Russian twists and quad fatigue

Athletes and coaches,

I started all progressions at PE 1 wk1. I am currently on wk 6 of Russian Twists (4x18 reps). This is the first week of difficulty for me especially with this exercise. I felt extreme fatigue in my quads and hip flexors; so much so that I could not continue with proper form after 3 sets. Is it normal to feel those muscle groups firing with this exercise? I have never felt those muscles firing in previous weeks.

I had this problem for a little bit. I think it comes from overcompensating when trying to balance. Try holding your weight differently or using a kettle bell or a plate. Also relax your body, create just enough tension to keep position.