The hosts made a poor start in Nottingham and ended up all out for 215 following a combination of poor batting and an inspired five-wicket display from Peter Siddle.
However, James Anderson and Steven Finn hit back for England to leave the tourists on 75-4 at the end of the opening day, and Strauss believes that the amount of wickets taken proves that both teams were feeling the pressure.
"The obvious explanation is nerves," Strauss told Sky Sports News.
"[There's been] huge build-up, huge attention and the players had a lot of adrenaline going through their body.
"There were some loose shots, I don't think anybody can deny that, but they were from both sides."
Strauss captain England to Ashes glory in their previous two Test series.