The quickie workout

(This article was first printed in the September 2005 issue of the Harvard Heart Letter. For more information or to order, please go to www.health.harvard.edu/heart.)

Some fitness plans promise great results with brief workouts. But can you take these shortcuts to good health?

Perhaps you’ve seen one of these fitness guides at your local bookstore. Maybe a Curves franchise has opened in your area. The claim is that a few minutes of exercise a day will shape you up or slim you down.

But most studies show that you need much more exercise than that to prevent disease and weight gain. According to the federal government’s guidelines, it takes an hour of moderately intense activity on most days to prevent unhealthy pounds from accumulating, and even more exercise to maintain weight loss. The guidelines recommend combining aerobic activity (which raises the heart rate and boosts cardiovascular health) with stretching exercises (which provide flexibility) and strength training (which makes muscles stronger).

So where does this leave the brief or “no-sweat” workouts?

Four popular programs

The quick fitness plans vary widely in tone and in the time, equipment, and types of exercises they require. Some are based in fitness centers; others are available only in books. Center-based programs have some obvious advantages. They provide exercise machines that target specific muscle groups, and they help to make exercise social instead of solitary. Here are two examples:

Curves (www.curvesinternational.com), 90 minutes per week. This company has more than 9,000 centers worldwide. For women only, it features a 30-minute, three-days-a-week mix of aerobic activity, strength training, and flexibility exercises. The style is friendly and accessible. Membership costs $29 per month (often more in metropolitan areas), plus a $149 signup fee (usually discounted by 50%–60%). There’s also an “at-home” version: Gary Heavin and Carol Colman’s book, Curves (2003).

The Blitz (www.timetoblitz.com), 60 minutes per week. The Blitz offers a 20-minute, thrice-weekly routine of strength training with boxing and martial arts techniques. Men are clearly the target, although some centers offer a “military-style Hardcore Fitness Boot Camp” that is also open to women. Membership costs $30 per month, plus a $124 signup fee (usually steeply discounted).

And here are two books:

Quick Fit: The Complete 15-Minute No-Sweat Workout, 105 minutes per week. The author, Richard Bradley III, has headed the fit­ness center at the U.S. Department of Transpor­tation for 25 years, and he introduced his quick workout there in 1998. In essence, Quick Fit is a mini version of the recommendations in the federal guidelines. The workout includes aerobic activity (a brisk 10-minute walk) and strength training (a 4-minute routine), with stretching exercises (1 minute) to cool down.

8 Minutes in the Morning for Extra-Easy Weight Loss, 48 minutes per week. The author, Jorge Cruise, has written a best-selling series of weight-loss and fitness books. He also has a Web site that claims to have three million subscribers. His ultra-short workout requires just eight minutes of strength training, six days a week. Cruise guarantees that you’ll lose two pounds a week. He uses a wide range of motivational techniques, and the book is larded with anecdotes, testimonials, and before-and-after photos. Some readers may be inspired. Other may find it too much of a come-on and too good to be true.

Fit to be measured

Quickie workouts promise to improve your fitness, but aren’t particularly clear in defining what that means. “The key question is: What’s the definition of ‘fit’?” notes Dr. I-Min Lee, a Harvard Medical School faculty member and leading researcher on the relationship between physical activity and health. “Any exercise will get you fitter than you were before” — as long as it gives you a higher workload than you’re used to.

And it’s hard to compare the quickie workouts’ vaguely defined fitness goals against the research findings. Most research has examined the effect of physical activity on specific outcomes, such as heart disease, stroke risk, or weight loss. Moreover, researchers don’t generally measure physical activity in terms of the expenditure of calories. The scientific literature more often employs “metabolic equivalents” (METs), which are multiples of an individual’s metabolic rate while seated and resting. Using METs rather than calories allows for simpler comparisons among individuals of different weights.

