Kayakers may find that their backs, neck and shoulders get tight with a limited range of movement. Pain can likely be found in the trapezius and it is common for your forearms to feel uncomfortable the more you paddle.
To prevent these problems you should strengthen the lower back, trapezius, deltoids and rotator cuffs. A good dynamic stretching regime before hand can make a significant difference to your paddle, you should focus on your back, neck, shoulders and hamstrings.
A Sports Massage can be helpful this is because a trained massage therapist can palpate to feel adhesions, trigger points and scar tissue in the muscle fibres these can then be released.