Favouring a structural segmentation based essentially on the harmonic and thematic parameters, the traditional analysis of classic and romantic instrumental music fails to fully grasp the internal dynamism of the work. This is particularly evident in the case of many postromantic works in which tempi, dynamics and textures become primordial parameters. The analysis of "tensional cycles" takes all the parameters of the musical discourse in account (dynamics, rhythm, textures, themes, harmony) and groups them within a model of arsis/accent/thesis. The work then appears as a succession of movements of tension and relaxation, unified by a vast gesture of tension and relaxation at the macrostrucural scale. In order to illustrate this phenomenon, we chose the symphonic poem In a Summer Garden by Frederick Delius (1911).