In model theory, the burden is a notion of dimension for NTP2 structures, which form a relatively tame class of first order structures. Chernikov and Simon (2016) consider exact sequences of abelian groups A -> B -> C, and modulo the hypothesis that B/nB is finite for all integers n, they prove a quantifier elimination result. Then, they compute the burden in a particular case: if the burden of A and burden of C are equal to 1, so is the burden of A->B->C. However, the condition of finite classes modulo n is restrictive. For instance, it is known that abelian groups with finite classes modulo n are exactly the ones of burden 1 (Jahnke, Simon, Walsberg). Using a new quantifier elimination result of Aschenbrenner, Chernikov, Gehret and Ziegler, one can show in general that the burden of a pure exact sequence of abelian groups is given by the following formula: bdn(A->B->C) = max_n (bdn(A/nA) + bdn(nC)). I will present some examples and a sketch of the proof. I will also present some applications of this result.