There are various levels of "efficiency".
The whole issue "competition: to be or not to be" is exactly over this.
When you have competition people tend to make a confusion; they tend to believe that testing a technique with a partner equals fighting with an opponent.
It is like saying that picking up vegetables at the local supermarket is just the same as recognizing them among other plants in a desert island at which you are lost.
It may seem similar, but the consequences of each action are far more dangerous.
In real combat size, strength and technique are of lesser relevance; it is the proper mindset and willingness to go as far as turns out to be necessary that make the difference (and luck too!).
For this reason some school thought unwise to allow their students to keep a practice that might lead them to see combat as being the same as dueling over victory.
But since modern martial artists are basically a bunch of guys who like to train in skills that they never actually use (even those in police and military, as contexts change), new ways of evaluating were emphasized, one of them being competition.
As mentioned by Mr Ignatius, the background of those students maybe made Aikido incomprehensible to them.
Actually, even if you had "showed them" i don't believe that they would get the idea...
About some claims within this topic over fitness...well, i apologize for the next lines, that are kind of "preaching", but i must say that i worry about it...alot.
Basically i lost my father because he allowed himself to lose his health over bad habits, like over caloric diet and lack of exercise.
I see people over and over again explaining me how the have hormonal problems or genetic disposition to gain weigh...sorry, but the human body doesn't convert O into fat; it needs extra income of food.
And from a martial perspective i tend to believe that it is easier to train with a lighter body.
Extra pounds necessarily mean eating more than necessary and pushing the heart a little too hard..why not be kinder to our own bodies? And exercise some frugality in the process?
This is not something unique to Aikido...it is very common to athletes, after ending their competitive careers to gain weigh and lose some stamina...it is like if they had lost their motivation to keep a balance between eating and exercising.
I am not talking about six-pack abs.
I am talking about keeping a sharp eye for cholesterol, diabetes, flexibility, cardio-respiratory adaptive responses...in one word: HEALTH.
I don't think someone who trains Aikido should end his days with a cardio condition, diabetes and/or stiff as a barrel...at least i'll try my best not to