Research suggests that encouraging the inactive to embrace any physical activity—even at levels that fall short of industry guidelines—may offer a bevy of benefits.
Every day, consumers are bombarded with bogus claims about the benefits of quick workouts. Magazine covers offer the “60-second ab exercise” that will “peel off 7 pounds” or tout faster workouts to “burn double the fat in half the time.” Fitness infomercials claim that just minutes a day will “get you ripped, guaranteed” and boast testimonials from users who have (supposedly) lost more than 50 pounds, or three dress sizes, with just 3 minutes of exercise a day.
While the appeal of such claims is obvious, marketing grossly exaggerates the physical transformation that is possible from short workouts. However, the fact that exaggerated claims sell products points to an important reality: nonexercisers are often intimidated and overwhelmed by the evidence-based guidelines for physical activity. The most widely accepted guideline—supported by the American College of Sports Medicine (ACSM), the American Heart Association, the U.S. Department of Health and Human Services and the World Health Organization—recommends that adults engage in a minimum of 30 minutes of moderate-intensity physical activity 5 days a week. This is in addition to ordinary, everyday activity. To lose weight or sustain a weight loss, even more exercise is required. ACSM’s latest recommendation, based on a thorough analysis of existing evidence, suggests that significant weight loss is unlikely with less than 250–300 minutes of moderately vigorous exercise per week, or about 1 hour a day, 5 days a week (Donnelly et al. 2009).
Many in the fitness industry see 30–60 minutes a day as a reasonable goal, and yet only 11% of Americans currently meet the minimum recommendation (Schoenborn & Adams 2010). A large section of the population isn’t even trying. According to the most recent survey data, 33% of American adults never exercise and 55% never engage in vigorous activity (CDC 2010). These numbers only increase with age, as the health consequences of being inactive—such as cardiovascular disease (CVD)—also climb.
To sedentary adults, 30–60 minutes a day can seem impossible. They may feel that they can’t find the time or that health challenges or physical pain prevent them from being physically active for that long. These nonexercisers are most likely to be tempted by the promise of benefits from shorter workouts. But can smaller doses of exercise lead to any real change?
This article reviews the evidence that even short sessions of exercise—5–15 minutes a day—have very real benefits for physical and mental health. While fitness professionals must steer clear of unrealistic claims that such short doses can “transform your body” or lead to significant weight loss, there is good reason to encourage baby steps among the most reluctant and overwhelmed nonexercisers. If we can’t convince sedentary individuals to embrace the industry ideal, we can encourage them to start small, which will still improve their quality of life.
In a 2001 landmark report, the Women’s Health Study revealed the results of a longitudinal study of almost 40,000 women, aged 45 years or older, in the United States and Puerto Rico (Lee et al. 2001). Participants were observed for an average of 5 years. The report examined whether physical activity levels at the beginning of the study predicted who developed CVD over the next several years. The researchers found a classic dose-response relationship, with more physical activity providing a greater protective effect against CVD. But the amount required to get a significant benefit was quite small. As little as 60 minutes of walking per week—less than 10 minutes a day, or a simple stroll around the block—was associated with significantly reduced CVD risk. In fact, among women who reported no regular vigorous exercise, women who walked at a light to moderate pace for at least 1 hour a week had half the risk of women who did not walk regularly. This effect held even when the researchers statistically controlled for factors such as smoking, diet, alcohol use, menopausal status, hormone use and family history of heart disease.
The cardiovascular benefits of low levels of exercise are not fully understood. However, there is evidence that even small doses of exercise have a positive influence on metabolism and cardiovascular physiology. For example, physical activity reliably reduces blood pressure—not just in the long term, as the cardiovascular system adapts to exercise and people become more fit—but immediately, after a single bout of exercise (MacDonald 2002). This effect, dubbed “postexercise hypotension,” appears to last for several hours after physical activity and is especially pronounced among those with hypertension.
