I am not unfamiliar with having injuries, nothing too serious though; the worst I have had my entire life is a broken finger and a badly sprained ankle. I do have a few reoccurring issues with my body that can hamper my training. My right knee sometimes acts up after I have been kicking a lot. My neck gave me a few problems last year after stetching it a bit carelessly. This weekend I managed to strain my lower back pulling covers off a cricket pitch. Sunday I could hardly walk and I was a bit worried how I would pull up the following morning. Luckily for me, it felt a lot better, and for good measure I rubbed some Nurofen gel in before the morning training. I was a bit stiff and it was holding me back a bit, mainly when kicking. This made me think of what I could do that didn’t hurt and then give my all to those techniques. It turned out punching and turning my hips felt ok, and this made me really concentrate on my posture as even slightly bending my back was uncomfortable.
Come the evening training and my back had loosened up more throughout the day. Putting aside the speed training for this session, we concentrated on our stepping and transitions between stepping. No punching was involved, everything was focused on below the belt. Stance is such a fundamental part of karate, because your balance, movement and power all originates from the stance.
When training with injuries, it is important to not make things worse, you should give the injuries time to heal. I felt my injury was minor enough to continue training, and you really need to know your own body to make that call.