It's been a long time since I've had a muscle pain after aikido sessions, but today I do. On Thursday we had a special session when our trainer made one of the best students lead the training and joined us in exercises to "get us know better" :)
In our training we have an emphasis on how the uke (the attacker, who is then being thrown around by the one doing the technique) must help nage (the one doing the throwing) to do the technique properly by only reacting to a proper technique. That means to not fall if you're not out of balance or in pain.
So, then the trainer paired up with me for one of the techniques. We bowed and started the practise. I was the uke, so I attacked. The trainer caught my wrist and twisted my arm. I just stood there as there was no pain - he didn't twist it enough. The trainer looked at me, looked at my arm, said "Hmm" and we started over. Again attack, grab, twist (as hard as he could) and again a "Hmm" - this time a much louder one.
It appears that during the year and a half that I've been showing up to the aikido sessions (very irregularly) my joints have gained really impressive flexibility and some of the techniques just don't work on me anymore (I have been commented on my flexibility before - in a mountain climbing class). So the trainer spent next 20 minutes trying out all the extreme variations of the technique we were doing trying to find a way to bend my arm further. He got to try every one of the dangerous moves he always wanted to and many times I managed to escape grips that he thought were solid as rock. At few point the rest of pupils stopped doing their exercises and just watched me and the trainer rolling on the floor in a deadlock (usually with few of my limbs bent far beyond the angles they were designed for, but still resisting).
It was a really great fun both for me and for our trainer. Except for the muscle ache that for a strange reason only kicked in yesterday evening and really shines today. Ouch. :)