Okay...I have to admit, right off the bat, Coach is not really a soft-core sex flick. Sure, the poster kind of suggests that, and the film was retitled Swinging Coach(!) when it was re-issued in the U.S. (wait, this film was re-issued...?), but there are very few sex scenes, and even less nudity. What kind of sex flick is this?
Now having seen the film, I agree with this reviewer who suggested Coach is what a soft-core flick would seem like if produced by the Lifetime Channel. The main plot is about how a high school basketball team ("The Stallions", heh) loses its coach after a really humiliating series of losses. Desperate, the school principal (played by Keenan Wynn) hires the coach whose resume--that of an Olympic medal winner--lands on his desk. He's less than happy when that coach turns out to be...gasp! A woman!
There's some sub-plots in the movie, like one about another player who is such a bad student he has to be hypnotized into remembering his math, with the help of a trigger word ("Jabberwocky"). They then go even further, using the same technique to make him think he's a superstar basketball player, which actually works!
There's another plot about a rich kid on the team that defends Coach Rawlings to his snooty parents (who happen to be the principal and his wife), and he angrily rebuffs their sexism, in what turns out to be a fairly dramatic, well-played scene.
When the team falls behind, Coach Rawlings herself uses the "Jabberwocky!" bit, leading to a come-from-behind win! I'd say this calls for some hot teacher-on-student loving to celebrate, no?
Overall, this film will appeal to you if you like films steeped in the decade they were made in, in this case the 1970s. To be fair, Coach does have more on its mind than most films of this type, but to keep promising some hot-and-heavy content only to cut away from it is frustrating, to say the least!