The purpose of this paper is to describe human motions and emotions that appear on real video images with compact and informative representations. We aimed to recognize expressive motions and analyze the relationship between human body features and emotions. We propose a new descriptor vector for expressive human motions inspired from the Laban movement analysis method (LMA), a descriptive language with an underlying semantics that allows to qualify human motion in its different aspects. The proposed descriptor is fed into a machine learning framework including, random decision forest, multi-layer perceptron and two multiclass support vector machines methods. We evaluated our descriptor first for motion recognition and second for emotion recognition from the analysis of expressive body movements. Preliminary experiments with three public datasets, MSRC-12, MSR Action 3D and UTkinect, showed that our model performs better than many existing motion recognition methods. We also built a dataset composed of 10 control motions (move, turn left, turn right, stop, sit down, wave, dance, introduce yourself, increase velocity, decrease velocity). We tested our descriptor vector and achieved high recognition performance. In the second experimental part, we evaluated our descriptor with a dataset composed of expressive gestures performed with four basic emotions selected from Russell’s Circumplex model of affect (happy, angry, sad and calm). The same machine learning methods were used for human emotions recognition based on expressive motions. A 3D virtual avatar was introduced to reproduce human body motions, and three aspects were analyzed (1) how expressed emotions are classified by humans, (2) how motion descriptor is evaluated by humans, (3) what is the relationship between human emotions and motion features.