We will study the behavior of such a system as activity increases. Here, parameterization of activity is done using the dimensionless Peclet number parameter Pe = v𝜎/D, where v -active velocity, 𝜎 -diameter of the monomer units and D -translational diffusion coefficient. This parameter describes the ratio between activity-induced diffusion and classical temperature dependent one (more strictly -ratio between characteristic times of rotational and translational diffusion). The main result is presented in Figure . For relatively short chains, for example for N=256, at a certain critical value Pe ≈ 15, a transition to an even more swollen state occurs. This transition is caused by an effective stiffening of the chain, an apparent increase in persistence length and has previously been described, see for example , but for a slightly different set of model parameters, and therefore a different critical value of Pe. The same work noted a slight shrinking before swelling, which the authors attributed to the formation of zigzag conformations near the transition. However, if we start increasing the length of the chains in question, the situation changes drastically. As the degree of polymerization increases, an increasingly deeper and wider minimum appears at intermediate Pe; we can talk about the observation of the collapse phenomenon. For the degree of polymerization N = 4096, one can clearly observe the presence of some stable region of the collapsed conformation; in the range 15 < Pe < 25, the radius of gyration is only 25% of the unperturbed swollen coil. Activity-induced collapse of the chain of self-propelled monomer units is followed by polymer re-swelling at high-enough Pe.