A total of 2,969 new cases of covid-19 have been reported by the Scottish Government on June 23.
Out of the 42,310 new tests that reported results, 7.3% of these were positive.
This compares to 2,167 new cases reported on June 22 with a 9.1% test positivity rate.
Professor Stephen Reicher – a behaviour expert from the University of St. Andrews – suggested that men meeting up to watch Euro 2020 is behind the rise.
He told the BBC's Good Morning Scotland programme: "A few weeks ago it was about 50:50, men and women got infected at the same rate. Yesterday the data showed that young men - men under 45 were about three times more likely to get infected.
"We can't be sure why that is, but the obvious explanation is that people were getting together for the football and not taking precautions."
A gender gap is particularly noticeable in those aged between 20 and 24.
In the latest figures, males made up more than three quarters of people testing positive in that age group.
Public health expert Professor Linda Bauld said it was too early to associate the spike in male cases to one particular activity but said it was "striking" and should be investigated further.
Professor Jason Leitch told BBC Radio Scotland's Drivetime with John Beattie programme he did not not believe football was directly to blame, however he expressed concerns about large gatherings of football fans.
He said: "As soon as you bring people together the virus moves."
Asked about case rates among young men, he said: "It's socialising. It's mainly indoor socialising, not outdoor socialising."
There have been five new reported deaths of people who have tested positive with the virus.
Overall, 18 people were in intensive care – the same as the previous day – and 170 people were in hospital – one less than the previous day – yesterday with recently confirmed covid.
Ms Sturgeon proposed August 9 as the official date to the end of coronavirus restrictions in Scotland.
However, National Clinical Director Prof Jason Leitch said he believed indoor socialising was the main factor, though not necessarily linked to football.
Talking about Wednesday’s increase in figures, Ms Sturgeon said: “Another big increase in covid cases today.
"First, some context: a record number of tests were done yesterday, and % positive is down a bit.
"If we want to get to end of restrictions on 9 August safely, we should take this increase seriously.
"Vaccines are breaking link between cases/illness/deaths - that’s and lets us target 19/7 & 9/8 as dates for lifting all restrictions.
"BUT…period between now & then, with a sizeable (though reducing daily) % of population not yet fully vaccinated demands caution.
"So - even tho we’re all fed up & frustrated if we see others breaking rules - its still important to take this seriously.”
As of this morning, 3,681,620 people have received the first dose of the Covid vaccination and 2,617,450 have received their second dose.