With this iM, I feel pretty comfortable. I cool down with a set of 8-10lbs (I dabbled with 12lbs, but my biceps made it evident that I'm still not ready for that yet), so doing 5lbs. is pretty easy. I know, I know that the last reps in that later sets might qualify as 'grinding reps,' but I feel like I'm still locking out and keeping my core tight so I'm not sure where that leaves me.