Do your muscles start shaking when doing certain exercises? Do they only start as you do more challenging exercises? Such as the plank, or leg pull prep
This could mean that your muscles are working near to their limit of capability and are getting tired it might be the time to reduce the effort you are making, and take a rest or change to another exercise working a different muscle group.
The shaking is not necessarily a problem. As you become stronger, the shaking should subside
In Pilates the number of repetitions is low, so the shaking may stop as you move on to the next exercise.
If you find that your muscles are continually shaking it may be because you are dehydrated or haven’t had enough time to recover from your last workout. Always ensure that you have enough to drink and give your muscles time to recover between workouts.