New York, Sep 23 (IANS): Now, you may know why you drink more on days when you hit the gym or attend aerobic classes at the neighbourhood park - as a reward for sweating out!

Using smartphone technology, a fascinating study has found that that on days when people exercise more - typically Thursdays to Sundays - they also drink more alcohol too.

"Monday through Wednesday, people batten down the hatches and they cut back on alcohol consumption. But once that 'social weekend' kicks off on Thursdays, physical activity increases and so does alcohol consumption," said lead study author David E. Conroy from the Northwestern University's Feinberg School of Medicine.

To reach this conclusion, researchers analysed 150 participants, ages 18 to 89, who 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.

"In this study, people only have to remember one day of activity or consumption at time, so they are less vulnerable to memory problems or other biases that come in to play when asked to report the past 30 days of behaviour," Conroy noted.

The previous studies, which relied on 30-day self-reporting, concluded that physically active people tend to drink more alcohol.

"We looked very closely and found that it is not people who exercise more drink more -- it is that on days when people are more active they tend to drink more than on days they are less active," Conroy pointed out.

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," Conroy stated.

Once we understand the connection between the two variables, we can design novel interventions that promote physical activity while curbing alcohol use, he concluded.

The study was published online in Health Psychology, a journal of the American Psychological Association.