While the exact relationship between exercise and drinking is ambiguous in the published literature,18
there are reasons why physical inactivity and alcohol consumption might be positively correlated. Numerous studies in the literature have explored the clustering of health risk behaviors such as smoking, physical inactivity, unhealthy dietary practices, and heavy alcohol consumption, and conclude that behavioral risk factors tend to concentrate within individuals. Health consciousness might encourage a person who is physically active to avoid heavy drinking as well.
Conversely, for some individuals, heavy drinking is part of a sensation-seeking lifestyle. Heavy drinkers were found to score high on sensation-seeking measures such as the Minnesota Multiphasic Personality Inventory,32
or Zuckerman’s Sensation seeking Scale.33
Also, certain physical activities such as skiing, mountaineering, kayaking, or deep sea diving are considered high-risk activities. It is quite possible to observe the co-occurrence of heavy drinking and a high level of physical exercise in risk-loving individuals that are predisposed to choose such sensation-seeking behaviors as part of a risk-taking lifestyle. A positive correlation between physical activity and alcohol consumption could also be the result of people socializing and drinking after participating in organized group sports. Moreover, individuals who drink heavily may engage in frequent physical exercise to compensate for the extra calories gained through drinking or to counter-balance the negative health effects of drinking. This would explain a surprising finding of several epidemiological studies.34–36
These studies recognize that calories from alcohol are added to the energy intake from other foods rather than substituted, but they find no evidence of a positive correlation between alcohol intake and body weight. It is plausible that the additional energy intake through alcohol is offset by the extra energy consumed through physical activity.
While it is not possible to directly test any of the mechanisms noted above, our results provide evidence that, in a nationally representative sample of U.S. adults, alcohol consumption and physical activity are positively correlated for both women and men. Moreover, this association persists at moderate as well as heavy drinking levels. Finding that exercise and alcohol consumption are positively related contradicts the view that risk behaviors are clustered within individuals. On average, current heavy drinkers exercise about 10 more minutes per week than current moderate drinkers and about 20 more minutes per week than current abstainers. Given the extremely large analysis samples from the BRFSS, even relatively small coefficient estimates can sometimes be statistically different from zero. Indeed, some of the statistically significant estimates for the drinking variables in this study correspond to small absolute differences in minutes of exercise, raising questions about practical significance. As presented in the Results section, however, what appear to be relatively small absolute differences actually correspond to fairly large percentage increases when compared to baseline mean values for weekly minutes of exercise.
In conclusion, these results point to a complex set of relationships between health behaviors that do not always follow expected patterns. Similar to an unhealthy diet and cigarette smoking, heavy drinking and physical inactivity are two behavioral practices that are strongly discouraged by health professionals because they significantly contribute to preventable chronic disease morbidity and mortality.1–3
For the reasons discussed earlier, individuals may be making behavioral decisions based on aggregate risk rather than incremental risk. If this is the case, then perhaps health professionals and policy makers should consider aggregate risks as well as individual risks when they advise patients and formulate health promotion, disease prevention, alcohol abuse programs.
One potential limitation of the present study is the unknown reliability of self-reported data in the BRFSS, especially for measures such as alcohol consumption or physical activity. It is sometimes hypothesized that individuals tend to over-report exercise and under-report drinking.43
Such measurement error, if present and systematic, could bias our estimates. Nevertheless, the standard measures of physical activity and alcohol consumption used in the BRFSS are thought to have high reliability.25,44
A second limitation directly pertains to the exercise and drinking measures reported in the BRFSS dataset. Namely, these health behaviors are reported only for the past 30 days instead of the past year or longer. If the past 30 days is atypical of drinking and/or exercise for some respondents, and the measurement error is systematic, then our results could be biased. While it is not possible to rigorously explore this possibility, we have no reasons to believe that any misreporting or atypical behavior is systematic across the drinking groups.
Another limitation is related to the interpretation of our findings. If alcohol use is strictly exogenous, our estimates represent unbiased and causal effects of alcohol consumption on physical activity. However, it is possible that alcohol use is endogenous in some specifications whereby key unobserved or unavailable explanatory variables in the exercise equations (e.g., motivation, discipline) are significantly correlated with the alcohol use measures. Moreover, alcohol use could be directly influenced by physical activity (i.e. reverse causality). In the absence of panel data (the BRFSS draws a new sample every year), we attempted to address this endogeneity issue by employing instrumental variables techniques.45
The exhaustive list of possible instruments included state-specific alcohol taxes,46
and alcohol policies.48
Unfortunately, we were unable to find a common set of valid and reliable instrumental variables for all specifications. Thus, we cautiously view the reported findings as evidence of associations between alcohol use and exercise rather than causal effects.