Especially in competition, the Shinai is to be checked for damage. You should also do this before every training session and occasionally during the training to ensure that you don't injure others.
Length 39 Shinais are suitable for men; 38 for women. Especially for women, kendo-sport offers the Shinai kenyu AA. It is light, but, with 444 g to 460 g., is allowed for competition, and is solidly processed from AA quality bamboo.