We examined the length of inactivity due to injury as it relates to level of psychological shock and posttraumatic growth. A total of 117 college students on a lacrosse team completed a questionnaire. A weak positive correlation was shown between the length of inactivity significantly positively and the level of psychological shock score on a scale of 1 to 10. The results of a single regression analysis indicated length of inactivity period positively predicted the four factors of the sports injury-specific Post-Traumatic Growth Scale (the PTGS-AI). In addition, the classification of free descriptions based on KJ method revealed the following effects of the period of inactivity on posttraumatic growth: injury prevention, objective point of view, changes in daily life, and gratitude. These results suggest the longer the suspension due to injury, the greater the psychological impact, but that the mental struggle leads to psychological growth. Besides, psychological growth during periods of inactivity was not only related to playing sports but also on one’s life.