Yeh but arn't you best trading, or better still sharing, the load on your legs by getting your arms to take some of the load by having a couple of handles.
Not really. You are using brute muscle to substitute for a firm immovable backrest for your legs to push against - as much as you would be applying force forward towards the pedals, you are also expending energy reducing the back force pushing on the seat - trying to force your torso to act as a solid object held firm by your muscles at considerable effort. I'm not saying it doesn't work at all, but it's very inefficient.
Imagine that your arms are ropes that extend from a sling around your back to a sturdy fixed point - like those handles. That is what you are achieving by "pulling" with your arms. Only the rope doesn't have to expend its own energy.
Maybe you feel like you have to reduce the back force on the seat. If you feel like you need to pull forward when pedaling hard, could it be because you don't feel like you are firmly enough planted in the seat? Is the back too floppy? Are you sliding or moving? The standard AI seat can be strapped in quite firmly, but it isn't very tall - many recumbent bicycle seats support the entire back (rolling barcoloungers!).
I'd suggest experimenting with adjusting the AI seat for a firmer support. If that doesn't do it, replacing it with a sturdier higher back model might be called for.