A 4 minute workout? Could this be the solution you’ve been seeking to squeeze exercise into your deaily routine? If you saw Gretchen Reynold’s recent New York Times column, widely disseminated in the media, perhaps your heart skipped a few beats in excitement. If not, let me recap here. According to her column, exercise scientists have finally stripped the necessary length of a workout down to the barebones of 4 minutes at a time. Don't have time for the gym? No problem! Take the stairs, sprint uphill, even walk fast down a hallway, and you’ll be getting all the human frame requires to keep your cardiovascular system humming nicely.
Ordinarily, I find Reynold’s columns to be accurate and helpful. There was something about this one, though, that raised my suspicions. I’m pretty open to new ideas, and I’m definitely in favor of saving time. However, before I was about to change the advice I provide in my own writing I decided to do a little digging and check the facts myself.
Shall I break the news to you now, or would you rather work through the logic with me? OK, I’ll start with the “what” and get to the “why” in a minute. The bad news is this. You can't get the exercise you need in a 4-minute workout. As you'll learn, the participants in the research that Reynolds cites exercised for a minimum of 19 minutes. Even if you could get all the human heart required in 4 minutes, it still wouldn't be enough.
Aerobic exercise is only part of the formula for health and fitness. You still need to engage in resistance training in order to build muscle tone and bone strength. There’s no way you can get out of the gym in under 20 minutes (much less 4) and train those quads, pecs, abs, and other major muscle groups (and bones). If you want to build in flexibility training, crucial for maintaining your joint health, you’ll need to add in another minimum of 15 to 20 minutes and maybe longer. Finally, one of the biggest benefits of exercise is stress reduction. If you’re so busy that you can’t afford to exercise, it’s likely that you need more time in the gym, not less.
Now let’s look at the “why’s;” specifically, what was wrong with the study itself. Published in PLoS One, the article was written by a team with Arnt Erik Tjonna, a postdoctoral researcher in Norway, at the helm (Tjonna et al, 2013). The 24 men who completed the 10-week study averaged 35-45 years of age, and had BMI’s that placed them in the “moderately overweight” category (27-28 on average). They seemed to be genuine couch potatoes who had not formally exercised in at least 2 years prior to being in the study. However, either the researchers didn't ask, or didn't report, on their other activity habits. Perhaps they didn't "exercise," but rode their bikes or engaged in physical labor. In any case, the men were randomly assigned to the 1-AIT (Aerobic Interval Training) intervention consisting of a single 4-minute bout, or the 4-AIT, consisting of 4, 4-minute bouts, with 3-minutes of active recovery in between each.
Here’s the first bit of fine print to which I alluded earlier. The “4-minute” group actually exercised 19 minutes each day, and the comparison group exercised for 40 minutes. The four minutes were simply the part of their workout at which they turned the intensity up (i.e. interval training). They didn’t just hop on and off a treadmill at breakneck speed. The 4 minutes were embedded in a much more conventional exercise routine that many people pretty much use already. The second bit of not-so-fine print is that there was no non-exercise control group, considered the gold standard in efficacy research. Although the participants were randomly assigned to one of the two treatment groups, furthermore, the 1-AIT group actually had slightly higher body mass at the start of the study than did the 4-AIT’s (27.8 compared to 27).
Now onto the results: Everyone’s aerobic capacity increased a similar amount (10-13%), they lost 1-2% of body weight, and shaved about 6mmHg from their blood pressure and fasting glucose levels. The two groups did not differ at all from each other on any of the measures in the post-tests done after the training ended. Hence, the authors concluded that 4 minutes (i.e. 19) is actually as good as 16 (i.e. 40). However, with no true control group, there’s no baseline for comparison.
These researchers are pretty serious about the need to save time in the gym, though, and therefore cite an earlier study that did employ a control group. University of Western Ontario researcher Tom Hazell and his colleagues looked at the effect of 10-second (you read that right) vs. 30-second (also right) sprint interval periods of stationary cycle training. The sprint bouts turned out to be equally effective, and both groups improved more over training than did controls.
Before you conclude that you can cut your own workout down to 10 seconds, though, there’s more fine print in this study. In addition to the obvious fact that you can’t sit down and do an immediate 10-second all-out sprint on a stationary cycle, you need to know who was in this study. These were not your middle-aged, middle-weight sedentary men. Instead, the participants in the Hazell study were young adult men and women (average 24 yrs old), and included kinesiology students, ultimate Frisbee players, and other athletically active types. They hadn’t trained for the 4 months prior to the study, and they were restricted from many of the usual college student bad habits of too much to drink and too much coffee for 24 hours before each test or training session. They were, however, allowed to maintain their usual exercise habits throughout the study, so no Frisbees felt neglected.
As Tjonno and his colleagues note, it would be wonderful if everyone would exercise more, and they'd be more likely to do so if they could get it out of the way quickly. This is a laudable goal. What’s neither laudable nor acceptable is providing the non-exercising public with distorted information about the reasonable expectations they can have for how much exercise they need to get in shape.
If you don’t (or think you don’t) have time to exercise, it’s fine to look for ways to squeeze extra activities into your normal day. Take those stairs, sprint up that hill, or just walk a bit more quickly as you buzz about your home or office. However, I would question your assumption that you don’t have time for proper cardio and other fitness workouts. In the long run, you’ll save countless hours and dollars in lost wages due to illness and medical expenses, not to mention time with your friends and loved ones. If that doesn’t entice you, consider that physical exercise improves your mood and mental efficiency. The extra hour you spend at the gym can save you at least as long in trying to solve a thorny problem at work or in your relationships.
Once you start getting into the exercise habit, you’ll find that it becomes fun in its own right. If you keep at it, you’ll find that like all pleasurable experiences, the longer it goes on, the better.
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Copyright Susan Krauss Whitbourne, Ph.D. 2013
Hazell, T. J., Macpherson, R. E., Gravelle, B. M., & Lemon, P. W. (2010). 10 or 30-s sprint interval training bouts enhance both aerobic and anaerobic performance. Eur J Appl Physiol, 110, 153-160. doi: 10.1007/s00421-010-1474-y
Tjonna, A. E., Leinan, I. M., Bartnes, A. T., Jenssen, B. M., Gibala, M. J., Winett, R. A., & Wisloff, U. (2013). Low- and high-volume of intensive endurance training significantly improves maximal oxygen uptake after 10-weeks of training in healthy men. PLoS One, 8, e65382. doi: 10.1371/journal.pone.0065382