Can regular exercise avert or undo some of the harm associated with binge drinking? Perhaps even better, could exercising beforehand pre-emptively reduce your urge to overindulge in alcohol later? Or does exercising actually drive you to drink? Those questions, relevant to any of us whose memories of New Year’s Eve are fuzzy, have been the subject of a growing number of studies recently, with thought-provoking results.

One of the more telling new studies examined the issue of whether being fit and exercising reduces the urge to drink. For the experiment, researchers used adult male rats with an inbred taste for alcohol. Half of the rats were given access to running wheels for three weeks.

The others were kept in cages without wheels. After three weeks, the running wheels were removed, and half of the animals from each group were allowed unlimited access to alcohol for 21 days. Earlier studies by other researchers found that animals given equal access to exercise and alcohol — they were allowed to sip booze while on a running wheel — chose to drink less than animals not exercising.

Based on those results, "we had anticipated that exercise would reduce” the rats’ drive to drink, said J. Leigh Leasure, Ph.D., an associate professor in the department of psychology at the University of Houston in Texas and senior author of the study, which was presented in November at the 2010 annual meeting of the Society for Neuroscience in San Diego. Instead, the exercising animals turned to alcohol with significantly more enthusiasm than the sedentary rats, mainly during the first week of the experiment. "It was a bit of surprise,” Dr. Leasure said.

But the findings are right in line with those from a recent, large-scale national survey of human subjects published in The American Journal of Health Promotion. Bluntly titled, "Do Alcohol Consumers Exercise More?” it answers its own query with a resounding if counterintuitive yes. In fact, the data show, the more people drink, the more they exercise.

The study, based on replies from an annual telephone survey of hundreds of thousands of American adults about their health habits, found that "drinking is associated with a 10.1 percentage point increase in the probability of exercising vigorously,” the authors write. More specifically, "heavy drinkers exercise about 10 more minutes per week than current moderate drinkers and about 20 more minutes per week than current abstainers.” Meanwhile, the authors continue, "an extra episode of binge drinking increases the number of minutes of total and vigorous physical activity per week for both women and men.”

Why would drinking increase exercise time? The authors don’t have a definitive answer. The survey results do not "follow expected patterns,” they admit, in which people who indulge in one unhealthy habit tend to indulge in others and vice versa.

Smokers, for instance, statistically are less likely than average to exercise regularly and eat well. But this is not the case when it comes to drinking and exercise. 

Maybe, the authors speculate, some of the drinkers are drawn to a "sensation-taking lifestyle” that includes adventurous, extreme styles of exercise. Alternatively, imbibers could be "socializing and drinking after participating in organized group sports.” Or they might be trying "to compensate for the extra calories gained through drinking or to counterbalance the negative health effects of drinking.”

Dr. Leasure suspects that alterations in the brain circuitry of drinkers and exercisers may also play a role. 

Drinking and exercising both preferentially alter activity in "the mesocorticolimbic neural circuitry,” she said, a portion of the brain associated with reward. Brain activity patterns there suggest that, for rats and presumably for people, exercise and drinking are rewarding activities; we enjoy doing them (although, in the case of exercise, it may be that we "enjoy having done it,” Dr. Leasure said, since the exercise itself sometimes feels like drudgery).

When the exercising rats were deprived of their running wheels and the accompanying rewards, they may have sought a replacement in booze, which lights up the same brain centers.

Finally, it may be that exercising allows you to become a little less stupid as a result of binge drinking. Binge drinking does, as you may have heard, kill brain cells. Repeated animal studies have shown that even one episode of serious binge drinking leads to a slaughter of brain cells, particularly in the dentate gyrus, a portion of the brain associated with memory and emotion.

But a study by Dr. Leasure and her colleagues published last year showed that when rats exercised for two weeks before being allowed to binge drink, they lost fewer cells due to cell death in their dentate gyrus.

They also, however, had less growth of new brain cells than might have been expected; exercise should provoke a wild burst of neurogenesis in the dentate gyrus, and that response seems to have been blunted by the alcohol binging. So the drinking exercisers did not benefit as much from their exercising as if they hadn’t indulged, but they didn’t lose as many brain cells, in aggregate, as they otherwise would have. To some degree, the exercising had offered "neuroprotection.”

Which does not mean that you should heedlessly indulge. All of the binging rats experienced cell death in portions of their brains outside the dentate gyrus, and most of those were not reduced by exercise. It’s also not clear yet how the reward issues involved in drinking and exercise intermingle. Would rats with ongoing access to running wheels in their cages choose to drink more or less outside those cages than sedentary rats when they’re given the chance? "We’d like to find out,” Dr. Leasure said.

For now, it might be encouraging to know that if you did overimbibe during the holidays, the decision-making portions of your brain should still be functioning adequately enough to tell you to get out and, as you know you should, exercise.

NYTimes