What is the State of the art method for full body gesture recognition in images
If you are planing to train a model which is using images taken by a single camera, I encourage you to take a look at this paper. They use a camera to track a person and recognize gestures involving arm motion. In this paper, two alternative methods for gesture recognition are compared: a template based approach and a neural network approach. 

However, another way which I suggest is using depth cameras such as Intel Realsense or Microsoft Kinect cameras. This paper uses depth cameras for full body gesture recognition. I think using these cameras take your project a step ahead and more accurate in initial states.