A study from the University of Connecticut and Hartford Hospital asked, Does a short workout provide the same blood pressure benefits as a longer workout (Guidry et al. 2006)? The researchers recruited 45 sedentary men to test the effects of two sessions of indoor cycling (15 minutes vs. 30 minutes) on blood pressure. The men were randomly assigned to one of two intensities (light = 40% VO2max, and moderate = 60% VO2max). Each participant then completed 3 days of study: a short-workout day, a long-workout day and, for comparison, a nonexercise control day. Exercise took place between 8:00 am and 11:00 am, and the participants’ blood pressure levels were tracked throughout the day.
Compared with control days—when participants did not exercise—both the 15- and 30-minute exercise sessions led to lasting reductions in blood pressure over the subsequent 9 hours. Interestingly, the shorter dose provided the same benefit as the longer dose, and the two intensity levels led to equivalent reductions.
It’s worth noting that the participants in this study were overweight, mostly middle-aged men, with below-average fitness, an average body mass index (BMI) of 29.2 and high-normal to stage 1 hypertension—exactly the kind of people who might be interested in the health benefits of exercise, but who might feel overwhelmed by having to fit in 30–60 minutes per day. The reduced-blood-pressure benefit observed in this study was immediate; the men did not have to “get in shape” first or achieve any particular fitness standard. Based on their findings, Guidry and colleagues suggested that short doses of low-intensity exercise, especially when performed in the morning (and, ideally, again in the afternoon), could provide significant cardiovascular health benefits to a sedentary, aging population.
Another study looked at longer-term changes in physiology and supported the idea that 15–20 minutes of exercise a day can improve cardiovascular health (Lippincott et al. 2008). Seventy-two sedentary employees, aged 22–62, participated in the National Heart, Lung, and Blood Institute’s “Keep the Beat” program. The program gave employees outlines for 15-minute cardiovascular and strength training workouts they could do in the National Institutes of Health (NIH) campus fitness centers. It also offered tips on fitting short bursts of exercise into the workday—for example, by taking the stairs or walking around campus.
The study’s first observation was that employees did indeed become more active; adding a 15-minute workout was a feasible change that previously sedentary employees could fit into their workday. Program participants averaged 98 minutes of exercise per workweek, equivalent to one 15-minute fitness center workout and a few minutes of extra activity each day. By the end of the 3-month study, the exercise had paid off. Employees in the program showed significant improvements in several measures of fitness and CVD risk, including increased peak VO2, improved endothelium function, reduced blood pressure and lower cholesterol.
Mitigating the Effects of Sitting
A 15-minute workout may seem to yield impressive benefits, but the smallest dose of exercise that can improve cardiovascular health may be even shorter. A growing body of research suggests that spending long stretches of time sitting is a significant risk factor for health problems, independent of whether or not a person exercises regularly (Hamilton et al. 2008). More uninterrupted sitting is associated with higher waist circumference, blood pressure, blood glucose, cholesterol and triglycerides levels. The good news: A study from the University of Queensland in Brisbane, Australia, found that the simple act of breaking a period of sitting with any physical activity was associated with a healthier metabolic profile (Healy et al. 2008).
For this study, 168 adults (mean age 53.4 and mean BMI of 27.2) wore accelerometers—a device that measures the body’s acceleration—during all waking hours for 1 week. The researchers were able to track and record every time a participant broke a sedentary period by standing or taking a single step. The participants also kept a log of any moderate to vigorous physical activity, so researchers could separate the benefits of standing up from the benefits of regular exercise. The participants who took a higher number of breaks from being sedentary had smaller waist circumferences, as well as lower blood glucose and triglyceride levels. The frequency of stand or step breaks predicted these health measures independent of time spent exercising and total sedentary time. In other words, every time a person stood up or took a single step, it contributed to his or her health. It didn’t matter how active or inactive that person was.
This research suggests that fitness professionals can credibly recommend even the smallest of behavior changes—such as standing up every half-hour—to sedentary individuals (see the sidebar “Recommending the Smallest Dose of Exercise”). Even if people are unwilling or unable to commit to a formal exercise program, they can fit brief moments of activity into their days to support their health.
While more attention is typically paid to the physical health benefits of exercise, its effects on mental health are also well established (Stathopoulou et al. 2006). However, unlike the dose-response relationship observed for physical health—where a little exercise is good, but more is often better—the latest research suggests that when it comes to psychological well-being, short doses work as well as, or better than, longer workouts (see the sidebar “Get Your Exercise Mood Boost”).
