I attended Aikido lessons for 15 days last month and afterwards I started to feel pain in my knee. In Aikido,

the most common injuries do not occur in the elbow or wrist, they usually happen in the knee.

I know some aikido instructors

who have troubling walking later in life after years of teaching.

I wear supports on my knees to protect them and a

void problems later.

By the way, I wear Gi, Aikido clothes more than Kimono.

That's weird.

I feel pain in my knee after I attend Aikido lessons 15 days last month.

In Aikido, the point trainees injure most is 

Not wrist or elbow.

It's knee. 

I know some aikido teachers who couldn't walk after doing Aikido long years.

I wear supporters on my knee before I feel pain.

By the way, 

I wear Gi,Aikido clothes more than Kimono.

That's wiered.