I recently published an article in Canoe & Kayak UK about fitness and training, and the response to that has prompted me to share some of the advice from it here, too.
If you paddle a kayak, especially in the UK where it's a bit chilly a lot of the time, you are probably guilty of getting in the boat without doing any kind of physical preparation. Maybe you think you can ease into it by paddling gently at first. But the forces of nature might have other plans. So...
Warm up and Stretch
I never did bother with this when I was younger. And I was injured a lot. I also found that after thirty minutes in the boat I was starting to get tired, because I was fighting cold muscles and unyielding tendons. By the time I was properly warmed up, it was game over.
I was worn out from battling against my own body. I thought I was really, really unfit, but I wasn't.
I was just doing it wrong...
It takes ten minutes of gentle exercise like fast walking, jogging, star-jumps or whatever you like, if you're a teenager. If you are middle aged I would suggest thirty minutes of even more gentle exercise than that. It's a massive drag and I never feel like doing it, especially as it cuts into my actual boating time, but it does help a lot.
Stretchy power bands like those pictured here are a really good warm up strategy that you can use in the car park (attach them to the roof rack, or a tree) and won't make you feel too much of a loon!
Having warmed up, do a range of basic stretches on dry land. Google them, I'm not a trainer!
Finally do some rotation and forward and backward stretches in the boat. This has the added advantage of making sure your range of movement in the kayak is unencumbered and that there's nothing in the cockpit that is likely to injure you. That reverse cross-deck rotation is a good way of checking you've screwed the drain plug in, too...
If you do this, I'm willing to bet you'll enjoy your paddling more, and be far less injury prone to boot!