Exercise-lite: Feels good, less fulfilling

Still, research casts some doubt on the value of “no-sweat” workouts. In 2000, for example, Dr. Lee and her colleagues concluded that mortality was unaffected by light physical activity (less than 4 METs). Moderate activity (at least 4, but less than 6 METs) appeared somewhat beneficial, and vigorous activity (6 METs or more) “clearly predicted lower mortality rates.”

Studies of walking also indicate that benefits are greatest when the pace is brisk. The threshold varies with age, gender, weight, and overall fitness, but generally speaking, 3–4 miles per hour qualifies.

Furthermore, most exercise guidelines stress getting at least 30 minutes of physical activity a day, even if it’s done in 10–15 minute spurts. Taking the stairs instead of the elevator, walking further to your car; they can count toward the 30-minute total.

Yet some research suggests that if you exercise hard enough maybe you can get away with doing it less often. For example, a 2004 study of “weekend warriors” by Dr. Lee and others found that engaging in physical activity just once or twice a week lowered mortality rates if the energy expended totaled 1,000 calories or more. But this relationship only held true for men with no major risk factors; for subjects with one or more risk factors for pre­mature death, there was no reduction in mortality. And it’s not easy to burn that many calories; you need to play singles tennis for almost 2 hours or walk at a brisk pace for 2½.

Muscles aren’t everything

Some quickie workouts focus on strength training, skimping on aerobic activity and stretching to save time. Aerobic exercise, which raises your heart rate and improves cardio­vascular health, has proven long-term payoffs. It’s the most studied form of exercise, and the evidence of its benefits is overwhelming. A workout routine that doesn’t include aerobic exercise is sorely lacking. And though some studies have raised questions about the value of stretching before exercise, stretching almost certainly helps us stay limber, especially as we get older.

On the other hand, a 2002 study by Dr. Mihaela Tanasescu and other Harvard researchers found that strength training may be as effective as aerobic exercise in reducing the risk for heart disease. And Dr. Lee notes that muscle mass is “metabolically more active” than other tissues, so strength training “makes some sense from a weight-loss perspective.”

The shortcomings

Obviously the quickie workouts reviewed here are shortcuts. They don’t require the 30 minutes of exercise on most days recommended by government guidelines. The Curves plan comes closest, giving you the requisite 30 minutes three days a week.

Curves and Blitz provide adequate workout intensity and energy expenditure. The two center-based workouts also use the recommended combination of aerobic, strength, and flexibility training. Some may be especially attracted to — or put off by — the Blitz because of its macho appeal.

Cruise’s 8 Minutes in the Morning has the least to offer. The workouts are too short and not particularly intense. “Cardiovascular exercise (aerobics) and dieting are out,” Cruise pronounces, “and strength training is in.” Hogwash. And don’t believe his promise that you’ll “shed two pounds a week without any equipment or dieting!”

By contrast, Bradley and Wernick’s Quick Fit is a good workout. The routine is compact and balanced. The question is whether 15 minutes of exercise really is enough. The book includes a chapter on extending the program for longer and more challenging workouts. And you could do it a couple of times a day instead of once. But if you take the book at its word and aim for “no-sweat” workouts, you probably won’t get much benefit. The equipment recommendations might be a turnoff, too. In addition to a required set of dumbbells, the book strongly suggests that you buy a motorized treadmill.

Every little bit helps

Brief bouts of activity like the ones promoted by these centers and books may be worthwhile. James Hill, head of clinical nutrition research at the University of Colorado, argued in a 2003 Science article that Americans could avoid weight gain by burning just 100 more calories a day — an extra 15 (not 30) minutes of walking would do the trick. Hill used data from two national surveys to calculate Americans’ overall energy balance and derived the 100-calorie target from his results.

The bottom line? The quickie workout programs over-promise — what else is new? But any physical activity is better than none. If these programs help some people exercise, they’re serving a healthful as well as a commercial purpose. If you’re in the market, do some comparison shopping to find a program with a style and intensity level that suit you.

(This article was first printed in the September 2005 issue of the Harvard Heart Letter. For more information or to order, please go to www.health.harvard.edu/heart.)

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