Originally Posted by Shadow
Strength decrease is probably due to exhaustion, since this is all new to her, and maybe DOMs is inhibiting her a little bit. Get her to eat a little more than normal, and remind her that adequate calories and rest are important.
Progression for women is generally a lot slower than men. I would focus less on a set linear style of progression and focus on completing more reps than the previous week or session. The main thing to note about her progression is going to be just like a man's; is the form failing, progression in weight should not continue. If the form is falling apart in the later sets and/or higher reps, then she is not ready to add more weight. If she can just manage the sets and reps, then you need to focus on adding just a little bit more volume, whether that be sets or reps or both before increasing the weight.
Form is more important than anything. It doesn't matter how much weight you can lift if you cannot lift it correctly. In my experiences with my wife, it normally takes her about 2-3 weeks to add 5-10lbs. But it is highly dependant on the lift. From my experiences, OHP and bench are certainly not strong exercises for most women.
^^This. Keep in mind that in general, a women's strength is in her lower body. We're typically much weaker in the upper body, which is why guys can usually out-bench even the strongest woman. Try moving her more toward incline presses; she will be building the upper pecs more (and that's what chicks want, so our breasts will appear larger and we'll improve our cleavage) and I know for myself, I hate traditional bench presses because it's hard on my elbows which could cause some loss of strength/motivation.
I find with myself that I might lift heavy for a couple weeks, then the following week I'm struggling just to make my reps with the same weight and I'm always like
. DOMS and general muscle fatigue can cause this, as well as I'm sure our normal hormonal fluctuations during the course of a month. Also make sure her diet is in check. You can't put that much new strain on a body and not fuel it correctly as the body will obviously not cooperate for very long.
Theoretically speaking, though, you shouldn't expect to train a woman any differently than a man.