People tend to consume more alcohol on the days they workout at the gym, a new study finds.

The study was conducted by researchers from Northwestern University. They noted that on days that people exercise more, which are usually Thursdays and Saturdays, people tend to consume more alcohol.

"Monday through Wednesday people batten down the hatches and they cut back on alcohol consumption," said David E. Conroy, lead author of the study, in a press statement. "But once that 'social weekend' kicks off on Thursdays, physical activity increases and so does alcohol consumption."

The study was conducted on 150 participants, aged between 18 and 89 years. Researchers recorded their physical activity and alcohol use in smartphones at the end of the day. They did so for 21 days at a time, at three different times throughout one year.

"Insufficient physical activity and alcohol use are both linked to many health problems, and excessive alcohol use has many indirect costs as well," Conroy said. "We need to figure out how to use physical activity effectively and safely without having the adverse effects of drinking more alcohol."

To overcome the self reporting measurement problems the people were asked to remember only one day of activity or consumption a t a time.

 A previous 30-day study conducted by the same team reported that physically active people tend to drink more alcohol -- something this study did not find.

"We zoomed in the microscope and got a very up-close and personal look at these behaviors on a day-to-day basis and see it's not people who exercise more drink more -- it's that on days when people are more active they tend to drink more than on days they are less active," Conroy said. "This finding was uniform across study participants of all levels of physical activity and ages."

"Perhaps people reward themselves for working out by having more to drink or maybe being physically active leads them to encountering more social situations where alcohol is consumed -- we don't know," Conroy said. "Once we understand the connection between the two variables we can design novel interventions that promote physical activity while curbing alcohol use."

The National Institute on Aging and the National Institute on Drug Abuse funded this study.  Findings were published online in Health Psychology, an American Psychological Association journal.