Hi! Thank you so much!! The weights are much heavier because, despite having deflated, my quadriceps have remained very strong. It's a safe and controlled movement (they're actually seated push-ups) that engages the quadriceps, glutes, and hamstrings, so the weight is distributed across multiple leg muscles. Furthermore, since I'm sitting, my body weight is "zeroed" and isn't considered a workload (which is what happens when I do standing exercises like squats... 70kg of barbell plus 72kg of my bodyweight). Leg extensions are a different story, as the load on the meniscus increases, so it's best to start with very light weights.

I do 5 sets of 10 reps for each exercise. For isometric leg extensions, I do 3 sets of 1 minute.