ATP/Phosphocreatine stores and clear lactic acid so that I am as ready as I can be for the next maximum effort. The duration of my recovery interval varies considerably from interval to interval. I go by “feel” and start the next sprint when my body tells me it is ready to go again.
This approach was inspired by Art De Vany's "alactic" [without lactic acid] exercise protocol. (Art believes that the lactate build up that is inevitable with longer high intensity efforts isn't helpful for building strength or power -- better not to go there unless one is training specifically for anaerobic events like the 200, 400, or 800 meter runs.) De Vany believes that brief, predominantly phosphocreatine-fueled bursts of high intensity effort that are voluntarily terminated before or just as the phosphocreatine runs out and glycolysis takes over produce a superior neuro-endocrine response that best stimulates positive adaptations by the body. So far I have not been able to locate credible research that supports these claims, but Art’s arguments were so compelling I had to try it for myself. [See New Thinking on Lactic Acid: http://www.cbass.com/Lacticacid.htm ]
My sense of the results over a few months is that Art is really on to something. I feel stronger and faster, and my endurance is improving as well. But mainly, these short, hard sprints are FUN, especially when one is 72 like I am. I feel like I’ve discovered a time machine and the clock is now running backwards!
So, with regard to the second article in your July post, it should come as no surprise that 30 seconds (deep into lactic acid burn at high intensity but still “intense”) is better than 3 minutes (a duration over which it is not at all hard to generate truly awesome pain, but only a superior athlete can sustain real "intensity" -- at a nasty physiological price). However -- assuming one is interested in strength or speed -- 10-15 second intervals of everything you can give it with as many major muscle groups involved as possible and a variable, “full recovery” rest interval (repeated 4 to 8 times) is almost certainly BEST. And I do mean BEST.
Here's Dan "The Stick Man"
striding out for all he's worth.
Makes you want to get out there with him, doesn't it? Thanks, Dan, for providing the photo.
I give myself 3-4 days to recover from one of these sprint interval sets -- old dudes need plenty of recovery time -- but I just about can't wait to do it again! There has got to be something really good about that.
Of course not everybody is lucky enough to have access to a resource like my 1.5 mile long, 100 acre sandbox, but trekking poles can be adapted to any surface (including pavement), and the extra resistance and low impact benefits of sand are just gravy -- they aren't necessary for the kind of sprint interval workouts I like. In fact, I would expect that one could achieve pretty much the same pattern of effort and, most likely, the same pattern of results in a swimming pool, on an Exercycle, bicycle, or rowing machine, or sprinting with or without poles on a running track or grassy field.
What is most important, I believe, is activating a pattern of effort/recovery/duration inputs to the body that produces systematic and controlled muscle fiber disruption and optimizes the resulting neuro-endocrine response with as little “collateral damage” (coming mostly from excess lactic acid accumulation and excess cortisol production) as possible. This is where a lot of traditional interval protocols (including Tabatas) appear to drop the ball.
Keep up the good work,
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