A recent meta-analysis (Barton & Pretty 2010) reviewed 10 studies that examined how exercise influences psychological well-being. All 10 studies—which collectively observed more than 1,200 participants—involved “green exercise,” or physical activity that takes place outdoors. Green exercise includes walking, running, biking, hiking, swimming, gardening, rollerblading, taking your dog or kids to the park or anything that gets you outside and moving.
The researchers were especially interested in what the best “dose” of green exercise was for self-esteem and mood. To their surprise, the biggest benefits came from the shortest workouts. “The biggest difference was seen in the first 5 minutes,” says Jo Barton, PhD, lecturer in sports and exercise science at the University of Essex, England, and lead author of the review. “Longer amounts do not necessarily equate to greater rewards.” In fact, a 5-minute session improved self-esteem and mood more than a workout lasting 10–60 minutes. The only dose that came close to the psychological benefits of 5 minutes was a whole day spent being active outdoors—in other words, a green vacation.
Barton thinks that “5 Minutes a Day” is a great, targeted message for sedentary individuals who want to experience the benefits of being active but feel overwhelmed by the amount of activity recommended for weight loss and better physical health. “Five minutes seems achievable,” says Barton. “If you can engage them in these shorter bouts, once they start experiencing the benefits, they will be more likely to participate more frequently, and for longer periods.”
Can’t get outdoors? Indoor exercisers need not despair. While a blue sky and green leaves might enhance the mood benefits of exercise, you don’t need an inspiring view to get a psychological boost from working out. One study compared the benefits of indoor cycling at 60% VO2max for 10, 20 and 30 minutes (Hansen, Stevens & Coast 2001). All three exercise sessions increased participants’ energy and decreased their fatigue and negative mood. However, these benefits reached their peak at 10 minutes, and there was no significant benefit to working out longer.
A quick mood boost is good, but it’s also important to consider whether short doses of exercise can contribute to lasting changes in psychological well-being. A 2009 meta-analysis looked, not just at the immediate mood benefits of exercise, but at the longer-term effects on depression (Rethorst, Wipfli & Landers 2009). Researchers analyzed the results of 58 randomized trials and found that, overall, exercise interventions (lasting anywhere from 4 to 26 weeks) resulted in significant reductions in depression. Once again, shorter workouts yielded the biggest benefit.
Interventions that assigned participants to exercise for fewer than 30 minutes at a time had significantly larger effects than interventions that assigned longer workouts (e.g., 45–59 minutes or more than 60 minutes). When researchers compared overall time spent exercising with degree of improvement, they did not find a linear dose-response relationship. More exercise time did not translate into bigger improvements. These findings—drawn from a very large number of studies—provide further support to the idea that sedentary individuals can reap substantial mental health benefits from short exercise sessions.
The research shows there are substantial benefits to merely moving out of the “sedentary” category. With some outcomes—such as overall risk for cardiovascular disease—more activity is better. But for other measures—such as mood—simply becoming active provides the full benefit. Barton, who analyzed the benefits of green exercise, suggests that health professionals might think about “quitting” sedentary living as equivalent to giving up smoking. Any activity—even a short dose of light intensity—will have immediate positive health outcomes. (For evidence that exercise can help with food cravings, see the sidebar “ A Short Dose of Exercise Strengthens Self-Control. ”) Getting a person out of the sedentary category is a worthy goal, even if it falls short of ideal activity levels.
A 2009 randomized controlled trial led by researchers at Louisiana State University demonstrates this point for a wide range of physical and psychological outcomes (Martin et al. 2009). This 6-month study assigned 430 sedentary, overweight or obese women (mean BMI of 31.8) with high blood pressure to one of four conditions: a no-exercise control group, and three different exercise groups aiming to achieve 50%, 100% and 150% of NIH-recommended physical activity levels, respectively. (In actual reported activity over the study, this translated into an average of 74, 138 and 184 minutes of exercise per week at an intensity of 50% VO2max.)
