With me you are dealing with a coach in recovery. I’ve been down the road of training athletes and crafting strength programs for basketball squads. I’ve grown into yoga in such a way that others might term me a “purist”. So bear that in mind.
My gut instinct on this is two-fold. The first is that you might find more pertinent feedback on a fitness forum as that would align a more closely with the class you’re attending. I will only be able to respond within a Yoga context and by your description there isn’t much Yoga in that yoga.
Second is that the focus here is very physical, even more so than a Yoga class that is very physical. It may be helpful to begin a dialogue with the teacher since that is the person you have chosen to teach you, either consciously or subconsciously.
When the practice is Yoga and the conversation is asana (the postures that make up a small percentage of that practice) then there is a requisite alignment, requisite actions, and requisite sequence in order for the process of self-discovery to be facilitated (or available).
Generally, muscle tremors are agitating to the nervous system and not at all a desired effect of an asana practice (read: yoga). Asana is not designed to kick someone’s butt, It is not designed as a “work out” but rather a work IN. It is not designed as exercise. And yet…we look around and that is how the sword is being wielded.
If you are looking for strength I suggest a functional strength coach who has a background in science and a certification from one of the more prominent or primary certifying bodies in that field.
It is also possible that you are working muscles to the point of fatigue (as designed by the class curriculum) and that you will move through this stage as your muscles build in response to the work.