Abstract
The authors have developed the smart suit and the smart suit lite as an assist suit for fatigue reduction. The smart suit has elastic materials and actuators. The elastic materials are sources of assisting force and the actuator can control the assist force by adjusting the length of the elastic materials. On the other hand, the smart suit lite has only elastic materials like supporters. In this study, we apply the smart suit and the smart suit lite to racehorse trainers because their work accompanied by a large burden. In the results, we confirmed large effect of fatigue reduction through field experiments.