Strongly interacting quantum systems are known to display very rich low-energy phenomena, often associated to non-perturbative energy scales. Their collective behaviour when external perturbations drive them away from thermal equilibrium is currently attracting a great theoretical interest in a number of different physical contexts. Motivated by recent experimental developments in probing the dynamics of isolated and open quantum systems, I will discuss the transient evolution in prototype models of correlated electrons under local and global sudden perturbations. I will start considering a small interacting quantum system coupled to a zero temperature fermionic bath. I will show that a non trivial relaxation dynamics can arise whenever the system is driven across a local quantum critical point where the effective coupling to the environment scales to zero at low energy. I will then focus on the evolution of isolated macroscopic systems of interacting fermions excited by global perturbations. I will show that upon increasing the energy injected into the system a rich short-to-intermediate time dynamics emerges, characterized by long-lived metastable states trapping the evolution, dynamical transitions and fluctuations-induced instabilities.