so when a top pro hits a "hands clasped" most muscular there triceps are unflexed and resting? I wonder why the tricep muscles jump out on that pose? 
You are confusing the term 'fully contracted' with 'flexed'. Think about a tricep pushdown. Where is the peak contraction point? That is correct, when the arm is fully extended.
I am not disputing the fact that you can flex a tricep with a bent arm.
Hope that clears up my point
