Ive always wondered if there was a cable or pulley based machine that could allow you to:
do tricep pushdown and bicep curl in the same movement (up then down) with positive resistance on both movements without having to stop and adjust the machine. This would hold true with many different excercises. Another example, you could do a lateral raise turn your wrist and do a hercules curl. Or even a bench press movement that would then turn into a rowing back excercise.
I would invent this if i had the money but is there anything out there!!!??????