The usual suspects—early morning meetings, kids’ soccer games, Friday dinner plans—are all understandable reasons why the best of exercise intentions can get waylaid. Americans are working more (on average more than 150 extra hours per year compared to our 1950’s predecessors) and working out less. An estimated 80 percent of Americans don’t fulfill the Centers for Disease Control and Prevention’s recommendations for weekly exercise (two and a half hours of moderate aerobic activity, like walking, or one hour and 15 minutes of “vigorous” activity, like jogging). So, many have been relegated to finding other ways to sneak exercise into busy schedules.

"Weekend warriors," a term often used derogatively, refers to people who cram their exercise into weekend soccer games or tennis matches. With long periods of inactivity, interspersed with sometimes-excessive bursts of activity, the exercise habits of the weekend warrior don’t fit the recommended model of regular daily exercise.  More consistent exercise (an hour of moderate exercise or 30 minutes of vigorous exercise per day) has been shown to reduce risk of heart failure by nearly 50 percent. But research appears to at least partially vindicate the exercise habits of weekend warriors, too.

To be classified as a weekend warrior, as the medical literature defines it, one must stuff the recommended weekly exercise requirement of 150 minutes or more into one or two days rather than spreading it out evenly over the week. While it seems like a lot of modern 9-to-5-ers would fall into this category, a 2007 survey found that only 1 to 3 percent of U.S. adults qualified as “weekend warriors.” Of those that did fit the bill, the low-intensity activity of gardening was as popular among the exercisers as more intense forms of activity, such as training or competing in a sport.

Of course, the proper amount—or more accurately, the absolute minimum acceptable amount—of exercise has been considerably discussed in cardiovascular research. It’s clear that many Americans aren’t able to meet the CDC’s recommendations, and research has lately endeavored to find out the health benefits of lesser amounts of exercise. After all, as sales of Thighmasters and Tae-Bo tapes show, people are interested in fitness programs and weight-loss products that promise quick results.

So while the weekend warrior was once disparaged as an exercise dilettante, sports-medicine experts are starting to recognize the value of any exercise, even if it takes place in spurts. Dr. Jordan Metzl, a sports medicine physician and author of The Exercise Cure, says, “While more consistent exercise is optimal, the clearest information is that doing nothing is the least favorable option, making any amount of exercise or activity helpful.”

But can occasional exercisers get enough out of infrequent activity to make a real difference in their health? Yes, according to one 2004 study, published in the American Journal of Epidemiology, which found that one to two workout sessions per week were enough to reduce all-cause mortality among those with no major risk factors. The authors conclude the study with the statement, “For individuals with no major risk factors who are too busy for daily exercise, this may offer a measure of encouragement.”

In contrast, for those that prefer their exercise in regular but small, doses, recent research in the Journal of the American College of Cardiology suggests that just five minutes of daily running may be enough to stave off all-cause mortality. After researching the association of running and mortality over a 15-year period in more than 55,000 runners, researchers concluded, “Running, even five to 10 min/day and at slow speeds [of less than] six miles per hour, is associated with markedly reduced risks of death from all causes and cardiovascular disease.”

This led the authors of the study to conclude that vigorous-intensity activity, such as running, may be a more time-efficient option, generating similar, if not greater, health benefits in 5 to 10 minutes a day than 15 to 20 minutes a day of moderate intensity activity.

The authors of the study write, “This study may motivate healthy but sedentary individuals to begin and continue running for substantial and attainable mortality benefits.” The research also suggests that 25 percent of the cardiovascular disease deaths in the study population could have been avoided if non-runners became runners.

The bottom line seems to be that even small amounts of vigorous activity—a quick run or a pick-up basketball game—can have significant health benefits. Taking it one step further, scientists have investigated how to make the most of a brief workout. One way is to work out in brief, high-intensity intervals of exercise, rather than a moderate but steady jog.

A review article in the journal Sports Medicine concluded, “High-intensity training appears to promote superior improvements in aerobic fitness and similar improvements in some cardio-metabolic risk factors in comparison to continuous moderate exercise.” Efficiency is a prime selling point that could help public health workers convince the sedentary to exercise. Long used by endurance athletes, these brief high-intensity intervals may also hold the key to rapid improvements in fitness and health.

Despite the health benefits, there is a potential downside to sporadic exercise—increased risk of injury, especially acute injuries such as muscle strains or tendon injuries.  Weekend warriors get hurt more often, Metzl explains, but not in the usual manner. “Typically in those that exercise regularly, overuse injuries are more common, but weekend warriors experience less overuse and more acute injury,” he says. “They experience a bigger stress over a shorter period of time.”

Investigating the reason for the higher rate of injury seen among weekend athletes, research presented in the Canadian Journal of Surgery observed, “One wonders if this is a result of fatigue secondary to physically demanding and prolonged exercise on the weekend beyond one’s inherent exercise tolerance.” The study’s authors went on to hypothesize, “Another possibility may be that weekend warriors are more inexperienced at various sporting activities than daily or more regular recreational athletes.”

Attempting to cram a week’s worth of exercise into a weekend may not be optimal, public health experts contend, but it seems like it’s at least better than spending the weekend on the coach. “What’s most important,” Metzl says, “is that people find exercise that makes them happy and motivated to continue, even if it’s just on the weekends.”