"slight strain" is correct and usable in written English.
You can use it when you want to describe something that is just a little bit difficult or strenuous. For example: "I've been feeling a slight strain in my leg ever since I bumped it on the table."
Her smoothly muscled arm bulges with the slight strain of holding it aloft.
Blackburn sustained a slight strain of a groin muscle midway through the third period but remained in the game.
Her right knee was wrapped, as she has been struggling with a slight strain during the Olympics.
A slight strain with the strength of −5% to 5% usually does not change much the SO splitting.
Dimitri Mascarenhas, who has a slight strain, Tim Bresnan on his home ground, and Graeme Swann, an off-spinner whose chances are not enhanced by an unsettled forecast, are probably contesting two places.
They could carry the show anywhere, even as they communicated, through a slight strain in Mulder's voice or a small twist in Scully's lip, that they were in on the joke.
Slight strains don't happen too often, so it's not too big of a deal to take a week or two break if one happens.
Indeed, she has evidently disciplined and conditioned herself to the point where she can go through such an ordeal without showing the slightest strain.
She picked up her speed and began to run as she segued into her incredible story of survival in a corporate world of sexual harassment and gender backbiting (without the slightest strain in her breathing, thank you very much).
Boss David Wagner had set his side up with a high defensive line which, with Jamie Vardy absent with a slight groin strain, initially proved effective in keeping the less mobile pairing of Slimani and Shinji Okazaki at bay.
Fifty years ago when high voltage lines were first put up the wires were under stress during the mounting process and would often acquire a slight permanent strain.