The researchers measured changes in many dimensions of quality of life, including physical functioning, general health, mental health, social functioning and vitality. Exercise improved all of these outcomes over the course of the 6-month study. Importantly, all three exercise groups improved, while the control group did not. There was a clear dose-response relationship for physical and social functioning, with minimum exercise (averaging 10 minutes a day) producing some improvements, but more exercise (up to an average of 26 minutes a day) leading to even greater improvements. But for general health, mental health and vitality, the benefits of the smallest dose were equivalent to those of the two larger doses. Simply transitioning from a sedentary lifestyle to any level of exercise enhanced every aspect of the women’s quality of life.
Perhaps the most interesting finding of this study is that all of the benefits were independent of weight loss. The average weight loss in the exercise groups over the 6-month period was small (2–3 pounds) and did not vary by exercise condition. But even when the researchers compared the outcomes of women who lost weight with those who maintained or gained weight, there was no relationship between weight loss and any of the positive outcomes. Other studies—including the “Keep the Beat” program that increased workplace activity and led to improved fitness and cardiovascular health—have reported similar findings. The improvement of health does not require weight loss; and often, the two do not go together.
This finding is particularly important because it points to a current tension within the fitness industry. We know that many, if not most, clients turn to exercise because they want to lose weight. And while there is growing evidence to support the benefits of 5–15 minutes of exercise a day for currently sedentary individuals, this dose falls far short of what research suggests is required to lose a significant amount of weight. At the same time, few sedentary individuals seem willing to invest the time needed to lose weight or maintain weight loss.
The fitness industry is in a perfect position to make inroads with the population most resistant to exercise. One way to do this is by encouraging nonexercisers to commit to as little as 5 minutes a day. To make use of the growing evidence supporting short workouts for the sedentary, fitness professionals must become comfortable shifting their focus—and their clients’ focus—away from losing weight as the sole goal of exercise, and toward other goals, including decreasing risk for CVD, increasing energy and quality of life, and improving mood, self-esteem and self-control. These are worthy goals both for the sedentary individual and for the industry as a whole.
Imagine this: You’re a participant in a scientific study, and you’ve just been put through a challenging mental test designed to stress you out. The researcher then walks in with your favorite instant stress reliever: chocolate. The researcher offers you a variety of chocolate bars, asks you to choose your favorite and instructs you to unwrap it. But before you can savor the first creamy mouthful, she tells you not to eat it.
Researchers at the University of Exeter, England, put 25 chocolate lovers through this mini stress test as part of a study on exercise and self-control (Taylor & Oliver 2009). We tend to think of exercise as something that requires self-control, but psychologists are now considering the possibility that it also increases self-control. For this study, the researchers wanted to know: Could a 15-minute walk before the mental stress test help people resist the temptation to soothe their stress with chocolate?
All participants were asked to abstain from chocolate for 3 days, which previous research has shown increases cravings (Polivy, Coleman & Herman 2005). When the participants arrived at the laboratory, half of them were asked to walk briskly on a treadmill. These participants showed smaller blood pressure increases during both the stressful mental task and the self-control test, suggesting that exercise helped them cope better with both challenges. Exercise also reduced these participants’ chocolate cravings and urges to eat the candy bar.
This is just one study demonstrating that short doses of exercise can strengthen self-control. The same research team has shown that a 15-minute treadmill walk reduces cravings for cigarettes among smokers and improves concentration in the face of distractions (Janse Van Rensburg & Taylor 2008; Janse Van Rensburg, Taylor & Hodgson 2009; Janse Van Rensburg et al. 2009). One study looked at brain activation among smokers presented with images of cigarettes. After exercise, the brain’s reward system—which is responsible for feelings of desire and craving—was less reactive to the images. Another study tracked the eye gaze of smokers and found that those who had just exercised spent less time looking at smoking-related images.
Kate Janse Van Rensburg, MSc, lead author of these studies, says, “A single session of exercise can reduce the attention-grabbing power of temptations. Daily sessions of brief exercise could be integrated into any behavior change attempt to help reduce cravings and handle withdrawal.” Clients who are trying to quit smoking, cutting back on caffeine, conquering their sweet tooth or changing to a vegetarian diet could all benefit from short doses of physical activity. Recommending exercise as a coping strategy for stress and cravings can also transform working out from a chore into a source of strength—a motivation that could help people stick with exercise in the long run.