Abstract: Fatigue-adaptation-refatigue-adaptation, as an adaptive process that athletes must go through to improve their competitive ability, reminds coaches of the need to focus on controlling the negative effects of psychological fatigue on athletes, and previous research suggests that perceived social support may play a protective role in the negative effects of mental fatigue on motivation. Thus, the present study aimed to clarify the specific ways in which perceived social support acts on psychological fatigue to affect motivation through a mediating and moderating effect model. It was found that psychological fatigue negatively predicted weightlifters' motivation; perceived social support partially mediated the negative effect of psychological fatigue on weightlifters' motivation; and perceived social support did not have a moderating effect between psychological fatigue and weightlifters' motivation. Accordingly, the study confirmed the protective effect of perceived social support in the process of psychological fatigue influencing motivation, emphasized the value of perceived social support in the process of "fatigue-adaptation-refatigue-adaptation", and reminded coaches that they could use it in this process. The study also reminded that coaches can enhance the level of perceived social support in this process and exert its protective effect to maintain weightlifters' motivation.

Key words: mental fatigue, athletic motivation, perceived social support, weightlifter