What is the ideal time under tension for an exercise set to achieve maximum strength development?

Answer 1

There are a number of different philosophies on that question. Some would say 6 repetitions per set and hold the maximum contraction for 2 seconds. There is also the "Maximum Static Contraction" philosophy which would say to use much more weight and only do the last part of the contraction and hold it for 30 to 40 seconds.

For example, on a 45 degree leg press machine, you would just lift the weight off the rest mechanism and hold it without locking out your knees and hold it there for 45 seconds, without ever dropping your knees back to your chest. In my case I can manage about 450 pounds at 6 repetitions bringing my knees back to my chest, and then pushing the weight up again. But using the Maximum contraction technique, I can load up about 850 pounds and hold it just shy of locking my knees for about 45 seconds one time. It leaves my thighs really shaking, and I can barely walk afterwards. But I do think that my strength developed more doing that. It just takes so much longer to load up the machine with all that weight and then only do 1 set and then unload it all again. People look at you strange when you do that.

But, if you want to read more on this idea, here is an overview:
http://www.maxcontraction.com/what.htm