Quantitative infrared techniques were developed and used to assess small temperature variations of samples undergoing cyclic loadings during mechanical spectrometry tests. A standard setup of dynamic mechanical thermal analysis (DMTA) was therefore modified for this purpose. Thermal and mechanical data were used to quantify the viscous dissipated and the thermoelastic coupling energies that can be both associated with the hysteretic stress-strain response of polymers. Energy balances were then performed to quantify the relative importance of dissipative and thermoelastic coupling heat sources. The consequences of the obtained results on the identification of the material rheological properties within a linear viscoelastic framework were finally discussed.