Tense / Relaxed Muscles

When I was 20 and did a lot of bodybuilding type exercises I had a very toned, muscular physique with tight muscles very similar to a bodybuilder but at 160 pounds a lot smaller.

My instructor who was great at juijitsu looked at me and said "You have a narrow range". He then displayed his calf muscles and said: "feel them". I did and they were soft -- extremely relaxed. He then flexed them and told me "feel them". I did and they were hard as steel. In his grappling training you could tell he was constantly going back and forth between being extremely relaxed and then extremely tense. He had an awesome guard position.

My question for those here is what type of exercises do you do to develop this time of physique, and secondly where is it useful and when is it not?

I myself find that when I do cycling, chinups, dips I am almost sure I tend to develop this kind of muscular control. When i do traditional bodybuiding protocols my muscles are always tense.

Also do you think being relaxed/tense has its disadvanatges? I mean how do you drive a charging opponent back to a wall if your muscles don't produce constant tension?

Interesting.. where exactly does this constant muscle tension come from/what causes it?

The relaxed/tense cycle is best for fighting since most fighting is not an all-out-all-the-time activity but is split up in bursts of activity and short rest periods. If you were really tense all the time you'd gas much quicker than the adapting, relaxing fighter. Not to forget most technique and timing go out the window if you're too cramped in the fight.